Teaching neuroImage: MRI in multiple system atrophy: "hot cross bun" sign and hyperintense rim bordering the putamina.

A 59-year-old man developed progressive gait ataxia, dysarthria, sexual dysfunction, and Raynaud phenomenon over 2 years. On examination he also manifested bradykinesia and rigidity, postural and action tremor of the upper limbs, and orthostatic hypotension. Family history was negative. Brain MRI disclosed the “hot cross bun” sign typical of multiple system atrophy (MSA) (figure).1,2 This sign is probably related to degeneration of transverse pontocerebellar fibers, whereas the hyperintense rim bordering the putamina has been associated with neuronal loss, reactive microgliosis, and astrogliosis.2 Glial cytoplasmic inclusions, neuronal inclusions, and demyelination have been linked to MSA, but the mechanisms involved require further clarification.2 MRI has diagnostic potential in parkinsonism-plus syndromes; several typical findings like those depicted here have been described.1,2