In this, the third of a 3-part series on peripheral neuropathy, the syndromes of vasculitic, infectious, inherited, and idiopathic neuropathy are discussed. Vasculitis is a frequent cause of neuropathy in the setting of a connective tissue
disease. The infectious neuropathies most likely to be encountered in the United States are those due to varicella-zoster virus, human immunodeficiency virus,
Lyme disease, hepatitis C virus, and, most recently, West Nile virus. Inherited neuropathies are divided into 2 main types: predominant motor or predominant sensory. The former are generally classed as the Charcot-Marie-Tooth diseases and the latter as the hereditary sensory neuropathies. Each category has a number of different subtypes. If the results of routine screening tests are negative, the clinician must consider special testing for unusual disorders, including evaluations for underlying autoimmune or malignant disorders, genetic tests for inherited neuropathies, and other unusual or selectively ordered tests. These tests are very expensive and should be ordered only after the common causes of neuropathy are excluded. Unless the neuropathy can be substantially alleviated or cured, symptomatic treatment (most often for pain) plays a significant role for these patients.