Motor evoked potentials during interventional neuroradiology

Following transcranial electrical cortex stimulation motor evoked potentials (MEP) were monitored in 4 patients during 2 angiographic examinations and 4 therapeutic embolization procedures. Changes of MEP were observed in all 4 patients. Temporary decrease of MEP amplitudes as found in two patients was not followed by any additional postoperative neurological deficits. Incomplete recovery of amplitudes in one case associated with a corresponding hemiparesis post-angiographically. In the last patient amplitude reduction was found one week after the second embolization of an av-angioma. Consequently, an angiographic control was performed early, showing a partial revascularisation by newly opened fistulae which needed to be embolized again. In our opinion, monitoring of MEP during interventional neuroradiology is a sensitive method for early detection of impending neurological deficits. The use of MEP monitoring is discussed with respect to the advantages and limitations of conventional SEP monitoring. Because of the discomfort associated with electrical stimulation a magnetic stimulator may be used.