Electrodiagnostic Evidence of Berrettini Anastomosis.

PURPOSE Cadaveric palmar dissections reveal an ulnar sensory crossover (Berrettini anastomosis) to the third common palmar nerve so frequently that this crossover is considered a normal part of the anatomy. No literature has documented electrophysiologic evidence of the Berrettini anastomosis (BA). Presentation of third digit ulnar sensory crossover waveforms. METHODS Retrospective chart review case series. Clinical office. Nerve conduction waveforms and data. RESULTS Ulnar stimulation sensory crossover waveforms to digit three consistent with BA are presented. CONCLUSIONS Third digit BA is measurable in routine electrodiagnostic nerve conduction study in some patients. The observed BA latency is the same and the amplitude is smaller (25% to 33%) than the ulnar sensory response. The clinical significance of the BA sensory response is unclear. The presence of a BA in severe carpal tunnel syndrome may give a small amplitude normal latency sensory response that could be misinterpreted and lead to a false negative result.