Olivopontocerebellar atrophy (OPCA) spectrum of progressive neurodegenerative diseases of cerebellum and brainstem characterized by progressive balance loss(disequilibrium), progressive impairment of voluntary movements (cerebellar ataxia), and slurred speech (dysarthria).

Sporadic (more common) Main type is Multisystem Atrophy (MSA) that has transverse demyelinating strip across the pons producing the crossed buns sign. Also ShyDrager and striatonigral degeneration.

Hereditary Hereditary spinocerebellar ataxia, autosomal dominant cerebellar ataxia, and MachadoJoseph Disease. Can be autosomal recessive or x linked as well.