In a rare peripheral neuropathy of AIDS termed diffuse infiltrative lymphocytosis syndrome (DILS), a variety of clinical syndromes have been described including all patterns of the usual HIV polyneuropathies. Some instances of polyneuropathy in AIDS patients are probably caused by the nutritional depletion that characterizes advanced stages of the disease and to the effects of therapeutic agents. These HIV-related neuropathies are discussed in Chap. 43 and are summarized by Wulff and Simpson.
A primary myopathy, taking the form of an inflammatory polymyositis, has been described in HIV patients at any stage of the disease (Simpson and Bender). In some of these cases, the myopathy has improved with corticosteroid therapy. The original anti-AIDS drug, zidovudine (AZT), has caused a myopathy, probably because of its effect on mitochondria, but some investigators have attributed almost all such cases to be attributable to the AIDS virus itself (see “HIV and HTLV-I Myositis” in Chap. 45). It is apparent that this remains an area of some controversy.
Opportunistic Infections and Neoplasms of the CNS With HIV
In addition to the direct neurologic effects of HIV infection, a variety of opportunistic disorders, both focal and generalized, occur in such patients as outlined in Table 32-2. As noted earlier, recent treatment with antiretroviral agents have decreased the frequency of these complications. Interestingly, there appears to be a predilection for certain ones—toxoplasmosis, CMV infection, primary B-cell lymphoma, cryptococcosis, and progressive multifocal leukoencephalopathy (discussed further on under Syndromes of Herpes Zoster), in approximately this order of frequency (Johnson). The focal encephalitis and vasculitis of VZV infection, considered earlier in this chapter, and unusual types of tuberculosis and syphilis are other common opportunistic infections of AIDS. Usually P. carinii infection and Kaposi sarcoma do not spread to the nervous system. In almost of these categories, the infectious process is accelerated or intensified by the presence of the HIV infection.
Toxoplasmosis and CNS lymphoma Of the focal infectious complications, cerebral toxoplasmosis is the most frequent (and treatable; see Chap. 31). In the autopsy series reported by Navia, Petito, Gold, and colleagues, areas of inflammatory necrosis caused by
Toxoplasma were found in approximately 13 percent (see Fig. 31-6). Lumbar puncture, contrast-enhanced CT scanning, and MRI are useful in diagnosis. The spinal fluid usually shows an elevation of protein in the range of 50 to 200 mg/dL, and one-third of patients have a lymphocytic pleocytosis. Because the disease usually represents reactivation of a prior Toxoplasma infection, it is important to identify Toxoplasma-seropositive patients early in the course of AIDS and to treat them with oral pyrimethamine (200 mg initially and then 50 mg daily) and a sulfonamide (4 to 6 g daily in four divided doses). Curiously, the toxoplasmosis, so common in the brains of AIDS patients, does not frequently cause myositis in these patients, as it does in non-HIV infected individuals.