HIV-associated neuropathies: role of HIV-1, CMV, and other viruses

The role of the human immunodeficiency virus (HIV) and other viruses in the development of neuropathies associated with HIV infection is controversial. Distal symmetric polyneuropathy (DSP), the most common subtype of HIV-associated neuropathy, is characterized by an abundance of reactive macrophages within the peripheral nerve, but HIV replication is limited to a small percentage of the macrophages. Thus, the pathological destruction may be mediated by pro-inflammatory signals amplified by activated glial elements within the nerve, similar to the proposed mechanism of damage caused by HIV within the central nervous system. In contrast, in mononeuropathy multiplex (MM) and progressive polyneuropathy (PP), cytomegalovirus (CMV) replication in the peripheral nerve is consistently demonstrable, and this replication likely results in direct damage to the infected cells (neurons and glia). The rarest form of HIV-associated neuropathy, the diffuse infiltrative lymphocytosis syndrome (DILS), is characterized by an intense CD8+ T lymphocyte infiltration into the nerve and abundant HIV infection of macrophages. Finally, while other viruses (varicella zoster, herpes simplex) are associated with myelitis in HIV-infected individuals, there is little support for a role for these viruses in HIV-associated neuropathy.