Freidreich's ataxia, other hereditary ataxias and olivopontocerebellar
atrophies should be taken into consideration in cases with significant ataxia.
Furthermore, symmetric signal abnormalities of bilateral MCPs might also be apparent in other clinical conditions including Wilson disease, hepatic encephalopathy, extrapontine myelinolysis, acute disseminated encephalomyelitis, leukodystrophy, olivopontocerebellar
atrophy, spinocerebellar degeneration, toluene abuse, adrenoleukodystrophy, alcoholic liver disease, hypoglycemic coma, and progressive multifocal leukoencephalopathy.,,, Although these lesions are rare, clinicians still need to carefully identify them using clinical and laboratory investigations combined with imaging findings to prevent misdiagnosis.
Multiple system atrophy (MSA) is an adult onset, progressive, idiopathic neurodegenerative disease that involves, to varying degree, the basal ganglia, olivopontocerebellar
complex and autonomic system.1-3 It has three clinical subtypes: MSA-C when cerebellar signs are predominant, MSA-P when parkinsonian features are predominant and MSA-A when the patient presents with autonomic signs and symptoms.3 The presence of hot cross bun sign on T2WI is a powerful tool for diagnosis of MSA-C in appropriate clinical setting.
In particular, in MSA-C, neuronal loss predominantly involves the olivopontocerebellar
structure and frequently the nigrostriatal tract and autonomic nuclei [3, 13].
Matsushita, "The distribution and dynamic density of oligodendroglial cytoplasmic inclusions (GCIs) in multiple system atrophy: a correlation between the density of GCIs and the degree of involvement of striatonigral and olivopontocerebellar
systems," Acta Neuropathologica, vol.
Definite MSA requires "neuropathological findings of widespread and abundant CNS alpha-synuclein-positive glial cytoplasmic inclusions," along with "neurodegenerative changes in striatonigral or olivopontocerebellar
structures" at autopsy.
In the CBD variant associated with olivopontocerebellar
atrophy, the pons and cerebellum are markedly atrophied.
On neuropathological grounds, deterioration of nigrostriatal as well as olivopontocerebellar
pathways contributes to the clinical phenotype of MSA  with the predominant Parkinsonian symptoms (MSA-P subtype) on the one hand and the predominant cerebellar dysfunction (MSA-C subtype) on the other hand.
atrophy type III (13) and is now known as
(5) In a patient with MSA where a combination of olivopontocerebellar
atrophy and striato-nigral degeneration was present, the typical impairments of eye movement characteristic of PD were evident, viz., abnormal eye movements, (6) in combination with a vertical optokinetic nystagmus.
It is seen with increasing prevalence in patients with Parkinson's Disease (PD), multiple system atrophy (MSA), diffuse Lewy-Body disease with dementia (DLBD), corticobasal degeneration, olivopontocerebellar
atrophy, and progressive supranuclear palsy (PSP).
MSA was originally divided into Shy-Drager syndrome, striatonigral degeneration, and olivopontocerebellar
atrophy, but this distinction is no longer made.