Focal Neurological Disease in Patients with Acquired Immunodeficiency Syndrome [Skiest DJ. CID 2002;34:103] The author reviews focal neurologic disease associated with HIV infection with an emphasis on toxoplasmosis, PML, CMV and lymphomas. Highlights are the following:

Toxoplasmosis

• Clinical: Subacute over weeks with headache, fever, behavior changes, lethargy and focal neurologic findings. Over 80% have a CD4 count <100/mm³.
• Imaging: Two or more ring enhancing legions with edema.
• Diagnosis: Patients with typical imaging and positive serology are usually treated empirically and 86% show clinical improvement by 7 days and 95% by 14 days. Serologies with IFA or EIA are positive in 94-97% of patients. PCR of CFS has a sensitivity of only 50% and specificity of 96-100%.
• Treatment: Pyrimethamine plus sulfadiazine are successful in 70-85%. Induction therapy lasts six weeks followed by maintenance therapy.

Progressive Multifocal Leukoencephalopathy (PML)

• Frequency: 1-2% in patients with AIDS and apparently not decreasing in the HAART era.
• Clinical: CD4 cell count is usually 35-104/mm³, but a subset of 7-25% has CD4 cell counts above 200/mm³. Symptoms include cognitive defects, speech deficits, incoordination, visual disturbances, and focal neurologic findings.
• Imaging: Hypodense lesions of white matter without mass affect or enhancement.
• Diagnosis: PCR for JCV DNA of CSF shows sensitivity of about 80% and specificity of about 95%.
• Prognosis: Median duration of survival is 1-6 months. Factors associated with improved survival are HAART, high CD4 cell count, low JCV levels in CSF and clearance of JCV from CSF.
• Treatment: None with established merit. HAART shows best results, but PNL may develop during HAART and may not respond despite immune reconstitution; recent report shows patients with PML responding to HAART with enhancing lesions on MRI (AIDS 1999;13:1426).

Cytomegalovirus (CMV)

• Clinical: Rapidly progressive delirium, cranial nerve deficits, nystagmus and ataxia.
• Diagnosis: CSF shows pleocytosis with mononuclear cells unless there is concomitant radiculomyelitis showing a predominance of PMLs. PCR shows a sensitivity of at least 80% and specificity of 90%.
• Imaging: Ventricular enlargement, periventricular enhancement.
• Treatment: Nothing works well. A trial of foscarnet plus ganciclovir in 31 patients showed a median survival of 94 days compared to 42 days in historic controls (AIDS 2000;14:517).

CNS lymphoma

• Frequency: 4-7% in AIDS patients in the pre-HAART era with less reduction in the HAART era compared to other AIDS related conditions (JAIDS 2000;25:451).
• Clinical: Altered mental status, focal neurologic findings, mean duration of 22-54 days, usually with B symptoms (fever and weight loss) and CD4 cell count <50/mm³.
• Imaging: Single or multiple hypodense lesions with enhanced contrast, usually homogeneous, but sometimes with ring forms.
• Diagnosis: PCR for EBV in CSF shows sensitivity of 80% and specificity of 94-100%.
• Treatment: Studies in the pre-HAART era showed a median survival of only 1-2.5 months. Cranial whole brain radiation provided a survival benefit of only 1-3 months. Results with chemotherapy have been disappointing. The role of HAART is unclear. Preliminary results with methotrexate appear promising [AIDS 1997;11:1725].

Role of brain biopsy:

Several retrospective series using CT or MRI-guided stereotactic biopsy have shown a diagnostic yield over 90% and a low morbidity rate as summarized with several reports in the following table:

New imaging techniques: The new techniques include SPECT and PET scans. The findings with these techniques compared to MRI are summarized in the following table:

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