Cerebrovascular pulsation and width of subarachnoid space during electroconvulsive therapy.

Background: The mechanism of electroconvulsive therapy (ECT) has not been comprehensively explained. A new noninvasive method of monitoring intracranial homeostasis during and after ECT provides additional insight into the mechanism of ECT. The investigations on changes in the width of the subarachnoid space (SAS) and intracranial pulsation amplitude by near infrared-transillumination/backscattering sounding method can throw new light on changes in type and volume induced by ECT.

Method: In this study, a new method of noninvasive investigation of width of SAS and intracranial pulsation parameters was used. This method has been called near infrared-transillumination/backscattering sounding. The method consists of light beam analysis in near infrared whereby the light beam is emitted by an emitting diode. The light beam passes through head's anatomic layers, is reflected multiple times in SAS, and returns outward-to be recorded by the receiving diode. The novelty of this method is the patented invention that allows skin flow under the probe to be eliminated and thereby "to look" under the skull bone.

Results: After ECT, a highly significant increase in pulsation amplitude was observed. The pulsation amplitude rose by a factor of 2.5 times after a mean of 90 seconds after the ECT stimulus. A pause in SAS pulsation-not longer than 26 seconds-directly after administration of electroshocks was observed. After approximately 90 seconds, the amplitude decreased slowly, and this was consistent in all analyzed cases. A decrease in SAS width was also observed.