Dying brain

Dying brain Editor—Ancillary tests used to confirm clinically diagnosed brain death may substantially influence the time of diagnosis, as in the following case. A 48-yr-old woman was shot to the head and was admitted to the hospital at 01:00 a.m. with a Glasgow Coma Scale (GCS) of 1 (eye), 5 (motor), 1 (verbal); brain tissue oxygen tension measured with an intraparenchymal catheter was 12 mm Hg (normal range 15–35 mm Hg), and the intracranial pressure was 25 mm Hg. At 07:00 a.m., GCS score was 3 with absent brainstem reflexes. Brain CT revealed massive cerebral oedema, the brain tissue oxygen tension was zero, and the intracranial pressure was 81 mm Hg with a cerebral perfusion pressure of zero. EEG showed a persistent low amplitude theta activity at the vertex and transcranial Doppler (TCD) a persistent cerebral blood flow in middle cerebral arteries (systolic flow velocity: 30 cm s–1) (Fig. 1A). At 09:00 a.m. of the next day, EEG was flat, and the 6 h observation period required by the Italian law to declare brain death was started; however, a TCD still showed a very low systolic flow velocity and a residual diastolic flow velocity (Fig. 1B). At 03:00 p.m., deep coma, absent reflex motor response and brainstem reflexes, and flat EEG persisted. Brain death was declared. TCD showed a reverberating flow indicating cerebral circulatory arrest (Fig. 1C). There is widespread acceptance of the concept of brain death in the Western hemisphere,1 and a fairly uniform agreement in Europe regarding the clinical criteria.2 There is, however, considerable variation in the use of additional confirmatory tests.1 2 These include flat EEG and determination of cerebral circulatory arrest by means of cerebral angiography, brain CT or MRI angiography, TCD, or cerebral scintigraphy. In the UK,1 only clinical criteria are used and brain death is defined as the complete, irreversible loss of brainstem function. In Sweden,1 cerebral angiography is the facultative ancillary test to confirm brain death; in Italy, EEG is mandatory, while cerebral angiography, brain CT angiography, TCD, or cerebral scintigraphy are all permitted methods to document cerebral circulatory arrest in children of ,1 yr of age, or if a complete and reliable clinical evaluation is not possible.