Atrophy of foot muscles: a measure of diabetic neuropathy.

OBJECTIVE Diabetic neuropathy is a length-dependent process that leads to reduced muscle strength and atrophy of leg muscles in some patients. We hypothesized that intrinsic foot muscles are atrophied in diabetic neuropathy and that the degree of atrophy is a measure of motor dysfunction closely related to the neuropathic process. RESEARCH DESIGN AND METHODS Consecutive cross-sectional magnetic resonance images of the nondominant foot were obtained for stereological determination of the total volume of the intrinsic foot muscles (VFM) in 23 long-term diabetic patients with (n = 15) and without (n = 8) chronic neuropathy and in 23 matched healthy nondiabetic control subjects. Based on clinical examination, nerve conduction studies, and quantitative sensory examination, a neuropathy rank-sum score was calculated for each patient. RESULTS Total VFM was 86 +/- 52, 165 +/- 34, and 168 +/- 42 cm3 in neuropathic patients, nonneuropathic patients, and healthy control subjects, respectively (P < 0.001). There was a close inverse relationship between the neuropathy rank-sum score and the VFM (r = -0.75, P < 1 x 10(-5)). CONCLUSIONS Total volume of the foot muscles is halved in patients with diabetic neuropathy. Atrophy of foot muscles is closely related to the severity of neuropathy and reflects motor dysfunction.