[Noninvasive evaluation of hemispheric cerebral circulation and brain function in acute intracranial hypertension]

Disturbance of the hemispheric cerebral circulation and brain dysfunction in acute intracranial hypertension were evaluated noninvasively by ultrasonic Doppler technique and multimodality evoked potentials consisting of auditory evoked brain-stem response (ABR), cortical somatosensory evoked potential (SEP) and visual evoked potential (VEP) in 36 patients with severe head injury and cerebrovascular disease. Glasgow coma scale score was less than 8 in all cases and the age ranged from 17 to 75 years (mean of 46 years). Intracranial pressure (ICP) was measured from the extradural space using Gaeltec transducer and systemic blood pressure was simultaneously recorded. Common carotid blood flow velocity (CBFV) was recorded on both sides and mean velocity (M), diastolic mean velocity (Md) and mean blood flow were calculated. The abnormalities on MEPs were graded into 4 categories. M and Md values on CBFV were significantly (p less than 0.05 and p less than 0.01) lowered on affected side (main lesion side) even when ICP was staying less than 20 mmHg comparing with control value obtained from the normal subjects (M: 19.48 +/- 3.52, Md: 15.98 +/- 2.01 cm/sec). With the increase of ICP more than 21 mmHg, CBFV on the contralateral side was also decreased and M as well as Md values were maintained at the lowered level during 21 to 60 mmHg of ICP. A significant rapid decrease of CBFV was observed at extreme intracranial hypertension more than 61 mmHg. Lowered CBFV was also noted when cerebral perfusion pressure was reduced less than 50 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)