Type of Manuscript: Case Report Massive Cerebellar Infarction Caused by Spontaneously Isolated Posterior Inferior Cerebellar Artery Dissection: A Case Report

Abstract Background Diagnosis of posterior inferior cerebellar artery dissection (PICAD) based on radiological images is difficult. Massive cerebellar infarctions caused by spontaneous isolated PICAD are rare and the relevant clinical, imaging, and treatment options are unclear. Case presentation: A 39-year-old man was admitted with dizziness, an unstable gait for two days. Physical examination showed decreased muscle strength in the right limb and right-sided ataxia. Brain magnetic resonance imaging (MRI) showed a massive acute right cerebellar infarction but other modalities including head and neck computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) showed no obvious abnormalities. High-resolution vessel wall MRI (HR-VW-MRI) revealed right PICAD. The patient was diagnosed with massive cerebellar infarction caused by PICAD and began active conservative treatment. The initial PICAD lesion disappeared 1.5 months after discharge. The patient experienced only slight weakness in the right limb by 3 months. Conclusions Since MRA or CTA may fail in identifying PICAD, HR-VW-MRI is key in diagnosis and follow-up evaluation. Aggressive medication may be effective and safe for PICAD.