1989 Volume 11 Issue 4 Pages 371-381
Simultaneous overnight recordings of intracranial pressure (ICP) and electroencephalography (EEG) were conducted on 85 neurosurgical patients with intracranial hypertension and/or ventriculomegaly. Intracranial pressure waves were classified into five types according to the pattern of appearance, and their correlation with sleep cycles and clinical conditions of patients were investigated. A-waves appeared exclusively in patients with long-standing intracranial hypertension, and episodic B-waves appeared in patients with chronic hydrocephalus or a postoperative tumor-free condition. When these episodic pressure waves appeared, the patients were conscious and sleep cycles including REM stage were observed. Persistent, high pressure B-waves were seen mostly in patients with an acute phase of intracranial hemorrhages. The consciousness of these patients ranged from drowsy to stupor. EEG showed alternate appearances of light sleep and waking rhythms in accordance with cyclic oscillations of B-waves which coincided with periodic, apneic respiratory rhythms. When markedly regular B-waves of moderately high pressure appeared continuously, the patients were severely impaired in consciousness and were mainly in a subacute phase of intracranial hemorrhages. EEG showed continuous slow activities and sleep stages were not scored in these patients. No characteristic clinical features were found in patients whose ICP remained within normal range without pressure waves throughout the recording.