Evaluation of Splint and Exercise Interventions for Carpal Tunnel Syndrome: Insights from Ultrasonographic Measurements

Introduction

Carpal tunnel syndrome (CTS) is caused by compression of the median nerve at the wrist in the carpal tunnel and accounts for 90% of all neuropathies. The condition typically causes symptoms in the hand but can also affect the forearm, thumb, index finger, and middle finger [1]. CTS symptoms include paraesthesia and pain in the hand, which is innervated by the median nerve. In cases of severe impairment, there is a potential for weakness and atrophy to occur in the median-innervated thenar muscles [2,3]. CTS is typically categorized as mild, moderate, or severe, according to the severity of symptoms and the results of clinical and electrophysiological examinations. In the treatment of CTS, a conservative approach is recommended for mild and moderate cases. The treatment plan can include the use of wrist splints, neurodynamic exercises, therapeutic ultrasound, and steroid injections. In cases of significant severity, surgical intervention can be the preferred course of action [2,4].

CTS often accompanies diabetes and obesity, but repetitive wrist movements can also cause CTS [5]. CTS affects an estimated 5% of the general population, with a higher prevalence in women than in men [6]. The typical diagnostic approach for CTS involves a physical examination. Ultrasonography (USG) is a valuable tool for assessing all musculoskeletal conditions [7] and is an important tool for assessment of the median nerve’s cross-sectional area enlargement at the wrist; it is increasingly used in clinical practice to detect nerve variations, cysts, and other anatomical abnormalities [8–10].

Studies commonly consider a cross-sectional area of 9 to 10 mm2 as the standard measurement for diagnosis [11,12]. The considerable variability in cross-sectional area measurements of the median nerve was influenced by diverse study conditions, measurement techniques, and individual factors, such as age, weight, and sex. The most common conservative approach in clinical settings for treating CTS is the splinting of the wrist, in an attempt to restrict wrist movements, particularly flexion, to minimize pressure within the carpal tunnel. On the other hand, physical exercise, in terms of neurodynamic mobilization exercises and tendon gliding exercises, plays a crucial role in sustaining tissue nutrition and enhancing nerve conduction by alleviating pressure and reducing edema and adhesions [13].

Numerous studies have investigated the effectiveness of splinting and physical exercises in treating CTS, yet a consensus on the optimal therapeutic approach remains elusive [14,15]. In this study, we aimed to evaluate and compare the efficacy of splint usage and physical exercises in the management of CTS and used a variety of assessment tools for a comprehensive analysis.

Material and Methods

Study Parameters

ULTRASONOGRAPHY: All patients were evaluated by an ultrasound examination of the wrist and the region 10 cm above the wrist using USG (Figures 1, 2). The USG evaluations of both hand extremities of all patients were performed and interpreted by the same radiologist, who was experienced in the viewing of wrist and related anatomic structures [19].

DYNAMOMETER: The standardized grip strength test with a dynamometer, as described in the guidelines of the American Society of Hand Therapists, has been found to have high validity and reliability in many studies, and is therefore considered the criterion standard. In the present study, a Jamar hand dynamometer was used to measure the hand grip strength [20].

A finger pinch meter was used to measure the baseline finger grip strength. Measurements were done with patients in the standard sitting position recommended by the American Society of Hand Therapists, with the shoulder in adduction and neutral rotation, the elbow in 90° flexion, the forearm in mid-rotation and supported, and the wrist in a neutral position. Three consecutive measurements were made for hand grip and finger grip strengths, with a 1-min break between each measurement, and the averages were recorded [21].

VAS SCORE: The VAS is presented as a horizontal or vertical line chart with 2 end identifiers that range from no pain to unbearable pain. The patient selects the most appropriate pain degree, depending on the severity of symptoms [22].

LANSS SCORE: The LANSS was used in this study to determine whether pain was attributable to nerve damage and to distinguish between neuropathic and nociceptive pain. Widely utilized in clinical settings, the LANSS neuropathic pain scale consists of 7 items designed to assess neuropathic pain. A LANSS score exceeding 12 indicates an increased likelihood of neuropathic pain [23].

Q-DASH SCORE: The Q-DASH consists of 11 items from the original 30-item DASH questionnaire. It aims to evaluate physical function and symptoms in patients with musculoskeletal disorders of the upper limbs. The scale scores are calculated, ranging from 0 (no disability) to 100 (most severe disability) [24].

SF-36 SCORE: The patients were evaluated using the Turkish-validated version of the SF-36 survey. The components of the SF-36 are divided into 8 scales: physical functioning, role limitations due to physical health, bodily pain, mental health, vitality, social functioning, role limitations due to emotional problems, and general health. The physical component summary and mental component summary are scored according to a standardized scoring protocol [25].

STATISTICAL ANALYSIS:

We used G*Power software, version 3.1.9.7, to calculate the optimal sample size and power. With a power of 80%, a 2-sided alpha level of 0.05, and a 1: 1 allocation ratio, we calculated the required sample size to be 20 patients per treatment group. We enrolled a total of 44 patients in the study. The Cohen’s d was used for the determination of the effect size and was interpreted based on Cohen [26], as 0.21–0.49=small effect size; 0.50–0.79=medium effect size; and >0.80=large effect size.

Analyzes were performed with Number Cruncher Statistical System 11 (2017 Statistical Software) and MedCalc Statistical Software version 18 (Medcalc Software, Ostend, Belgium; available at http://www.medcalc.org; 2018). Chi-square analysis was used for relationships between categorical variables. The independent-sample t test was performed to compare 2 groups of continuous independent variables with normal distribution. For dependent variables with normal distribution, the dependent-sample t test was performed to compare the 2 groups. A P value of <0.05 was considered statistically significant.

Results

The baseline patient characteristics were comparable between the 2 groups (Table 1). All patients received the treatment as allocated and adhered to the prescribed exercise program and splinting regime. In our study, 44 patients (39 women, 5 men) were evaluated within 6 months of the study period. The average age was 49.82±9.28 years, and average body mass index was 30.66±4.21 kg/m2.

Table 2 compares USG and dynamometer variables between the groups at the 2 follow-up time points: the first month and third month after starting treatment. The assessment includes measurements at the wrist level and 10 cm proximal to the wrist, with values presented as mean±SD and median (min–max). All P values indicated no statistically significant differences between the 2 groups for USG variables at the first and third month time points (P=0.747, P=0.391, respectively). The comparison of dynamometer evaluation scores between the groups at different follow-up times did not yield statistically significant differences between the groups (P=0.329), whereas intra-group measurements within the control group showed statistical significance of P<0.05, compared with the baseline.

Table 3 presents the comparison of scores from the questionnaires between the study and control groups at different measurement time points and includes effect size. The VAS scores during activity and resting are reported as mean±SD and median (min–max). No statistically significant differences were found between the groups across the 3 measurements. The comparison of LANSS scores between the groups (P=0.923, P=0.968, P=0.546, Cohen’s d=−0.039) at different follow-up time points yielded no significant difference.

There was no statistically significant difference in the Q-DASH scores between the groups (P=0.767, P=1.000, P=0.532, Cohen’s d=−0.320, respectively, for the evaluation time points) at the end of the treatment. SF-36 comparisons were also not significantly different between the study and control groups in terms of the physical component summary and mental component summary.

Discussion

CTS is the most common entrapment neuropathy, with a lifetime surgical prevalence of 3%. It is the most common orthopedic surgery for upper limb disorders. CTS surgery costs an estimated $2 billion per year in the United States [27]. We must explore alternative management pathways and evaluate current treatment modalities, given the escalating demand for appropriate CTS management and the increasing burden on the healthcare system. Median nerve entrapment has been identified in CTS by intraoperative, ultrasound, and magnetic resonance imaging (MRI) studies [28–30]. Intraneural edema has the potential to cause irreversible fibrotic changes to the median nerve, with the possibility of severe CTS developing over time [31]. The use of splinting and exercise has been shown to reduce intraneural edema and can potentially inhibit the progression of CTS [32].

In our study, we compared the effectiveness of using a splint in combination with an exercise program with that of exercise alone in patients with CTS. Various assessment tools, including USG, dynamometer, universal quality of life, and pain scales, showed similar and comparable results between the 2 groups. A multicenter, randomized controlled trial evaluated 105 patients with CTS on a waiting list for surgical consultation [15]. While the study group received a combination of training, splinting, and nerve and tendon gliding exercises, the control group received no intervention. After the 24-week follow-up period, the conversion to surgery rate was 59% in the experimental group and 80% in the control group, indicating that a therapist-led pathway may have reduced the necessity for carpal tunnel surgery. Although our study did not include data on the transition to surgical management, the comparable outcomes in the study and control groups suggest that a well-designed and focused exercise program alone can produce efficient results, comparable to the addition of splinting to physical exercise.

The other non-surgical options available for the treatment of CTS include therapeutic ultrasound, extracorporeal shock wave therapy, medication, such as steroids and non-steroidal anti-inflammatory drugs, vitamins, and complementary therapies [33–35]. Additionally, it has been documented that the administration of ultrasound-guided injections in conjunction with the use of dynamic ultrasound can facilitate the alleviation of discomfort without causing any damage to the median nerve. This approach can potentially diminish the necessity for surgical intervention [36]. The intensity and duration of the intervention can vary considerably, with duration ranging from a few days to several months. Furthermore, the therapy can be self-administered or provided by trained professionals. The findings of our study are consistent with those of previous research that yielded conflicting results regarding the addition of splint immobilization to a well-designed exercise program. The Cochrane Review by Page et al concluded that the evidence base for the use of exercise and mobilization interventions for CTS is limited. The authors therefore suggest that consideration of treatment options should be based on the preferences of clinicians and patients [37]. In their comprehensive review of 16 studies, the authors also concluded that further research with high evidence quality is required to evaluate functional outcomes, quality of life, neurophysiologic parameters, and adverse effects. Furthermore, concerns have been raised regarding the long-term sustainability and maintenance of these treatments. In the follow-up evaluations conducted in our study groups at various time points, consistent results were observed in the comparison of study variables during all follow-up visits.

Conversely, Ashworth’s findings indicated that nerve and tendon gliding exercises were less efficacious than splint immobilization in alleviating symptoms and enhancing and regaining hand function [38]. A multidisciplinary treatment guideline agrees that the recommended duration of splint use is between 4 and 12 weeks and that the splint should be worn either at night only or both at night and during the day, depending on the patient’s level of aggravating activity [13]. In our study, patients were given splints day and night for the first 10 days, and then only at night for the next 20 days. However, results can vary with longer periods of splint use, depending on the severity of the symptoms and the duration of the condition. In an MRI study evaluating the effects of exercise and splint use on median nerve intraneuronal edema, patients were randomized to either a splint or exercise group [39]. The results showed an approximately 11% reduction in signal intensity after 1 week of intervention in both groups.

In our study, while we did not observe a difference between the combined treatment and exercise-only groups, there was a consistent improvement in the cross-sectional area of the median nerve at the wrist in the splint and exercise group during the follow-up period. However, USG results remained similar in the exercise-only group, suggesting that the use of the splint may have contributed to a direct or placebo effect.

It is worth noting that although not reaching statistical significance, the dynamometer assessments of the splint and exercise group showed an increase in grip strength during the follow-up period, whereas the exercise-only group had significantly reduced measurements. An observational study of patients with electrophysiologically proven CTS reported that 34% of patients with idiopathic CTS experienced complete resolution of symptoms within 6 months of diagnosis without treatment [40]. Our study focused on patients who had a diagnosis of CTS and who did not experience a remission of symptoms during the waiting period for allocation to a treatment modality.

The study has several limitations, including a relatively short follow-up period and a limited sample size. In addition, the frequency with which patients used non-prescribed painkillers during the study period was not assessed. Despite these limitations, the strength of the study lies in the use of different assessment tools that produced consistent results. In addition, the study and control groups had a homogeneous distribution, and patient randomization was based on a consensus decision between doctor and patient.

The increasing prevalence of CTS is contributing to a growing demand for outpatient physiotherapy clinics, placing an additional burden on the healthcare system. This increase is leading to congestion and increased waiting times for appointments. Due to the significant changes brought about by the COVID-19 pandemic and the limitations of face-to-face interventions, the British Association for Plastics, Reconstructive and Aesthetic Surgeons, the British Society for Surgery of the Hand, and the British Association of Hand Therapy recommended that patients be directed to online resources for hand exercises and therapy [41]. This measure aims to prevent non-emergency hand and wrist care from being interrupted during the pandemic. Although we know that exercise is an effective treatment for almost all musculoskeletal conditions, exercise habits and patient continuity are barriers to treatment. Therefore, we believe that exercise protocols are beneficial, in addition to splinting, physiotherapy, injections, and even surgical interventions.

Conclusions

Our comprehensive evaluation using a variety of assessment tools to compare treatment efficacy between groups showed similar results when a splint was incorporated into the exercise routine. Our results underline the efficacy of regular exercise in the management of CTS and provide additional insight into the effectiveness of self-administered, online-based exercise programs for patients. Future studies with longer follow-up periods and evaluation of different exercises will contribute to the literature.