[Monitoring somatosensory evoked potentials during surgery of cerebral vessels].

In 43 patients serial SSER recordings were made during operations for the clipping of arterial aneurysms of cerebral vessels performed under controlled arterial hypotension. SSER recordings during the preliminary phase of the operation showed an average decrease in the response amplitude of 20% during trepanation and a reduction (by 23% of the initial value) during the phase of arterial hypotension. The response recovered to 84% of its initial level by the moment of the beginning of the operation. There was no statistically significant relationship between serial SSER parameter values during arterial pressure reduction and the duration or degree of hypotension. The results testify to the higher information content of such SSER parameters as the amplitude of the first positive complex, as compared with latency criteria and in particular the CCT. It has also been found that a significant increase in the information value of the SSER for the evaluation of ischemia effect on the brain function may be obtained by synchronous stimulation of both arms and registration of cortical responses from both hemispheres.