Direct infection of peripheral nerves by HIV, resulting in sensory and motor changes due to destruction of axons or their myelin covering. Acute or chronic inflammatory myelin damage may be the first sign of peripheral nerve involvement. Patients display gradual or abrupt onset of motor weakness and diminished or absent reflexes. Diagnostic biopsies of peripheral nerves show inflammatory changes and loss of myelin. Distal sensory neuropathy occurs in up to 30% of patients with AIDS, usually late in the disease. There is increased risk in older patients and those with diabetes mellitus, nutritional deficiencies, low CD4 cell counts, and vitamin B12
deficiencies. Patients report sharp pain, numbness, or burning in the feet. Destruction of dorsal root ganglions and degeneration of central peripheral axons are seen on autopsy. Some older antiretroviral drugs (ddI, ddC, and d4T) also cause a reversible peripheral neuropathy in about 20% of patients. See: AIDS
; Guillain-Barré syndrome
; chronic inflammatory demyelinating polyneuropathy
Nonsteroidal anti-inflammatory drugs, opioids, gabapentin, anticonvulsants, and topical agents have all been used with variable success to treat the pain of AIDS-related sensory neuropathy. Acupuncture is not effective. Human nerve growth factor, which stimulates regeneration of damaged nerve fibers, is being studied, esp. to minimize the neuropathy that antiretroviral drugs cause.