Absent Cerebellar Circulation With Intact Cerebral Blood Flow on a 99mTc Bicisate "Brain Death" Study

A 55-year old woman presented in an obtunded state and was found to have a subarachnoid hemorrhage. After endovascular repair, her condition deteriorated, and brain death was suspected. A Tc bicisate brain blood flow study was performed, which showed a complete absence of blood flow to the cerebellum despite intact circulation to the cerebral hemispheres. These atypical findings are likely a result of a transient intracranial pressure differential and the timing of the study. A timely and accurate declaration of brain death has important psychosocial and ethical implications, particularly when organ donation is being considered.