Infarct in territory of bilateral medial branches of PICA

A 55 y o male with sudden onset of vertigo, followed by loss of consciousness. 

MRI Brain Diffusion shows an acute infarct involving bilateral cerebellar hemispheres confined to the territory of the medial branches of the posterior inferior cerebellar arteries. 

Three days later follow up CT showed increase in odema and mass effect, brain stem and fourth ventricle compression leading to mild to moderate hydrocephalus. Clinically patient showed mild dysarthria, dysequilibrium with retropulsion, symmetrical bilateral horizontal gaze-evoked nystagmus on lateral gaze, and marked gait ataxia. 

MRI Angiography of brain and neck shows narrowing of intra cranial portion of right vertebral. Normal cervical vertebral and rest of the neck vessels. 

MRI brain FLAIR shows, intra cranial portion of right vertebral with abnormal high signal implies to occlusion. 

So we speculate that our patient has occlusion of the origin of the right posterior inferior cerebellar artery, which probably gave rise to the bilateral medial branches of posterior inferior cerebellar arteries. This caused infarction in the territory of the medial branches on both sides without remaining brain stem signs. Such an unusual pattern of cerebellar infarction often accompanied by acute hydrocephalus.