Failure of electroencephalography to diagnose brain death in comatose children

Two isoelectric electroencephalograms obtained 24 hours apart support a clinical diagnosis of brain death in prolonged coma. Without documentation of electrocerebral silence, physicians are reluctant to discontinue vital support systems. A radionuclide bolus technique has been developed that documents the absence of cerebral blood flow in suspected brain death and supplements the flat EEG. In a recent review of this technique, all 27 adults who had EEG activity maintained the integrity of their cerebral blood flow. This contrasts to our studies of 5 children, all of whom demonstrated persistent EEG activity but had no evidence of cerebral blood flow by either the isotope bolus technique (5 patients) or cerebral angiography (4 patients). These children (mean age, 7 months) lacked cephalic reflexes and were maintained on assisted ventilation for an average of 15 days. Multiple electroencephalographic tracings persistently demonstrated low-voltage cortical activity over this time. Despite the lack of cerebral blood flow, all patients were continued on respiratory support. At autopsy, extensive brain liquefaction necrosis was noted. In comatose children, EEG monitoring may be of limited value while cerebral blood flow measurements can provide more practical and prognostic information.