Confusion in a Patient With HIV

John R. Gaughen, Jr., M.D.

June 02, 2005

Discussion

The salient finding in this case is asymmetric white matter disease, without mass effect or contrast enhancement. In an immunocompetent patient, this could result from a host of etiologies. However, in an HIV-positive patient, the major differential considerations include progressive multifocal leukoencephalopathy (PML), AIDS dementia complex (ADC), and CMV encephalitis. If mass effect or enhancement is present, lymphoma and toxoplasmosis should be considered. PML, ADC, and CMV encephalitis possess many similarities radiologically, making diagnosis challenging. PML usually manifests as asymmetric demyelination, which can occur anywhere in the brain and spinal cord, but most often occurring in the parieto-occipital regions. It rarely demonstrates mass effect or enhancement; when it does, it can overlap radiologically with lymphoma or toxoplasmosis. ADC is usually diffuse and symmetric, with associated global atrophy. Its course is more indolent than PML. CMV encephalitis usually occurs in the setting of systemic disease, and other manifestations are often present (esophagitis, colitis, retinitis, adrenal insufficiency). It can be associated with ventriculitis and meningeal enhancement, and if untreated, it usually has a more rapid course than either PML or ADC. Progressive multifocal leukoencephalopathy (PML) is a virally-induced demyelinating disease, caused by infection of oligodendrocytes by the JC papovavirus. It occurs predominantly in immunocompromised patients, most notably in AIDS. Clinical presentation varies among a number of neurological signs and symptoms, and it can be an AIDS defining disease. As discussed above, the radiological findings overlap with ADC and CMV encephalitis, and it usually presents as asymmetric white matter disease without mass effect or contrast enhancement. Note that both mass effect and enhancement rarely occur. Serologic testing using PCR and tissue sampling aid in diagnosis confirmation. Although antiretroviral therapy may offer some treatment benefit, at this point there is no consistent therapy. The disease progresses inexorably to death over the course of months, with less than a 10% one-year survival rate.

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