The effect of thiopentone on somatosensory evoked responses and EEGs in comatose patients

EEGs and somatosensory evoked responses from the brachial plexus, neck and scalp were recorded in seven comatose patients on continuous thiopentone infusion. Although pathological in five of the patients, the evoked responses were present in all. Additional amounts of thiopentone producing a full suppression of all spontaneous EEG activity had no effects either on the configuration of the evoked responses or on the central conduction times. This resistance of the somatosensory evoked responses to a deep and sustained thiopentone narcosis makes it a useful test in comatose patients receiving this treatment.