A comparison of clinically atypical with typical chronic inflammatory demyelinating polyradiculoneuropathy.

BACKGROUND: There is a paucity of prospective studies evaluating the atypical features of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). AIMS: To compare clinical and electrodiagnostic features of clinically typical and atypical CIDP patients. METHODS: The patients with typical and atypical CIDP diagnosed according to the European Federation of Neurological Societies/Peripheral Nerve Society were included. The disability was graded on a 0-10 scale. Neurophysiological study included motor and sensory nerve conduction and F wave studies of both upper and lower limbs. The patients were treated with prednisolone with or without azathioprine. The outcome was evaluated at 6 months and improvement was defined as at least 2 grades improvement. RESULTS: Eight out of 37 CIDP patients had atypical features, which included asymmetry in 2, dysautonomia in 3 and pure motor weakness, amyotrophic-lateral-sclerosis-like syndrome and distal weakness in 1 patient each. Tendon reflexes were retained in 3 patients. The mean duration of symptoms was 43 weeks in the typical and 30 weeks in the atypical group. The age, sex, disability, therapeutic response and neurophysiological features were similar in the 2 groups. CONCLUSION: About one fifth of CIDP patients may have atypical clinical features; however, their electrodiagnostic features and response to treatment are no different from typical CIDP.