"Alpha-pattern coma" in high voltage electrical injury.

Two cases are reported in which reversible deep coma subsequent to high voltage electrical injury occurred in association with alpha frequencies in the EEG. The EEG pattern differs from the alpha rhythm of the normal awake patient by its diffuse distribution and unresponsiveness to a variety of stimulation. The term "alpha-pattern coma" is introduced to designate the occurrence of this pattern in comatose patients. The EEG in the cases described initially demonstrated activity in the alpha frequency which occurred in a generalized distribution and was unresponsive to stimulation. During the early stages of recovery an increased incidence of theta and delta activity was observed. The recovery records contained a low voltage alpha rhythm and responded to photic stimulation. The literature on this subject is reviewed and the possible modes of pathogenesis are discussed. The authors conclude that such examples of alpha-pattern coma are the result of diffuse cerebral damage and might be detected more frequently in comatose patients who survive if these patients are studied earlier in their clinical course with EEGs.