Effectiveness of low-level laser therapy for patients with carpal tunnel syndrome: design of a randomized single-blinded controlled trial

Raman spectroscopy of dorsal root ganglia from streptozotocin-induced diabetic neuropathic rats submitted to photobiomodulation therapy

In this study, we used Raman spectroscopy as a new tool to investigate pathological conditions at the level of chemical bond alterations in biological tissues. Currently, there have been no reports on the spectroscopic alterations caused by diabetic neuropathy in the dorsal root ganglia (DRG). DRG are a target for the treatment of neuropathic pain, and the need for more effective therapies is increasing. Photobiomodulation therapy (PBMT) through infrared low-level laser irradiation (904 nm) has shown analgesic effects on the treatment of neuropathy. Thus, the aim of this study was to use Raman spectroscopy to characterize the spectral DRG identities of streptozotocin (STZ)-induced diabetic neuropathic (hyperalgesic) rats and to study the influence of PBMT over such spectra. Characteristic DRG peaks were identified at 2704, 2850, 2885, 2940, 3061 and 3160 cm^-1 , whose assignments are CH₂ /CH₃ symmetric/asymmetric stretches, and C─H vibrations of lipids and proteins. DRG from hyperalgesic rats showed an increased normalized intensity of 2704, 2850, 2885 and 3160 cm^-1 . These same peaks had their normalized intensity reduced after PBMT treatment, accompanied by an anti-hyperalgesic effect. Raman spectroscopy was able to diagnose spectral alterations in DRG of hyperalgesic rats and the PBMT reduced the intensity of hyperalgesia and the altered Raman spectra.

Carpal Tunnel Syndrome: Evaluation of the Effects of Low-Level Laser Therapy With Ultrasound Strain Imaging

OBJECTIVES

To evaluate the efficacy of low-level laser therapy on median nerve stiffness by using strain elastography in carpal tunnel syndrome (CTS).

METHODS

This study included 37 wrists of 34 patients with mild or moderate CTS between January 2016 and August 2016. The control group comprised 17 patients (18 wrists) with CTS who were treated with wrist splinting for 3 weeks. The low-level laser therapy group included 17 patients (19 wrists) with CTS who were treated with a combination of splinting and low-level laser therapy, which was applied 5 times per week for 3 weeks. Clinical assessment scales, including the Symptom Severity Scale (SSS) and Functional Status Score (FSS), were obtained from our database. The cross-sectional area by ultrasound and strain ratio by elastography were studied. The differences in the strain ratio, cross-sectional area, SSS, and FSS between pretreatment and posttreatment periods in the groups were compared by the paired-sample t test. The correlations between changes in the strain ratio and the cross-sectional area, SSS, and FSS were analyzed by Pearson correlation coefficients.

RESULTS

The control group included 13 women and 4 men, and the therapy group included 14 women and 3 men. In the therapy group, the mean values of the strain ratio, cross-sectional area, SSS, and FSS decreased significantly after laser therapy (P < .001) in contrast to the control group. No significant correlation was observed between the decreasing degree of the strain ratio and the cross-sectional area, SSS, and FSS after laser therapy.

CONCLUSIONS

The strain ratio and cross-sectional area of the median nerve decrease after low-level laser therapy. These changes may be related to the therapeutic effects of low-level laser therapy, such as nerve regeneration and improvement of the vascular supply.

The Mechanistic Basis for Photobiomodulation Therapy of Neuropathic Pain by Near Infrared Laser Light

Background and Objective Various irradiances have been reported to be beneficial for the treatment of neuropathic pain with near infrared light. However, the mechanistic basis for the beneficial outcomes may vary based on the level of irradiance or fluence rate used. Using in vivo and in vitro experimental models, this study determined the mechanistic basis of photobiomodulation therapy (PBMT) for the treatment of neuropathic pain using a high irradiance.

Study Design/Materials and Methods ln vitro experiments: Cultured, rat DRG were randomly assigned to control or laser treatment (L T) groups with different irradiation times (2, 5, 30, 60 or 120s). The laser parameters were: output power = 960 mW, irradiance = 300mW/cm2, 808 nm wavelength and spot size = 3cm diameter/ area = 7.07cm2, with different fluences according to irradiation times. Mitochondrial metabolic activity was measured with the MTS assay. The DRG neurons were immunostained using a primary antibody to β-Tubulin III. ln vivo experiments: spared nerve injury surgery (SNI), an animal model of persistent peripheral neuropathic pain, was used. The injured rats were randomly divided into three groups (n = 5). 1) Control: SNI without LT, 2) Short term: SNI with LT on day 7 and euthanized on day 7, 3) Long term: SNI with LT on day 7 and euthanized on day 22. An 808 nm wavelength laser was used for all treatment groups. Treatment was performed once on Day 7 post-surgery. The transcutaneous treatment parameters were: output power: 10 W, fluence rate: 270 mW/cm2, treatment time: 120s. The laser probe was moved along the course of the sciatic/sural nerve during the treatment. Within 1 hour of irradiation, behavior tests were performed to assess its immediate effect on sensory allodynia and hyperalgesia caused by SNI.

Results ln vitro experiments: Mitochondrial metabolism was significantly lower compared with controls for all LT groups. Varicosities and undulations formed in neurites of DRG neurons with a cell body diameter 30µm or less. ln neurites of DRG neurons with a cell body diameter of greater than 30µm, varicosities formed only in the 120s group. ln vivo experiments: For heat hyperalgesia, there was a statistically significant reduction in sensitivity to the heat stimulus compared with the measurements done on day 7 prior to LT. A decrease in the sensitivity to the heat stimulus was found in the LT groups compared with the control group on day 15 and 21. For cold allodynia and mechanical hyperalgesia, a significant decrease in sensitivity to cold and pin prick was found within 1 hour after L T. Sensitivity to these stimuli returned to the control levels after 5 days post-L T. No significant difference was found in mechanical allodynia between control and L T groups for all time points examined.

Conclusion These in vitro and in vivo studies indicate that treatment with an irradiance/fluence rate at 270 m W/cm2 or higher at the level of the nerve can rapidly block pain transmission. A combination therapy is proposed to treat neuropathic pain with initial high irradiance/fluence rates for fast pain relief, followed by low irradiance/fluence rates for prolonged pain relief by altering chronic inflammation.

Efficacy of low-level laser therapy associated to orthoses for patients with carpal tunnel syndrome: A randomized single-blinded controlled trial

OBJECTIVE

Compare the efficacy of orthoses and patient education with and without the addition to Low-Level Laser Therapy (LLLT - 660 nm, 30 mW, a continuous regime and bean area of 0.06 cm2). The laser irradiation was delivered with the fluency of 10J/cm2 in patients with mild and moderate Carpal Tunnel Syndrome (CTS).

METHODS

48 patients were randomized and 30 finished the protocol (a sample loss of 37.5%), 90% female and 10% males. Randomization was applied to allocate the patients in each one of the groups, with association or not to LLLT (group orthoses or LLLT and orthoses). All of them were submitted to ergonomic home orientations. The short-term symptoms and function outcome were assessed through: Boston Carpal Tunnel Questionnaire (BCTQ) - Severity of Symptoms (SS) Functional Score (FS). Pain (VAS), Semmes-Weinstein monofilaments, 2PD and pinch strength was used for characterization of the sample. Most of the participants were women, over 4th decade enrolled on heavy hand duties occupations, right-handed, 66.7% affected on dominant hand, without alterations in sensory median nerve thresholds or pinch strength.

RESULTS

Both groups showed a reduction of total BCTQ score and its subdomains after six weeks, with significant difference (p< 0.05), comparing to baseline. No significant difference was found between groups. A Minimal clinical change was observed after the intervention in 92.3% of participants for BCTQ subdomain severity of symptoms at individual comparison for LLLT and orthoses group and 76.5% for the orthoses group, demonstrating clinical relevance. Effect size Cohen's index was moderate for the severity of symptoms.

CONCLUSION

LLLT in association to orthoses and ergonomic orientation seems to be effective in short-term symptoms relieve for patients with mild and moderate CTS.

The effect of polarized polychromatic noncoherent light (bioptron) therapy on patients with carpal tunnel syndrome

INTRODUCTION

To study the effects of Polarized Polychromatic Noncoherent Light (Bioptron) therapy on patients with carpal tunnel syndrome (CTS).

METHODS

This study was designed as a randomized clinical trial. Forty four patients with mild or moderate CTS (confirmed by clinical and electrodiagnostic studies) were assigned randomly into two groups (intervention and control goups). At the beginning of the study, both groups received wrist splinting for 8 weeks. Bioptron light was applied for the intervention group (eight sessions, for 3/weeks). Bioptron was applied perpendicularly to the wrist from a 10 centimeter sdistance. Pain severity and electrodiagnostic measurements were compared from before to 8 weeks after initiating each treatment.

RESULTS

Eight weeks after starting the treatments, the mean of pain severity based on Visual Analogue Scale (VAS) scores decreased significantly in both groups. Median Sensory Nerve Action Potential (SNAP) latency decreased significantly in both groups. However, other electrophysiological findings (median Compound Motor Action Potential (CMAP) latency and amplitude, also SNAP amplitude) did not change after the therapy in both groups. There was no meaningful difference between two groups regarding the changes in the pain severity.

CONCLUSION

Bioptron with the above mentioned parameters led to therapeutic effects equal to splinting alone in patients with carpal tunnel syndrome. However, applying Bioptron with different therapeutic protocols and light parameters other than used in this study, perhaps longer duration of therapy and long term assessment may reveal different results favoring Bioptron therapy.