Isolated brainstem death: case presentation demonstrating preserved supratentorial perfusion on

backgroundThe diagnosis of brain death (BD) is primarily clinical and usually straightforward when both supratentorial and infratentorial structures are irreversibly injured. In contrast, isolated catastrophic posterior fossa lesions-particularly those involving the brainstem-are uncommon and may demonstrate preserved supratentorial perfusion or cortical electrical activity on ancillary testing, even in the absence of brainstem function. This apparent dissociation is typically transient and invariably progresses to global cerebral circulatory arrest and death. Few reports have documented the natural evolution of this phenomenon, highlighting the rarity of such cases and their uniformly poor outcome. CASE PRESENTATION: A 47-year-old woman with no known history of chronic seizure disorder presented in an obtunded state. On arrival, she experienced continuous seizures and the clinical status rapidly deteriorated. Initial head CT scan without contrast revealed basilar artery thrombosis. She received intravenous tissue plasminogen activator (tPA) and levetiracetam. She underwent mechanical thrombectomy with partial recanalization (TICI 2b). Despite intervention, neurologic examination remained poor with absent spontaneous respiration and brain stem reflexes. Subsequent non contrast head CT scan demonstrated worsening brain stem edema and obstructive hydrocephalus. Due to poor clinical status, a

conclusionsThis is a rare case of isolated posterior fossa injury with preserved supratentorial perfusion compatible with "brainstem death". The case highlights the importance of ancillary testing in uncommon supra/infra tentorial dissociation to differentiate brain death from brainstem death.