Limitations of median nerve somatosensory evoked potential monitoring during carotid endarterectomy

Abstract

OBJECTIVE Hypoperfusion during carotid artery cross-clamping (CC) for carotid endarterectomy (CEA) may result in the major complication of perioperative stroke. Median nerve somatosensory evoked potential (MNSSEP) monitoring, which is an established method for the prediction of cerebral ischemia, has low sensitivity in detecting such hypoperfusion. In this study the authors sought to explore the limitations of MNSSEP monitoring compared to tibial nerve somatosensory evoked potential (TNSSEP) monitoring for the detection of CC-related hypoperfusion. METHODS The authors retrospectively analyzed data from patients who underwent unilateral CEA with routine shunt use. All patients underwent preoperative magnetic resonance angiography and were monitored for intraoperative cerebral ischemia by using MNSSEP, TNSSEP, and carotid stump pressure during CC. First, the frequency of MNSSEP and TNSSEP changes during CC were analyzed. Subsequently, variables related to stump pressure were determined by using linear analysis and those related to each of the somatosensory evoked potential (SSEP) changes were determined by using logistic regression analysis. RESULTS A total of 94 patients (mean age 74 years) were included in the study. TNSSEP identified a greater number of SSEP changes during CC than MNSSEP (20.2% vs 11.7%; p < 0.05). Linear regression analysis demonstrated that hypoplasia of the contralateral proximal segment of the anterior cerebral artery (A hypoplasia) (p < 0.01) and hypoplasia of the ipsilateral precommunicating segment of the posterior cerebral artery (P hypoplasia) (p = 0.02) independently and negatively correlated with stump pressure. Both contralateral A hypoplasia (OR 26.25, 95% CI 4.52-152.51) and ipsilateral P hypoplasia (OR 8.75, 95% CI 1.83-41.94) were independently related to the TNSSEP changes. However, only ipsilateral P hypoplasia (OR 8.76, 95% CI 1.61-47.67) was independently related to MNSSEP changes. CONCLUSIONS TNSSEP monitoring appears to be superior to MNSSEP in detecting CC-related hypoperfusion. Correlation with stump pressure and SSEP changes indicates that TNSSEP, and not MNSSEP monitoring, is a reliable indicator of cerebral ischemia in the territory of the anterior cerebral artery.

Combination of Single- and Paired-Pulse Somatosensory Evoked Potentials in Ischemic Monitoring: Preliminary Investigation in Carotid Endarterectomy

“…Persistent imbalances, if intraoperatively identified, will be managed in the same way as conventional SEPs through intentional hypertension, minimization of time for declamping, and administration of edaravone [ 27 ]. Identification of such imbalances will aid in timely and proper postoperative management not only by performing DWI MRI but through prescribing medications, which turned out to be effective for treating impaired cognitive function and inducing functional recovery of the rescued penumbra [ 7 , 8 ].…”

Surgical Technique for Carotid Endarterectomy: Current Methods and Problems

“…Several studies have discussed the best monitoring systems for use during CEA. 26 – 30) Some of those studies considered the need for shunt, 29) but some used monitoring to predict neurological deficit. 28 , 30) To date, no monitoring technique during CEA has proven clearly superior to any other.…”