An unusual presentation of varicella zoster virus with acute cerebellitis and SIADH without a rash.

We report a case of varicella-zoster virus (VZV) infection with acute cerebellitis and encephalitis with associated Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) in an elderly man presenting with acute cerebellar ataxia without antecedent rash. Cerebrospinal fluid examination (CSF) revealed a mononuclear pleocytosis, high protein, normal glucose, positive for VZV polymerase chain reaction (PCR). Early acyclovir treatment is beneficial for acute VZV cerebellitis. Clinicians should consider infectious Central Nervous System (CNS) causes for presentations of acute cerebellar ataxia in adult patients, particularly if there is an accompanying clouded sensorium.