[Ataxic neuropathy in the elderly--clinicopathological study of six cases].

The combination of ataxia with peripheral neuropathy (ataxic neuropathy) is rare. Six elderly patients with peripheral neuropathy who developed ataxia were studied. Of the peripheral neuropathies, ataxic neuropathy was significantly more frequent in patients aged more than 65 years compared with younger patients. Ataxic neuropathy was associated with carcinoma (2 cases), Sjögren's syndrome (1 case), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP, 1 case) and chronic idiopathic ataxic neuropathy (2 cases). The two cases of carcinomatous neuropathy initially showed ataxia, which preceded detection of the carcinomatous lesions in the lung by approximately 1 year. The study cases had many clinical features in common. In the nerve conduction study, sural nerve action potential could not be measured in five of the cases; sural nerve biopsy revealed a decreased density of myelinated fibers in all cases. In particular, the large myelinated fibers were markedly decreased. These findings were common, regardless of the underlying disease, except in the case of CIDP in which there was only a slight decrease in the number of large myelinated fibers. Differential diagnosis based on the clinicopathological features was difficult. Therefore, in cases of ataxic neuropathy, systemic evaluation is necessary to rule out the possibility of carcinoma or various systemic diseases, especially in elderly patients.