Progressive multifocal leukoencephalopathy with predominant cerebellar involvement after antiretroviral therapy initiation in an HIV-positive patient: a case report

Abstract

Case Presentation: A 56-year-old woman with human immunodeficiency virus infection had recently initiated antiretroviral therapy and presented to the emergency department with progressive gait disturbance, imbalance, and lower limb dysmetria. Neurological examination revealed marked cerebellar ataxia without significant motor weakness or sensory deficits. Brain magnetic resonance imaging demonstrated extensive FLAIR hyperintensity involving the cerebellar hemispheres, without evidence of mass effect or contrast enhancement. The imaging pattern raised suspicion for a demyelinating process in the context of immunosuppression. Clinical and radiological findings were consistent with progressive multifocal leukoencephalopathy by JC virus reactivation. Discussion: Progressive multifocal leukoencephalopathy is an opportunistic demyelinating disease of the central nervous system caused by reactivation of the JC virus, typically occurring in immunosuppressed individuals, particularly patients with advanced HIV infection. Although classically involving supratentorial white matter, cerebellar-predominant presentations are less common and may pose diagnostic challenges. The primary diagnostic method is the detection of JC virus DNA in the cerebrospinal fluid. In the literature, the main radiological findings described include multifocal or diffuse lesions involving the cerebellar white matter and cerebellar peduncles on magnetic resonance imaging, appearing hyperintense on T2-weighted and FLAIR sequences and hypointense on T1-weighted images, reflecting white matter destruction. These lesions typically do not show significant mass effect or edema and, in the classic presentation, do not exhibit contrast enhancement, as also observed in the present case. Immune restoration with antiretroviral therapy constitutes the cornerstone of treatment, as no specific antiviral therapy has demonstrated proven efficacy for progressive multifocal leukoencephalopathy. The use of corticosteroids may be considered only in situations of immune reconstitution inflammatory syndrome when significant inflammatory activity is present. Final Comments: Progressive multifocal leukoencephalopathy should be considered in HIV-positive patients presenting with subacute cerebellar symptoms, even when imaging predominantly involves the posterior fossa. Early recognition is essential for prompt management and for monitoring potential immune reconstitution inflammatory syndrome following the initiation of antiretroviral therapy. Cerebellar-predominant PML represents an atypical but important manifestation of JC virus reactivation.