Proximal Martin-Gruber anastomosis mimicking ulnar neuropathy at the elbow.
We present a case of Martin-Gruber anastomosis (MGA) mimicking conduction block between the above- and below-elbow sites of ulnar nerve stimulation. We review the anatomical and electrophysiological literature on this subject and discuss its clinical implications. The potential for a MGA to occur very proximally in the forearm and thus mimic ulnar neuropathy at the elbow is underrecognized. We recommend that a check for MGA be performed on all patients with an apparent conduction block at the elbow, and suggest that 3 cm distal to the medial epicondyle may be an optimal below-elbow ulnar nerve stimulation site.
Department of Neurophysiology, St. Michael's Hospital, 9-C Victoria Wing, 30 Bond Street, Toronto, Ontario M5B 1W8, Canada.
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D000328:Adult; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D003937:Diagnosis, Differential; D004550:Elbow / Q000294:innervation* / Q000502:physiology; D005260:Female; D006801:Humans; D009431:Neural Conduction / Q000502:physiology; D020424:Ulnar Neuropathies / Q000175:diagnosis* / Q000503:physiopathology*