The cutaneous silent period in diabetes mellitus

The cutaneous silent period (CSP) may be useful as a method for the evaluation of smaller and unmyelinated fiber dysfunctions. CSP refers to the brief interruption in voluntary contraction that follows strong electrical stimulation of a cutaneous nerve. The aim the present study is to establish whether CSP can be instrumental in the determination of diabetic neuropathy. The nerve conduction studies and CSP evaluations were both used in patients with Diabetes Mellitus and control group. All patients were given clinical neurological examinations for the determination of small-fiber neuropathy (SFN). The CSP values for patients with SFN were compared with values of those without SFN. The nerve conduction velocities had changed unfavorably in diabetic patients. No median nerve CSP reponse could be obtained in two of the diabetic patients. CSP latency (84.6 ± 14.0) in diabetics was longer than controls (76.2 ± 13.1) (p = 0.018). The duration of CSP was similar for the two groups (p = 0.46). The CSP latency showed a correlation with routine nerve conduction studies. While the CSP latencies (86.7 ± 15.8) of patients who were clinically diagnosed with SFN were similar to the latencies (81.3 ± 10.4) of patients without SFN (p = 0.606), the duration of CSP (44.6 ± 13.7) in patients with SFN was shorter than the duration (55.3 ± 12.2) in patients without SFN (p = 0.012). These results indicate that eventhough the CSP does not provide any advantage over routine electrodiagnostic studies in determining diabetic neuropathy, still it may be a useful method for the early detection of diabetic SFN.