Abstract
Background The brainstem anatomy is complex, and the diagnosis of brain death (BD) in patients with isolated catastrophic posterior fossa lesions may pose a diagnostic dilemma. This is because all brainstem reflexes (which are the basis of neurologic examination) are lost; however, from an anatomical standpoint, the mesopontine tegmental reticular formation (MPT-RF) can theoretically be intact in patients with brainstem death. Moreover, supratentorial perfusion and electrical activity may be present. The significance of preserved supratentorial perfusion in the context of isolated catastrophic brainstem damage is not clear. We report the outcomes of an adult patient with catastrophic basilar artery thrombosis with preserved cerebral perfusion on brain scintigraphy.Patient presentation: A 47-year-old woman presented in an obtunded state and was found to have distal basilar artery thrombosis. After mechanical thrombectomy, her condition deteriorated, and a head CT scan revealed brain stem edema. Subsequently, brain death was suspected, and a 99mTc bicisate brain blood flow study was performed, which revealed the complete absence of blood flow to the cerebellum despite intact circulation to the cerebral hemispheres. Accordingly, life support continued. The next day, the patient was declared clinically brain dead with no follow-up imaging.Conclusions The significance of preserved supratentorial brain perfusion in the context of isolated catastrophic posterior fossa lesions is unclear. In keeping with a few additional cases in the literature, preserved supratentorial perfusion in our patient quickly evolved. The complex brain stem anatomy warrants further ancillary tests for the confirmation of brain death in patients with isolated fatal posterior fossa lesions.