The Significance of Intraoperative Monitoring of Muscle Motor Evoked Potentials during Unruptured Large and Giant Cerebral Aneurysm Surgery

Abstract

The goal of this study was to characterize the utility of muscle motor evoked potentials (MMEPs) elicited by direct cortical stimulation as a means of monitoring during unruptured large and giant cerebral aneurysm surgery. This analysis focused on intraoperative changes in MMEPs and their relationship to postoperative motor function. The study population consisted of 50 patients who underwent surgery for large (n = 31) or giant (n = 19) cerebral aneurysms. Intraoperative MMEPs were continuously and successfully obtained in muscles belonging to the vascular territory of interest. There was no postoperative motor paresis in 31 (62%) patients in whom intraoperative MMEPs remained unchanged. Transient MMEP change occurred in 15 (30%) of the 50 patients, but 9 of those patients had no postoperative motor deficits, 5 had transient motor deficits, and 1 suffered permanent motor deficits resulting from postoperative delayed blood flow insufficiency due to arteriosclerosis of the parent artery. Permanent MMEP loss occurred in 4 (8%) of 50 patients, all of whom developed severe and permanent postoperative motor deficits. MMEP is a useful monitoring modality in patients undergoing surgery for large or giant cerebral aneurysms. This strategy can help predict functional prognosis or guide the neurosurgeon intraoperatively in an effort to promote better outcomes.

Intraoperative use of transcranial motor/sensory evoked potential monitoring in the clipping of intracranial aneurysms: evaluation of false-positive and false-negative cases

“…13,22, 26,37 ,57,58,63,64,68,69 For example, Takebayashi et al used the complete loss of MEP amplitude as the alert criterion, whereas Szelényi et al included a case in which the patient experienced delayed motor weakness as a false-negative case. 63,64 Hence, simple comparison of EP results from each report could lead to misinterpretation. To minimize this issue, we categorized the false-positive and false-negative criteria of previous studies and matched our definitions as closely as possible, depending on the existence of persistent MEP decline and immediate postoperative motor deficits.…”

“…Various methods of defining alert criteria have been discussed in previous studies, with the majority of authors suggesting that a decrease in amplitude of greater than 50% be considered the clinical warning sign. 13,22,25,26,37,57,63,64,69 Thus, we applied this criterion, and when any such reduction occurred, the neurophysiology team immediately shared the EP results with the surgeon. MEP stimulation was routinely performed after clipping.…”

Korean Clinical Practice Guidelines for Aneurysmal Subarachnoid Hemorrhage

“…Since the introduction of Guglielmi detachable coils in 1991, endovascular coiling has become one of the major treatment modalities for cerebral aneurysms. There have also been improvements in the treatment results from surgical clipping, using intraoperative monitoring 317) and intraoperative fluorescent angiography 275) , among other methods. There have been studies comparing endovascular coiling and surgical clipping in patients with aSAHs 168 , 210 , 219 , 221 , 222 , 309) .…”

Retrograde Suction Decompression for Clip Occlusion of Internal Carotid Artery Communicating Segment Aneurysms

“…In our series, postoperative ischemic lesions were mostly asymptomatic or transient, and relatively common in the territories of the AchA and ATPA, and mostly related to the size (large or giant) of the C1 aneurysm; however, this is unsurprising because the reported postoperative morbidity rate for large or giant C1 aneurysms is 36%e67% of cases. 19,20 Theoretically, in cases of strong attachments and adherences to the perforators, careful dissection of the aneurysm dome after gentle suction of the aneurysm through the RSD may be helpful to decrease the rate of perforator injury and consequently reduce the rate of ischemic events. However, our study did not assess this aspect.…”