The value of sensory electrophysiology in chronic inflammatory demyelinating polyneuropathy.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of sensory nerve conduction studies in comparison and in combination with motor conductions in diagnosing chronic inflammatory demyelinating polyneuropathy (CIDP). METHODS: We retrospectively compared the electrophysiology of 20 patients with CIDP to that of 20 controls with axonal polyneuropathy, and 20 controls with myopathy. Five sensory abnormality patterns were evaluated. RESULTS: The "abnormal radial normal sural" ("ARNS") pattern showed a sensitivity of 25% for CIDP and specificity of 100% versus axonal neuropathies (p=0.047). The "abnormal sural normal radial" ("ASNR") pattern had a sensitivity of 75% for axonal neuropathy with a specificity of 80% versus CIDP (p=0.0012). Presence of ARNS or absence of ASNR patterns showed equivalent or superior sensitivity and specificity to most individual motor demyelinating defects for CIDP. Presence of ARNS or absence of ASNR patterns, integrated within three different sets of electrodiagnostic criteria for CIDP, increased sensitivity in all without significantly altering specificity. Effects were most remarkable with the American Academy of Neurology criteria (1991), which showed significantly improved sensitivity (50-85%; p=0.041), with preserved specificity of 100%. CONCLUSIONS: The use of sensory abnormality patterns appears justified in comparison and combination with motor defects in diagnosing CIDP. SIGNIFICANCE: Sensory studies may be useful in contributing to the electrodiagnosis of CIDP and their inclusion in existing electrodiagnostic criteria deserves consideration.