抄録
Epidural pressure and respiratory movement were simultaneously monitored in sixteen patients with various conditions such as brain tumor, hypertensive intracerebral hematoma, ruptured cerebral aneurysm and normal pressure hydrocephalus. Durations of the monitorings ranged from 12 to 233 hours, with an average of 5.2 days. In the majority of cases, higher levels of intracranial pressure were noticed during the night and early in the morning. Rapid variations of intracranial pressure appeared to some extent in all instances. Occurrence of the pressure waves were closely related to changes in respiratory movement, the latter being suppressed during the phase of pressure rise and activated in the phase of pressure fall.
Lundberg's A-waves were divided into two different patterns: typical A-waves with a stable plateau of pressure elevation like a trapezium and atypical A-waves with irregular fluctuations during rises of pressure, usually related to oscillatory changes in respiration. Typical A-waves appeared in both sleeping and waking stages of patients with brain tumors. This type of A-wave showed a tendency of rhythmical repetition when it appeared. On the other hand, atypical A-waves occurred prominently during the sleeping stage and their occurrence was predominant in patients with cerebrovascular accidents. Concerning the levels of rising pressure, atypical A-waves started from a relatively low base pressure, mostly below 22 mmHg, compared to the rising pressure of typical A-waves which ranged between 15 and 66 mmHg.
B-waves appeared in close correlation with the periodic changes in respiratory movement and their occurrence was clearly predominant in the sleeping stage of the patients, showing a similarity to atypical A-waves. Such B-type waves appeared in wide base pressure ranges between 0 and 70 mmHg.
Interestingly, oscillatory B-waves were transformed into atypical A-waves, in some cases. These findings may indicate a common mechanism in the appearance of B-waves and atypical A-waves.
