Abstract
BACKGROUND: Electromyographers are frequently confronted by anomalous innervations and some may challenge the interpretation of nerve conduction studies (NCS). Reports of 2 or more anomalous innervations in the same patient are rare. I describe the NCS in a patient referred for an evaluation of carpal tunnel syndrome (CTS) who was found to harbor a combined Martin-Gruber anastomosis (MGA) and complete Riché-Cannieu anastomosis (RCA). CASE PRESENTATION: This 31-year-old man was referred for electrodiagnostic studies following several months of intermittent right hand numbness and tingling. Clinical exam was normal. Median and ulnar motor NCS showed evidence of a combined MGA and complete RCA. Prolongation of the median sensory peak latency and median-2nd lumbrical motor distal latency provided the electrodiagnostic clues in support of CTS. DISCUSSION: In summary, this report describes the rare occurrence of a combined MGA and complete RCA in a patient with CTS, demonstrates how NCS can sort out this dual anomaly, and discusses the electrodiagnostic and cadaveric literature on the topic.