Protocol for electrophysiological monitoring of carotid endarterectomies

Abstract

Near zero stroke rates can be achieved in carotid endarterectomy (CEA) surgery with selective shunting and electrophysiological neuromonitoring. though false negative rates as high as 40% have been reported. We sought to determine if improved training for interpretation of the monitoring signals can advance the efficacy of selective shunting with electrophysiological monitoring across multiple centers, and determine if other factors could contribute to the differences in reports. Processed and raw beta band (12.5-30 Hz) electroencephalogram (EEG) and median and tibial nerve somatosensory evoked potentials (SSEP) were monitored in 668 CEA cases at six surgical centers. A decrease in amplitude of 50% or more in any EEG or SSEP channel was the criteria for shunting or initiating a neuroprotective protocol. A reduction of 50% or greater in the beta band of the EEG or amplitude of the SSEP was observed in 150 cases. No patient showed signs of a cerebral infarct after surgery. Selective shunting based on EEG and SSEP monitoring can reduce CEA intraoperative stroke rate to a near zero level if trained personnel adopted standardized protocols. We also found that the rapid administration of a protective stroke protocol by attending anesthesiologists was an important aspect of this success rate.

Indications for General versus Local Anesthesia during Carotid Endarterectomy

“…The reasons for preference of GA were clopidogrel use (88 patients), patient preference (80), increased risk of shunt insertion (43), unfavorable anatomical conditions (41), surgeon preference (21), simultaneous CEA and cardiac surgery (18), emergent carotid endarterectomy (12), and sleep apnea syndrome (1) (►Table 1).…”

“…The gold standard in brain function monitoring is intraoperative electrophysiologic monitoring (somatosensory evoked potentials and electroencephalography). 20,21 Departments that do not have electrophysiologic monitoring (mostly the department of vascular surgery) or an electrophysiologic team fully covering the needs of a neurosurgical department are therefore forced to use LA or operate under GA with routine shunt insertion. The occasional unavailability of intraoperative electrophysiologic monitoring can also be substituted by carotid artery stenting (CAS).…”

“…This finding is supported by other authors. 20,21 It is also clear that preoperative computed tomography angiography is not sensitive enough to reliably select patients with insufficient collateral circulation who need an intraoperative shunt. No imaging method can predict reliably the need for intraoperative shunt.…”

Extra-Thoracic Supra-aortic Bypass Surgery Is Safe in Thoracic Endovascular Aortic Repair and Arterial Occlusive Disease Treatment

“…These factors improve the safety of surgery to the supra-aortic vessels. 18,19 Another contributing factor is that all surgeons who performed the bypass implantation used the same technique and conducted it regularly, which is known to improve surgical outcome. 20 Two cases of temporary Horner syndrome as well as recurrent laryngeal nerve palsy occurred.…”

Frequency-Domain Objective Response Detection Techniques Applied to Evoked Potentials: A Review

“…The somatosensory evoked potential (SEP) is often obtained by applying electric current pulses and is useful for detecting peripheral nerve lesions, plexopathies and radiculopathies (Linden et al, 1997), and for monitoring vascular and spine surgeries such as desobstruction of the carotid artery (Liu et al, 2010), aortic aneurism repair (Keyhani et al, 2009, Van Dongen et al, 2001, aortic coarctation repair (Faberowski et al, 1999), scoliosis correction procedures (Cruccu et al, 2008) and lumbar pedicle screw placement for in situ posterior spinal fusion (Gundanna, 2003), due to its sensitivity to mechanical stress, hypotension and ischemia.…”