[A case of bilateral middle cerebellar peduncle infarction with hot cross bun sign].

A 71-year-old man with hypertension and diabetes mellitus presented to our hospital because he felt lightheaded. Diffusion-weighted images (DWI) on brain MRI showed high signal lesions in the left cerebellar hemisphere and the right pons. The diagnosis of cerebellar infarction was made, but he refused treatment. One month later, he came to our hospital because his body leaned to the left. Neurological examination revealed dysarthria and cerebellar truncal ataxia. An electrocardiogram showed atrial fibrillation. DWI on brain MRI showed high signal lesions in the bilateral cerebellar hemispheres and middle cerebellar peduncles (MCP). Dabigatran 300 ‍mg/day was administered for cardiogenic cerebral embolism. On the 12th day of onset, he was transferred to a rehabilitation hospital. At 72 years old, T₂*-weighted images on brain MRI showed hot cross bun sign (HCBs) in the pons. We considered that HCBs were caused by antegrade or retrograde degeneration (or both) of pontine infarcts and bilateral MCP infarcts in the pontine cerebellar tract. It seemed preferable to use T₂*-weighted images or proton density-weighted images rather than T₂-weighted images to detect HCBs. When HCBs is detected, it should be noted that HCBs can be caused by bilateral MCP infarcts in addition to multiple system atrophy.