1988 Volume 28 Issue 2 Pages 176-182
A new method has been developed for estimating the need for cerebrospinal fluid (CSF) drainage in patients with normal pressure hydrocephalus (NPH). The method was based on long-term electroencephalography (EEG) monitoring during CSF drainage and computerized analysis of the relationship between the EEG data and CSF pressure changes. Lumbar CSF pressure were monitored. Recordings were first obtained with a closed CSF drainage catheter in place. Subsequently, CSF drainage was carried out at various pressures and graphs of time-dependent trends in EEG parameters and CSF pressure were produced. According to the data obtained, if the magnitude or duration of alpha or beta waves increase and those of delta waves decrease in response to a reduction in CSF pressure, the patient is a good candidate for CSF drainage.
The authors applied this method to nine patients with cerebrovascular diseases who were diagnosed as having NPH on the basis of clinical and computed tomography findings. The seven patients who showed EEG improvement at different CSF pressures underwent ventriculoperitoneal, ventriculoatrial, or lumboperitoneal shunting procedures. One shunt was set at medium pressure (about 10cmH2O) and two at low pressure (about 5cmH2O), and four patients received shunts without a flushing device and slit valves, so that the pressure was 0cmH2O. All seven of these patients improved clonicinically after the operation, although one patient suffered from chronic subdural hematoma.
Thus, this method proved reliable in predicting the usefulness of CSF shunting in patients with NPH. Also, optimal shunt pressure could be determined prior to the operation. However, we must be alert to the possibility of complications, such as subdural hematoma or effusion, in patients with a low-pressure shunt system.
