Mid-palm recording technique, a new electrodiagnostic approach in Martin-Gruber anastomosis.

Introduction: Median and ulnar motor nerve conduction study recording from median-innervated 2nd lumbrical and ulnar-innervated 1st palmar and 2nd dorsal interossei is designated in electrodiagnostic evaluation of carpal tunnel syndrome. In this technique, both responses are recorded by the same surface recording electrode placing over their shared motor point in mid-palm. To the best of our knowledge, this technique has never been utilized in demonstration of Martin-Gruber anastomosis.

Case Reports: By applying this technique to the conventional CMAP comparison method, the authors accordingly demonstrated Martin-Gruber anastomosis in four cases. Three presented with focal mononeuropathies of the upper limbs, including a severe carpal tunnel syndrome, a mild to moderate carpal tunnel syndrome, and an ulnar neuropathy. One was a normal individual.

Significance: This report described a new electrophysiological pattern of MGA. Adding the mid-palm recording to conventional CMAP comparison method provides a broader view in terms of innervation of MGA. This technique is not complicated and can be added to the electrophysiological investigation for complete studying of the innervated muscles in MGA.