Cruciform Pontine MRI Hyperintensities (“Hot Cross Bun” Sign) in Non-Multiple System Atrophy Patients
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A 20-year-old woman presented with a 5-year history of gait disturbance and tremor. Her mother showed the same clinical features and expired due to aspiration pneumonia at the age of 28-year-old. She was diagnosed as a spinocerebellar ataxia type 2 with molecular genetic PCR analysis. Brain T2-weighted MR image showed cruciform signal hyperintensity in pons (Figure A). A 61-year-old man presented with a 7-year history of gait disturbance after cerebellar hemorrhage. He did not showed autonomic dysfunction. Brain T2-weighted MR image showed cruciform signal hyperintensity in pons (Figure B). Cruciform pontine MRI hyperintensities (“hot cross bun” sign) is a radiologic sign which has been said to specific for multiple system atrophy.[1,2] But our patients were diagnosed as spinocerebellar ataxia type 2 and old cerebellar hemorrhage. Therefore we suggest that “hot cross bun” sign reflects degeneration of transverse pontocerebellar fibers and is not a pathognomic sign of multiple system atrophy.

(A) Cruciform signal hyperintensities within the pons and atrophy of pons are demonstrated on the axial T2-weighted MRI of 20-year-old spinocerebellar atrophy type 2 patient with a 5-year history of ataxia. (B) Cruciform signal hyperintensities within the pons and atrophy of pons are demonstrated on the axial T2-weighted MRI of 61-year-old patient with a 7-year history of cerebellar hemorrhage.