Natural history of global and critical brain ischaemia. Part I: EEG and neurological signs during the first year after cardiopulmonary resuscitation in patients subsequently regaining consciousness.

Of 125 patients who had no detectable cortical activity (DCA) in the electroencephalograph (EEG) immediately upon resuscitation from circulatory arrest of primary cardiovascular aetiology, 37 subsequently regained consciousness; these patients had their EEG and neurological status serially investigated until they expired or had survived one year. The orderly cerebral recovery during postischaemic unconsciousness was characterized by a sequential appearance of EEG configurations and related neurological signs. The absence of DCA was at first accompanied by miosis and all the cranial nerve reflexes except the caloric vestibular reflex (phase of exclusive presence of cranial nerve reflexes) and then by motor responsiveness, predominantly decerebrate posturing (phase of cephalic reactivity). Electrocortical activity appeared thereafter first as a phase described as 'intermittent cortical activity' (ICA) accompanied by medium sized pupils, decorticate posturing and stereotypic reactivity and then as a phase described as 'continuous cortical activity' (CCA) associated with stereotypic reactivity. Consciousness returned 11-720 h later. The EEG and neurological recovery occurred independently after awakening; but elementary motor, sensory and mental faculties were regained in a characteristic sequence. Initially, the alert patient had a phase of 'severe disability' seen as communicating motor responses, eye-orientation and a bilateral Babinski response; in the subsequent phase of 'moderate disability' speech, auto-orientation, locomotor control, and a normal plantar response were then restored; finally in the phase of slight- or no disability allo-orientation, retention and recall reappeared. Thirteen patients made a complete recovery of all faculties 83--2150 h after cardiopulmonary resuscitation.