Application Of Monopolar High-frequency Electrical Stimulation In Intraoperative Localization Of Glioma In Motor Area Of Brain

Objiect: the safety and effectiveness of monopalar high-frequency electrical stimulation in intraoperative localization of gliomas in motor areas.Methods: We performed intraoperative single-stage high-frequency electrical stimulation in 20 patients with gliomas involving the motor region of the brain to locate the boundary between the tumors and normal brain tissues,including cortical and subcortical localization.Monopolar mapping of motor function differs from the most commonly used method of intraoperativemapping,i.e.bipolar direct electrical stimulation at 50–60 Hz(Penfield technique mapping),the monopolar probe emits a radial,homogenous electrical field different to the more focusedinter-tip bipolar electrical field,we combine monopolar stimulation with the short train tech-nique,also called high frequency stimulation,or train-of-five techniques.It consists of trains of four tonine monopolar rectangular electrical pulses of 200–500 s pulse length with an inter stimulus inter-val of 2–4 msec,High frequency short train stimulation triggers a time-locked motor-evoked potentialresponse,which has a defined latency and an easily quantifiable amplitude.In this way,motor thresh-olds might be used to evaluate a current-to-distance relation.The homogeneous electrical field and thecurrent-to-distance approximation provide the surgeon with an estimate of the remaining distance tothe corticospinal tract,enabling the surgeon to adjust the speed of resection as the corticospinal tractis approached.Furthermore,this stimulation paradigm is associated with a lower incidence of intraop-erative seizures,allowing continuous stimulation.Hence,monopolar mapping is increasingly used aspart of a strategy of continuous dynamic mapping.We try to combine unipolar probe with aspirator and two-stage electrocoagulation,so that it can continuously monitor the motion function of the feedback mapping area.Motion function monitoring does not need to interrupt the operation,but becomes a real-time feedback system of the relationship between the location of the real-time reverse operation area and the motion function area,so that the tumors can be safely removed in the largest range.Results: Among the 20 patients,the total resection rate was 85%.No patients had motor dysfunction or paralysis due to CST injury.The KPS score improved significantly after operation.One week after operation,motor function was significantly decreased in 2 cases and 1 case.After two weeks,muscle strength of 17 patients recovered to the preoperative level.Conclusions: Single-stage high-frequency electrical stimulation is safe and effective in the removal of gliomas in the motor area.It can accurately locate the motor function area and its subcutaneous conduction tract,and safely remove the tumors in the greatest extent.