II. Risk Factors: Immunosuppression
- AIDS Defining Illness (CD4 <200/mm3)
- Chemotherapy for Lymphoma
- Immunosuppressants post-organ transplant
- Multiple Sclerosis medications
- Rheumatoid Arthritis medications
- Systemic Lupus Erythematosus medications
III. Pathophysiology
- JC Virus infection (Polyomavirus JC) is common organism present without consequence in most patients
- Suppressed Immunity allows for Encephalitis
IV. Signs
- Cognitive Decline
- Cranial Nerve Palsy
- Aphasia
- Ataxia
- Weakness
- Sensory loss
- Seizure
V. Imaging: MRI Brain
- Single or multiple white matter lesions
- Minimal to no enhancement, edema, or mass effect
VI. Diagnosis
- JC Virus PCR detection from CSF
- Brain Biopsy (rarely done)
VII. Management
- Reverse immune deficiency
VIII. Prognosis
- Mortality: 30-50% over months following onset
- Morbidity: Debilitating residual cognitive deficits are common in those who survive