Median to ulnar nerve anastomosis: a review of the literature.

Median to Ulnar nerve anastomosis in the forearm has been shown to be of clinical significance leading to "anomalous" innervation and is correlated with misdiagnosis during the assessment of nerve lesions, injuries and Carpal Tunnel Syndrome (CTS). In 1763, Martin first described the anastomosis and Gruber next mentioning it, in 1870 thus referred to as Martin--Gruber anastomosis. Despite its long history, its nature remains unclear. Many anatomical, electrophysiological, histological and genetic studies have been published, reporting the anastomosis' frequency, citing its clinical importance and classifying it into various classes and types. Diagnosis is made mostly with electrophysiological studies whereby researchers have cited certain clues taking into consideration the asymptomatic nature of the anastomosis. The current literature on median to ulnar nerve anastomosis is reviewed, highlighting its frequency and clinical significance making an excellent tool for correct diagnosis in many clinicians.