The treatment of HIV infection/AIDS, as is true for any chronic, life-threatening disease, is difficult. Treatment with several antiretroviral drugs is required not just for control of the neurologic manifestations of retroviral infection but also to control secondary infections. Recommendations regarding drug therapy for HIV infection change rapidly (Rubin and Young) and the reader is referred to any of the modern sources for the details of treatment, including Harrison’s Principles of Internal Medicine. It is believed that these approaches will prolong survival but it might be expected also to increase the prevalence of neurologic complications of AIDS, each of which needs to be treated as it is recognized. A special result of HIV antiretroviral treatment may induce an intense inflammatory response to a coexistent infection. This complication, immune reconstitution inflammatory syndrome, or IRIS, is perhaps most pertinent to progressive multifocal leukoencephalopathy discussed later.
Tropical Spastic Paraparesis, HTLV-I Myelopathy
This is an endemic neurologic disorder in many tropical and subtropical countries. Its cause was overlooked until 1985, when Gessain and coworkers found IgG antibodies to HTLV-I in the sera of 68 percent of tropical spastic paraparesis (TSP) patients in Martinique. The same antibodies were then identified in the CSF of Jamaican and Colombian patients with TSP, and in patients with a similar neurologic disorder in the temperate zones of southern Japan. The latter disorder was originally called HTLV-I–associated myelopathy (HAM), but it is now considered to be identical to HTLV-I–positive TSP (Roman and Osame). It is a curious feature of this disorder that only a small proportion of HTLV-I–infected persons (estimated at 2 percent) develop a myelopathy. Sporadic instances have now been reported from many parts of the Western world. The virus is transmitted in one of several ways—from mother to child, across the placenta or in breast milk; by intravenous drug use or blood transfusions; organ transplantation, or by sexual contact. The age of onset is in mid adult life, and it is more common in females than in males, in a ratio of 3:1.
The clinical and pathologic features of the disease are described in Chap. 42 and in several reviews (Rodgers-Johnson et al and more recently, Gessain and Mahieux). The main characteristic is a very slowly progressive spastic gait with early sphincter control difficulty and some degree of later proprioceptive loss and Romberg sign. Differentiation from the progressive spinal form of multiple sclerosis, hereditary spastic paraparesis, and with subacute combined degeneration, with which it may be confused. There are also clinical and pathologic differences from the myelopathy caused directly by HIV infection. No form of treatment has proved effective in reversing this disorder, although there are anecdotal reports that corticosteroids or the intravenous administration of immune globulin may temporarily halt its progress. More recently, the anti-CCR4 antibody, mogamulizumab, an agent used in the treatment of T-cell lymphoma, has been found to have activity against the virus and may have been effective in this disease in phase 1-2 trials (Sato et al).
HTLV-II myelopathy The retrovirus HTLV-II is less common than HTLV-I but the two are virologically very similar. There is a high rate of infection with HTLV-II among drug users who are coinfected with HIV. A few cases of myelopathy have been reported in HTLV-II–infected patients, similar in all respects to HTLV-I–associated myelopathy (Lehky et al).
VIRAL INFECTIONS OF THE DEVELOPING NERVOUS SYSTEM (SEE CHAP. 37)