Abstract
A total of 128 cases with ruptured cerebral aneurysms were operated on within two weeks after subarachnoid hemorrhage (SAH) . Postoperatively, cerebrospinal fluid (CSF) was continuously drained from the lateral ventricle and the basal cistern. Using the intraventricular catheter, intracranial pressure (ICP) was monitored for an average of three weeks after operation. The development of normal pressure hydrocephalus (NPH) was estimated from ICP pattern and other diagnostic studies such as CT scan, infusion test and RI cisternography.
NPH developed in 26% of these cases. Patients who had a large volume of CSF drainage of over 200 ml daily underwent shunt surgery in a higher proportion (56%). It was postulated that the defect of the subarachnoid space might be aggravated by CSF drainage.
A total of 49 long-term recordings of ICP was obtained in 31 cases. Within two weeks after SAH, ICP was usually higher than 20 mmHg, but thereafter became lower. This early high pressure was mostly due to acute hydrocephalus and not to the so-called acute brain swelling. However, when mildly elevated ICP with B-wave lasted beyond the third week of SAH, almost all patients developed NPH. This characteristic pattern of ICP plays an important role in the development of NPH and is useful for selecting patients for shunt surgery.
Vasospasm was a frequent concomitant of increased ICP, and patients with vasospasm underwent shunt surgery in rather high incidences (34%). Both vasospasm and hydrocephalus could be explained to be the result of blood clots in the subarachnoid space.
