Nerve conduction studies and EMG in carpal tunnel syndrome: Do they add value?

Relative Motion of the Connective Tissue in Carpal Tunnel Syndrome: The Relation with Disease Severity and Clinical Outcome

Excursion of the median nerve and the surrounding subsynovial connective tissue (SSCT) is diminished in patients with carpal tunnel syndrome (CTS). This study sought to determine if SSCT excursion could be utilized to predict surgical outcome. Idiopathic CTS patients were reviewed with ultrasound and electrodiagnostic tests at baseline. A speckle tracking algorithm was used to determine SSCT relative to tendon motion (shear index). Analysis of variance tests were used to compare SSCT motion with disease severity at baseline. Adjusted linear regressions were used to test the association with patient-reported outcome. A total of 90 CTS patients were analyzed and found to have an average shear index of 79% (95% confidence interval: 76.3%-81.6%). SSCT motion was lower in CTS patients with increasing electrophysiological severity (p = 0.0475). There was no significant association of pre-operative SSCT motion with symptomatic improvement (p = 0.268). Overall, SSCT motion is decreased in CTS patients, but exhibits limited correlation with clinical severity.

Development of In-Office Laryngeal Nerve Conduction Studies: Computed Tomography and Cadaveric Study

OBJECTIVES/HYPOTHESIS

In-office recurrent laryngeal nerve conduction studies (NCSs) are a technique that can potentially provide information about laryngeal innervation. NCS is essential in the management of other neuropathies including carpal tunnel syndrome and spinal cord injury. We hypothesize that laryngeal NCS may have similar utility in managing patients with vocal fold paralysis, atrophy, and neurodegenerative disease. NCSs are technically challenging because they require transcervical stimulation of the recurrent laryngeal nerve (RLN). This study combines radiographic data with cadaveric dissection to describe the anatomic parameters for optimal RLN stimulation.

STUDY DESIGN

Radiographic and Cadaveric Study.

METHODS

Fifty computed tomography scans were reviewed to determine the dimensions for ideal needle electrode placement. These values were compared to measurements from 12 fresh human cadaveric neck dissections. Ultrasound imaging was utilized in select cases. The neck was dissected to assess the accuracy of electrode placement.

RESULTS

Radiographically, the mean transcervical depth to the RLN was 33.2 mm ± 8.3 mm in males versus 29.4 mm ± 9.4 mm in females. The working space between the lateral trachea and carotid artery was 15.3 mm ± 3.6 mm on the right and 14.1 mm ± 2.9 mm on the left. After placement of stimulating electrodes into the cadaveric neck, the electrode tips were consistently within 8 mm of the RLN. Ultrasound guidance improved placement accuracy of the stimulating electrode.

CONCLUSIONS

Laryngeal NCSs can provide detailed and objective information about laryngeal innervation that could dramatically improve the management of various neuropathies. In-office NCSs require technical precision, and this study describes anatomic factors that may affect the feasibility of performing this technique.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:1566-1569, 2021.

Associations Between Insurance Type and the Presentation of Cubital Tunnel Syndrome

PURPOSE

In the setting of cubital tunnel syndrome (CuTS), delays in diagnosis can have permanent effects including sensory loss, muscle weakness, and atrophy of intrinsic hand muscles. This study sought to evaluate the association of insurance type on the severity of CuTS. We hypothesized that publicly insured patients will have delayed presentation to the orthopedics office and more significant condition severity.

METHODS

A retrospective chart review was conducted for all patients evaluated for CuTS between December 2013 and January 2018 by a fellowship-trained orthopedic hand and upper extremity surgeon at our tertiary referral center. Insurance type, demographics, and measures of CuTS severity were compared.

RESULTS

Patients presenting with CuTS of severity greater than or equal to McGowan stage 2A had 4.4-fold greater odds of being publicly insured than privately. Motor and sensory velocities across the elbow were diminished at 42.2 ± 13.9m/s and 33.0 ± 20.8m/s in publicly insured patients compared with 47.5 ± 11.3 m/s and 47.0 ± 16.4m/s for privately insured patients. The same trend was present for motor and sensory amplitudes at 6.6 ± 3.8 μV and 16.9 ± 17.8 μV in publicly insured patients compared with 8.5 ± 3.2 μV and 26.0 ± 18.9 μV in privately insured patients. Patients with public insurance were symptomatic for longer prior to their initial visit, on average 82.8 ± 86.5 weeks, compared with 42.4 ± 58.9 weeks for patients with private insurance.

CONCLUSIONS

Publicly insured patients were significantly delayed in seeing an orthopedic surgeon for evaluation and treatment of CuTS and presented with more severe clinical and electrodiagnostic findings compared with privately insured patients. These findings suggest that insurance type, among other socioeconomic factors, may be a barrier to CuTS care.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prevalence IV.

A new method to define cutoff values in nerve conduction studies for carpal tunnel syndrome considering the presence of false-positive cases

BACKGROUND

Nerve conduction studies (NCS) are useful tools for diagnosing carpal tunnel syndrome (CTS). Establishing the normal values is the first step required for utilizing NCS for diagnosis. Previous epidemiological studies demonstrated the presence of fairly large number of false-positive subjects regarding NCS among control population, which has not been properly considered in past studies. This study proposed a new method to address this issue.

METHODS

Non-diabetic 144 CTS patients were retrospectively enrolled using clinically defined inclusion criteria. Controls consisted of 73 age-matched volunteers without hand symptoms. Six NCS parameters were evaluated including peak-latency difference by the thumb method (thumbdif) and that by the ring-finger method (ringdif). The Youden index of the receiver operator characteristic curve was used both to judge the sensitivity of a parameter and to identify false-positive cases that were thought to have subclinical median neuropathy at the wrist. The linear function of six parameters was constructed, and the coefficient for each parameter was variously changed.

RESULTS

When the Youden index took on the maximum value, seven control subjects (10%) were identified as false-positive and were excluded from the calculation of normal values. The most sensitive parameter before exclusion was thumbdif, whereas ringdif became the most sensitive after exclusion. The cut-off value for ringdif was 1.15 ms before exclusion, but was 0.37 ms after exclusion.

CONCLUSION

This method can be widely applied to solve the statistical problem when the gold standard is lacking, and the outside reference standard is not completely reliable.

Electrophysiological responsiveness and clinical outcomes of local corticosteroid injection in the treatment of carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common mononeuropathy caused by entrapment of the median nerve at the wrist. Common treatment options for CTS include oral analgesics, splinting, hand therapy, local injections with steroids or surgery. OBJECTIVE The aim of the present study was to assess the short-term clinical and electrophysiological outcomes of local corticosteroid injection (LCI) in patients with symptomatic CTS. METHODS Electrophysiological parameters were evaluated before and three months after LCI. Moreover, the Numeric Rating Scale (NRS), the Boston Symptom Severity Scale (SSS) and the Functional Status Scale (FSS) were administered before and after the injection. A mixture of 1 mL (40 mg) of methylprednisolone and 1 mL of 0.5% bupivacaine were injected blindly on the volar side of the forearm between the tendons of the radial carpal flexor muscle and long palmar muscle. RESULTS A total of 25 patients (45 hands) were enrolled in the study. Twenty women and five men with a mean age of 49.28 ± 11.37 years were included. A statistically significant difference was noted for improvement of sensory conduction velocities, sensory peak latency, and motor distal latency (p = 0.001) after LCI. A significant difference was recorded between pre- and post-injection for NRS, SSS and FSS scores (p = 0.000). CONCLUSION Local corticosteroid injection for CTS provides a short-term improvement in neurophysiological and clinical outcomes such as pain intensity, symptom severity and functional ability.

A Tablet-Based App for Carpal Tunnel Syndrome Screening: Diagnostic Case-Control Study

BACKGROUND

Carpal tunnel syndrome (CTS), the most common neuropathy, is caused by a compression of the median nerve in the carpal tunnel and is related to aging. The initial symptom is numbness and pain of the median nerve distributed in the hand area, while thenar muscle atrophy occurs in advanced stages. This atrophy causes failure of thumb motion and results in clumsiness; even after surgery, thenar atrophy does not recover for an extended period. Medical examination and electrophysiological testing are useful to diagnose CTS; however, visits to the doctor tend to be delayed because patients neglect the symptom of numbness in the hand. To avoid thenar atrophy-related clumsiness, early detection of CTS is important.

OBJECTIVE

To establish a CTS screening system without medical examination, we have developed a tablet-based CTS detection system, focusing on movement of the thumb in CTS patients; we examined the accuracy of this screening system.

METHODS

A total of 22 female CTS patients, involving 29 hands, and 11 female non-CTS participants were recruited. The diagnosis of CTS was made by hand surgeons based on electrophysiological testing. We developed an iPad-based app that recorded the speed and timing of thumb movements while playing a short game. A support vector machine (SVM) learning algorithm was then used by comparing the thumb movements in each direction among CTS and non-CTS groups with leave-one-out cross-validation; with this, we conducted screening for CTS in real time.

RESULTS

The maximum speed of thumb movements between CTS and non-CTS groups in each direction did not show any statistically significant difference. The CTS group showed significantly slower average thumb movement speed in the 3 and 6 o'clock directions (P=.03 and P=.005, respectively). The CTS group also took a significantly longer time to reach the points in the 2, 3, 4, 5, 6, 8, 9, and 11 o'clock directions (P<.05). Cross-validation revealed that 27 of 29 CTS hands (93%) were classified as having CTS, while 2 of 29 CTS hands (7%) did not have CTS. CTS and non-CTS were classified with 93% sensitivity and 73% specificity.

CONCLUSIONS

Our newly developed app could classify disturbance of thumb opposition movement and could be useful as a screening test for CTS patients. Outside of the clinic, this app might be able to detect middle-to-severe-stage CTS and prompt these patients to visit a hand surgery specialist; this may also lead to medical cost-savings.

Recent Advances in the Understanding and Management of Carpal Tunnel Syndrome: a Comprehensive Review

PURPOSE OF REVIEW

Carpal tunnel syndrome (CTS) is an entrapment neuropathy that involves the compression of the median nerve at the wrist and is considered the most common of all focal entrapment mononeuropathies. CTS makes up 90% of all entrapment neuropathies diagnosed in the USA and affects millions of Americans.

RECENT FINDINGS

Age and gender likely play a role in the development of CTS, but additional studies may further elucidate these associations. Of known associated risk factors, diabetes mellitus seems to have the greatest association with CTS. One of the most commonly reported symptoms in CTS is a "pins-and-needles" sensation in the first three fingers and nocturnal burning pain that is relieved with activity upon waking. Treatment for CTS is variable depending on the severity of symptoms. Conservative management of CTS is usually considered first-line therapy. In cases of severe sensory or motor deficit, injection therapy or ultimately surgery may then be considered. Still CTS is often difficult to treat and may be reoccurring. Novel treatment modalities such as laser and shockwave therapy have demonstrated variable efficacy though further studies are needed to assess for safety and effect. Given the unknown and potentially complex etiology of CTS, further studies are needed to explore combinations of diagnostic and therapeutic modalities.