Pain

Lasers Med Sci. 2017 Jul 28. doi: 10.1007/s10103-017-2284-9. [Epub ahead of print]

Photobiomodulation therapy by NIR laser in persistent pain: an analytical study in the rat.

Micheli L1, Di Cesare Mannelli L2, Lucarini E1, Cialdai F3, Vignali L3, Ghelardini C1, Monici M3.

Author information

1
Department of Neuroscience, Psychology, Drug Research and Child Health-NEUROFARBA-Pharmacology and Toxicology Section, University of Florence, VialePieraccini 6, 50139, Florence, Italy.
2
Department of Neuroscience, Psychology, Drug Research and Child Health-NEUROFARBA-Pharmacology and Toxicology Section, University of Florence, VialePieraccini 6, 50139, Florence, Italy. lorenzo.mannelli@unifi.it.
3
ASA Campus Joint Laboratory, ASA Res. Division-Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Florence, Italy.

Abstract

Over the past three decades, physicians have used laser sources for the management of different pain conditions obtaining controversial results that call for further investigations. In order to evaluate the pain relieving possibilities of photobiomodulation therapy (PBMT), we tested two near infrared (NIR) laser systems, with different power, against various kinds of persistent hyperalgesia animal models. In rats, articular pain was reproduced by the intra-articular injection of sodium monoiodoacetate (MIA) and complete Freund’s adjuvant (CFA), while compressive neuropathy was modelled by the chronic constriction injury of the sciatic nerve (CCI). In MIA and CFA models, (NIR) laser (MLS-Mphi, ASA S.r.l., Vicenza, Italy) application was started 14 days after injury and was performed once a day for a total of 13 applications. In MIA-treated animals, the anti-hyperalgesic effect of laser began 5 min after treatment and vanished after 60 min. The subsequent applications evoked similar effects. In CFA-treated rats, laser efficacy started 5 min after treatment and disappeared after 180 min. In rats that underwent CCI, two treatment protocols with similar fluence but different power output were tested using a new experimental device called Multiwave Locked System laser (MLS-HPP). Treatments began 7 days after injury and were performed during 3 weeks for a total of 10 applications. Both protocols reduced mechanical hyperalgesia and hindlimb weight bearing alterations until 60 min after treatment with a higher efficacy recorded for the animals treated using the higher power output. In conclusion, this study supports laser therapy as a potential treatment for immediate relief of chronic articular or neuropathic pain.

J Neuroinflammation. 2016 Aug 26;13(1):200. doi: 10.1186/s12974-016-0679-3.

Red LED photobiomodulation reduces pain hypersensitivity and improves sensorimotor function following mild T10 hemicontusion spinal cord injury.

Hu D1, Zhu S1, Potas JR2,3.

Author information

  • 1The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Rd, Canberra, ACT 2601, Australia.
  • 2The John Curtin School of Medical Research, The Australian National University, Building 131, Garran Rd, Canberra, ACT 2601, Australia. jason.potas@anu.edu.au.
  • 3ANU Medical School, The Australian National University, Canberra, ACT 2601, Australia. jason.potas@anu.edu.au.

Abstract

BACKGROUND:

The development of hypersensitivity following spinal cord injury can result in incurable persistent neuropathic pain. Our objective was to examine the effect of red light therapy on the development of hypersensitivity and sensorimotor function, as well as on microglia/macrophage subpopulations following spinal cord injury.

METHODS:

Wistar rats were treated (or sham treated) daily for 30 min with an LED red (670 nm) light source (35 mW/cm(2)), transcutaneously applied to the dorsal surface, following a mild T10 hemicontusion injury (or sham injury). The development of hypersensitivity was assessed and sensorimotor function established using locomotor recovery and electrophysiology of dorsal column pathways. Immunohistochemistry and TUNEL were performed to examine cellular changes in the spinal cord.

RESULTS:

We demonstrate that red light penetrates through the entire rat spinal cord and significantly reduces signs of hypersensitivity following a mild T10 hemicontusion spinal cord injury. This is accompanied with improved dorsal column pathway functional integrity and locomotor recovery. The functional improvements were preceded by a significant reduction of dying (TUNEL(+)) cells and activated microglia/macrophages (ED1(+)) in the spinal cord. The remaining activated microglia/macrophages were predominantly of the anti-inflammatory/wound-healing subpopulation (Arginase1(+)ED1(+)) which were expressed early, and up to sevenfold greater than that found in sham-treated animals.

CONCLUSIONS:

These findings demonstrate that a simple yet inexpensive treatment regime of red light reduces the development of hypersensitivity along with sensorimotor improvements following spinal cord injury and may therefore offer new hope for a currently treatment-resistant pain condition.

Laser Ther. 2016 Jun 29;25(2):121-129.

A randomized clinical trial comparing the efficacy of bite wafer and low level laser therapy in reducing pain following initial arch wire placement.

Bayani S1, Rostami S1, Ahrari F2, Saeedipouya I2.

Author information

  • 1Department of Orthodontics, School of Dentistry, Kerman University of Medical Sciences, Kerman, Iran.
  • 2Dental Research Center, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.

Abstract

Background and aims: This study aimed to evaluate the efficacy of ibuprofen, bite wafer and low power red and infrared lasers in orthodontic pain management.

Subjects and methods: One hundred subjects were randomly assigned to 5 groups of 20 each. The patients in each group received one of the following treatments after the placement of fixed orthodontic appliances: 1. placebo medication, 2. ibuprofen, 3. bite wafer, 4. irradiation from a low level red laser (LLRL; 660 nm, 200 mW, 1 J/point, 6 points), 5. irradiation from a low level infrared laser (LLIL; 810 nm, 200 mW, 1 J/point, 6 points). A Visual Analogue Scale (VAS) was used to record pain intensity while chewing, biting, fitting front teeth, and fitting back teeth at 2 hours, 6 hours, bedtime, 24 hours, 2 days, 3 days and 7 days following arch wire placement.

Results: Significant between-group differences were found in pain at chewing, biting, fitting front teeth and fitting back teeth at all time points (p<0.001). Generally, VAS scores in the LLIL, ibuprofen and bite wafer groups were close to each other and significantly lower than those in the LLRL and control groups (p<0.05), which showed comparable pain level at most intervals. The infrared laser group (LLIL) showed significantly lower pain than all other groups at some points over the experiment (p<0.05).

Conclusions: A single irradiation from a low level infrared laser proved to be the best strategy for orthodontic pain control. Alternatively, chewing on a bite wafer could be recommended. These methods should be considered as suitable alternatives for ibuprofen in orthodontic patients.

J Back Musculoskelet Rehabil. 2015;28(1):153-8.

Efficacy of low level laser therapy and intramuscular electrical stimulation on myofascial pain syndrome.

Sumen A, Sarsan A, Alkan H, Yildiz N, Ardic F.

Abstract

BACKGROUND:

Myofascial pain syndrome (MPS) which is an important cause of musculoskeletal pain has shown a dramatic increase in recent years.

OBJECTIVES:

We aimed to evaluate the efficacy of intramuscular electrical stimulation therapy (IMS) and low-level-lasertherapy (LLLT) in patients with MPS.

METHODS:

Patients were randomly divided into three groups. First group were treated with LLLT and stretching exercise. Second group were treated with IMS and stretching exercise. Third group were treated with only stretching exercise. The patients were evaluated through the pain intensity, pain threshold, cervical joint movement range and the neck disability index parameters.

RESULTS:

An improvement was found in all parameters for all groups, except for the pain threshold within the control group at the end of the treatment and one month after the treatment. It was found that pain score was significantly lower in Group 1 and 2 at one month after the treatment compared to Group 3. Similarly, it was found that pain threshold score was significantly higher in Group 2 at one month after the treatment compared to Group 3.

CONCLUSIONS:

In this study we observed that both LLLT and IMS treatments added on to stretching are effective in improving pain parameters in patients with MPS.

Photomed Laser Surg. 2016 Jul 15. [Epub ahead of print]

Photobiomodulation: Implications for Anesthesia and Pain Relief.

Chow RT1, Armati PJ2.

Author information

  • 11 Honorary Research Associate, Brain & Mind Centre, The University of Sydney , Camperdown, New South Wales.
  • 22 Neuroinflammation Group, Brain & Mind Centre, The University of Sydney , Camperdown, New South Wales, Australia .

Abstract

OBJECTIVE:

This review examines the evidence of neural inhibition as a mechanism underlying pain relief and anesthetic effect of photobiomodulation (PBM).

BACKGROUND:

PBM for pain relief has also been used for more than 30 years; however, the mechanism of its effectiveness has not been well understood.

METHODS:

We review electrophysiological studies in humans and animal models and cell culture studies to examine neural responses to PBM.

RESULTS:

Evidence shows that PBM can inhibit nerve function in vivo, in situ, ex vivo, and in culture. Animal studies using noxious stimuli indicate nociceptor-specific inhibition with other studies providing direct evidence of local conduction block, leading to inhibited translation of pain centrally. Evidence of PBM-disrupted neuronal physiology affecting axonal flow, cytoskeleton organization, and decreased ATP is also presented. PBM changes are reversible with no side effects or nerve damage.

CONCLUSIONS:

This review provides strong evidence in neuroscience identifying inhibition of neural function as a mechanism for the clinical application of PBM in pain and anesthesia.

Neurophotonics. 2016 Jan;3(1):015003. doi: 10.1117/1.NPh.3.1.015003. Epub 2016 Jan 25.

Transcranial low-level laser therapy (810 nm) temporarily inhibits peripheral nociception: photoneuromodulation of glutamate receptors, prostatic acid phophatase, and adenosine triphosphate.

Pires de Sousa MV1, Ferraresi C2, Kawakubo M3, Kaippert B4, Yoshimura EM5, Hamblin MR6.
Author information
1Massachusetts General Hospital, Wellman Center for Photomedicine, BAR414, 40 Blossom Street, Boston, Massachusetts 02114, United States; University of São Paulo, Institute of Physics, Laboratory of Radiation Dosimetry and Medical Physics, Rua do Matão, Travessa R, 187, Cidade Universitária, São Paulo, Brazil; Bright Photomedicine Ltd., CIETEC Building, 2242 Lineu Prestes, São Paulo 05508-000, Brazil.
2Massachusetts General Hospital, Wellman Center for Photomedicine, BAR414, 40 Blossom Street, Boston, Massachusetts 02114, United States; Federal University of São Carlos, Department of Physical Therapy, Laboratory of Electro-Thermo-Phototherapy, Street Washington Luis, km 235. Monjolinho, São Carlos, São Paulo 13565-905, Brazil; Federal University of São Carlos, Post-Graduation Program in Biotechnology, Street Washington Luis, km 235. Monjolinho, São Carlos, São Paulo 13560-000, Brazil; University of São Paulo, Optics Group, Physics Institute of São Carlos, Street Miguel Petroni, 146-Jardim Bandeirantes, São Carlos, São Paulo 13560-970, Brazil.
3Massachusetts General Hospital , Wellman Center for Photomedicine, BAR414, 40 Blossom Street, Boston, Massachusetts 02114, United States.
4Massachusetts General Hospital, Wellman Center for Photomedicine, BAR414, 40 Blossom Street, Boston, Massachusetts 02114, United States; Federal University of Rio de Janeiro, Carlos Chagas Filho, 373-Cidade Universitária, Rio de Janeiro, RJ 21941-170, Brazil.
5University of São Paulo , Institute of Physics, Laboratory of Radiation Dosimetry and Medical Physics, Rua do Matão, Travessa R, 187, Cidade Universitária, São Paulo, Brazil.
6Massachusetts General Hospital, Wellman Center for Photomedicine, BAR414, 40 Blossom Street, Boston, Massachusetts 02114, United States; Harvard Medical School, Department of Dermatology, 50 Staniford Street #807, Boston, Massachusetts 02114, United States; Harvard-MIT, Division of Health Sciences and Technology, 77 Massachusetts Avenue, E25-518, Cambridge, Massachusetts 02139, United States.
Abstract
Photobiomodulation or low-level light therapy has been shown to attenuate both acute and chronic pain, but the mechanism of action is not well understood. In most cases, the light is applied to the painful area, but in the present study we applied light to the head. We found that transcranial laser therapy (TLT) applied to mouse head with specific parameters (810 nm laser, [Formula: see text], 7.2 or [Formula: see text]) decreased the reaction to pain in the foot evoked either by pressure (von Frey filaments), cold, or inflammation (formalin injection) or in the tail (evoked by heat). The pain threshold increasing is maximum around 2 h after TLT, remains up to 6 h, and is finished 24 h after TLT. The mechanisms were investigated by quantification of adenosine triphosphate (ATP), immunofluorescence, and hematoxylin and eosin (H&E) staining of brain tissues. TLT increased ATP and prostatic acid phosphatase (an endogenous analgesic) and reduced the amount of glutamate receptor (mediating a neurotransmitter responsible for conducting nociceptive information). There was no change in the concentration of tubulin, a constituent of the cytoskeleton, and the H&E staining revealed no tissue damage. This is the first study to show inhibition of peripheral pain due to photobiomodulation of the central nervous system.
Angle Orthod.  2012 Dec 14. [Epub ahead of print]

Effect of frequent laser irradiation on orthodontic pain.

Kim WT, Bayome M, Park JB, Park JH, Baek SH, Kook YA.

Source

a Former graduate student, Graduate School of Clinical Dental Science, The Catholic University of Korea, Seoul, Korea.

Abstract

Abstract Objective: To analyze the effect of low-level laser therapy (LLLT) on perception of pain after separator placement and compare it with perceptions of control and placebo groups using a frequent irradiation protocol.

Materials and Methods: Eighty-eight patients were randomly allocated to a laser group, a light-emitting diode (LED) placebo group, or a control group. Elastomeric separators were placed on the first molars. In the laser and LED groups, first molars were irradiated for 30 seconds every 12 hours for 1 week using a portable device. Pain was marked on a visual analog scale at predetermined intervals. Repeated measure analysis of variance was performed for statistical analysis.

Results: The pain scores of the laser group were significantly lower than those of the control group up to 1 day. The pain scores in the LED group were not significantly different from those of the laser group during the first 6 hours. After that point, the pain scores of the LED group were not significantly different from those of the control.

Conclusions: Frequent LLLT decreased the perception of pain to a nonsignificant level throughout the week after separator placement, compared with pain perception in the placebo and control groups. Therefore, LLLT might be an effective method of reducing orthodontic pain.

Lasers Med Sci. 2012 Jul 21. [Epub ahead of print]

Analgesic effect of a low-level laser therapy (830 nm) in early orthodontic treatment.

Artés-Ribas M, Arnabat-Dominguez J, Puigdollers A.

Source

Dental School, International University of Catalunya, Campus Sant Cugat, Josep Trueta s/n, 08195-St. Cugat del Vallès, Barcelona, Spain.

Abstract

The aim of this study was to evaluate the pain sensation that orthodontic patients experience when elastic separators are placed between molars and premolars and to determine the degree of analgesic efficacy of low-level laser therapy (LLLT) compared to a placebo treatment. The study was conducted with 20 volunteers who were fitted with elastic separators between the maxillary molars and premolars. One quadrant was randomly chosen to be irradiated with an 830-nm laser, 100 mW, beam diameter of 7 mm, 250 mW/cm(2) applied for 20 s per point (5 J/cm(2)). Three points were irradiated in the buccal face and three were irradiated in the palate. The same procedure was applied in the contralateral quadrant with a placebo light. A visual analogue scale was used to assess pain 5 min, 6 h, 24 h, 48 h, and 72 h after placement of the separators. Maximum pain occurred 6-24 h after placement of the elastic separators. Pain intensity was significantly lower in the laser-treated quadrant (mean, 7.7 mm) than in the placebo-treated quadrant (mean, 14.14 mm; p?=?0.0001). LLLT at these parameters can reduce pain in patients following placement of orthodontic rubber separators.

Photmed Laser Surg.  2012 Jun 29. [Epub ahead of print]

Meta-Analysis of Pain Relief Effects by Laser Irradiation on Joint Areas.

Jang H, Lee H.

Source

Department of Information and Communications, Gwangju Institute of Science and Technology , Gwangju, Republic of Korea.

Abstract

Abstract Background: Laser therapy has been proposed as a physical therapy for musculoskeletal disorders and has attained popularity because no side effects have been reported after treatment. However, its true effectiveness is still controversial because several clinical trials have reported the ineffectiveness of lasers in treating pain.

Methods: In this systematic review, we investigate the clinical effectiveness of low-level laser therapy (LLLT) on joint pain. Clinical trials on joint pain satisfying the following conditions are included: the laser is irradiated on the joint area, the PEDro scale score is at least 5, and the effectiveness of the trial is measured using a visual analogue scale (VAS). To estimate the overall effectiveness of all included clinical trials, a mean weighted difference in change of pain on VAS was used.

Results: MEDLINE is the main source of the literature search. After the literature search, 22 trials related to joint pain were selected. The average methodological quality score of the 22 trials consisting of 1014 patients was 7.96 on the PEDro scale; 11 trials reported positive effects and 11 trials reported negative effects. The mean weighted difference in change of pain on VAS was 13.96?mm (95% CI, 7.24-20.69) in favor of the active LLLT groups. When we only considered the clinical trials in which the energy dose was within the dose range suggested in the review by Bjordal et al. in 2003 and in World Association for Laser Therapy (WALT) dose recommendation, the mean effect sizes were 19.88 and 21.05?mm in favor of the true LLLT groups, respectively.

Conclusions: The review shows that laser therapy on the joint reduces pain in patients. Moreover, when we restrict the energy doses of the laser therapy into the dose window suggested in the previous study, we can expect more reliable pain relief treatments.

Med Chem. 2012 Jan 1;8(1):14-21.

Mechanism of Pain Relief by Low-Power Infrared Irradiation: ATP is an IR-Target Molecule in Nociceptive Neurons.

Yachnev IL, Plakhova VB, Podzorova SA, Shelykh TN, Rogachevsky IV, Krylov BV.

Source

Pavlov Institute of Physiology of Russian Academy of Sciences, Nab. Makarova 6, 199034, St. Petersburg, Russia. krylov@infran.ru.

Abstract

Effects of infrared (IR) radiation generated by a low-power Co2-laser on the membrane of cultured dissociated nociceptive neurons of newborn rat spinal ganglia were investigated using the whole-cell patch-clamp method. Lowpower IR radiation diminished the voltage sensitivity of activation gating machinery of slow sodium channels (Nav1.8). Ouabain known to block both transducer and pumping functions of Na+,K+-ATPase eliminated IR irradiation effects. The molecular mechanism of interaction of Co2-laser radiation with sensory membrane was proposed. The primary event of this interaction is the process of energy absorption by ATP molecules. The transfer of vibrational energy from Na+,K+- ATPase-bound and vibrationally excited ATP molecules to Na+,K+-ATPase activates this enzyme and converts it into a signal transducer. This effect leads to a decrease in the voltage sensitivity of Nav1.8 channels. The effect of IR-radiation was elucidated by the combined application of a very sensitive patch-clamp method and an optical facility with a controlled Co2-laser. As a result, the mechanism of interaction of non-thermal low-power IR radiation with the nociceptive neuron membrane is suggested.

Med Chem. 2012 Jan 1;8(1):33-9.

Modulation of signal-transducing function of neuronal membrane na+,k by endogenous ouabain and low-power infrared radiation leads to pain relief.

Lopatina EV, Yachnev IL, Penniyaynen VA, Plakhova VB, Podzorova SA, Shelykh TN, Rogachevsky IV, Butkevich IP, Mikhailenko VA, Kipenko AV, Krylov BV.

Source

Pavlov Institute of Physiology of Russian Academy of Sciences, Nab. Makarova 6, 199034, St. Petersburg, Russia. krylov@infran.ru

Abstract

Effects of infrared (IR) radiation generated by a low-power Co2-laser on sensory neurons of chick embryos were investigated by organotypic culture method. Low-power IR radiation firstly results in marked neurite suppressing action, probably induced by activation of Na+,K+-ATPase signal-transducing function. A further increase in energy of radiation leads to stimulation of neurite growth. We suggest that this effect is triggered by activation of Na+,K+-ATPase pumping function. Involvement of Na+,K+-ATPase in the control of the transduction process was proved by results obtained after application of ouabain at very low concentrations. Physiological significance of low-power IR radiation and effects of ouabain at nanomolar level was investigated in behavioral experiments (formalin test). It is shown that inflammatory pain induced by injection of formalin is relieved both due to ouabain action and after IR irradiation.

Clin Rehabil.  2011 Dec 14. [Epub ahead of print]

Efficacy of low level laser therapy associated with exercises in knee osteoarthritis: a randomized double-blind study.

Alfredo PP, Bjordal JM, Dreyer SH, Meneses SR, Zaguetti G, Ovanessian V, Fukuda TY, Junior WS, Martins RA, Casarotto RA, Marques AP.

Source

Department of Speech Therapy, Physical Therapy and Occupational Therapy, School of Medicine, Sao Paulo University, Sao Paulo, Brazil.

Abstract

Objectives: To estimate the effects of low level laser therapy in combination with a programme of exercises on pain, functionality, range of motion, muscular strength and quality of life in patients with osteoarthritis of the knee.

Design: A randomized double-blind placebo-controlled trial with sequential allocation of patients to different treatment groups.

Setting: Special Rehabilitation Services.Subjects: Forty participants with knee osteoarthritis, 2-4 osteoarthritis degree, aged between 50 and 75 years and both genders.Intervention: Participants were randomized into one of two groups: the laser group (low level laser therapy dose of 3 J and exercises) or placebo group (placebo laser and exercises).

Main measures: Pain was assessed using a visual analogue scale (VAS), functionality using the Lequesne questionnaire, range of motion with a universal goniometer, muscular strength using a dynamometer, and activity using the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) questionnaire at three time points: (T1) baseline, (T2) after the end of laser therapy (three weeks) and (T3) the end of the exercises (11 weeks).

Results: When comparing groups, significant differences in the activity were also found (P = 0.03). No other significant differences (P > 0.05) were observed in other variables. In intragroup analysis, participants in the laser group had significant improvement, relative to baseline, on pain (P = 0.001), range of motion (P = 0.01), functionality (P = 0.001) and activity (P < 0.001). No significant improvement was seen in the placebo group.

Conclusion: Our findings suggest that low level laser therapy when associated with exercises is effective in yielding pain relief, function and activity on patients with osteoarthritis of the knees.

Photomed Lasers Surg.  2011 Jun;29(6):365-81. Epub 2011 Apr 1.

Inhibitory effects of laser irradiation on peripheral mammalian nerves and relevance to analgesic effects: a systematic review.

Chow R, Armati P, Laakso EL, Bjordal JM, Baxter GD.

Source

Nerve Research Foundation, Brain and Mind Research Institute, The University of Sydney, Camperdown, New South Wales, Australia. robertachow@iinet.net.au

Abstract

OBJECTIVE:

The objective of this review was to systematically identify experimental studies of non-ablative laser irradiation (LI) on peripheral nerve morphology, physiology, and function. The findings were then evaluated with special reference to the neurophysiology of pain and implications for the analgesic effects of low-level laser therapy (LLLT).

BACKGROUND:

LLLT is used in the treatment of pain, and laser-induced neural inhibition has been proposed as a mechanism. To date, no study has systematically evaluated the effects of LI on peripheral nerve, other than those related to nerve repair, despite the fact that experimental studies of LI on nerves have been conducted over the past 25 years.

METHODS:

We searched computerized databases and reference lists for studies of LI effects on animal and human nerves using a priori inclusion and exclusion criteria.

RESULTS:

We identified 44 studies suitable for inclusion. In 13 of 18 human studies, pulsed or continuous wave visible and continuous wave infrared (IR) LI slowed conduction velocity (CV) and/or reduced the amplitude of compound action potentials (CAPs). In 26 animal experiments, IR LI suppressed electrically and noxiously evoked action potentials including pro-inflammatory mediators. Disruption of microtubule arrays and fast axonal flow may underpin neural inhibition.

CONCLUSIONS:

This review has identified a range of laser-induced inhibitory effects in diverse peripheral nerve models, which may reduce acute pain by direct inhibition of peripheral nociceptors. In chronic pain, spinal cord changes induced by LI may result in long-term depression of pain. Incomplete reporting of parameters limited aggregation of data.

Photomed Laser Surg.  2011 Sep 9. [Epub ahead of print]

Treatment of Persistent Idiopathic Facial Pain (PIFP) with a Low-Level Energy Diode Laser.

Yang HW, Huang YF.

Source

1 Oral Medicine Center, Chung Shan Medical University Hospital , Taichung City, Taiwan .

Abstract

Abstract Objective: The purpose of this study was to test the therapeutic efficacy of low- level energy diode laser on persistent idiopathic facial pain (PIFP). Background data: PIFP has presented a diagnosis and management challenge to clinicians. Many patients were misdiagnosed, which resulted in unnecessary dental procedures. Low-level energy diode laser therapy has been applied to different chronic and acute pain disorders, including neck, back, and myofacial pain; degenerative osteoarthritis; and headache, and it may be an effective alternative treatment for PIFP.

Methods: A total of 16 patients, who were diagnosed with PIFP, were treated with an 800-nm wavelength diode laser. A straight handpiece having an end size of 0.8?cm in diameter, or an angled handpiece with an end size of 0.5?cm in diameter was used. When laser was applied, the handpiece directly contacted the involved symptomatic region with an energy density of 105?J/cm(2). Overall pain and discomfort was analyzed with a 10-cm visual analogue scale (VAS) before and after treatment. Results: All patients received diode laser therapy between 1 and10 times. The average pain score was 7.4 before the treatment (ranging from 2.9 to 9.8), and 4.1 after the treatment. An average pain reduction of 43.87% (ranging from 9.3% to 91.8%) was achieved. The pain remained unchanged at a lower level for up to 12 months.

Conclusions: Low-level energy diode laser may be an effective treatment for PIFP.

Arq Neuropsiquiatr.  2011;69(2B):356-9.

Low-level laser therapy, at 830 nm, for pain reduction in experimental model of rats with sciatica.

Bertolini GR, Artifon EL, Silva TS, Cunha DM, Vigo PR.

Source

Injury and Physiotherapeutic Resource Study Laboratory, Western Paraná State University, Cascavel, PR, Brazil.

Abstract

Chronic pain, resulting from nerve compression, is a common clinical presentation. One means of conservative treatment is low-level laser therapy, although controversial. The aim of this study was to evaluate the effects of two doses of low-level laser, at 830 nm, on pain reduction in animals subjected to sciatica. Eighteen rats were used, divided into three groups: GS (n=6), sciatica and simulated treatment; G4J (n=6), sciatica and treatment with 4 J/cm²; and G8J (n=6), sciatica and irradiation with 8 J/cm². The right sciatic nerve was exposed and compressed using catgut thread. Five days of treatment were started on the third postoperative day. Pain was assessed by means of the paw elevation time during gait: before sciatica, before and after the first and second therapies, and the end of the fifth therapy. Low-level laser was effective in reducing the painful condition.

Lasers Med Sci.  2011 May 31. [Epub ahead of print]

The effect of two phototherapy protocols on pain control in orthodontic procedure-a preliminary clinical study.

Esper MA, Nicolau RA, Arisawa EA.

Source

Centro de Laserterapia e Fotobiologia, Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraíba, Av. Shishima Hifumi, 2911 – Bairro Urbanova, 12244-000, São José dos Campos, SP, Brazil, angela_esper@hotmail.com

Abstract

Phototherapy with low-level coherent light (laser) has been reported as an analgesic and anti-inflammatory as well as having a positive effect in tissue repair in orthodontics. However, there are few clinical studies using low-level LED therapy (non-coherent light). The aim of the present study was to analyze the pain symptoms after orthodontic tooth movement associated with and not associated with coherent and non-coherent phototherapy. Fifty-five volunteers (mean age?=?24.1?±?8.1 years) were randomly divided into four groups: G1 (control), G2 (placebo), G3 (protocol 1: laser, InGaAlP, 660 nm, 4 J/cm(2), 0.03 W, 25 s), G4 (protocol 2: LED, GaAlAs, 640 nm with 40 nm full-bandwidth at half-maximum, 4 J/cm(2), 0.10 W, 70 s). Separators were used to induce orthodontic pain and the volunteers pain levels were scored with the visual analog scale (VAS) after the separator placement, after the therapy (placebo, laser, or LED), and after 2, 24, 48, 72, 96, and 120 h. The laser group did not have statistically significant results in the reduction of pain level compared to the LED group. The LED group had a significant reduction in pain levels between 2 and 120 h compared to the control and the laser groups. The LED therapy showed a significant reduction in pain sensitivity (an average of 56%), after the orthodontic tooth movement when compared to the control group.

Photomed Laser Surg.  2011 Apr 1. [Epub ahead of print]

Inhibitory Effects of Laser Irradiation on Peripheral Mammalian Nerves and Relevance to Analgesic Effects: A Systematic Review.

Chow R, Armati P, Laakso EL, Bjordal JM, Baxter GD.

1 Nerve Research Foundation, Brain and Mind Research Institute, The University of Sydney , Camperdown, New South Wales, Australia .

Abstract

Abstract Objective: The objective of this review was to systematically identify experimental studies of non-ablative laser irradiation (LI) on peripheral nerve morphology, physiology, and function. The findings were then evaluated with special reference to the neurophysiology of pain and implications for the analgesic effects of low-level laser therapy (LLLT).

Background: LLLT is used in the treatment of pain, and laser-induced neural inhibition has been proposed as a mechanism. To date, no study has systematically evaluated the effects of LI on peripheral nerve, other than those related to nerve repair, despite the fact that experimental studies of LI on nerves have been conducted over the past 25 years.

Methods: We searched computerized databases and reference lists for studies of LI effects on animal and human nerves using a priori inclusion and exclusion criteria.

Results: We identified 44 studies suitable for inclusion. In 13 of 18 human studies, pulsed or continuous wave visible and continuous wave infrared (IR) LI slowed conduction velocity (CV) and/or reduced the amplitude of compound action potentials (CAPs). In 26 animal experiments, IR LI suppressed electrically and noxiously evoked action potentials including pro-inflammatory mediators. Disruption of microtubule arrays and fast axonal flow may underpin neural inhibition.

Conclusions: This review has identified a range of laser-induced inhibitory effects in diverse peripheral nerve models, which may reduce acute pain by direct inhibition of peripheral nociceptors. In chronic pain, spinal cord changes induced by LI may result in long-term depression of pain. Incomplete reporting of parameters limited aggregation of data.

Eur Arch Paediatr Dent.  2011 Apr;12(2):93-5.

The effect of low level laser therapy on pain during dental tooth-cavity preparation in children.

Tanboga I, Eren F, Altinok B, Peker S, Ertugral F.

Dr I. Tanboga, Marmara Üniversitesi Di? Hekimli?i Fak. Pedodonti AD, Büyükçiftlik sok. No:6 Kat:4, Ni?anta??, ?i?li/?stanbul 34365, Turkey. Email: itanboga@marmara.edu.tr

Abstract

AIM: To evaluate the effect of low level laser therapy on pain during cavity preparation with laser in paediatric dental patients.

STUDY DESIGN AND METHODS: The study was carried out on 10 children aged 6 to 9 years old for a total of 20 primary molar teeth. For laser preparation an Er: YAG laser was used. Half of the preparations were treated by low level laser therapy (LLLT) before laser preparation and the remaining half without LLLT (non-LLLT) before laser preparation. All cavities were prepared by ER:YAG laser, restored with light-cured composite resin following the application of acid etching and bonding agent. Children were instructed to rate their pain on the visual analogue scale (VAS) from 0 to 5 points. Statistical analyses were performed using Mann Whitney U test.

RESULTS: VAS Median (min-max) scores were 1(0-2) for LLLT and 3(1-4) for the non-LLT treated children. Between LLLT and non- LLLT groups results were statistically significant (p<0.01).

CONCLUSIONS: The use of LLLT before cavity preparation with laser decreased pain in paediatric dental patients.

Clin J Pain. 2010 Oct;26(8):729-36.

A meta-analysis of the efficacy of laser phototherapy on pain relief.

Fulop AM, Dhimmer S, Deluca JR, Johanson DD, Lenz RV, Patel KB, Douris PC, Enwemeka CS.

College of Health Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA.

Abstract

OBJECTIVE: Laser phototherapy has been widely used to relieve pain for more than 30 years, but its efficacy remains controversial. To ascertain the overall effect of phototherapy on pain, we aggregated the literature and subjected the studies to statistical meta-analysis.

METHODS: Relevant original studies were gathered from every available source and coded. Articles that met preestablished inclusion criteria were subjected to statistical meta-analysis, using Cohen’s d statistic to determine treatment effect sizes.

RESULTS: Fifty-two effect sizes were computed from the 22 articles that met the inclusion criteria. The resulting overall mean effect size was highly significant; d = +0.84 (95% confidence interval = 0.44-1.23). The effect size remained significant even when a high outlying d value was conservatively excluded from the analysis; d = +0.66 (95% confidence interval = 0.46-0.86). The fail-safe number associated with the overall treatment effect, that is, the number of additional studies in which phototherapy has negative or no effect on pain needed to negate the overall large effect size of +0.84, was 348.

DISCUSSION: These findings warrant the conclusion that laser phototherapy effectively relieves pain of various etiologies; making it a valuable addition to contemporary pain management armamentarium.

Photomed Laser Surg.  2010 Jun;28(3):417-22.

Effects of low-level laser therapy on pain and scar formation after inguinal herniation surgery: a randomized controlled single-blind study.

Carvalho RL, Alcântara PS, Kamamoto F, Cressoni MD, Casarotto RA.

Source

Postgraduate Program in Rehabilitation Sciences, University of São Paulo, São Paulo, Brazil.

Abstract

OBJECTIVE:

The aim of this study was to investigate the efficacy of an infrared GaAlAs laser operating with a wavelength of 830 nm in the postsurgical scarring process after inguinal-hernia surgery.

BACKGROUND:

Low-level laser therapy (LLLT) has been shown to be beneficial in the tissue-repair process, as previously demonstrated in tissue culture and animal experiments. However, there is lack of studies on the effects of LLLT on postsurgical scarring of incisions in humans using an infrared 830-nm GaAlAs laser.

METHOD:

Twenty-eight patients who underwent surgery for inguinal hernias were randomly divided into an experimental group (G1) and a control group (G2). G1 received LLLT, with the first application performed 24 h after surgery and then on days 3, 5, and 7. The incisions were irradiated with an 830-nm diode laser operating with a continuous power output of 40 mW, a spot-size aperture of 0.08 cm(2) for 26 s, energy per point of 1.04 J, and an energy density of 13 J/cm(2). Ten points per scar were irradiated. Six months after surgery, both groups were reevaluated using the Vancouver Scar Scale (VSS), the Visual Analog Scale, and measurement of the scar thickness.

RESULTS:

G1 showed significantly better results in the VSS totals (2.14 +/- 1.51) compared with G2 (4.85 +/- 1.87); in the thickness measurements (0.11 cm) compared with G2 (0.19 cm); and in the malleability (0.14) compared with G2 (1.07). The pain score was also around 50% higher in G2.

CONCLUSION:

Infra-red LLLT (830 nm) applied after inguinal-hernia surgery was effective in preventing the formation of keloids. In addition, LLLT resulted in better scar appearance and quality 6 mo postsurgery.

The Lancet, Early Online Publication, 13 November 2009

doi:10.1016/S0140-6736(09)61522-1

Efficacy of low-level laser therapy in the management of neck pain: a systematic review and meta-analysis of randomised placebo or active-treatment controlled trials.

Original Text

Dr Roberta T Chow MBBS a , Prof Mark I Johnson PhD b, Prof Rodrigo AB Lopes-Martins PhD c, Prof Jan M Bjordal PT d e

Summary

 

Background

 

Neck pain is a common and costly condition for which pharmacological management has limited evidence of efficacy and side-effects. Low-level laser therapy (LLLT) is a relatively uncommon, non-invasive treatment for neck pain, in which non-thermal laser irradiation is applied to sites of pain. We did a systematic review and meta-analysis of randomised controlled trials to assess the efficacy of LLLT in neck pain.

Methods

We searched computerised databases comparing efficacy of LLLT using any wavelength with placebo or with active control in acute or chronic neck pain. Effect size for the primary outcome, pain intensity, was defined as a pooled estimate of mean difference in change in mm on 100 mm visual analogue scale.

 

Findings

We identified 16 randomised controlled trials including a total of 820 patients. In acute neck pain, results of two trials showed a relative risk (RR) of 1·69 (95% CI 1·22—2·33) for pain improvement of LLLT versus placebo. Five trials of chronic neck pain reporting categorical data showed an RR for pain improvement of 4·05 (2·74—5·98) of LLLT. Patients in 11 trials reporting changes in visual analogue scale had pain intensity reduced by 19·86 mm (10·04—29·68). Seven trials provided follow-up data for 1—22 weeks after completion of treatment, with short-term pain relief persisting in the medium term with a reduction of 22·07 mm (17·42—26·72). Side-effects from LLLT were mild and not different from those of placebo.

 

Interpretation

We show that LLLT reduces pain immediately after treatment in acute neck pain and up to 22 weeks after completion of treatment in patients with chronic neck pain.

 

Funding

None.

Masui. 2009 Nov;58(11):1401-6.

Phototherapy for chronic pain treatment

 

[Article in Japanese]

Ide Y.

Department of Anesthesia, Toho University Sakura Medical Center Sakura 285-8741.

Abstract

Three types of machines are used in the field of phototherapy for chronic pain. One type is an instrument for low reactive level laser therapy (LLLT), one is an instrument for linear polarized infrared light irradiation (SUPER LIZER), and the last one is an instrument for Xenon light irradiation (beta EXCEL Xe10). The available machines for LLLT all project laser by semiconductor. The newest machine (MEDILASER SOFT PULSE10) has peak power of 10 W and mean power of 1 W. This machine is as safe as 1 W machine and is effective twice as deep as the 1 W machine. The irradiation by low reactive level laser induces hyperpolarization, decreased resistance of neuronal membrane, and increased intra-cellular ATP concentrations. The effects of low reactive level laser might be induced by the activation of ATP-dependent K channel. The significant analgesic effects of 1 W and 10 W LLLT were reported with double blind test. The significant analgesic effects of linear polarized near infrared light irradiation with double blind test were also reported. The effects of low reactive level laser upon the sympathetic nerve system were thought to result from its normalization of the overloaded sympathetic nerve system.

Cranio. 2009 Oct;27(4):243-7.

Evaluation of low intensity laser therapy in myofascial pain syndrome.

 

Carrasco TG, Guerisoli LD, Guerisoli DM, Mazzetto MO.

Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Brazil.

Limited studies have demonstrated that low intensity laser therapy (LILT) may have a therapeutic effect on the treatment of myofascial pain syndrome (MPS). Sixty (60) patients with MPS and having one active trigger point in the anterior masseter and anterior temporal muscles were selected and assigned randomly to six groups (n=10): Groups I to Ill were treated with GaAIAS (780 nm) laser, applied in continuous mode and in a meticulous way, twice a week, for four weeks. Energy was set to 25 J/cm2, 60 J/cm2 and 105 J/cm2, respectively. Groups IV to VI were treated with placebo applications, simulating the same parameters as the treated groups. Pain scores were assessed just before, then immediately after the fourth application, immediately after the eighth application, at 15 days and one month following treatment. A significant pain reduction was observed over time (p<0.001). The analgesic effect of the LILT was similar to the placebo groups. Using the parameters described in this experiment, LILT was effective in reducing pain experienced by patients with myofascial pain syndrome. Thus, it was not possible to establish a treatment protocol. Analyzing the analgesic effect of LILT suggests it as a possible treatment of MPS and may help to establish a clinical protocol for this therapeutic modality.

Photomed Laser Surg.. [Epub ahead of print]

Acute Low Back Pain with Radiculopathy: A Double-Blind, Randomized, Placebo-Controlled Study.

Konstantinovic LM, Kanjuh ZM, Milovanovic AN, Cutovic MR, Djurovic AG, Savic VG, Dragin AS, Milovanovic ND.

1 Clinic for Rehabilitation, Medical School , Belgrade, Serbia.

Abstract Objective: The aim of this study was to investigate the clinical effects of low-level laser therapy (LLLT) in patients with acute low back pain (LBP) with radiculopathy. Background Data: Acute LBP with radiculopathy is associated with pain and disability and the important pathogenic role of inflammation. LLLT has shown significant anti-inflammatory effects in many studies. Materials and Methods: A randomized, double-blind, placebo-controlled trial was performed on 546 patients. Group A (182 patients) was treated with nimesulide 200 mg/day and additionally with active LLLT; group B (182 patients) was treated only with nimesulide; and group C (182 patients) was treated with nimesulide and placebo LLLT. LLLT was applied behind the involved spine segment using a stationary skin-contact method. Patients were treated 5 times weekly, for a total of 15 treatments, with the following parameters: wavelength 904 nm; frequency 5000 Hz; 100-mW average diode power; power density of 20 mW/cm(2) and dose of 3 J/cm(2); treatment time 150 sec at whole doses of 12 J/cm(2). The outcomes were pain intensity measured with a visual analog scale (VAS); lumbar movement, with a modified Schober test; pain disability, with Oswestry disability score; and quality of life, with a 12-item short-form health survey questionnaire (SF-12). Subjects were evaluated before and after treatment. Statistical analyses were done with SPSS 11.5. Results: Statistically significant differences were found in all outcomes measured (p < 0.001), but were larger in group A than in B (p < 0.0005) and C (p < 0.0005). The results in group C were better than in group B (p < 0.0005). Conclusions: The results of this study show better improvement in acute LBP treated with LLLT used as additional therapy.

Masui. 2009 Nov;58(11):1401-6.

Phototherapy for chronic pain treatment

[Article in Japanese]

Ide Y.

Department of Anesthesia, Toho University Sakura Medical Center Sakura 285-8741.

Three types of machines are used in the field of phototherapy for chronic pain. One type is an instrument for low reactive level laser therapy (LLLT), one is an instrument for linear polarized infrared light irradiation (SUPER LIZER), and the last one is an instrument for Xenon light irradiation (beta EXCEL Xe10). The available machines for LLLT all project laser by semiconductor. The newest machine (MEDILASER SOFT PULSE10) has peak power of 10 W and mean power of 1 W. This machine is as safe as 1 W machine and is effective twice as deep as the 1 W machine. The irradiation by low reactive level laser induces hyperpolarization, decreased resistance of neuronal membrane, and increased intra-cellular ATP concentrations. The effects of low reactive level laser might be induced by the activation of ATP-dependent K channel. The significant analgesic effects of 1 W and 10 W LLLT were reported with double blind test. The significant analgesic effects of linear polarized near infrared light irradiation with double blind test were also reported. The effects of low reactive level laser upon the sympathetic nerve system were thought to result from its normalization of the overloaded sympathetic nerve system.

Med Oral Patol Oral Cir Bucal. 2008 Oct 1;13(10):E648-52

Analgesic action of laser therapy (LLLT) in an animal model.

Pozza DH, Fregapani PW, Weber JB, de Oliveira MG, de Oliveira MA, Ribeiro Neto N, de Macedo Sobrinho JB.

Laser Technology, Universidade Federal da Paraíba and Universidade Federal da Bahia, Universidade do Porto, Portugal.

OBJECTIVES: To evaluate the analgesic effect of laser therapy on healthy tissue of mice. STUDY DESIGN: Forty-five animals were divided in three groups of 15: A–infrared laser irradiation (830 nm, Kondortech, São Carlos, SP, Brazil); B–red laser irradiation (660 nm, Kondortech, São Carlos, SP, Brazil); C– ham irradiation with laser unit off. After laser application, the mice remained immobilized for the injection of 30 microl of 2% formalin in the plantar pad of the irradiated hind paw. The time that the mouse kept the hind paw lifted was measured at 5 min intervals for 30 minutes. RESULTS: Results showed statistically significant differences comparing the control group with the infrared laser group at 5, 20, 25 and 30 accumulated minutes, and with the red laser group at all time points. The analysis of partial times, at each 5 minutes, showed statistically significant differences between the control and the laser groups up to 20 minutes. CONCLUSIONS: Laser therapy had an analgesic effect and red laser had the best results.

Anesth Analg. 2008 Sep;107(3):1058-63.

Pre-Irradiation of blood by gallium aluminum arsenide (830 nm) enhances peripheral endogenous opioid analgesia in rats.

 

Hagiwara S, Iwasaka H, Hasegawa A, Noguchi T.

Department of Brain and Nerve Science, Anesthesiology, Oita University Faculty of Medicine, 1-1 Idaigaoka-Hasamamachi-Yufu City-Oita 879-5593, Japan. saku@med.oita-u.ac.jp

BACKGROUND: Low-level laser therapy (LLLT) has been reported to relieve pain, free of side effects. However, the mechanisms underlying LLLT are not well understood. Recent studies have also demonstrated that opioid-containing immune cells migrate to inflamed sites and release beta-endorphins to inhibit pain as a mode of peripheral endogenous opioid analgesia. We investigated whether pre-irradiation of blood by LLLT enhances peripheral endogenous opioid analgesia.

METHODS: The effect of LLLT pretreatment of blood on peripheral endogenous opioid analgesia was evaluated in a rat model of inflammation. Additionally, the effect of LLLT on opioid production was also investigated in vitro in rat blood cells. The expression of the beta-endorphin precursors, proopiomelanocortin and corticotrophin releasing factor, were investigated by reverse transcription polymerase chain reaction.

RESULTS: LLLT pretreatment produced an analgesic effect in inflamed peripheral tissue, which was transiently antagonized by naloxone. Correspondingly, beta-endorphin precursor mRNA expression increased with LLLT, both in vivo and in vitro.

CONCLUSION: These findings suggest that that LLLT pretreatment of blood induces analgesia in rats by enhancing peripheral endogenous opioid production, in addition to previously reported mechanisms.

J Peripher Nerv Syst. 2007 Mar;12(1):28-39.

830 nm laser irradiation induces varicosity formation, reduces mitochondrial membrane potential and blocks fast axonal flow in small and medium diameter rat dorsal root ganglion neurons: implications for the analgesic effects of 830 nm laser.

Chow RT, David MA, Armati PJ

The authors report the formation of 830 nm (cw) laser-induced, reversible axonal varicosities, using immunostaining with beta-tubulin, in small and medium diameter, TRPV-1 positive, cultured rat DRG neurons. Laser also induced a progressive and statistically significant decrease in MMP in mitochondria in and between static axonal varicosities. In cell bodies of the neuron, the decrease in MMP was also statistically significant, but the decrease occurred more slowly. Importantly we also report for the first time that 830 nm (cw) laser blocked fast axonal flow, imaged in real time using confocal laser microscopy and JC-1 as mitotracker. Control neurons in parallel cultures remained unaffected with no varicosity formation and no change in MMP. Mitochondrial movement was continuous and measured along the axons at a rate of 0.8 mum/s (range 0.5-2 mum/s), consistent with fast axonal flow. Photoacceptors in the mitochondrial membrane absorb laser and mediate the transduction of laser energy into electrochemical changes, initiating a secondary cascade of intracellular events. In neurons, this results in a decrease in MMP with a concurrent decrease in available ATP required for nerve function, including maintenance of microtubules and molecular motors, dyneins and kinesins, responsible for fast axonal flow. Laser-induced neural blockade is a consequence of such changes and provide a mechanism for a neural basis of laser-induced pain relief. The repeated application of laser in a clinical setting modulates nociception and reduces pain. The application of laser therapy for chronic pain may provide a non-drug alternative for the management of chronic pain.

Photomed Laser Surg. 2005 Feb;23(1):60-5

Retrospective study of adjunctive diode laser therapy for pain attenuation in 662 patients: detailed analysis by questionnaire.

Nakaji S, Shiroto C, Yodono M, Umeda T, Liu Q.

Department of Hygiene, Hirosaki University School of Medicine, Aomori, Japan.

OBJECTIVE: The aim of this study was to assess the long-term effects of low-level laser therapy (LLLT) through a retrospective survey using questionnaires.

BACKGROUND DATA: The use of LLLT for chronic pain attenuation has been reported in the international literature for over 20 years.

METHODS: We used a series of diode laser systems in which the most effective wavelength was consistently found to be 830 nm with an output power in continuous-wave of 60 mW. Subjects were 1,087 patients treated by LLLT at the Shiroto Clinic from April 1992 to August 1995. Questionnaires were sent to subjects in September and October 1996.

RESULTS: The reply rate was 60.9%, comprising 662 questionnaires (265 males, 397 females, mean age of 53.4 years). The total efficacy rating (excellent plus good) immediately after LLLT was 46.8% in men and 47% in women. At the time of the survey, this rose to 73.3% in men and 76.8% in women, with positive effects also recorded on psychosomatic factors such as well-being, physical energy, general fatigue, mental vigor, and emotional stability. LLLT effects continued for 1-3 days. No statistically significant difference in efficacy was seen between males and females. LLLT as used in the study is therefore considered safe, effective, and side-effect-free, making it an ideal adjunctive therapeutic modality for intractable chronic and other pain.

CONCLUSION: Infrared diode LLLT is therefore considered safe, effective, and side-effect-free, making it an ideal adjunctive therapeutic modality for intractable chronic pain.

Wiad Lek. 2006;59(9-10):630-3.

Comparison of analgetic effect of magnetic and laser stimulation before oral surgery procedures.

[Article in Polish]

Koszowski R, Smieszek-Wilczewska J, Dawiec G.

Z Katedry i Zak?adu Chirurgii Stomatologicznej w Bytomiu Slaskiej Akademii Medycznej w Katowicach. chirstom@slam.katowice.pl

Abstract

Oral surgery procedures are often the cause of painful sensations because of their tissue invasiveness. To avoid these sensations a wide use of nonsteroid antiinflammatory drugs is usually accepted. Because of plenty side effects of these drugs alternative antipain agents are desired. The goal of this study was to assess antipain effect of laser stimulation and alternating magnetic field in oral surgery procedures. Pain sensations in patients during: local anesthetics application, surgical procedure and after it were assessed according to VAS scale. Level of stomatological fear was assessed with the use of Corah’s scale. Achieved results were analyzed statistically. Conclusion of this analysis is that laser stimulation and alternating magnetic field applied directly before oral surgery procedure are effective antipain agents that decrease intra and postoperative sensations. It was observed that patients with high level of stomatological fear had more pain sensations but even in this group laser and magnetic stimulation significantly lowered these complaints.

Photomed Laser Surg. 2004 Aug;22(4):323-9.

The efficacy of low-power lasers in tissue repair and pain control: a meta-analysis study.

Enwemeka CS, Parker JC, Dowdy DS, Harkness EE, Sanford LE, Woodruff LD.

School of Health Professions, Behavioral and Life Sciences, New York Institute of Technology, Old Westbury, NY 11568-8000, USA. Enwemeka@nyit.edu

Abstract

OBJECTIVE: We used statistical meta-analysis to determine the overall treatment effects of laser phototherapy on tissue repair and pain relief.

BACKGROUND DATA: Low-power laser devices were first used as a form of therapy more than 30 years ago. However, their efficacy in reducing pain or promoting tissue repair remains questionable.

METHODS: Following a literature search, studies meeting our inclusion criteria were identified and coded. Then, the effect size of laser treatment, that is, Cohen’s d, was calculated from each study using standard meta-analysis procedures.

RESULTS: Thirty-four peer-reviewed papers on tissue repair met our inclusion criteria and were used to calculate 46 treatment effect sizes. Nine peer-reviewed papers on pain control met the inclusion criteria and were used to calculate nine effect sizes. Meta-analysis revealed a positive effect of laser phototherapy on tissue repair (d = +1.81; n = 46) and pain control (d = +1.11; n = 9). The positive effect of treatment on specific indices of tissue repair was evident in the treatment effect sizes determined as follows: collagen formation (d = +2.78), rate of healing (d = +1.57), tensile strength (d = +2.13), time needed for wound closure (d = +0.76), tensile stress (d = +2.65), number and rate of degranulation of mast cells (d = +1.87), and flap survival (d = +1.95). Further, analysis revealed the positive effects of various wavelengths of laser light on tissue repair, with 632.8 nm having the highest treatment effect (d = +2.44) and 780 nm the least (d = 0.60). The overall treatment effect for pain control was positive as well (d = +1.11). The fail-safe number-that is, the number of studies in which laser phototherapy has negative or no effect-needed to nullify the overall outcome of this analysis was 370 for tissue repair and 41 for pain control.

CONCLUSIONS: These findings mandate the conclusion that laser phototherapy is a highly effective therapeutic armamentarium for tissue repair and pain relief.

Photomed Laser Surg. 2005 Apr;23(2):177-81.

 

Analgesic effect of He-Ne (632.8 nm) low-level laser therapy on acute inflammatory pain.

 

Ferreira DM, Zângaro RA, Villaverde AB, Cury Y, Frigo L, Piccolo G, Longo I, Barbosa DG.

Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraíba, São José dos Campos, São Paulo, SP, Brazil.

OBJECTIVE: The aim of this study was to evaluate the analgesic effect of the low level laser therapy (LLLT) with a He-Ne laser on acute inflammatory pain, verifying the contribution of the peripheral opioid receptors and the action of LLLT on the hyperalgesia produced by the release of hyperalgesic mediators of inflammation.

BACKGROUND DATA: All analgesic drugs have undesired effects. Because of that, other therapies are being investigated for treatment of the inflammatory pain. Among those, LLLT seems to be very promising.

MATERIAL AND METHODS: Male Wistar rats were used. Three complementary experiments were done. (1) The inflammatory reaction was induced by the injection of carrageenin into one of the hind paws. Pain threshold and volume increase of the edema were measured by a pressure gauge and plethysmography, respectively. (2) The involvement of peripheral opioid receptors on the analgesic effect of the laser was evaluated by simultaneous injection of carrageenin and naloxone into one hind paw. (3) Hyperalgesia was induced by injecting PGE2 for the study of the effect of the laser on the sensitization increase of nociceptors. A He-Ne laser (632.8 nm) of 2.5 J/cm2 was used for irradiation.

RESULTS: We found that He-Ne stimulation increased the pain threshold by a factor between 68% and 95% depending on the injected drug. We also observed a 54% reduction on the volume increase of the edema when it was irradiated.

CONCLUSION: He-Ne LLLT inhibits the sensitization increase of nociceptors on the inflammatory process. The analgesic effect seems to involve hyperalgesic mediators instead of peripheral opioid receptors.

Photomed Laser Surg. 2004 Aug;22(4):306-11.

Comparison of laser, dry needling, and placebo laser treatments in myofascial pain syndrome.

Ilbuldu E, Cakmak A, Disci R, Aydin R.

Department of Physical Medicine and Rehabilitation, Istanbul Medical Faculty, Istanbul University, 34390 Sehremini, Istanbul, Turkey.

Abstract

OBJECTIVE: We aimed to evaluate the effectiveness of laser therapy in myofascial pain syndrome treatment.

BACKGROUND DATA: Myofascial pain syndrome is a disease that is characterized by hypersensitive points called trigger points found in one or more muscles and/or connective tissues. It can cause pain, muscle spasm, sensitivity, stiffness, weakness, limitation of range of motion and rarely autonomic dysfunction. Physical therapy modalities and exercise are used in the treatment of this frequently encountered disease.

METHODS: The placebo controlled, prospective, long-term follow up study was planned with 60 patients who had trigger points in their upper trapezius muscles. The patients were divided into three groups randomly. Stretching exercises were taught to each group and they were asked to exercise at home. Treatment duration was 4 weeks. Placebo laser was applied to group 1, dry needling to group 2 and laser to group 3. He-Ne laser was applied to three trigger points in the upper trapezius muscles on both sides with 632.8 nm. The patients were assessed at before, post-treatment, and 6 months after-treatment for pain, cervical range of motion and functional status.

RESULTS: We observed a significant decrease in pain at rest, at activity, and increase in pain threshold in the laser group compared to other groups. Improvement according to Nottingham Health Profile gave the superiority of the laser treatment. However, those differences among the groups were not observed at 6-month follow up.

CONCLUSIONS: Laser therapy could be useful as a treatment modality in myofascial pain syndrome because of its noninvasiveness, ease, and short-term application.

J Clin Laser Med Surg. 1996 Aug;14(4):163-7.

 

Low level laser therapy with trigger points technique: a clinical study on 243 patients.

Simunovic Z.

Laser Center, Locarno, Switzerland.

Among the various methods of application techniques in low level laser therapy (LLLT) (HeNe 632.8 nm visible red or infrared 820-830 nm continuous wave and 904 nm pulsed emission) there are very promising “trigger points” (TPs), i.e., myofascial zones of particular sensibility and of highest projection of focal pain points, due to ischemic conditions. The effect of LLLT and the results obtained after clinical treatment of more than 200 patients (headaches and facial pain, skeletomuscular ailments, myogenic neck pain, shoulder and arm pain, epicondylitis humery, tenosynovitis, low back and radicular pain, Achilles tendinitis) to whom the “trigger points” were applied were better than we had ever expected. According to clinical parameters, it has been observed that the rigidity decreases, the mobility is restored (functional recovery), and the spontaneous or induced pain decreases or even disappears, by movement, too. LLLT improves local microcirculation and it can also improve oxygen supply to hypoxic cells in the TP areas and at the same time it can remove the collected waste products. The normalization of the microcirculation, obtained due to laser applications, interrupts the “circulus vitiosus” of the origin of the pain and its development (Melzak: muscular tension > pain > increased tension > increased pain, etc.). Results measured according to VAS/VRS/PTM: in acute pain, diminished more than 70%; in chronic pain more than 60%. Clinical effectiveness (success or failure) depends on the correctly applied energy dose–over/underdosage produces opposite, negative effects on cellular metabolism. We did not observe any negative effects on the human body and the use of analgesic drugs could be reduced or completely excluded. LLLT suggests that the laser beam can be used as monotherapy or as a supplementary treatment to other therapeutic procedures for pain treatment.

Used by the kind permission of the Czech Society for the Use of Lasers in Medicine, www.laserpartner.org.

Lasers and Pain Treatment

Dr. Kevin Moore

Department of Anaesthesia

The Royal Oldham Hospital, UK

Summary

The clinical application of low incident power density laser radiation for the treatment of acute and chronic pain is now a well established procedure. This paper reviews the currently available English speaking literature and summarises a selection of serious scientific papers which report a beneficial effect following the treatment of a wide variety of acute and chronic syndromes whose main presenting symptom is pain.

Introduction

The Helium-Neon (He-Ne) laser at a wavelength of 632.8 nm has proved very successful in promoting wound healing particularly in indolent ulcers resistant to conventional methods of therapy. However, its limited depth of penetration and low power output have rendered it less effective when treating more deep seated causes of pain. The laser more frequently used for pain therapy is the Gallium Aluminium Arsenide (GaAlAs) diode emitting coherent light in the near infra-red waveband, usually 820 – 830 nm, and with a continuous wave power output of some 60 mW. The optoelectronic rationale for choosing these parameters has been discussed by Moore and Calderhead (1).

During the past 15 years experimental research has greatly added to our knowledge of the response of tissue radiation. Figure 1 summarises some 10 years work by Karu (2) into the cellular response to photon energy. Additional research at the Tissue Repair Research Unit at Guy`s Hospital, London, has detailed the local tissue changes following exposure to laser light. The current concept is one of a dual response to laser bioactivation.

The immediate or primary effect is a local tissue response to direct irradiation and comprises vasodilatation with increased circulatory flow: enhanced lymphatic drainage; increased neutrophil, macrophage and fibroblast activity; and an improved metabolic function in depressed or damaged cells. The delayed or secondary response consists of a systemic effect caused by circulating photoproducts of irradiation in the blood and lymphatic systems. Increased plasma concentrations of certain types of prostaglandins, enkephalins and endorphins have all been identified and most probably play a major role in the mechanism of pain attenuation.

Figure 1: Cellular response to laser irradiation

IRRADIATION

PHOTORECEPTORS ON MITOCHONDRIAL CHAINS

ELECTRON TRANSPORT CHAINS PROTON MOTIVE FORCES

RESPIRATION CHAIN ACTIVITY OXIDATION OF NADH POOL

REDOX CHANGES IN MITOCHONDRIA  AND CYTOPLASM

CELL MEMBRANE ACTIVITY
MEMBRANE TRANSPORT MECHANISMS

CYTOPLASM CHANGES
?H+   ?ph   ?Ca++   ?cAMP

DNA : RNA SYNTHESIS

GROWTH AND PROLIFERATION

Acute pain therapy

Acute trauma is invariably associated with a degree of soft tissue injury comprising swelling, haematoma, pain, reduced mobility and in the lower limbs impaired weight bearing. Sporting injuries and domestic accidents usually involve damage to muscles, joint ligaments and tendons. Examples include a sprained ankle or wristed or a twisted knee. Most extensive soft tissue damage tends to result from industrial crush injuries or road traffic accidents. In the absence of bone fracture or other injury demanding priority treatment laser therapy should be instituted at the earliest opportunity. Kumar (3) reported a comparative study in 50 patients with inversion injuries of the ankle. He found that compared to conventional physiotherapy the laser treated patients showed a more rapid resolution of symptoms and an earlier return to full weight bearing. Patients were treated with a GaAlAs diode laser (830 nm: 60 mW) at 48 hour intervals on a maximum of 3 occasions. A similar therapeutic regime has been described for whiplash injuries of the cervical spine (4). Ben Hatit and Lammens (5) used a defocussed CO2 laser to treat a variety of acute musculoskeletal problems. The energy density varied between 40 – 70 J/cm2. Patients were treated twice a week for up to 10 sessions.

Beneficial effects of laser therapy in acute small joint inflammation in rheumatoid arthritis has been described by Asada et al (6). Multiple point irradiation using a GaAlAs diode (830 nm:60 mW) was applied for 15 seconds to each point. Pain was reduced by up to 66 % together with an improvement in the measured range of movement (ROM).

In a similar report involving 938 patients with osteoarticular pain Soriano (7) found pain attenuation of 88 % when treating a variety of acute conditions such as tendosynovitis, lumbago and cervical pain. He used a GaAs diode (940 nm: pulsed 10,000 Hz: average power 40 mW) to treat patients twice weekly for a maximum of 10 sessions. The energy density delivered was 6 – 10 J/cm2 per irradiated point.

Laser therapy also proved helpful in reducing the severity and duration of postoperative pain. In a comparative study involving 20 patients undergoing elective cholecystectomy Moore et al (8) reported a 50 % reduction in the postoperative pain experienced by the laser treated patients together with a concomitant reduction in analgesie requirements.

Chronic pain syndromes

Chronic pain, as the name implies, may last for months or years. Pain may arise as a result of damage caused by trauma or surgery or be manifested as a symptom of a systemic desease process. In later life pain due to musculoskeletal “wear and tear” is very common. Finally neuralgic pain such as postherpetic or trigeminal neuralgia can cause prolonged problems to sufferers. A high percentage of patients referred for laser therapy will have already shown little or no response to conventional methods of treatment.

In rheumatoid arthritis (RA) laser therapy can benefit not only the pain of acute small joint inflammation but also the more established chronic pain of the disease. Gartner (9) in an excellent review article on rheumatology considered some 18 papers published over a 10 year period. All involved double blind trials of therapy with 5 having a cross-over element. In considering the effect of laser therapy in chronic rheumatoid and associated musculoskeletal conditions all but one of the reports noted a significant improvement in pain. In his own work Gartner used a 904 nm infra-red laser to treat a variety of tendinopathies with a better than 80 % success rate in relieving pain. He compared this to a similar rate of pain attenuation using anti-inflammatory drugs

(NSAIDs) but noted that whilst laser therapy was free of side effects some 20 % of patients treated with NSAIDs suffered unacceptable side effects of medication. Asada and his colleagues (10) in a further study of some 170 patients with rheumatoid arthritis used similar laser parameters and treatment protocols to their earlier reported work. The group achieved pain attenuation of up to 90 % and improvement in ROM of up to 56 %.

In a report of some 1000 treatments using a GaAlAs diode laser (830 nm: 60 mW) for a wide variety of chronic pain syndromes Moore (11) noted an overall reduction in pain levels of some 70 %. Trelles et al (12) used a similar diode laser to treat 40 patients with degenerative joint disease to the knee. They delivered 18 J/cm2 to each of 4 points around the knee twice a week for 8 weeks and reported a significant pain reduction in 82 % with improved joint mobility. Li (13) used a 25 mW combined CO2/HeNe laser to treat 90 patients with cervical spondylosis. Laser therapy was administered to a variety of acupuncture points for 10 minutes daily for 2 periods each of 10 days with an intervening rest period of 10 days. 90 % of patients showed symptoms improvement with an excellent result in 43 %.

Fender and Diffee (14) reported an interesting trial involving patients suffering from chronic generalized musculoskeletal pain. They irradiated the stellete ganglion using a HeNe laser with an initial exposure of 6 minutes (36 J/cm2) gradually increasing over 4 – 6 weeks to a maximum of 15 minutes (90 J/cm2). They postulated a mechanism of reduced sympathetic irritability causing a stabilisation of the response loop and a breaking of the pain cycle. In resistant cases they also treated segmental dermatomes and site specific trigger points.

Patients suffering from postherpetic neuralgia (PHN) have shown a good response to laser therapy. In a double blind cross-over trial Moore et al (15) reported a mean reduction in pain levels of 74 %. Patients were treated with a GaAlAs diode (830 nm: 60 mW) with the laser applied in contact mode to the centre of each 2 cm2 grid over the affected area giving 24 – 30 J/cm2 to each point. Treatment was given twice a week for 4 weeks. Using an identical treatment protocol but an extended regime of some 12 weeks Kemmotsu et al (16) reported at the end of treatment pain attenuation of 89 %. Otsuka and colleagues (17) used an 8.5 mW HeNe scanner to treat the acute rash of herpes zoster. Once the skin rash has subsided treatment was continued using a GaAlAs laser (830 nm: 60 mW). Within 1 month pain had been reduced by 76 % with a final end treatment improvement of 97 %. The early introduction of laser therapy produced a rapid resolution of acute herpes zoster rash and a reduced incidence of PHN.

Discussion

Laser therapy is effective for a wide variety of acute and chronic pain syndromes. During the past 7 years the Laser Therapy Journal has featured some 30 papers on the subject. The preferred laser is the GaAlAs diode emitting light in the near infra-red usually at 830 nm. The majority of reports detail a power output of 60 mW continuous wave. Recently, however, researchers have been assessing the use of higher output powers in the range of 150 – 300 mW.

In a prelim inary trial Yamada and Ogawa (18) compared the results of treating PHN with 60 and 150 mW. They found that the higher output power reduced both the frequency and duration of the treatment sessions and improved pain attenuation by some 25 %. Ohshiro (19) has devised an ingenious protocol for a computer controlled double blind comparative trial which compensates for the placebo effect of treatment and for patient and therapist bias. In a paper comparing the therapeutic outcomes in 2 geographically separate but otherwise identical clinics Shiroto (20) described how a positive therapist attitude motivated by enthusiasm and commitment can improve the results of therapy by 15 – 20 %.

There remains a need for more scientific studies based on well constructed double blind comparative trials. Nevertheless the bulk of published work to date supports the use of laser therapy for the treatment of pain. In a repor of the cost-effective benefits of using laser therapy to treat PHN Moore (21) noted that, compared with conventional methods of treatment, laser proved to be not only more effective but more economical as well. The added advantage of absence of side effects, non-invasive nature of therapy and the case of application ensured good patient acceptance of the treatment modality.

References

  1. MOORE & CALDERHEAD: The clinical application of low incident power density 830 nm GaAlAs diode laser radiation in the therapy of chronic intractable pain: a historical ond optoelectronic rationale and clinical review. Int. Jour. Optoelectronics 6: 503-520, 1991
  2. KARU: Photobiology of low power laser therapy. Chur, Switzerland, Harwood Academic Publishers, 1989
  3. KUMAr et al.: A comparative study of low level laser therapy and conventional physiotherapy for the treatment of inversion injuries of the ankle. Lasers and Medical Science, Abstract issue 298, 1988
  4. OHSHIRO: Low reactive level laser therapy: practical application 103-110, Chichester, UK, John Wiley & Sons, 1991
  5. BEN HATIT & LAMMENS: Laser therapy with defocussed CO2 laser, Laser Therapy 4: 175-178, 1992
  6. ASADA et al.: Diode laser therapy for rheumatoid arthritis: a clinical evaluation of 102 joints treated with low reactive level laser therapy (LLLT), Laser Therapy 1: 147-151, 1989
  7. SORIANO: The analgesic effect of 904 nm GaAs semiconductor low level laser therapy (LLLT) on osteoarticular pain: a report on 938 irradiated patients, Laser Therapy 7: 75-80, 1995
  8. MOORE et al.: The effect of infra-red diode laser irradiation on the duration and severity of postoperative pain: a double blind trial, Laser Therapy 4: 145-149, 1992
  9. GARTNER: Low reactive level laser therapy (LLLT) in rheumatology: A review of the cllinical experience in the author`s laboratory, Laser Therapy 4: 107-115, 1992
  10. ASADA et al.: Clinical application of GaAlAs 830 nm diode laser in treatment of rheumatoid arthritis, Laser Therapy 3: 77-82, 1991
  11. MOORE: LLLT for the treatment of chronic pain, Frontiers of Electro-optics (Conference proceedings) 283-290, 1990
  12. TRELLES et al.: Infra-red diode laser in low reactive level laser therapy (LLLT) for knee osteoarthrosis, Laser Therapy 3: 149-153, 1991
  13. LI: Laser therapy for radicular cervical spondylosis, Laser Therapy 4: 151-153, 1992
  14. FENDER & DIFFE: Physiological response in chronic pain patients to a new LLLT protocol, Laser Therapy 4: 169-173, 1992
  15. MOORE et al.: A double blind cross-over trial of low level laser therapy in the treatment of postherpetic neuralgia, Laser Therapy (pilot issue) 7-9, 1998
  16. KEMMOTSU et al.: Efficacy of low reactive level laser therapy for pain attenuation of postherpetic neuralgia, Laser Therapy 3: 71-75, 1991
  17. OTSUKA et al.: Effects of Helium-Neon laser therapy on herpes zoster pain, Laser Therapy 7: 27-32, 1995
  18. YAMADA & OGAWA: Comparative study of 60 mW diode laser therapy and 150 mW diode laser in the treatment of postherpetic neuralgia, Laser Therapy 7: 71-74, 1995
  19. OHSHIRO et al.: Critical considerations in protocol design for the double blind trial on pain attenuation by laser therapy, Laser Therapy 6: 101-106, 1994
  20. SHIROTO et al.: The importance of therapist education and motivation on diode LLLT efficacy in pain therapy: a comparative study, Laser Therapy 5: 175-179, 1993
  21. MOORE: Cost effective benefits of the use of laser therapy in the treatment of intractable postherpetic neuralgia, Laser Applications in Medicine and Surgery, 61-63 Bologna, Italy, Monduzzi Editore, 1992

***

Joint International Laser Conference in Edinburgh

In September, 2003, the Edinburgh International Conference Centre in Scotland hosted the Joint International Laser Conference, organized jointly by the American Society for Laser Medicine and Surgery, European Laser Association and British Medical Laser Association. More than 500 registered participants had the opportunity of seeing not only the most advanced laser medical technology presented by 39 exhibitors, but also of attending numerous meetings and presentations, getting acquainted with top issues of laser surgery and therapy. A significant portion of scientific papers and  posters dealt with laser therapy (LLLT), and theory was well supplemented with a series of educational courses called “How I do it”. The organizers provided Laser Partner with full text of some of the lectures and now we bring the first one.

Low Level Laser-Therapy in pain treatment of the ambulatory system.

Dr. med. Matteo Rossetto M.D., Basel

Zusammenfassung

 

Summary

In spring 1995 we expanded our treatment methods with Low Level Laser Therapy. We decided to test the effectiveness of this kind of therapy through a study on 41 consecutive patients with ailments of the ambulatory system. For each case respective parameters, such as diagnosis, localisation, number of treatment points and output of the applied laser energy, were listed on a individual protocol where the patient also had to assess his pain (before and after the treatment) to a number on the so called visual-analog pain scala (rating from 1 to 10). Furthermore the doctor had to note objective parameters like mobility, inflamation and swellings before and after the laser therapy. The indications concerned exclusively pain of the ambulatory system, especially epicondylitis and other posttraumatic or stress induced pain of tendons and articulations, but also some degenerative changes of joints (arthrosis of knee and shoulder).

During this study no other therapy method or drugs were applied, in order to allow a reliable judgement of the effectiveness of laser therapy. Conventional methods were only used if the treatment by laser light was not sufficiently effective.

Generally, the results obtained with laser therapy were very good – both subjectively and objectively rated. Only 12 percents of the patients felt no pain release, one patient had to stop the laser therapy after two applications because of an increasing subjective pain. 73 percent of the patients felt a good or very good effect of the therapy. The treated patients liked laser therapy very much, because there are no side effects, the treatment is painless and the ailment decreases rapidly.

Pain. 1993 Jan;52(1):63-6.

 

The effect of low-level laser therapy on musculoskeletal pain: a meta-analysis.

Gam AN, Thorsen H, Lonnberg F.

Department of Rheumatology, Bispebjerg Hospital, Copenhagen, Denmark.

A meta-analysis was undertaken of low-level laser therapy (LLLT) on musculoskeletal pain. A literature search revealed 23 LLLT trials and of these 17 were controlled trials. Ten were double blind and 7 were insufficiently blinded. Within the studies identified pain was assessed by visual analogue scale or by “some other indices of pain”. Nine double-blind trials and 4 controlled trials presented results in a form which allowed pooling of data. In the double-blind trials, the mean difference in pain between LLLT and placebo was 0.3% (S.E.(d) 4.6%, confidence limits -10.3-10.9%). In the insufficiently blinded trials the mean difference in pain was 9.5% (S.E.(d) 4.5%, confidence limits -2.9-21.8%). We conclude that LLLT has no effect on pain in musculoskeletal syndromes.

Scand J Rheumatol. 1992;21(3):139-41.

Low level laser therapy for myofascial pain in the neck and shoulder girdle.  A double-blind, cross-over study.

Thorsen H, Gam AN, Svensson BH, Jess M, Jensen MK, Piculell I, Schack LK, Skjott K.

Department of General Practice, University of Copenhagen, Denmark.

In a controlled, cross-over study the effect of low level laser therapy (LLLT) was evaluated. During a five weeks period forty-seven female laboratory technicians received six laser and six placebo treatments to tender points in the neck and shoulder girdle. Subjects rated the placebo treatment significantly more beneficial than LLLT (p = .04). There was no reduction in consumption of analgesics associated with either laser or placebo treatment. The results indicate no beneficial effect of LLLT for myofascial pain.