Purpose: To describe the clinical features of new-onset seizures in HIV-1-infected persons with progressive multifocal leukoencephalopathy (PML), and to discuss potential mechanisms.
Patients and methods: Forty-nine consecutive HIV-1-infected patients with PML attended our institutions between January 1988 and September 1993. We retrospectively analyzed cases with seizures as the presenting symptom of PML.
Results: Twenty percent of the HIV-1-infected patients with PML presented with new-onset seizures of various types, generalized or partial. None of them met the criteria of the AIDS dementia complex or had a concomitant opportunistic infection. Their mean CD4 cell count was < 60/mm3. Brain magnetic resonance imaging showed areas of increased signal intensity on T2-weighted images in 9 cases, and atrophy in only 1 case. Lesions most often involved subcortical white matter in parieto-occipital or frontal lobes, but 2 patients had posterior fossa lesions. Image-guided stereotactic brain biopsies in 8 cases and postmortem examination in 2 confirmed the diagnosis of PML. Typical histological lesions were observed in all cases, and positive immunolabelling of oligodendroglial nuclei was obtained in all cases with the polyclonal antibody directed against late SV40 antigens. Putative causative factors for the seizures include demyelinated lesions adjacent to the cerebral cortex acting as irritative foci, axonal conduction abnormalities, or disturbances of the neuron-glia balance.
Conclusion: These cases illustrate that PML should be considered as a possible cause of new-onset seizures in patients with HIV-1 infection.