Acute cerebellitis as a post-infectious complication of primary varicella in an immunocompetent young adult: A case report.

BACKGROUND: Acute cerebellitis is a well-documented neurological sequela of primary varicella-zoster virus (VZV) infection. Although frequently reported in children, this complication remains uncommon in adults and may present diagnostic difficulties, especially when neuroimaging studies are normal.

CASE PRESENTATION: A previously healthy, immunocompetent 20-year-old man was admitted with a four-day history of progressive gait instability and imbalance. Nine days prior to admission, he had developed a generalized vesicular rash consistent with primary varicella, initially involving the trunk and subsequently spreading to the face and extremities. He also reported occipital and frontal headaches, undocumented fever during the active phase of the rash, and postprandial nausea with vomiting. Neurological examination revealed intact consciousness, normal cranial nerve function, truncal ataxia, a wide-based gait, impaired tandem gait, and inability to maintain balance during Romberg testing even with eyes open. No appendicular ataxia was detected. Laboratory studies showed a normal complete blood count and an erythrocyte sedimentation rate of 13 mm/hour. Brain computed tomography and magnetic resonance imaging revealed no acute pathological findings. Cerebrospinal fluid polymerase chain reaction (PCR) was positive for VZV. Intravenous acyclovir (750 mg three times daily) was initiated, with subsequent gradual clinical improvement.

CONCLUSION: Post-varicella cerebellitis should be included in the differential diagnosis of adults presenting with acute truncal ataxia following recent primary varicella infection, even when neuroimaging is normal. Cerebrospinal fluid VZV PCR is a valuable diagnostic aid, and early antiviral therapy may be associated with favorable outcomes.