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Effective self-stretching of carpal ligament for the treatment of carpal tunnel syndrome: A double-blinded randomized controlled study

Open AccessPublished:May 03, 2020DOI:https://doi.org/10.1016/j.jht.2019.12.002

      Highlights

      • Self-Stretching of Carpal Ligament for Carpal Tunnel Syndrome.
      • Self-Stretching shows improvement symptom severity and pinch strength.
      • Providing self-care technique may help alleviate the need for skilled therapy.

      Abstract

      Introduction

      Carpal tunnel syndrome (CTS) is the most common nerve entrapment syndrome worldwide. There are limited studies on the effectiveness of carpal ligament stretching on symptomatic and electrophysiologic outcomes.

      Purpose of the Study

      The purpose of this study was to evaluate the effect of self-myofascial stretching of the carpal ligament on symptom outcomes and nerve conduction findings in persons with CTS.

      Study Design

      This is a prospective, double-blinded, randomized, placebo-controlled trial.

      Methods

      Eighty-three participants diagnosed with median mononeuropathy across the wrist by nerve conduction study were randomized 1:1 to sham treatment or self-carpal ligament stretching. Participants were instructed to perform the self-treatment four times a day for six weeks. Seventeen participants in the sham treatment group and 19 participants in the carpal ligament stretching group completed the study. Pre- and post-treatment outcome measures included subjective complaints, strength, nerve conduction findings, and functional scores.

      Results

      Groups were balanced on age, sex, hand dominance, symptom duration, length of treatment, presence of nocturnal symptoms, and compliance with treatment. Even though the ANOVA analyses were inconclusive about group differences, explorative post hoc analyses revealed significant improvements in numbness (P = .011, Cohen's d = .53), tingling (P = .007, Cohen's d = .60), pinch strength (P = .007, Cohen's d = −.58), and symptom severity scale (P = .007, Cohen's d = .69) for the treatment group only.

      Conclusions

      The myofascial stretching of the carpal ligament showed statistically significant symptom improvement in persons with CTS. Larger comparative studies that include other modalities such as splinting should be performed to confirm the effectiveness of this treatment option.

      Keywords

      Introduction

      Median mononeuropathy at the wrist, also known clinically as carpal tunnel syndrome (CTS), is caused by compression of the median nerve as it crosses the wrist in the carpal tunnel. With a prevalence of approximately 10%, it is the most common nerve entrapment syndrome worldwide and accounts for up to 90% of all nerve compression syndromes.
      • Padua L.
      • Coraci D.
      • Erra C.
      • et al.
      Carpal tunnel syndrome: clinical features, diagnosis, and management.
      Risk factors include diabetes mellitus, hypothyroidism, advanced age, obesity, female sex, pregnancy, rheumatoid arthritis, and repetitive wrist work, among others.
      • Rempel D.M.
      • Diao E.
      Entrapment neuropathies: pathophysiology and pathogenesis.
      Clinically, patients may present with hyperesthesia or paresthesia in the sensory distribution of the median nerve in the hand, and in severe cases, weakness in median innervated intrinsic muscles of the hand.
      Various treatment modalities have been studied including medications, steroid injections, wrist orthotics, therapies, nerve gliding, and surgical treatment.
      • Burke D.T.
      • Burke M.M.
      • Stewart G.W.
      • Cambré A.
      Splinting for carpal tunnel syndrome: in search of the optimal angle.
      • Finestone H.M.
      • Woodbury G.M.
      • Collavini T.
      • Marchuk Y.
      • Maryniak O.
      Severe carpal tunnel syndrome: clinical and electrodiagnostic outcome of surgical and conservative treatment.
      • Gelberman R.H.
      • Aronson D.
      • Weisman M.H.
      Carpal-tunnel syndrome. Results of a prospective trial of steroid injection and splinting.
      • Irwin L.R.
      • Beckett R.
      • Suman R.K.
      Steroid injection for carpal tunnel syndrome.
      • Walker W.C.
      • Metzler M.
      • Cifu D.X.
      • Swartz Z.
      Neutral wrist splinting in carpal tunnel syndrome: a comparison of night-only versus full-time wear instructions.
      • Celik B.
      • Paker N.
      • Celik E.C.
      • Bugdayci D.S.
      • Ones K.
      • Ince N.
      The effects of orthotic intervention on nerve conduction and functional outcome in carpal tunnel syndrome: a prospective follow-up study.
      Burke et al
      • Burke D.T.
      • Burke M.M.
      • Stewart G.W.
      • Cambré A.
      Splinting for carpal tunnel syndrome: in search of the optimal angle.
      showed that a “neutral splinting” provided the best symptomatic relief, and Walker et al
      • Walker W.C.
      • Metzler M.
      • Cifu D.X.
      • Swartz Z.
      Neutral wrist splinting in carpal tunnel syndrome: a comparison of night-only versus full-time wear instructions.
      demonstrated that wearing a static wrist orthosis full-time is better than wearing one only overnight. It has been suggested that the therapeutic effects of orthosis arise from decreasing pressure in the carpal tunnel. “Nerve gliding” techniques have been also studied, but the two review articles on this technique both concluded that this technique did not show conclusive evidence to support its efficacy.
      • Lim Y.H.
      • Chee D.Y.
      • Girdler S.
      • Lee H.C.
      Median nerve mobilization techniques in the treatment of carpal tunnel syndrome: a systematic review.
      ,
      • Medina McKeon J.M.
      • Yancosek K.E.
      Neural gliding techniques for the treatment of carpal tunnel syndrome: a systematic review.
      Carpal tunnel pressure has been implicated in the pathophysiology of CTS.
      • Ibrahim I.
      • Khan W.S.
      • Goddard N.
      • Smitham P.
      Carpal tunnel syndrome: a review of the recent literature.
      Various manual therapy interventions have been studied as treatment option for CTS.
      • Sucher B.M.
      Myofascial manipulative release of carpal tunnel syndrome: documentation with magnetic resonance imaging.
      • Sucher B.M.
      Myofascial release of carpal tunnel syndrome.
      • Sucher B.M.
      Palpatory diagnosis and manipulative management of carpal tunnel syndrome.
      • Sucher B.M.
      • Hinrichs R.N.
      Manipulative treatment of carpal tunnel syndrome: biomechanical and osteopathic intervention to increase the length of the transverse carpal ligament.
      • Burke J.
      • Buchberger D.J.
      • Carey-Loghmani M.T.
      • Dougherty P.E.
      • Greco D.S.
      • Dishman J.D.
      A pilot study comparing two manual therapy interventions for carpal tunnel syndrome.
      Manipulative therapy in which a practitioner would hold the patient's dorsal wrist and manipulate with the intent to stretch the carpal ligament may theoretically decrease the pressure in the carpal tunnel. This manipulative maneuver, performed by a practitioner and/or by the patient with a home self-stretching program, has been illustrated by Sucher.
      • Sucher B.M.
      Myofascial manipulative release of carpal tunnel syndrome: documentation with magnetic resonance imaging.
      • Sucher B.M.
      Myofascial release of carpal tunnel syndrome.
      • Sucher B.M.
      Palpatory diagnosis and manipulative management of carpal tunnel syndrome.
      • Sucher B.M.
      • Hinrichs R.N.
      Manipulative treatment of carpal tunnel syndrome: biomechanical and osteopathic intervention to increase the length of the transverse carpal ligament.
      In several case reports, manipulative therapy has been documented to alleviate symptoms of CTS, such as pain, paresthesia, and numbness.
      • Sucher B.M.
      Myofascial manipulative release of carpal tunnel syndrome: documentation with magnetic resonance imaging.
      • Sucher B.M.
      Myofascial release of carpal tunnel syndrome.
      • Sucher B.M.
      Palpatory diagnosis and manipulative management of carpal tunnel syndrome.
      • Sucher B.M.
      • Hinrichs R.N.
      Manipulative treatment of carpal tunnel syndrome: biomechanical and osteopathic intervention to increase the length of the transverse carpal ligament.
      There are also several case reports documenting improved electrophysiologic findings in the form of decreased motor and sensory distal latencies (DLs) and increased motor and sensory action potential amplitudes (Amp).
      • Sucher B.M.
      Myofascial release of carpal tunnel syndrome.
      Using magnetic resonance imaging, Sucher has shown an increase in carpal tunnel cross-sectional area after treatment with myofascial manipulative release of the carpal ligament.
      • Sucher B.M.
      Myofascial manipulative release of carpal tunnel syndrome: documentation with magnetic resonance imaging.
      Improvements in symptoms and nerve conduction parameters have been demonstrated after treatment.
      • Sucher B.M.
      Myofascial manipulative release of carpal tunnel syndrome: documentation with magnetic resonance imaging.
      Multiple techniques have been developed for manual therapy intervention performed under guidance from a trained clinician.
      • Burke J.
      • Buchberger D.J.
      • Carey-Loghmani M.T.
      • Dougherty P.E.
      • Greco D.S.
      • Dishman J.D.
      A pilot study comparing two manual therapy interventions for carpal tunnel syndrome.
      ,
      • Talebi G.A.
      • Saadat P.
      • Javadian Y.
      • Taghipour M.
      Manual therapy in the treatment of carpal tunnel syndrome in diabetic patients: a randomized clinical trial.
      Burke et al
      • Burke J.
      • Buchberger D.J.
      • Carey-Loghmani M.T.
      • Dougherty P.E.
      • Greco D.S.
      • Dishman J.D.
      A pilot study comparing two manual therapy interventions for carpal tunnel syndrome.
      demonstrated efficacy of “Graston Instrument-assisted soft tissue mobilization” and manual “soft tissue mobilization” performed by a trained manual therapy clinician. More recently, Talebi et al
      • Talebi G.A.
      • Saadat P.
      • Javadian Y.
      • Taghipour M.
      Manual therapy in the treatment of carpal tunnel syndrome in diabetic patients: a randomized clinical trial.
      reported “manual therapy” that consisted of “carpal bone mobilization”, “transverse carpal ligament release” similar to the Sucher's release, pronator teres soft tissue manipulation, and “median nerve mobilization” to be more effective in treatment of CTS in patients with diabetes compared with ultrasound and transcutaneous nerve stimulation treatment.
      To our knowledge, there has only been one study on the effectiveness of a self-administered manual therapy intervention, which was described by Madenci.
      • Madenci E.
      • Altindag O.
      • Koca I.
      • Yilmaz M.
      • Gur A.
      Reliability and efficacy of the new massage technique on the treatment in the patients with carpal tunnel syndrome.
      The “Madenci” massage consisted of effleurage, friction, petrissage, and shaking that was self-performed by patients. In addition, the patients were asked to perform a “tendon gliding exercise” and “nerve gliding exercise” at least three times per day. The advantages of a self-administered versus clinician-performed therapy program are several-fold and may include ease of access to treatment, decreased financial cost, and increased compliance for patients. One limitation of the Madenci study is the incorporation of three exercises (massage, tendon gliding, and nerve gliding), which makes it unclear which exercise may have helped the most.
      The objective of this study was to investigate the efficacy of a simple one-maneuver carpal stretching that individuals with CTS can perform by themselves at their convenience. Using a randomized, double-blinded, controlled study design, we evaluated the effectiveness of a self-carpal ligament stretching (CLS) program versus a sham massage program in the treatment of CTS. We hypothesized that patients undergoing myofascial manipulative release of the carpal ligament would report lower pain scores, demonstrate greater strength, and have improved nerve conduction studies when compared with the sham treatment group at 6 weeks after intervention.

      Methods

      Study design

      A prospective, double-blinded, randomized, placebo-controlled trial was performed to investigate the short-term efficacy of myofascial stretching of the carpal ligament in alleviating symptoms and improving physical function in patients with median mononeuropathy at the wrist. This protocol was approved by the Human Subjects Committee at the study site, which is a county hospital in a suburb. All participants were enrolled and completed participation in this study from 1999 to 2010.
      Potential participants were recruited from an electrodiagnostic medicine clinic. These individuals were referred to the clinic to be assessed for CTS based on symptoms consistent with CTS. A single electrophysiologist performed each nerve conduction study at the baseline and at 6 weeks after treatment and was blinded to the control and treatment group. Participants were diagnosed with median mononeuropathy electrodiagnostically with a Neuromax EMG machine and using a standard protocol of the median nerve conduction studies.
      American Association of Electrodiagnostic Medicine, American Academy of Neurology, and American Academy of Physical Medicine and Rehabilitation
      Practice parameter for electrodiagnostic studies in carpal tunnel syndrome: summary statement.
      Median sensory studies were performed antidromically with stimulation site 14 cm from the recording site at digit 2 and with distal latency (DL) measured to the peak. Median motor studies were performed orthodromically with the recording electrode placed at the abductor pollicis brevis and with stimulation site 8 cm proximal to the recording electrode. The temperature of each participant's forearm was maintained at greater than 32°C by applying an electrical warmer as needed. Participants were diagnosed with median mononeuropathy if the median sensory DL was equal to or greater than 3.6 ms.
      American Association of Electrodiagnostic Medicine, American Academy of Neurology, and American Academy of Physical Medicine and Rehabilitation
      Practice parameter for electrodiagnostic studies in carpal tunnel syndrome: summary statement.
      Ulnar nerve conduction studies were performed at the baseline to rule out peripheral polyneuropathy. Participants were recruited from the Electrodiagnostic Medicine Clinic by the principal investigator (KS) who remained blinded to the group assignment for each participant until the completion of post-treatment assessment for each participant.
      The inclusion criterion was (1) presence of median mononeuropathy across the wrist, diagnosed by Neuromax EMG machine using standard technique as described previously. The exclusion criteria were (1) presence of peripheral polyneuropathy, (2) consistent use of adaptive equipment, such as wheelchair or cane, and (3) inability to provide informed consent in English. Although not specifically excluded from the study, participants who had additional neurological or musculoskeletal conditions, such as cervical radiculopathy, upper extremity fractures, or brachial plexus injuries did not participate in this study. Of those eligible to enroll in the study, two participants refused enrollment indicating their preference to try other treatment options such as orthosis.
      Eligible participants were randomly assigned to undergo either sham or CLS treatment protocols. Participants randomly selected an envelope containing intervention allocation, which was then shown to a study assistant who instructed the intervention as described in the following. Allocation ratio was 1:1. Participants remained blinded to the intervention group until completion of the post-treatment assessment. At the post-treatment follow-up evaluation, technique was re-evaluated to confirm that participants performed their respective treatments correctly. If the participant was assigned to the sham control group, they were instructed on the CLS technique at the post-treatment follow-up evaluation. No changes were made to methods, including eligibility criteria, or outcomes after trial commencement.

      Interventions

      Participants in the CLS treatment group were instructed to perform self-myofascial stretching of the carpal ligament, which was a slight modification of the myofascial stretching described by Sucher.
      • Sucher B.M.
      Myofascial manipulative release of carpal tunnel syndrome: documentation with magnetic resonance imaging.
      • Sucher B.M.
      Myofascial release of carpal tunnel syndrome.
      • Sucher B.M.
      Palpatory diagnosis and manipulative management of carpal tunnel syndrome.
      The modification was made to specifically enable the participants to perform the stretch by himself/herself independently, without physiatrist or therapist involvement. Each participant was instructed to extend his or her wrist at 90° against a wall and to gently retract the thenar eminence with the contralateral hand to stretch the carpal ligament (Fig. 1). Participants in the sham treatment group were instructed to hold their hands perpendicularly and to massage lightly down the dorsal wrist (Fig. 2). For control, sham massage similar to stroking massage technique was designed by the PI (KS) with the intent that the participants needed to at least be doing a hands-on massage-like maneuver over the wrist without substantial manipulation of soft tissue. The use of a sham massage group allowed for a double-blinded study design and a superior control group compared with orthosis and/or no treatment control groups.
      Figure thumbnail gr1
      Fig. 1In the self-treatment group of myofascial release, each participant was instructed to extend his/her wrist at 90 degree against a wall and hold the near eminence with the contralateral hand as to stretch the carpal ligament.
      Figure thumbnail gr2
      Fig. 2Every participant in the placebo group was instructed to hold his/her hand up perpendicularly and to massage down the dorsal wrist.
      All participants in both groups were instructed to perform the self-treatment for 30 seconds at a time, four times a day for six weeks. Instruction was provided by another member of the study personnel to maintain blindedness of the principal investigator (KS). Participants were also provided with written instructions on their respective self-treatment program and a calendar sheet to log when they performed self-treatment. No work or activity restrictions were imposed on participants in the sham or CLS treatment groups. If participants sought other treatments such as therapies, injections, or surgeries while participating in this project, they were withdrawn from the study without any repercussions.

      Outcome assessment

      Baseline data and other characteristics such as hand dominance, symptomatic side, duration of symptoms, and presence of nocturnal symptoms were collected at the baseline (Table 1). A total of 12 outcome measures were collected. Each participant was asked to complete a questionnaire which included (1) visual analog scale (VAS) for wrist pain, hand pain, hand numbness, and hand tingling, (2) symptom severity scale (SSS), and (3) functional states scale (FSS). Both SSS and FSS have been validated to be reliable symptomatic scales in patients with CTS.
      • Khosrawi S.
      • Dehghan F.
      Determination of the median nerve residual latency values in the diagnosis of carpal tunnel syndrome in comparison with other electrodiagnostic parameters.
      The SSS consists of 11 questions and the FSS consists of 8 questions, with responses scored on a scale of 1 to 5. Lower scores on the SSS and FSS represent no symptoms or normal function, respectively. The pinch and grip strengths were also measured on the affected side and calculated by averaging three measurements; pinch strength was measured using a standard pinch gauge (B&L Engineering) with 0.5 kg increments and grip strength was measured using a Jamar Hand Dynamometer (5030J1) with 2 kg increments. At 6 weeks follow-up, participants were asked to complete the same questionnaires and strength testing. Nerve conduction study of the median nerve was performed also at 6-week follow-up. Sensory and motor distal latencies (milliseconds; ms) and amplitudes (microvolts, uV for sensory amplitude; millivolts, mV for motor amplitudes) at the baseline and 6-week follow-up were included as outcome measures. Electrodiagnostically, decrease in the distal latencies and increase in the amplitudes constitute as improvements. The principal investigator (KS) collected all data and outcome measures while remaining blinded to the intervention assignment.
      Table 1Demographics and clinical characteristics of sham and CLS treatment groups at baseline
      DemographicsSham treatment (n = 17)CLS treatment (n = 19)P-value
      Age, y
       Mean ± SD48.18 ± 7.1850.05 ± 9.71.521
       Range31-6435-66
      Sex, n
       Male46.722
       Female1313
      Hand dominance, n
       Right1414.702
       Left35
      Symptomatic side, n
       Right24.422
       Left02
       Bilateral1513
      Length of symptoms, years
       Mean ± SD2.82 ± 2.893.03 ± 2.93.831
      Nocturnal symptoms, n
       Yes1512.132
       No27
      Length of treatment, days
       Mean ± SD46.12 ± 9.6643.11 ± 6.01.261
      Compliance, %
       Mean ± SD96.78 ± 4.2687.13 ± 20.5.161
      CLS = carpal ligament stretching.
      Table 1 summarizes the means, standard deviations (SD), and counts (n) for the demographic and clinical characteristics. Superscripts represent either (1) t-test or (2) Fisher's exact test.

      Statistical analysis

      The data were analyzed according to the intent-to-treat principle. Outcomes measured included subjective complaints (wrist pain, hand pain, numbness, tingling), strength (pinch and grip strength), nerve conduction findings (sensory and motor distal latency and amplitude), and functional scores (SSS and FSS). One participant in the sham treatment group was missing post-intervention SSS and FSS total scores, one participant (sham treatment group) was missing pre-intervention pinch and grip strength, and one participant (treatment group) was missing pre-intervention FSS total score. Individuals with missing values were excluded from the specific outcome measure analysis. Each outcome measure was analyzed separately using a Group (treatment × sham treatment) × Time (pre- × post-intervention) repeated measure ANOVA (rmANOVA). Baseline to post-intervention within-group effects were further explored using post hoc t-tests. A P-value cutoff of P ≤ .05 was used to determine significance (Table 2). Partial eta squared values were included for significant rmANOVA effects (group, time, and group × time interaction) and Cohen's d was calculated for each significant post hoc t-tests. All analyses were conducted in SPSS version 24 except for Cohen's d and 3 × 2 (symptom side) Fisher's exact test that was calculated in excel.
      Table 2Summary of within-group post hoc t-tests (baseline compared with follow-up) for rmANOVAs
      VariableSham treatmentCLS treatment
      NBaselineF/UP-valueNBaselineF/UP-value
      Wrist pain174.19 (2.98)4.21 (2.92).974193.01 (2.96)2.70 (2.31).518
      Hand pain173.62 (3.23)4.20 (2.96).280193.85 (3.30)3.09 (2.96).134
      Numbness175.59 (2.86)5.51 (2.80).892195.66 (3.41)4.23 (3.03).011
      Tingling175.24 (3.07)5.29 (3.10).927195.65 (2.96)4.08 (2.60).007
      Pinch (kg)166.69 (1.41)6.92 (1.50).606197.25 (2.69)8.41 (3.07).007
      Grip (kg)1625.8 (7.82)26.5 (7.58).6121929.1 (8.97)29.5 (8.82).754
      Sensory DL (ms)174.95 (1.01)4.74 (.993).018195.00 (.864)4.94 (.889).513
      Sensory Amp (μV)1732.2 (19.7)31.8 (21.1).9201931.9 (20.3)23.0 (15.5).021
      Motor DL (ms)175.58 (1.27)5.39 (1.39).134195.68 (.975)5.65 (.919).843
      Motor Amp (mV)177.09 (3.23)7.18 (2.49).867197.60 (2.31)7.33 (2.01).621
      SSS1632.3 (7.68)29.3 (7.19).0521930.8 (8.76)27.0 (10.0).007
      FSS1623.3 (10.3)23.1 (9.57).9251829.3 (9.08)26.9 (11.3).062
      CLS = carpal ligament stretching; N = count; F/U = post-treatment follow-up; kg = kilogram; DL = distal latency; ms = milliseconds; Amp = amplitude; μV = microvolts; mV = millivolts; SSS = symptom severity scale; FSS = functional states scale.
      Baseline and follow-up (F/U) values represent the means and standard deviations (in parentheses). Bold P-values correspond to P < .05.

      Results

      A total of 83 participants were enrolled in the study and randomized according to allocation ratio 1:1 to the sham and CLS treatment group. Two participants withdrew from the study for discomfort with the hand exercise, and one participant withdrew by choosing to get a steroid injection instead. Group allotment for these participants was unknown because they never returned for a follow-up assessment to confirm treatment group allocation. The remainder of participants who did not complete the 6-week treatment course were lost to follow-up (Fig. 3). Seventeen participants in the sham treatment group and 19 participants in the CLS treatment group completed the study and were included in the analysis (Table 1). Due to the presence of bilateral median nerve conduction findings in some participants, there were 32 single extremities examined in the sham and CLS treatment groups each. The analysis was performed on the original assigned groups, and there was no crossover between groups.
      Figure thumbnail gr3
      Fig. 3Randomization chart. Flow diagram showing study progress for the two participate groups. CLS = carpal ligament stretching.
      There was no significant difference in age (P = .52) or sex (P = .72), hand dominance (P = .70), symptomatic side (P = .42), or presence of nocturnal symptoms (P = .13) between sham and CLS treatment groups. The average duration of symptoms for the sham treatment and self-treatment group was 2.82 ± 2.89 and 3.03 ± 2.93 years, respectively (P = .83). There was no significant difference in length of treatment (P = .26) and compliance to prescribed treatment (P = .16) between sham and CLS treatment groups.
      Of the 12 outcome measures, the exploratory post hoc analysis revealed that the treatment group improved on 5 of 12 measures while the sham group improved on 1 of the 12 measures. These results are outlined in the following sections.

      Wrist pain

      Nineteen treatment and seventeen sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. No significant effects of group (F [1,34] = 2.40, P = .131), time (F [1,34] = .181, P = .673), or group × time interaction (F [1,34] = .223, P = .639) were observed. Follow-up t-tests were performed to investigate the within-group changes pre- and post-treatment. No significant effects of pre- to post-treatment were observed in the CLS treatment (P = .518) or sham treatment group (P = .974) (Table 2).

      Hand pain

      Nineteen treatment and seventeen sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. No significant effects of group (F [1,34] = .205, P = .654), time (F [1,34] = .067, P = .798), or group × time interaction (F [1,34] = 3.43, P = .073) were observed. Follow-up t-tests were performed to investigate the within-group changes before and after treatment. No significant differences changes were observed in the CLS treatment (P = .134) or sham treatment group (P = .280) (Table 2).

      Numbness

      Nineteen treatment and 17 sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. This analysis revealed no significant effects of group (F [1,34] = .418, P = .522), time (F [1,34] = 3.82, P = .059), or group × time interaction (F [1,34] = 3.08, P = .088) were observed. Follow-up t-tests were performed to investigate the within group changes before and after treatment. A significant reduction in numbness was observed in the CLS treatment group (P = .011, Cohen's d = .53), whereas no significant change was observed in the sham treatment group (P = .892) (Table 2; Fig. 4).
      Figure thumbnail gr4
      Fig. 4The visual analog scale (VAS) numbness rating at the baseline and after intervention for the sham and CLS treatment groups. Higher scores represent worse numbness. The asterisk represents a significant difference P ≤ .05. CLS = carpal ligament stretching.

      Tingling

      Nineteen treatment and 17 sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. This analysis revealed a significant group × time interaction (F [1,34] = 4.23, P = .048, partial eta2 = .111); No significant effect of time (F [1,34] = 3.69, P = .063) or group were observed (F [1,34] = .199, P = .658). Follow-up t-tests were performed to investigate the within-group changes before and after treatment. A significant reduction in tingling was observed (P = .007, Cohen's d = .60) in the CLS treatment group, whereas no significant change was observed in the sham treatment group (P = .927) (Table 2; Fig. 5).
      Figure thumbnail gr5
      Fig. 5The visual analog scale (VAS) tingling rating at the baseline and after intervention for the sham and CLS treatment groups. Higher scores represent worse tingling. The asterisk represents a significant difference P ≤ .05. CLS = carpal ligament stretching.

      Pinch strength

      Nineteen treatment and 16 sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. This analysis revealed a significant effect of time (F [1,33] = 5.46, P = .026, partial eta2 = .142). No significant effects of group (F [1,33] = 1.93, P = .174) or group × time interaction (F [1,33] = 2.46, P = .126) were observed. Follow-up t-tests were performed to investigate the within-group changes before and after treatment. A significant increase in pinch strength was observed in the CLS treatment group (P = .007, Cohen's d = −0.58), whereas no significant change was observed in the sham treatment group (P = .606) (Table 2; Fig. 6).
      Figure thumbnail gr6
      Fig. 6The pinch grip in kilograms (kg) at baseline and post-intervention for the Sham and CLS treatment groups. The asterisk represents a significant difference P ≤ .05. CLS = carpal ligament stretching.

      Grip strength

      Nineteen treatment and 16 sham treatment participants were included in a group (treatment × sham treatment) × time (pre-× post-treatment) rmANOVA. No significant effects of group (F [1,33] = 1.41, P = .244), time (F [1,33] = .349, P = .559), or group × time interaction (F [1,33] = .027, P = .871) were observed. Follow-up t-tests were performed to investigate the within-group changes before and after treatment. No significant effects of pre- to post-treatment were observed in the CLS treatment (P = .754) or sham treatment group (P = .612) (Table 2).

      Sensory distal latency

      Nineteen treatment and 17 sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. This analysis revealed a significant effect of time (F [1,34] = 5.09, P = .031, partial eta2 = .130). No significant effects of group (F [1,34] = .172, P = .681) or group × time interaction (F [1,34] = 1.82, P = .187) were observed. Follow-up t-tests were performed to investigate the within-group changes before and after treatment. A significant decrease (improvement) in sensory distal latency was observed in the sham treatment group (P = .018, Cohen's d = .77) but not the CLS treatment group (P = .513) (Table 2).

      Sensory amplitude

      Nineteen treatment and 17 sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. No significant effects of group (F [1,34] = .611, P = .440), time (F [1,34] = 3.03, P = .091), or group × time interaction (F [1,34] = 2.54, P = .120) were observed. Follow-up t-tests were performed to investigate the within-group changes before and after treatment. A significant decrease in sensory amplitude was observed in the CLS treatment group (P = .021, Cohen's d = 0.48) but not the sham treatment group (P = .920) (Table 2).

      Motor distal latency

      Nineteen treatment and seventeen sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. No significant effects of group (F [1,34] = .230, P = .635), time (F [1,34] = 1.57, P = .219), or group × time interaction (F [1,34] = .958, P = .335) were observed. Follow-up t-tests were performed to investigate the within group changes before and after treatment. No significant effects of pre- to post-treatment were observed in the CLS treatment (P = .843) or sham treatment group (P = .134) (Table 2).

      Motor amplitudes

      Nineteen treatment and seventeen sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. No significant effects of group (F [1,34] = .202, P = .656), time (F [1,34] = .049, P = .827), or group × time interaction (F [1,34] = .216, P = .645) were observed. Follow-up t-tests were performed to investigate the within-group changes before and after treatment. No significant effects of pre- to post-treatment were observed in the CLS treatment (P = .621) or sham treatment group (P = .867) (Table 2).

      Symptom severity scale

      Nineteen treatment and 16 sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. This analysis revealed a significant effect of time (F [1,33] = 11.63, P = .002, partial eta2 = .261). No significant effects of group (F [1,33] = .494, P = .487) or group × time interaction (F [1,33] = .196, P = .661) were observed. Follow-up t-tests were performed to investigate the within-group changes before and after treatment. A significant improvement in SSS total scores was observed in the CLS treatment group (P = .007, Cohen's d = .69) but not the sham treatment group (P = .052) (Table 2; Fig. 7).
      Figure thumbnail gr7
      Fig. 7The symptom severity scale (SSS) total score at the baseline and after intervention for the sham and CLS treatment groups. Higher scores represent worse symptom severity. The asterisk represents a significant difference P ≤ .05. CLS = carpal ligament stretching.

      Functional states scale

      Eighteen treatment and sixteen sham treatment participants were included in a group (treatment × sham treatment) × time (pre- × post-treatment) rmANOVA. No significant effects of group (F [1,32] = 2.14, P = .153), time (F [1,32] = 1.95, P = .172), or group × time interaction (F [1,32] = 1.58, P = .217) were observed. Follow-up t-tests were performed to investigate the within-group changes before and after treatment. No significant effects of pre- to post-treatment were observed in the CLS treatment (P = .062) or sham treatment group (P = .925) (Table 2).

      Discussion

      There have been many studies published evaluating the effectiveness of different modalities in the treatment of CTS. Corticosteroid injections, oral steroids, surgery, massage, wrist mobilization, and orthoses have been shown to improve symptoms of CTS.
      • Burke D.T.
      • Burke M.M.
      • Stewart G.W.
      • Cambré A.
      Splinting for carpal tunnel syndrome: in search of the optimal angle.
      • Finestone H.M.
      • Woodbury G.M.
      • Collavini T.
      • Marchuk Y.
      • Maryniak O.
      Severe carpal tunnel syndrome: clinical and electrodiagnostic outcome of surgical and conservative treatment.
      • Gelberman R.H.
      • Aronson D.
      • Weisman M.H.
      Carpal-tunnel syndrome. Results of a prospective trial of steroid injection and splinting.
      ,
      • Walker W.C.
      • Metzler M.
      • Cifu D.X.
      • Swartz Z.
      Neutral wrist splinting in carpal tunnel syndrome: a comparison of night-only versus full-time wear instructions.
      ,
      • Celik B.
      • Paker N.
      • Celik E.C.
      • Bugdayci D.S.
      • Ones K.
      • Ince N.
      The effects of orthotic intervention on nerve conduction and functional outcome in carpal tunnel syndrome: a prospective follow-up study.
      ,
      • Burke J.
      • Buchberger D.J.
      • Carey-Loghmani M.T.
      • Dougherty P.E.
      • Greco D.S.
      • Dishman J.D.
      A pilot study comparing two manual therapy interventions for carpal tunnel syndrome.
      • Talebi G.A.
      • Saadat P.
      • Javadian Y.
      • Taghipour M.
      Manual therapy in the treatment of carpal tunnel syndrome in diabetic patients: a randomized clinical trial.
      • Madenci E.
      • Altindag O.
      • Koca I.
      • Yilmaz M.
      • Gur A.
      Reliability and efficacy of the new massage technique on the treatment in the patients with carpal tunnel syndrome.
      ,
      • Herskovitz S.
      • Berger A.R.
      • Lipton R.B.
      Low-dose, short-term oral prednisone in the treatment of carpal tunnel syndrome.
      ,
      • Wolny T.
      • Saulicz E.
      • Linek P.
      • Myśliwiec A.
      • Saulicz M.
      Effect of manual therapy and neurodynamic techniques vs ultrasound and laser on 2PD in patients with CTS: a randomized controlled trial.
      By contrast, literature reviews on median nerve gliding techniques have not conclusively shown the effectiveness of such techniques.
      • Lim Y.H.
      • Chee D.Y.
      • Girdler S.
      • Lee H.C.
      Median nerve mobilization techniques in the treatment of carpal tunnel syndrome: a systematic review.
      ,
      • Medina McKeon J.M.
      • Yancosek K.E.
      Neural gliding techniques for the treatment of carpal tunnel syndrome: a systematic review.
      ,
      • Madenci E.
      • Altindag O.
      • Koca I.
      • Yilmaz M.
      • Gur A.
      Reliability and efficacy of the new massage technique on the treatment in the patients with carpal tunnel syndrome.
      Most manual therapies are performed by clinicians and not by the patients themselves, which requires access to specialized care to receive treatment. Furthermore, most studies used combinations of multiple maneuvers, such as transverse carpal ligament release, carpal bone mobilization, or median nerve mobilization, making it impractical for a patient gain the sufficient training to do self-treatment.
      Findings from this study suggest that a single, simple, wrist self-stretching maneuver may improve sensation (numbness and tingling), strength (pinch), and overall symptom severity (SSS total score). Exploratory post hoc analysis revealed that individuals in the sham group improved on one of 12 measures (sensory distal latency), whereas the CLS treatment group improved on five of 12 measures (numbness, tingling, pinch strength, sensory amplitude, and SSS). Future studies are needed to asses changes in the sensory nerve conduction measures because a decrease in sensory amplitude was observed in the context of improving sensory changes of numbness, tingling, and overall symptom severity.
      Previous case studies have documented the success of Sucher's manual treatment, and it is used frequently in the field of manual medicine for the treatment of CTS
      • Sucher B.M.
      Myofascial manipulative release of carpal tunnel syndrome: documentation with magnetic resonance imaging.
      • Sucher B.M.
      Myofascial release of carpal tunnel syndrome.
      • Sucher B.M.
      Palpatory diagnosis and manipulative management of carpal tunnel syndrome.
      • Sucher B.M.
      • Hinrichs R.N.
      Manipulative treatment of carpal tunnel syndrome: biomechanical and osteopathic intervention to increase the length of the transverse carpal ligament.
      ; however, there has not been any randomized controlled study examining the effectiveness of Sucher's manual treatment. This study used a randomized, controlled, double-blinded design to evaluate the effectiveness of a single maneuver, self-stretching program on symptomatic and electrophysiologic outcomes in CTS. The CLS treatment group maneuver utilized myofascial stretching of the carpal ligament, which was modified from the Sucher's manual treatment to accommodate for self-stretching without aid from a therapist. In theory, myofascial release of the carpal ligament increases carpal tunnel cross-sectional area and decreases pressure in the carpal tunnel, thereby improving CTS symptoms.
      • Sucher B.M.
      Myofascial manipulative release of carpal tunnel syndrome: documentation with magnetic resonance imaging.
      In line with other studies investigating CTS, this study found significant improvements in overall symptom severity. Burnham et al
      • Burnham T.
      • Higgins D.C.
      • Burnham R.S.
      • Heath D.M.
      Effectiveness of osteopathic manipulative treatment for carpal tunnel syndrome: a pilot project.
      demonstrated a significant improvement in symptoms and functional scores as measured by the Boston Carpal Tunnel Questionnaire (BCTQ) after osteopathic manipulative treatment once a week for six weeks. However, similar to Sucher's studies, there was no control group and treatments were administered by a practitioner trained in osteopathic medicine. Pratelli et al
      • Pratelli E.
      • Pintucci M.
      • Cultrera P.
      • et al.
      Conservative treatment of carpal tunnel syndrome: comparison between laser therapy and Fascial Manipulation(®).
      compared fascial manipulation with low-level laser therapy in patients with CTS and demonstrated significant improvements in BCTQ and VAS from pre-treatment to 10 days post-treatment. The improvement was sustainable at 3 months after treatment. Similar to the Burnham study, Pratelli et al's fascial manipulation was administered by a health professional once per week over 3 weeks. The 6-week self-treatment program used in this study circumvents the need for specialized care and showed similar improvements in symptom severity. SSS total score changes observed in this sample, CLS treatment group decreased 3.8 points and sham treatment group decreased 30 points, are above the previous published clinically important change threshold of 1.04, which may represent general symptom severity improvements in both groups
      • Ozyürekoğlu T.
      • McCabe S.J.
      • Goldsmith L.J.
      • LaJoie A.S.
      The minimal clinically important difference of the carpal tunnel syndrome symptom severity scale.
      (Fig. 7).
      Individuals in the CLS treatment group also demonstrated significant improvements in numbness (Fig. 4), tingling (Fig. 5), and pinch strength (Fig. 6) at 6 weeks after treatment. Although these improvements were not observed in the sham treatment group (Table 2), only tingling showed a significant group × time interaction; numbness and pinch strength showed significant overall effect of time. Interestingly, there was a statistically significant improvement in the median sensory distal latency at 6 weeks in the sham treatment group; however, the distal latency remained significantly prolonged (greater than 3.6 ms)
      American Association of Electrodiagnostic Medicine, American Academy of Neurology, and American Academy of Physical Medicine and Rehabilitation
      Practice parameter for electrodiagnostic studies in carpal tunnel syndrome: summary statement.
      and would still be classified as median mononeuropathy at both time points. Although we hypothesized improvements in nerve conduction (sensory and motor distal latencies and amplitudes) and pain (wrist and hand) in the CLS treatment group, no statistically significant improvements were observed. More studies should be conducted to understand the durability of changes and long-term consequences of the CLS treatment.
      This study was limited by a high dropout rate resulting in a relatively small sample size. We surmise that the high dropout rate may be due to several factors, including frequency of treatments and difficulty adhering to regimen, lack of response to prescribed treatment, or desire to seek more invasive treatments such as injection or surgical release. Some participants that dropped out of the study reported that it was not secondary to discomfort from the treatment nor an increase in pain. In those participants who completed the study, the compliance rate was relatively high in both groups (97% in the sham group and 87% in the CLS treatment group). No significant demographic differences were observed, including dropout rates, between groups. This may represent that the study sample included particularly motivated individuals. Follow-up studies should include potential confounding factors such as nonsteroidal anti-inflammatory medication and orthosis usage, which were not controlled for in this study. Previous studies have not shown nonsteroidal anti-inflammatory medication as an effective treatment for CTS.
      • Chang M.H.
      • Chiang H.T.
      • Lee S.S.
      • Ger L.P.
      • Lo Y.K.
      Oral drug of choice in carpal tunnel syndrome.
      Based on this double-blinded randomized study, it can be suggested that patients may improve symptoms of CTS using a targeted self-treatment with myofascial manipulation whereas patients treated with a sham self-treatment of massage did not. This may delay more invasive treatments, such as injections or surgical release of the carpal ligament. However, there was no significant change in nerve conduction studies after 6 weeks of self-administered myofascial stretching program. Long-term follow-up to monitor electrodiagnostic changes and symptoms is needed.

      Conclusion

      This study is the first double-blinded, randomized control study to evaluate the effectiveness of myofascial self-stretching treatment of CTS. The results suggest that a self-myofascial stretching of carpal ligament can be a conservative and relatively easy treatment option for patients with CTS. Individuals in the CLS treatment group showed improvements across multiple measures (numbness, tingling, pinch strength, sensory amplitude, and SSS), whereas the sham treatment group only showed improvements in sensory distal latency. Manual manipulation provided through a trained health care professional may be more expensive, time-consuming, and less convenient for a patient than self-treatment administered at home. Larger studies with longer follow-up and comparative studies with other modalities such as therapies and orthosis may be performed to definitively confirm the effectiveness of this treatment option.

      Acknowledgments

      The authors would like to acknowledge Michael Prutton, research assistant, for his assistance with the manuscript preparation.
      This was not a funded study.

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