Optimal cerebral monitoring during carotid endarterectomy: Neurologic response under local anesthesia

Abstract

A prospective series of carotid endarterectomies were performed with patients given local anesthesia in an attempt to determine the efficacy of intraoperative EEG monitoring and/or stump pressure measurements in predicting the need for carotid shunting. Carotid artery stump pressure was measured and EEG changes noted; however, neither low stump pressure nor EEG changes influenced the decision for shunt insertion. A shunt was only used if a neurologic deficit developed during carotid clamping. A total of 134 carotid endarterectomies were done in 121 patients. Sixty-six patients were men and 55 were women with ages ranging from 41 to 88 years. Indications included transient ischemic attacks in 57 (43%), prior stroke in 25 (19%), vertebrobasilar symptoms in nine (6%), and asymptomatic patients with high-grade stenosis, 43 (32%). Thirteen patients (9.7%) developed neurologic deficits following carotid clamping and had shunts inserted. All deficits cleared following shunt insertion. Nine of the 13 had EEG changes, but in four, EEGs were unchanged despite the occurrence of clear-cut neurologic changes. Stump pressure in the 13 patients ranged from 14 to 78 mm Hg. Ten were greater than 24 mm Hg and three were more than 50 mm Hg. In 121 operations no neurologic deficits occurred during carotid clamping and no shunts were inserted. In 13 of these operations, significant EEG changes were noted. Stump pressures in these 13 with EEG changes ranged from 15 to 120 mm Hg. In seven, stump pressure was greater than 50 mm Hg. There were no deaths in the series. Two (1.5%) temporary and one (0.7%) permanent postoperative deficits occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective randomized trial of routine versus selective shunting in carotid endarterectomy based on stump pressure

“…This method is the most direct measure of cerebral ischemia. 16,[35][36][37] However, many patients may not be able to undergo carotid surgery under cervical block anesthesia secondary to patient (high level of anxiety) or surgeon preference.…”

Cerebral oximetry does not correlate with electroencephalography and somatosensory evoked potentials in determining the need for shunting during carotid endarterectomy

“…[6][7]31 However, the success of this technique is critically dependent on a cooperative patient, the appropriate level of sedation, and the quality of the regional block. Under general anesthesia, stump pressure measurement, pioneered by Moore, was considered a simple and inexpensive way to determine the need for a shunt.…”

“…4,5 CEA under regional anesthesia was proposed as the simplest and the most accurate way to monitor the patient, with shunts being placed only if there was a change in neurologic status. 6,7 The measurement of the internal carotid artery back pressure, or "stump" pressure, was the first monitoring technique used for selective shunting under general anesthesia. 4 Subsequently, the electroencephalogram (EEG), somatosensory evoked potentials (SSEP), and transcranial Doppler (TCD) were shown to be very effective in predicting the need for a shunt.…”

A clinical evaluation of near-infrared cerebral oximetry in the awake patient to monitor cerebral perfusion during carotid endarterectomy

“…If the patient is not awake, electroencephalography (EEG) is the standard monitoring system routinely used to detect alterations in cerebral perfusion during CEA [4,5]; however, this monitoring system requires a dedicated technician and EEG machine. Nearinfrared spectroscopy (NIRS) is a noninvasive technique that allows continuous monitoring of cerebral oxygenation through the scalp and skull [6] and has been demonstrated to accurately recognize cerebral hemoglobin oxygen desaturation produced by systemic hypoxemia [7].…”