Peripheral nerve tumors associated with Martin-Gruber anastomosis

Anomalous communications between median and ulnar nerve\r\nin the forearm have been widely described during the years. The\r\nmost common of these anastomosis, known as Martin–Gruber\r\nanastomosis (MGA), consists in a neural connection between median\r\nand ulnar nerve in the forearm, usually in its proximal part,\r\nthat results in an anomalous course of the fibers innervating the\r\nintrinsic muscles (and rarely cutaneous region) of the hand.\r\nIts frequency, firstly described by Gruber in 1870 as 15.2% in\r\n250 studied arms, is currently estimated through neurophysiological\r\nand anatomical studies to range between 10% and 40%\r\n(Amoiridis, 1992; Rodriguez-Niedenführ et al., 2002; Lee et al.,\r\n2005). Much rarer is ulnar to median communication, known as\r\nMarinacci communication, where fibers from the ulnar nerve cross\r\nover to the median nerve in the forearm (Marinacci, 1964).\r\nThe knowledge of such anatomical variants is important to\r\nexplain some electrodiagnostic (EDX) findings. Moreover, its identification\r\nis crucial for reaching a correct diagnosis and providing\r\ninformation on prognosis and treatment.\r\nWe report on two patients who presented with the coexistence\r\nof median–ulnar anastomosis and nerve tumors.