Combined proximal nerve conduction study and F wave analysis confirms diagnosis of unusual unilateral proximal median nerve lesion in a diabetic patient

Abstract

Diabetic patients usually present with multiple nerve lesions varying in intensity and distributions among them. Nerve conduction studies (NCS) are usually done for measuring the level of block, type of lesion and aid in diagnostic criteria of polyneuropathies. F waves are usually not done in clinical setting but only on demand from the neurophysician. We present a case of uncontrolled diabetic who had features of carpal tunnel syndrome. He had proximal conduction block (median nerve neuropraxia) with normal sensory distal conduction. Further, antidromic action potentials of F wave analysis confirmed a proximal median nerve lesion rather than distal. We hypothesise that F wave analysis may add to the confirmatory diagnosis of proximal nerve lesions to routine NCS.