Ataxic form of chronic inflammatory demyelinating polyradiculoneuropathy: clinical features and pathological study of the sural nerves.

We investigated clinical and pathological features of the sural nerves of 5 patients with the ataxic form of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and compared these features with those of chronic ataxic neuropathies due to other causes. The CIDP patients presented with slowly progressive ataxia with deep sensory impairment. The durations of the symptoms from onset were relatively short in CIDP (4-8 months) and cancer (3 and 10 months), but long in chronic idiopathic ataxic neuropathy (24-260 months). Corticosteroid therapy elicited a good response in all the patients with CIDP, but a poor response in the patients with other ataxic neuropathies. Sural nerve biopsy of CIDP patients showed a slight or moderate loss of myelinated fiber. This report suggests that ataxic form of CIDP is a steroid-responsive ataxic neuropathy, and large myelinated fibers of the sural nerves in ataxic form of CIDP were better preserved than those in nerves with other chronic ataxic neuropathies.