Residual latancy and terminal latancy index in diagnosis of chronic inflammatory demyelinating polyneuropathy

Diagnosis of chronic inflamattory demyelinating polyradiculopthy (CIDP) is based on clinical evaluation and electrophysiological analysis. Since CIDP is a treatable disease, accurate diagnosis is important in terms of prognosis of the disease.Conventional electrophysiological parameters are sometimes insufficient to correct diagnosis of the disease. For this reason, we've planned to investigate sensitivity and specificity of residual latency (RL) and terminal latency index (TLI) to diagnosis of CIDP.To this end, 30 patients diagnosed with CIDP from Gazi University Faculty of Medicine, Department of Neurology have been recruited the study. Control group is consisted of 34 healthy subjects without any neurological disorders.After determination of normative value of RL and TLI, sensitivity, specificity, positive and negative predictive values of these parameters to diagnosis of CIDP has been calculated.Take into consideration both of sensitivity and specificity, the best parameters for diagnosis of CIDP was F wave latency. Although sensitivity increases with RL for median nerve and with TLI for peroneal nerve, in overall, these two parameters didn't increase both of electrodiagnostic sensitivity and specificity for CIDP.We conclude that, since they reflect electrophysiological properties of distal segment of peripheral nerve, diagnostic values of TLI and RL are limited for CIDP. They may be more useful to diagnosis of CIDP variants that primary involves distal segments of peripheral nerve, such as distal acquired demyelinating symmetric neuropathy.