Primary Posterior Fossa Lesions and Preserved Supratentorial Cerebral Blood Flow: Implications for Brain Death Determination.

BACKGROUND: Patients with primary posterior fossa catastrophic lesions may clinically meet brain death criteria, but may retain supratentorial brain function or blood flow. These patients could be declared brain-dead in the United Kingdom (UK), but not in the United States of America (USA). We report the outcome of adult patients with primary posterior fossa lesions without concurrent major supratentorial injury. METHODS: Henry Ford Hospital database was reviewed over a period of 88 months in order to identify all adult patients with isolated brainstem or posterior fossa lesions. We excluded patients with concurrent significant supratentorial pathology potentially confounding the clinical brain death examination. One more patient from a different hospital meeting these criteria was also included. RESULTS: Three patients out of 161 met inclusion criteria (1.9% of all brain deaths during this period). With the addition of a fourth patient from another hospital, 4 patients were analyzed. All four patients had catastrophic brainstem and cerebellar injuries meeting the clinical criteria of brain death with positive apnea test in the UK. All had preserved supratentorial blood flow, which after a period of 2 h to 6 days disappeared on repeat testing, allowing declaration of brain death by US criteria in all four. One patient became an organ donor. CONCLUSIONS: Patients with primary posterior fossa catastrophic lesions, who clinically seem to be brain-dead, evolve from retaining to losing supratentorial blood flow. If absent cerebral blood flow is used as an additional criterion for the declaration of death by neurological criteria, these patients are not different than those who become brain death due to supratentorial lesions.