[Response of cerebral bioelectrical activity to changes in the cerebrospinal fluid pressure of neurooncologic...

The reaction of cerebral electric activity to induced changes in the cerebrospinal fluid pressure during examination of P-V dependence of the craniospinal cavity was appraised in 8 neuro-oncological patients in the postoperative period by means of spectral EEG analysis. Among 41 tests with artificial changes in CSF pressure decrease in CSF pressure was attended in 60 per cent of cases by an increase in the EEG p]ower by 6.4% on the average, while an increase in CSF pressure caused a decrease in EEG power by 8.6% on the average. In 40% of cases, however, a decrease in CSF pressure was attended not by an increase, but by a reduction of EEG power by 3.5% on the average; an increase in CSF pressure induced a rise in EEG power (by 3.7% on the average). The degree of the reactive changes in EEG power in response to induced CSF pressure fluctuations increased with deterioration of the patient's condition. Thus, rapid compression and decompression of the CSF system induces short-term (7 minutes at most) changes in EEG power. These changes are ambiguous both in direction and in degree of conspicuity.