Value of terminal latency index and sensory electrophysiology in idiopathic and diabetic chronic inflammatory demyelinating polyradiculoneuropathy

OBJECTIVES: To evaluate sensory electrophysiology, terminal latency index (TLI), and treatment response in idiopathic and diabetic chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). METHODS: We performed a retrospective review of 147 patients with CIDP who underwent electrodiagnostic evaluation (January 2000–December 2015). Eighty-nine patients fulfilled electrophysiological criteria described by the Ad hoc Subcommittee of the American Academy of Neurology and Albers et al. Fifty-eight patients were divided into idiopathic (N = 40) and diabetic (N = 18) groups. These groups were compared for age, sex, cerebrospinal fluid protein, response to treatment, sensory response abnormalities, and TLI measurements using chi-square tests for binary and categorical variables and using t-tests and mixed-effects models for continuous variables. RESULTS: The difference in abnormal rates of sensory responses was significant for the sural nerve, with the idiopathic group having a lower rate than the diabetic group (80% vs. 100%, p < 0.001). No group differences in the TLI measurements were significant. CONCLUSIONS: Sural sensory responses may have some value in differentiating idiopathic CIDP from diabetic CIDP. Larger prospective studies are needed to confirm our findings. SIGNIFICANCE: Our study suggests that abnormal sural sensory potentials may have some significance in differentiating idiopathic CIDP from diabetic CIDP.