Damage to sensory fibers in a martin-gruber anomaly after biceps tendon repair.

A patient with a distal biceps tendon rupture developed ulnar distribution sensory loss after surgical repair using the modified two-incision Boyd and Anderson technique. Electrodiagnosis demonstrated an absent ulnar sensory response but no clinical or electrodiagnostic evidence of ulnar neuropathy at the elbow. Nerve conduction studies demonstrated an anastomosis between the median and ulnar nerves (Martin-Gruber anomaly). Ulnar sensory fibers were probably damaged as they coursed with the median nerve at the elbow as a component of the innervation anomaly. This case documents the presence of ulnar sensory fibers as part of a Martin-Gruber anomaly.