Carpal tunnel syndrome caused by the entrapment of a bifid Lanz IIIA Type anatomical variant of median nerve: A case report and systematic literature review

Carpal tunnel syndrome caused by tophi deposited under the epineurium of the median nerve: A case report

Introduction

Usually caused by compression of the wrist's median nerve, carpal tunnel syndrome (CTS) is one of the most common types of peripheral neuropathy. Tophi deposited under the epineurium of the median nerve compress the median nerve, leading to CTS, which is very rare.

Case presentation

We report a 64-year-old man with a history of tophaceous gout who presented with typical CTS symptoms and was admitted to our hospital. A physical examination revealed swelling over the right volar aspect of the carpal region, and he was unable to flex due to subcutaneous rigidity. Tinel's sign and Phalen's maneuver were positive. Electrophysiological studies confirmed the diagnosis of CTS. A carpal tunnel release and surgery to remove the gouty tophus of the right wrist were performed when serum uric acid levels were within normal limits (5.8 mg/dl). During the operation, tophi deposited under the epineurium of the median nerve were found, and the tophi were completely removed. Operative findings confirmed the diagnosis of CTS due to gout. The patient recovered uneventfully without signs of recurrence of gout and CTS symptoms during a 1-year follow-up period.

Conclusion

A gouty tophus is an uncommon cause of CTS, and CTS may be caused by gouty tophi if there is evidence of extrinsic compression of the median nerve or symptoms emanating from the carpal tunnel.

Bifid median nerve as an anatomical risk factor for carpal tunnel syndrome: A meta-analysis

As the median nerve enters the carpal tunnel, it is a single nerve that soon bifurcates into lateral and medial branches into the hand. If the bifurcation is proximal to the carpel tunnel, a bifid median nerve results. Carpal tunnel syndrome is often associated with a bifid median nerve with or without a persistent median artery. Individual keywords and MeSH phrases were searched in the Google Scholar, SCOPUS, and PubMed databases. Full texts were then collected and assessed for suitability. The prevalence of bifid median nerve at the wrist joint in normal and carpal tunnel syndrome wrists (pre-canal part) and the mean difference between groups were recorded. Only human data were used to test the findings. The pooled odds ratio (with minimal heterogeneity) was 1.50 [1.17-1.93, 95% CI]. The bifid median nerve cross-sectional area (CSA) was significantly greater than that of a solitary median nerve in normal wrists. The mean difference in CSA between the two was 1.50 mm² [0.56-2.45 mm² , 95% CI] without heterogeneity (i²  = 0). Sex and laterality distributions scarcely differed between the two types of wrists. Owing to the insufficiency of data, the relationships with mean height and weight were not examined. There was a 50% greater incidence of bifid median nerves in carpal tunnel syndrome patients than in normal subjects. A bifid median nerve increases the mean CSA at the wrist joint by 1.5 mm² . These findings indicate that the bifid median nerve is an anatomical risk factor for carpal tunnel syndrome. This article is protected by copyright. All rights reserved.