Transcranial Doppler sonography in experimental Cushing response.

Searching for the early warning symptoms of brain ischaemia, transcranial Doppler sonography (TCD) was used in cats during the Cushing response. The study was performed on seven cats. The intracranial pressure was increased by means of different rate lumbar infusions. The TCD changes of middle cerebral artery (MCA) and basilar artery (BA) flows were analyzed at the stage of the slightest but significant systemic blood pressure increase. The first symptoms of Cushing phenomenon were accompanied by BA flow pattern alternations while the MCA flow remained unchanged. The study suggests the necessity of BA TCD monitoring in cases at risk from brain stem ischaemia. It was shown also that in such cases the MCA TCD study can be misleading.