The thenar index: an objective assessment and classification of thenar atrophy based on static hand imprints and clinical implications

Preoperative Evaluation of Thenar Muscles in Carpal Tunnel Syndrome by Ultrasonography

This article aims to evaluate the usefulness of ultrasonography for the measurement of thenar muscles in carpal tunnel syndrome (CTS). A total of 85 patients with CTS who had a carpal tunnel release procedure were included in this study. The transducer was applied onto the palmar surface of the hand perpendicularly to the longitudinal axis of the first metacarpal bone. Thenar atrophy was evaluated visually and classified using the visual grading scale. A nerve conduction test was performed and classified according to the electrophysiological severity scale. This technique is more precise than visual evaluation because it is a quantitative assessment.

Electrophysiological assessment of carpal tunnel syndrome in elderly patients: one-year follow-up study

PURPOSE

To objectively assess elderly patients with carpal tunnel syndrome to characterize their preoperative severity and prognosis after carpal tunnel release using a electrophysiological severity scale.

METHODS

Electrophysiologic assessment was performed preoperatively and 1 year postoperatively following carpal tunnel release in 112 hands in patients over 70 years of age prospectively by the use of the following electrophysiological severity scale: stage 1, normal distal motor latency (DML) and normal sensory conduction velocity (SCV); stage 2, DML ≥ 4.5 milliseconds and normal SCV; stage 3, DML ≥ 4.5 milliseconds and SCV < 40.0 m/s; stage 4, DML ≥ 4.5 milliseconds and non-measurable SCV; stage 5; non-measurable DML and non-measurable SCV. Additionally, the outcomes of clinical symptoms of pain, nocturnal symptoms, numbness, loss of 2-point discrimination in the median nerve territory, and thenar atrophy were assessed.

RESULTS

The mean age of patients was 77 years at the time of the operation. Preoperatively, the most common severity was stage 5 (70 of 112 hands, 63%), and clustering stage 4 and 5 together as severe resulted in 103 hands (92%). One year postoperatively, 97 hands (87%) demonstrated at least one stage improvement, and the numbers of mild (stage 1 or 2) increased from 3 (3%) to 45 hands (40%). Parallel with the electrophysiological improvement, pain and nocturnal symptoms resolved in 17 of 17 hands and 11 of 11 hands, respectively, in whom they were present preoperatively. Numbness, loss of 2-point discrimination, and thenar atrophy demonstrated the improvement in 96 of 112 (86%) hands, in 58 of 112 (52%) hands, and in 80 of 96 (83%) hands.

CONCLUSIONS

We observed electrophysiologic improvement in 86% of elderly patients following carpal tunnel release. Electrophysiologic outcomes correlated with improvement in clinical variables.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Delayed electrophysiological recovery after carpal tunnel release for advanced carpal tunnel syndrome: a two-year follow-up study

Advanced carpal tunnel syndrome presents severe thenar atrophy with the absence of electrophysiological motor and sensory responses. Because of severity of these conditions, a substantial period of recovery after surgery is required before improvement becomes evident. In this electrophysiological-based study, the reappearance of distal motor latency (DML) at the abductor pollicis brevis and/or sensory nerve conduction velocity (SCV) after wrist stimulation were evaluated 1 year and 2 years after carpal tunnel release . To categorize outcomes, the following grading scale was used: stage I, normal DML and SCV; stage II, DML ≥ 4.5 ms and normal SCV; stage III, DML ≥ 4.5 ms and SCV < 40.0 ms; stage IV, DML ≥ 4.5 ms and nonmeasurable SCV; stage V: nonmeasurable DML and SCV. The authors found measurable DML and/or SCV and significant improvement both 1 year and 2 years postoperatively. Furthermore, the percentage of patients who recovered to the extent that they presented as mild carpal tunnel syndrome (stage I or II) increased significantly. They conclude that electrophysiological assessment of DML and SCV of advanced carpal tunnel syndrome using the above grading scale was effective as an objective evaluation tool of recovery after carpal tunnel release.