Iatrogenic median and ulnar nerve injuries during carpal tunnel release: clinical, electrodiagnostic, and ultrasound features in 12 patients. Patient series.

Background: Nerve injuries during carpal tunnel release (CTR) are rare. Electrodiagnostic (EDX) and ultrasound (US) studies may be helpful in evaluating iatrogenic nerve injuries during CTR.
Observations: Nine patients sustained a median nerve injury, and 3 patients experienced ulnar nerve damage. Decreased sensation occurred in 11 patients, and dysesthesia occurred in 1 patient. Abductor pollicis brevis (APB) weakness occurred in all patients with median nerve injury. Of the 9 patients with median nerve injury, the compound muscle action potentials (CMAPs) of the APB and sensory nerve action potentials (SNAPs) of the 2nd or 3rd digit were not recordable in 6 and 5 patients, respectively. Of the 3 patients sustaining ulnar nerve injuries, the CMAPs of the abductor digiti minimi (ADM) and SNAPs of the 5th digit were not recordable in 1 patient; 2 patients showed prolonged latency and decreased amplitude of CMAPs/SNAPs. US studies of 8 patients with a median nerve injury showed a neuroma within the carpal tunnel. One patient underwent surgical repair urgently, and 6 did so after variable intervals.
Lessons: Surgeons should be cognizant of nerve injuries during CTR. EDX and US studies are useful in evaluating iatrogenic nerve injuries during CTR.