Chiari malformation presenting as loss of cerebellar substance on computed tomography

Abstract

Cerebral computed tomography (CT) is the primary imaging modality in the investigation of suspected cerebellar degeneration. A case is presented in which an inaccurate clinical and radiologic diagnosis of olivopontocerebellar degeneration resulted from CT imaging demonstrating loss of cerebellar substance. Subsequent clinical recognition of downbeat nystagmus led to a diagnosis of Chiari malformation. This malformation was classified as a "severe" Chiari type I via clivomyelography and angiography. Surgical decompression resulted in marked clinical improvement. Visualization of the loss of cerebellar substance should not be considered to exclude Chiari malformation.