Detection of acute femoral artery ischemia during neuroembolization by somatosensory and motor evoked potential monitoring

Neuromonitoring Identifies Occlusion of Femoral Artery in STA-MCA Bypass Procedure: A Case Report

Intraoperative neurophysiological monitoring (IONM) is a technique used to assess the somatosensory and gross motor systems during surgery. While it is primarily used to detect and prevent surgically induced nervous system trauma, it can also detect and prevent injury to the nervous system that is the result of other causes such as trauma or ischemia that occur outside of the operative field as a result of malpositioning or other problematic physiologic states. We present a case study where a neuromonitoring alert altered the surgical procedure, though the alert was not correlated to the site of surgery. A 69-year-old male with a history of bilateral moyamoya disease and a left middle cerebral artery infarct underwent a right-sided STA-MCA bypass and encephaloduroarteriosynangiosis (EDAS) with multimodal IONM. During the procedure, the patient experienced a loss of motor evoked potential (MEP) recordings in the right lower extremity. Blood pressure was elevated, which temporarily restored the potentials, but they were lost again after the angiography team attempted to place an arterial line in the right femoral artery. The operation was truncated out of concern for left hemispheric ischemia, and it was later discovered that the patient had an acute right external iliac artery occlusion caused by a fresh thrombus in the common femoral artery causing complete paralysis of the limb. This case highlights the importance of heeding IONM alerts and evaluating for systemic causes if the alert is not thought to be of surgical etiology. IONM can detect adverse systemic neurological sequelae that is not necessarily surgically induced.

Intraoperative neurophysiology monitoring in scoliosis surgery in children

Objective

Intraoperative neurophysiology monitoring (INM) is thought to reduce the risk of postoperative neurological deficits in children undergoing scoliosis and spine deformity surgery. INM is being used increasingly despite conflicting opinions, varied results, non-standard alarm criteria and concern regarding cost effectiveness. In this paper we present our experience with INM in scoliosis and spine deformation surgery in children, propose alert criteria and preferred anaesthetics in clinical practice.

Methods

We retrospectively analysed our experience with INM in 56 children who had 61 scoliosis and spine deformity surgeries.

Results

INM was successfully undertaken with transcranial electrical motor evoked potentials (TcMEP) and somatosensory evoked potentials. There were no injuries due to INM. Four children had 5 alerts during 4 surgeries. A postoperative deficit was seen in one child only. No new postoperative deficits were seen in any child who did not have an alert during INM. Total intravenous anaesthesia was better for INM compared to inhalational anaesthetics.

Conclusions

INM is useful in scoliosis surgery; it is likely to mitigate the risk of new deficits following surgery. We recommend alert criteria for TcMEPs that include multiple facets - amplitude, stimulus paradigm, morphology. We recommend propofol and remifentanil, in preference to sevoflurane and remifentanil for anaesthesia during INM.

Significance

Our study adds to the literature supporting the role of INM in scoliosis surgery in children. We provide guidelines for alarm criteria in clinical practice and recommend the use of total intravenous anaesthesia as the preferred anaesthetic option.