Placebo-Controlled Investigation of Low-Level Laser Therapy to Treat Carpal Tunnel Syndrome

Abstract

Objective: This study investigated the short-term efficacy of low-level laser therapy (LLLT) in patients with mild to moderate carpal tunnel syndrome (CTS), lasting for <1 year . Methods: Seventy-nine patients with CTS were included in this double-blind, placebo-controlled study, and randomly divided in two treatment groups: Experimental group (EG), active laser group (40 patients); and control group (CG), placebo (sham) laser group (39 patients). A GaAlAs diode laser [780 nm, 30 mW continuous wave (CW), 0.785 cm², 38.2 mW/cm²] was applied in contact with four points perpendicularly to the skin over the carpal tunnel area for 90 sec per point (2.7 J, 3.4 J/cm²/point). Both groups were treated five times per week, once a day over 2 weeks, followed by 10 treatments every other day for 3 weeks, that is, for a total of 20 treatments. Clinical assessment, including visual analogue scale (VAS) pain rating, Tinel's sign, and median nerve conduction studies (NCSs) were evaluated before, and 3 weeks after, the last LLLT treatment. Results: Significant reduction in pain, reduction in the percentage of patients with a positive Tinel's sign, and shortening of sensory and motor latency time in the NCS examination was observed in the experimental LLLT group (but not in the control group). Conclusions: This study has observed and documented the statistically significant short-term effects of LLLT on CTS patients in comparison with a placebo group. The results support this conclusion, especially if the LLLT is applied in the earlier stages of CTS, and with mild to moderate cases.

Introduction

Carpal tunnel syndrome (CTS) is the most frequently encountered peripheral neuropathy, caused by the compression of the median nerve at the wrist in the carpal canal.^1,2 The general incidence, 0.125–1%, and prevalence, 5–16%, varies, depending upon the criteria used for the diagnosis. The diagnosis of CTS should be based on detailed medical history, accurate examination of symptoms and signs, and the results of nerve conduction studies (NCSs).^3

–8

Several theories have been offered to explain the symptoms and results of impaired NCSs. The most common ones are compression and ischemia of the affected nerve segment (microvascular insufficiency theory).^9

–12 Tenosynovial thickening within the restricted space of the carpal tunnel is also thought to be the one of the causes of CTS.^13
–15

There is no consensus with regard to the choice of initial treatment for CTS, which may be conservative or surgical.^7,16

–20 Conservative treatment of CTS includes nonsteroidal anti-inflammatory drugs; local steroid injections; wrist splints; modification of activities; tendon and nerve gliding exercises; and physical therapy modalities, such as iontophoresis, ultrasound, transcutaneus electrical nerve stimulation (TENS), and low-level laser therapy (LLLT).^{20

–27} Although clinical improvements appear to be more prominent than electrophysiological changes, these improvements decrease as the severity of CTS increases.^28
–30

Exercise and mobilization have been applied to patients with mild to moderate CTS, although the effectiveness and duration of their benefit remain unknown. The review by Page et al. included 16 randomized or quasirandomized controlled trials comprising 741 participants with CTS. The authors concluded that until now, there has been limited evidence of benefit for the diverse collection of exercise and mobilization CTS interventions available.^31
–33

LLLT was used to treat a variety of musculoskeletal conditions including CTS, despite a lack of scientific evidence supporting its efficacy. The mechanisms of action are incompletely understood, though it has been established that LLLT can reduce oxidative stress and inflammation, and that this leads to pain relief.^{34, 35}

One of the main problems in the evaluation of LLLT effects is the extremely wide variations seen in crucial laser beam parameters and methods of application.

Analysis of seven laser therapy studies that were reviewed by Naeser³⁶ showed that three of them were designed without a control group,^37
–39 and two of them were incomplete with regard to the parameters of laser irradiation.^40,41 The study by Naeser et al.⁴² one of the first and most-cited placebo-controlled investigations, consisted of only 11 cases divided into two groups. Consequently, the number of investigated cases was too small to reach any statistically significant conclusion, despite that reduction in pain and in median nerve sensory latencies were observed after the real treatment series, but not after the sham series. The double-blind placebo-controlled investigation by Anderson et al.⁴³ confirmed a statistically significant improvement for the real laser group (versus the sham laser group) in grip and pinch strength, and nerve conduction across the wrist. In 2002, the United States Food and Drug Administration cleared the MicroLight 830 as the first Class IIIb laser to be used in the nonsurgical treatment and management of CTS.

Chang et al.⁴⁴ compared sham with active laser treatment in 36 patients, and reported symptomatic improvement without changes in median NCS. There was no description of how patients with bilateral disease were randomized in the investigated study groups. Also, the laser beam parameters used were missing from this study. Shooshtari et al.,⁴⁵ in a placebo-controlled investigation, evaluated 80 CTS patients. They found statistically significant improvement in pain score, grip strength, and electrophysiological parameters only in the LLLT group. Authors did not report all the required laser beam parameters. In the study by Elwakil et al.,⁴⁶ LLLT was shown to be an effective and noninvasive treatment modality for CTS, especially for early and mild to moderate cases in which pain was the main presenting symptom. This study was conducted to evaluate the effectiveness of LLLT for the treatment of CTS in comparison with standard open carpal tunnel release surgery, prior to and 6 months after treatment. This study was limited by the lack of documentation of relevant laser parameters. The placebo-controlled study by Evcik et al.⁴⁷ showed no statistically significant differences at follow-up between groups for the visual analogue scale (VAS) pain scale, Levine score, hand and pinch grip, or NCSs, but adequate, between-group statistical tests were not provided in the article.

At this time, no definitive conclusions can be made with regard to the efficacy of LLLT and other commonly used nonsurgical therapy methods of CTS treatment, because of the lack of high quality trials, the small number of participants in each trial, the heterogeneity of dosing regimens and methods of application, or missing crucial laser beam data, as well as a lack of long-term follow-up. Effective conservative treatment and activity modification for CTS is reasonable in patients with mild to moderate symptoms, and NCS results with an absence of progressive neurological or functional deficits.

The aim of this study was to investigate, in a double-blind and placebo-controlled manner, the short-term efficacy of low level laser therapy (LLLT) on clinical parameters and median NCSs in patients with CTS of unknown cause.

Materials and Methods

The study involved 79 patients (120 hands) diagnosed with CTS, of which the cause was unknown, defined by characteristic clinical symptoms such as pain, paresthesia, numbness, and tingling, including Tinel's sign, and confirmed by electromyography (EMG) examination and NCSs.

This was a prospective, randomized, placebo-controlled double-blind study. All the patients signed consent forms. The study was conducted at the Outpatient Clinic of the Institute for Rehabiliation in Belgrade, Serbia, after the study protocol had been approved by the local ethics committee.

Patients were randomly divided into two groups: experimental group (EG), active laser group; and and control group (CG), placebo (sham) laser group. In the CG, the laser probe was applied without turning the device on. Randomization was allocated by using the “numbered envelopes” method. The EG was composed of 40 patients (61 hands), 4 males and 36 females, of whom 19 patients had unilateral and 21 had bilateral CTS. Patient ages ranged between 27 and 72 years (mean, 50.5±10.1). The CG was composed of 39 patients (59 hands), 34 females and 5 males, with 19 with unilateral, and 20 with bilateral CTS. The mean age of the patients was 52.6±11.6 (range, 30–67 years).

The same physician evaluated the clinical assessment parameters both before and after treatment. NCS evaluations were performed by another physician. Both physicians, as well as the patients and the staff who applied the procedures, were unaware of the therapy.

Clinical assessment and NCSs were evaluated at baseline and at 3 weeks after the last LLLT treatment. Outcome measures were:

• Pain, assessed by using a 10 cm VAS. For statistical analyses, we have categorized pain as none (VAS 0), mild (VAS>0–4), moderate (VAS>4–7), or severe (VAS>7–10).

• Carpal tunnel provocative maneuver (Hoffman–Tinel's sign)

• Wrist median motor distal latency (MDL)

• Wrist to digit 2 median sensory nerve conduction velocity (SNCV)

Inclusion criteria

Patients needed to be≥18 years of age, with symptoms (pain and/or numbness) in at least two digits on one hand (thumb, index, middle, or ring finger) lasting for <1 year, mild to moderate CTS based on NCSs, and no thenar atrophy.

Patients were eligible for the study if NCSs demonstrated any of the following: a 7 cm wrist median MDL≥4.2 ms, a 14 cm (wrist to digit 2) median sensory distal latency (SDL)>3.2ms, median SNCV<45 m/sec, a 14 cm (wrist to digit 4) median to ulnar SDL difference>0.45 ms.^4,48

Exclusion criteria

Patients with evidence of severe CTS on EMG [defined as a median compound motor action potential compound muscle action potential (CMAP) amplitude of≤3.8 mV, and/or severe reduction of EMG interference pattern or denervation], thenar atrophy, or severe pain intensity>7 based on the VAS, were excluded from the study.

Other exclusion criteria were any previous hand or wrist surgery on the study hand; metabolic diseases such as diabetes mellitus, or thyroid or kidney disease; diffuse peripheral neuropathy, cervical radiculopathy, brachial plexopathy, or proximal median neuropathy (EMG findings); any known mass, tumor, or deformity of the wrist; any history of severe trauma to the wrist (such as fracture); existing pregnancy or lactation; connective tissue disorders or arthritis involving hand or wrist; tenosinovitis, fibromialgia, or any musculoskeletal disorders that could affect the follow up parameters. Also excluded were all patients whose type of employment could be a risk factor for CTS.

EMG analyses

EMG analyses were peformed with Medelec Synergy, Oxford instruments, UK EMG. Sensory and motor NCSs were performed for n.medianus and n.ulnaris. Sensory neural action potentials were recorded antidromically; stimulation at the wrist, registration with ring-electrodes from digit 2 for n.medianus and digit 4 for n.medianus and n.ulnaris, and SNCVs were calculated. Median and ulnar CMAPs were recorded with supramaximal stimulation at the wrist and registration from thenar and hypothenar muscles. All measurements were performed bilaterally. EMG testing was performed using a concentric needle electrode from m.abductor pollicis brevis and m.abductor digiti V.^4,48 Hand temperature was monitored using an adhesive surface thermometer placed over the thenar eminence, and a minimum temperature of 30°C was required before proceeding with measurements.

Treatment protocol

A GaAlAs diode laser [780 nm, 30 mW continuous wave (CW), 0.785 cm², 38.2 mW/cm², Medicolaser 637] was applied in contact with four points perpendicularly on the skin on the volar side of the wrist over the carpal tunnel area for 90 sec/point (2.7 J, 3.4J /cm²/ point).^49,50

A total of 20 treatments were administered in each case, with the following schedule: 10 treatments were administered once a day, 5 days a week (working days only) for 2 weeks, followed by 10 treatments every other day for 3 weeks. Clinical assessment and NCSs were evaluated at baseline and at 3 weeks after the last LLLT treatment.

Patients in both groups were instructed to perform nerve and tendon gliding exercises developed by Totten and Hunter, which they continued to perform at home during the investigation period of 2 months. During tendon gliding exercises, the fingers were placed in five positions. During the median nerve gliding exercise, the median nerve was mobilized by putting the hand and wrist in six different positions. During these exercises, the neck and the shoulder were in a neutral position, and the elbow was in supination and 90 degrees of flexion. Each position was maintained for 5 sec. These exercises were applied as five sessions daily. Each exercise was repeated 10 times at each session.^51,52

Other treatments, such as acupuncture, physical therapy, and wearing splints, were forbidden. The patients included in the study had had neither local nor oral administration of glucocorticoids for at least 1 month before or during the investigation period. The patients had no nonsteroidal anti-inflammatory drugs (NSAIDs) during the investigation period.

Statistical analysis

Statistical analysis was performed using SPSS Statistical Software version 17.0. The Mann–Whitney U test was used to compare between-group differences, and the Wilcoxon signed rank test was used to compare within-group differences of VAS scores at baseline and after the treatment. The between-group differences in the changes of the number of cases with positive Tinel's sign at baseline and after the treatment were analyzed by using Fisher's test, and within-group differences were analyzed by using McNemar's test. Analysis of variance (ANOVA) with Bonferroni correction was used to analyze changes in values of sensory and motor NCS parameters. A p value<0.05 was considered statistically significant.

Results

There were no significant differences in demographic characteristics (age, gender) before treatment (p>0.05) between the EG and CG. Also, there were no significant between-group differences in pain intensity based on the VAS scores, Tinel's sign, and NCS parameters before treatment (p>0.05) (Table 1).

Table 1.

Demographic Data and Clinical Characteristics of Patients with Carpal Tunnel Syndrome (CTS) in the Experimental Group (EG) and the Control Group (CG) Before Treatment

	EG (n = 40)	CG (n = 39)	p Value
Age (years)	50.5 ± 10.1	52.6 ± 11.6	0.904^a
Gender (males/females)	4/36	5/34	0.693^b
No. of treated wrists (unilateral/bilateral)	61 (19/21)	59 (19/20)	0.913^b
VAS			0.949^c
no pain	5/8.20%	3/5.09%
mild	38/62.30%	39/66.10%
moderate	18/29.50%	17/28.81%
Tinel's sign			0.303^d
positive	52/85.2%	46/78.0%
negative	9/14.8%	13/22.0%
Median MDL (ms)	4.88 ± 1.65	4.99 ± 2.01	0.908^e
Median SNCV (m/sec)	35.56 ± 9.48	35.29 ± 9.38	0.919^e

Student's t test.

Pearson χ².

Mann–Whitney U test.

Fisher's test.

ANOVA.

MDL, motor distal latency; SNCV, sensory nerve conduction velocity.

After treatment, the EG showed a significantly lower level of pain than did the CG (Z=−3.347; p=0.001). Within the EG, significant reduction of pain was observed after treatment, irrespective of the classifications of degree of pain prior to LLLT (Z=−6.325; p<0.001), whereas there was no significant reduction of pain within the CG (Z=−1.732; p>0.05). A greater proportion of patients who had only with mild pain prior to LLLT had no pain at 3 weeks post LLLT; that is, 81.6% of cases (Table 2).

Table 2.

Pain Intensity Based on the VAS Before and After the Treatment

		Pain after tx
Group		No pain	Mild	Moderate	Total	p Value
EG	Pain before tx					<0.001^a
	No pain
	n	5	0	0	5
	%	100%	0.0%	0.0%	100%
	Mild
	n	31	7	0	38
	%	81.6%	18.4%	0.0%	100%
	Moderate
	n	0	10	8	18
	%	0.0%	55.6%	44.4%	100%
	Total
	n	36	17	8	61
	%	59.0%	27.9%	13.1%	100%
CG	Pain before tx					>0.05^a
	No pain
	n	3	0	0	3
	%	100	0.0%	0.0%	100%
	Mild
	n	3	36	0	39
	%	7.7%	92.3%	0.0%	100%
	Moderate
	n	0	6	11	17
	%	0.0%	35.3%	64.7%	100%
	Total
	n	6	42	11	59
	%	10.2%	71.2%	18.6%	100%
	p value	0.001^b

Wilcoxon signed rank test.

Mann–Whitney U test.

VAS, visual analogue scale; tx, therapy; EG, experimental group; CG, control group.

At 3 weeks after the last LLLT treatment, both the EG and the CG had significantly fewer cases with a positive Tinel's sign (p<0.001). In addition, there were significantly fewer cases with a positive Tinel's sign in the EG, than in the CG, post-LLLT (χ²=4.025, p<0.05) (Table 3).

Table 3.

Analysis of Changes in Tinel's Sign Before and After the Treatment

		Tinel's sign after tx		Total
Group		Positive	Negative	n	%	p Value
EG	Tinel's sign before tx					<0.001^a
	Positive
	n	20	32	52	85.2%
	Negative
	n	0	9	9	14.8%
	Total
	n	20	41	61
	%	32.8%	67.2%		100%
CG	Tinel's sign before tx					<0.001^a
	Positive
	n	30	16	46	78.0%
	Negative
	n	0	13	13	22.0%
	Total
	n	30	29	59
	%	50.8%	49.5%		100%
	p value	<0.05^b

McNemar's test.

Fisher's test.

tx, therapy; EG, experimental group; CG, control group.

Within the EG, median MDL decreased at the end of treatment (p<0.01). However, although, after treatment, values in the EG were lower than the initial results, the difference in mean changes between groups was not significant (p>0.05) (Tables 4 and 5).

Table 4.

Nerve Conduction Studies; Median Nerve MDL Values Before and After Treatment (Within-Group Differences)

Group	n	Mean	SD	Mean change	p Value
EG
MDL₁	61	4.8820	1.64687	0.015	0.000
MDL₂	61	4.6902	1.51104
CG
MDL₁	59	4.9950	2.00617	0.000	1.000
MDL₂	59	4.9950	2.00617

ANOVA (Bonferroni correction).

MDL, motor distal latency; EG, experimental group; CG, control group.

Table 5.

Nerve Conduction Study Differences; Median Nerve MDL Values Before and After Treatment (Between-Group Differences)

Group	Mean change	p Value
MDL₁ Before tx
EG	0.004	0.908
CG
MDL₂ After tx
EG	0.019	0.580
CG

ANOVA (Bonferroni correction).

MDL, motor distal latency; tx, therapy; EG, experimental group; CG, control group.

After treatment, there was an increase in the median SNCV in both groups. This change was significant within the EG (p<0.001), as well as in the difference between the EG and the CG (p<0.05) after treatment (Tables 6 and 7).

Table 6.

Nerve Conduction Studies; Median Nerve SNCV Before and After Treatment (Within-Group Differences)

Group	n	Mean	SD	Mean change	p Value
EG
MSNCV₁	61	35.5603	9.47678	6.222	0.000
MSNCV₂	61	41.8068	10.12317
CG
MSNCV₁	59	35.2941	9.37926	1.265	0.127
MSNCV₂	59	36.5588	9.79139

ANOVA (Bonferroni correction).

SNCV, sensory nerve conduction velocity; MSNCV, median sensory nerve conduction velocity; EG, experimental group; CG, control group.

Table 7.

Nerve Conduction Study Differences; Median Nerve SNCV Before and After Treatment (Between-Group Differences)

Group	Mean change	p Value
MSNCV₁ Before tx
EG	0.266	0.919
CG
MSNCV₂ After tx
EG	5.624	0.041
CG

ANOVA (Bonferroni correction).

SNCV, sensory nerve conduction velocity; MSNCV, median sensory nerve conduction velocity; tx, therapy; EG, experimental group; CG, control group.

Discussion

Following a review of the latest publications, there appears to be consensus neither with regard to the choice of initial CTS treatment, nor with the physical modalities recommended for use. These discrepancies include, in particular, the methodology and treatment dosages used with LLLT.

The clinical evidence for LLLT is controversial, and consists of studies presenting ambiguous conclusions.

Many factors, including age, sex, and underlying disease can also affect treatment outcome.

Despite the fact that the World Association of Laser Therapy (WALT), as early as 2006 recommended that the energy dose in clinical investigations should be expressed in J instead of J/cm² [which represents energy density (ED)],⁵³ these two parameters are still often used interchangeably in a number of current, published studies. This confusion affects the validity and reproducibility of such studies. Frequently, even when both parameters are shown in studies, the calculations are incorrect and, therefore, misleading. This problem has also been noted by other authors.^54
–56

Apart from that, application site and location-specific doses are of great importance for the efficacy of laser therapy.

The investigations of Bjordal et al. proved that ED>4 J/cm², or power density>30 mW/cm² leads to inhibition of fibroblast activity, inadequate collagen production, and damage to superficial tendons. The same investigators' group also pointed out that the anti-inflammatory effect of LLLT is dose dependent, and the optimal energy dose range in clinical trials is very wide; 0.7–19 J, with a tendency to decrease the dose.^{49,55,57

–60}

The last dosage recommendations published by WALT were minimum 4 J/point in CTS, with the therapeutic dose windows ranging from±50% of given values. They also suggested daily treatment for 2 weeks or treatment every other day for 3–4 weeks.⁵⁰ Therefore, the design of this study and choice of laser beam parameters was in accordance with the latest WALT dose recommendations for CTS.

With the aim of adequately comparing published papers, in this discussion, we included only those with a similar methodological approach in the infrared spectra of wavelength, which contained all the necessary parameters of laser irradiation from which energy dose, power density, and ED could be calculated.

The objective of the Dincer et al. study⁶¹ was to investigate the effectiveness of splinting alone (Sp), splinting plus ultrasound (SpUS), and splinting plus LLLT (SpLLLT) in the management of mild to moderate CTS in 50 patients with bilateral CTS randomly assigned to three groups. An infrared GaAs diode laser (wavelength 904 nm, pulse duration of 200 nsec, maximum power output of 27 W, average power 2.4 mW, pulse frequency 1000 Hz) was used. The laser probe was applied directly and perpendicularly in contact with the skin for 30 sec at each of three points (0.072 J/point at an ED of 1 J/cm²; spot size of 0.07 cm²). A total of 10 LLLT sessions was performed once a day, five times a week, for 2 weeks. The authors concluded that combining US or LLLT with splinting appeared to be more effective than splinting alone in this study. However, the combination of LLLT with splinting appeared to be superior to SpUS, especially with regard to improvements in Boston Questionnaire (BQ) symptom severity, pain alleviation, and patient satisfaction at 3 months. Also, the number of completely normal hands according to EMG findings at 3 months was the highest in the SpLLLT group. Additionally, the authors believed that the increased effectiveness of LLLT in this study in comparison with others may be because of the lower power density (PD), ED, and energy dose used in this study.

Tascioglu et al.,⁶² in a double-blind and placebo-controlled study, randomly and equally assigned 60 patients with CTS to three groups. They concluded that LLLT was no more effective than placebo in clinical assessments, which included pain intensity, grip strength, symptom severity score, and functional status score, or in NCS and ultrasonography measurements. Detailed analyses of the parameters of the laser irradiation clearly showed observed errors in calculating the parameters of radiation. Therefore, in the first group in which a laser beam wavelength of 830 nm, in continuous mode of 50 mW, applied on five points for 2 min/point was: 50×120=6000 mJ or 6 J, not 1.2 J/point as noted by the authors in the study, and, consequently, the energy dose per one treatment was 30 J (not 6 J). In the second group, the CTS patients were treated with the same design of LLLT, but the irradiation time per point was shorter (1 min). Therefore, the energy dose per point was 3 J (not 0.6 J) and per treatment, it was 15 J (not 3 J). Because of the very small laser probe diameter of 1 mm, the spot area was 0.0025 cm² and PD was 20,000 mW/cm² (20 W/cm²). ED was 2400 J/cm² in the first group and, consequently, 1200 J/cm² in the second group. Therefore, it is very clear that the therapeutic effect was negated because of overdose. Moreover, the authors noted that tissue temperature increased a few hours after the last laser treatment, which also confirms overdosage.

In a study by Yagci et al.,⁶³ the efficacy of Sp and SpLLLT was compared in patients with idiopathic CTS. The authors used a Ga-Al-As laser with a wavelength of 830 nm and output power of 30 mW for 10 treatments. The laser probe diameter of 1 cm was applied for 90 sec on each of three wrist area points. The energy dose was 2.7 J/point and 8.1 J/treatment with PD of 38.2 mW/cm² and ED of 3.4 J/cm². The patients were splinted at night for 3 months, and also during the day whenever possible. The patients were evaluated at baseline and after 3 months of treatment. In the 3rd month follow-up, the SpLLLT group showed significant improvement in both the clinical (BQ symptom severity score) and the NCS parameters (median MDL, median SNCV). However, the Sp group showed improvement only in the BQ symptom severity score, with a significant decrease in grip strength. Grip strength in the SpLLLT group was without any change. Taking into account the duration of splint usage, it might be that grip strength could be much better immediately after the end of laser treatment than after 3 months. The reason might be, also, that the SpLLLT group experienced less pain and used splints for a shorter period of time and, thereby, retained their grip strength. It is possible that imobilization reduced the effects of LLLT on grip strength, or that LLLT may have some protective effect on muscle weakness during imobilization. This is a question that needs further investigation. Full recovery was found in 23.8% of the SpLLLT group and in only 4.2% of the splinting Sp group. Although the number was almost six times greater in the SpLLLT group, the authors concluded that these effects were of no significance.

This investigation used a method and laser beam parameters very similar to that in our study. The reason we achieved better results is most likely that splints were not used for such a long period of time, as well as the number of treatments (20).

It would appear that the applied lower PD and energy dose per point in this study, in comparison with some,^45,62,64 and similar to others^56,61,63 with a higher number and particular frequency of LLLTs, are crucial for better results.

In the present study, only mild and moderate patients with CTS were clinically evaluated for inclusion. Significant reduction of pain, reduction in the percentage of patients with a positive Tinel's sign, and shortening of median sensory and motor latencies in the NCS examinations in the experimental LLLT group were demonstrated at 3 weeks post-LLLT.

This study has observed and documented the statistically significant short-term effects of LLLT in CTS patients in comparison with a placebo group. The results support this conclusion, especially if LLLT is applied in the earlier stages of CTS (preferably within 1 year of symptom onset) and with mild to moderate cases.

Conclusions

The major limitation of this study was the duration of the follow-up period. Because of weak compliance, it was very difficult to follow up many of the patients for longer periods in our daily practice.

Further research with larger patient samples and longer follow-up periods is required to independently confirm our findings, and to determine the most effective parameters of laser beams and protocols for LLLT.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

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