Confirmatory tests in brain death determination: a critical role in posterior fossa lesions

Calixto Machado, Department of Clinical Neurophysiology, Institute of Neurology and Neurosurgery, Havana, Cuba

The determination of brain death or death by neurological criteria (BD/DNC) typically relies on clinical assessment: coma, absence of brainstem reflexes, and apnea. However, in cases with primary posterior fossa lesions, clinical criteria alone may be insufficient. Unlike supratentorial injuries, these lesions can selectively impair brainstem function without causing global cerebral circulatory arrest or significantly increasing intracranial pressure. As a result, patients may retain cerebral blood flow (CBF) and electroencephalogram (EEG) activity despite meeting clinical BD/DNC criteria. In such cases, confirmatory tests are not discretionary but diagnostically essential. Evaluations of bioelectrical activity (e.g., EEG and evoked potentials) and CBF (e.g., transcranial Doppler, computed tomography angiography, and radionuclide imaging) provide critical confirmation, reducing diagnostic errors and supporting ethical and legal standards. Clinical cases, including the widely known case of Jahi McMath, highlight the risks of declaring brain death without confirmatory confirmation in posterior fossa injuries. Therefore, BD/DNC protocols must be updated to require confirmatory testing when posterior fossa pathology is present, when clinical findings are unclear, or when a comprehensive examination is not feasible. This clinical viewpoint, accompanied by a literature synthesis, calls for an urgent revision of protocols, enhanced clinician education, and institutional preparedness to ensure that brain death determinations remain accurate, ethical, and credible.

Keywords: Confirmatory tests. Tests. Brain death/death by neurological criteria. Brainstem. Posterior fossa lesions.