The value of electroencephalography in prolonged coma: a comparative EEG-computed axial tomography study of two patients one year after trauma.

Interest was aroused in two patients of 16 and 17 years of age and similar craniocerebral trauma, but who had differing EEG's 1 year after injury while their later situation was the reverse of what the EEG would have led one to expect. The patient with an iso-electric EEG showed clinical improvement during the course of the second year, as indicated by a rise in his Glasgow coma rating from 8 to 11. This patient had marked cortical atrophy with discrete central atrophy, shown by computed axial tomography (CT); the isotope cisternogram showed good peripheral absorption of the isotope and no penetration into the ventricles. The other patient showed diffuse slow-wave activity in his EEG but failed to improve clinically or electroencephalographically. His CT-scan showed marked central and discrete cortical atrophy; his isotopic cisternogram showed penetration of isotope into the ventricles with poor peripheral absorption. These two cases illustrate the hazard of relying on an iso-electric EEG after 1 year of coma as an indicator of brain death, and the value of the CT-scan in the initial assessment of such cases.