[Experimental study on the effect of ultrasonic surgical aspiration on blood flow and nerve function by use of ultrasonic Doppler flowmeter and auditory brainstem evoked response].

The effect of intracranial use of an ultrasonic surgical aspirator on major cerebral vessels and nervous tissue was studied in anesthetised adult cats. Experiments were performed without suction in order to investigate only the effect of ultrasonic emulsification. The flow rate of irrigation saline over the tip of the ultrasonic aspirator was set at either slow (4 ml/min) or fast (24 ml/min). Flow in the common carotid artery and superior sagittal sinus was studied by ultrasonic Doppler flowmetry during direct or indirect (intermediated by muscle fragment) application to the vessels of ultrasonic vibration for periods of 5 min. each in increments of 20% from 20% of maximal intensity. Flow in both the carotid artery and the superior sagittal sinus changed only with direct application on vascular surface of ultrasonic vibration of at least 80% of maximal intensity; otherwise flow in these vessels was not changed. The temperature rise caused by ultrasonic vibration was studied by use of a thermister buried in the brain parenchyma of animals 2 mm from the ultrasonic vibratory probe tip. A rise above the physiological range could be prevented by sufficient irrigation. The effect of ultrasonic vibration on the brainstem was studied by using auditory brainstem evoked response (ABR) to monitor brainstem function. An ultrasonic vibratory probe was applied to the ventral surface of the brainstem exposed by transclival approach. ABR changed noticeably only when ultrasonic vibration of 60% or more of maximal intensity was applied directly; otherwise ABR was not changed. The effect of ultrasonic vibration on the intracranial acoustic nerve was also studied by ABR.(ABSTRACT TRUNCATED AT 250 WORDS)