Median nerve superficial to the transverse carpal ligament

Recurrent carpal tunnel syndrome occurs in up to 12% of cases after carpal tunnel release. Recurrent carpal tunnel syndrome is defined as recurrence of classic symptoms confirmed by electrodiagnostic studies after a symptom-free interval of a minimum of 6 months, as opposed to persistent carpal tunnel syndrome, where a symptom-free interval never occurs after carpal tunnel release, which is attributed to incomplete release of the transverse carpal ligament. The most common causes of recurrent carpal tunnel syndrome requiring reoperation are incomplete release of the transverse carpal ligament and scarring of the median nerve to the surrounding structures. Surgical exploration, release of the reconstituted transverse carpal ligament, and freeing of the median nerve from constricting scar will usually result in symptom relief. The authors describe an unusual presentation of recurrent carpal tunnel syndrome with healing of the transverse carpal ligament dorsal to the median nerve, trapping the median nerve in the subcutaneous tissue. Hand surgeons must be aware of this anomalous location when performing revision carpal tunnel release. The surgeon must locate the median nerve proximally in normal tissue before proceeding distally to avoid iatrogenic injury during revision carpal tunnel release.