Infectious and granulomatous neuropathies

Infectious and granulomatous neuropathies, including those associated with leprosy, Lyme disease, and sarcoidosis, share a number of clinical features. Asymmetric sensory and motor nerve involvement are typical, and cranial neuropathies are common, and help to distinguish infectious and granulomatous neuropathies from more common etiologies of peripheral nerve injury. Herpes zoster represents a re-activation of latent varicella zoster infection, and also results in asymmetric sensory loss, and less commonly weakness, in a radicular pattern. The diagnosis of infectious and granulomatous neuropathies rests on recognition of typical systemic involvement, serologic testing, and appropriate biopsy material. The diagnosis of herpetic neuropathies is made from the clinical features. Polymerase chain reaction techniques have an increasingly important role in diagnosis. Specific treatments are available for most infectious and granulomatous neuropathies and are generally effective in either reversing nerve damage or preventing further impairment. The prognosis is favorable when the cause is identified early in the disease course, but if treatment is delayed, permanent axonal damage is common in later stages. Herpetic neuropathies can be treated and post-herpetic pain successfully managed.