Failure of carotid stump pressures. Its incidence as a predictor for a temporary shunt during carotid endarterectomy

A total of 289 carotid endarterectomies were performed in 204 patients. A decision to place a temporary shunt during carotid endarterectomy in this series was made entirely on the basis of intraoperative EEG monitoring. Retrospectively, the correlation between stump pressures and the results of intraoperative EEG monitoring in each case was determined. Evidence of ischemia developed in 6% of the total series on intraoperative EEG monitoring despite a stump pressure of greater than 50 mm Hg. The degree of disagreement between stump pressure and EEG varied according to clinical category in this series. In those endarterectomies performed for completed stroke, all cases requiring shunting had stump pressures less than 50 mm Hg. In those cases performed for symptoms of vertebral basilar insufficiency, however, 77% of the cases requiring an intraoperative shunt had stump pressures greater than 50 mm Hg. A review of the complication rate in the various study groups indicates that the use of intraoperative EEG is a safe indicator of cerebral ischemia during carotid endarterectomy regardless of stump pressure.     

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

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)     

Routine electroencephalographic (EEG) monitoring during carotid endarterectomy.

Controversy continues concerning the advisability of routine shunting, no shunting, or selective shunting during carotid endarterectomy. Because of its reflection of the physiologic state of the end organ, the authors chose routine 18 lead EEG monitoring as a guide to selective shunting and as an indication of adequate shunt function during all carotid endarterectomies performed from December 1977 through July 1982. In that period, 200 patients underwent 219 endarterectomies under general anesthesia and EEG monitoring. Ischemic EEG changes at the time of carotid cross clamping suggested the need for intraluminal shunts in 16% of patients. Insertion of shunts restored the EEG pattern to normal in all instances, although in two patients, adjustment of the shunt was required to maintain this results. EEG changes requiring shunting occurred in 10% of patients with unilateral disease, in 27% of patients with bilateral disease, and in 42% of patients with unilateral stenosis and contralateral occlusion. Twenty-seven patients had small fixed neurologic deficits before operation. Surgery was not delayed in these individuals who demonstrated no increased requirement for shunts and no new postoperative neurologic deficits. In the group of 150 endarterectomies performed as separate procedures, there was one (0.7%) fixed neurologic deficit after operation, one transient deficit (0.7%), and one death (0.7%). Sixty-nine endarterectomies were performed simultaneously with open heart surgery and were associated with one fixed neurologic deficit (1.4%) and two transient deficits (2.9%). All four deaths in this group were attributable to the cardiac surgical procedures. These results indicate that selective shunting based on EEG monitoring permits the safe performance of carotid endarterectomy, even in patients considered to be at high risk for postoperative neurologic deficit.     

Benefits, shortcomings, and costs of EEG monitoring.

A 5-year experience with 562 carotid endarterectomies, using electroencephalogram (EEG) monitoring and selective shunting, was reviewed. EEG changes occurred in 102 patients (18%). The frequency of EEG changes, as related to cerebral vascular symptoms, was as follows: transient ischemic attacks, seven per cent (19/259); completed strokes, 37% (36/98); vertebral basilar insufficiency, 24% (32/135); asymptomatic, 21% (15/71). Patients with contralateral carotid occlusion exhibited EEG changes in 37% (28/76) of operations. Fifteen patients suffered perioperative strokes (2.6%). Nine of the 15 were associated with a technical problem of either thrombosis of the internal carotid artery (five) or emboli (four). Technical problems were more common when shunts were used (five per cent) than when they were not (0.9%). Patients who suffered strokes prior to surgery were more at risk to develop a perioperative stroke (three per cent) than those not suffering prior strokes (0.3%). The EEG did not change in three patients who had lacunar infarcts prior to surgery and who awoke with a worsened deficit. Our series does not clearly establish the advantages of EEG monitoring, which is expensive (+375/patient) and may not detect ischemia in all areas of the brain. However, the use of shunts may introduce a risk of stroke due to technical error that is equal or greater than the risk of stroke due to hemodynamic ischemia. Since the need for protection is unpredictable by angiographic or clinical criteria, the benefit of EEG monitoring may be in reducing the incidence of shunting in those patients whose tracing remains normal after clamping. The decision to shunt, however, when there is electrical dysfunction after carotid clamping should be based not only on the EEG but also on the clinical signs and computed tomography (CT) scan. Our data does not show a net benefit in selective shunting unless the patient has sustained a stroke prior to surgery.     

Advantages of continuous electroencephalographic monitoring during carotid artery surgery

One hundred carotid endarterectomies were performed using selective shunting based on continuous electroencephalographic monitoring (CEM) for the detection of cortical ischemia. Changes associated with ischemia were loss of frequency and amplitude. The results of CEM were correlated with carotid stump pressure (CSP) measurements. Only one (4%) of the 25 patients who developed an abnormal EEG had a mean CSP greater than 50 mmHg: however, CEM was positive in only 24 (45%) of the 53 patients with a CSP less than 50 mmHg. Using EEG as a standard, no CSP criterion (50 or 25 mmHg) was sufficiently sensitive and specific to recommend its routine use (50 mmHg--96% and 61% respectively; 25 mmHg--40% and 96% respectively). Operative mortality was 1%. The three intraoperative neurologic deficits (3%), one transient and two permanent, are analyzed with respect to the operative EEG findings. In the 100 endarterectomy patients and three more undergoing carotid exploration or excision of carotid body tumor EEG changes due to anesthetic problems not associated with carotid clamping were often identified. In 48 additional endarterectomies a computerized display and disk storage of six selected EEG leads, each with a reference trace for comparison, has provided information equivalent to that from the full EEG. EEG monitoring is more accurate than CSP measurement for identifying patients who require shunting, safely dispensing with a shunt in many cases which would otherwise be shunted by standard CSP criteria.(ABSTRACT TRUNCATED AT 250 WORDS)     

Minimizing the risks of carotid endarterectomy

In 1971 this study was undertaken to determine optimal methods and guidelines for lowering the mortality and neurologic complication rates associated with carotid endarterectomy. Of 570 carotid endarterectomies, 481 (84%) were performed under local anesthesia to provide continuous neurologic monitoring and to permit operation on the very elderly and poor-risk patient. In 418 of these procedures carotid stump pressures (CSPs) were measured with patients awake to determine the level of back pressure sufficient for brain protection during operative occlusion. Selective shunting was necessary in 40 (8%) of these cases. Of 78 patients with a CSP of 0 to 25 mm Hg, only 39 (50%) required shunting. Only one patient with a pressure >25 mm Hg (29 mm Hg) needed a shunt. The CSP/brachial blood pressure (BBP) index was calculated for 410 procedures. Of 97 patients with a CSP of 0 to 30 mm Hg, only 31 required a shunt (CSP/BBP index 0.01 to 0.18). No shunt was necessary for an index >0.18. Patients with a contralateral occlusion or severe stenosis required a shunt six times more frequently than those with unilateral disease. For 570 procedures the overall mortality rate was 0.7% and the neurologic complication rate was 0.9%. When local anesthesia was used for 481 procedures, there was only one death (0.2%). For 74 asymptomatic lesions there were no deaths or stroke. Neurologic monitoring under local anesthesia and CSPs are reliable indicators for selective shunting. Multiple-risk factors influence the outcome of carotid endarterectomy, but most can be avoided. (J VASC SURG 1984;1:392-7.)     

EEG as a criterion for shunt need in carotid endarterectomy

The efficacy of continuous intraoperative electroencephalographic (EEG) monitoring as a criterion for selective shunt use during carotid endarterectomy is evaluated in a group of 1661 operations in which the EEG was the sole criterion for shunt insertion. EEG monitoring is measured by the intraoperative stroke rate. Carotid stump pressure measurements were recorded as an additional observation in 1517 operations and represent a subset of the study group allowing comparison of this technique with EEG. Intraoperative stroke rate for the 1661 operations in the study group was 0.03% (five strokes). A statistically significant increase in intraoperative stroke rate was associated with the development of an abnormal EEG (1.1%), contralateral internal carotid artery occlusion (1.8%), and the combination of both abnormal EEG and contralateral internal carotid occlusion (3.3%). The EEG remained normal in 1295 operations including 75 operations with contralateral internal carotid artery occlusion. One minor intraoperative stroke (0.08%) which resolved in 1 week occurred in the absence of an EEG change with no intraoperative strokes in the 75 operations in which the contralateral internal carotid artery was occluded. Intraoperative EEG monitoring accurately (99.92%) identified patients who may safely have carotid endarterectomy without the need of a shunt.     

Stroke-related EEG changes during carotid surgery

EEG recordings from 230 carotid endarterectomies performed with an automatic EEG monitoring system were reviewed with the purpose of establishing the exact relation between EEG changes and intraoperative stroke. Patients were selectively shunted, based on the EEG changes occurring after carotid cross-clamping. Transient EEG asymmetry was not associated with intraoperative stroke. Only persisting EEG asymmetry reflected intraoperative major stroke, expressed by a positive predictive value of 0.50, but also in terms of specificity (0.99), sensitivity (0.80) and diagnostic gain (47.8%) of the EEG; minor strokes could not be detected with EEG monitoring. Analysis of the time course of the persisting asymmetry confirmed the thrombo-embolic origin of the majority of the major strokes.     

Carotid endarterectomy with routine electroencephalography and selective shunting: Influence of contralateral internal carotid artery occlusion and utility in prevention of perioperative strokes

OBJECTIVE: Carotid endarterectomy (CEA) is associated with a risk of cerebral ischemia during carotid clamping, particularly in the face of contralateral internal carotid artery (ICA) occlusion. We examined the results of CEA with continuous electroencephalography in patients without and with contralateral ICA occlusion. DESIGN AND SETTING: We reviewed 564 primary CEAs with routine electroencephalography and general anesthesia performed between April 1, 1989, and March 31, 1999, in a community teaching medical center. Main outcome measures were perioperative stroke, temporary lateralizing neurologic deficit, and death. Shunts were placed primarily for significant electroencephalographic changes after carotid clamping but also selectively for contralateral ICA occlusion, prior stroke, or surgeon choice. CEA was performed for asymptomatic disease in 35% of cases. RESULTS: Significant electroencephalographic changes occurred in 16% versus 39% (P <.001) and shunts were placed in 13% versus 55% (P <.001) of patients with patent (n = 507) versus occluded contralateral ICA (n = 57), respectively. The fraction of CEAs with significant electroencephalographic changes during clamping was stable, but shunt use declined slightly over time as our confidence in electroencephalography increased. Patches were placed more often (86% versus 65%; P =.002), but other operative details were similar when the contralateral ICA was occluded. Five early (30 days) strokes (0.9%) and eight early temporary postoperative neurologic events (1.4%) occurred, all ipsilateral to CEA and all after the patient left the operating room with none in patients with contralateral ICA occlusion. Two perioperative deaths occurred, one in a patient without and one in a patient with contralateral ICA occlusion. Neither of these deaths was related to ipsilateral stroke. No increase in stroke rate with decreased shunt use over time was seen. CONCLUSION: Routine use of electroencephalography was associated with apparent complete elimination of intraoperative strokes and less than 1% risk of perioperative strokes. These observations appear to be true even in the face of contralateral ICA occlusion. Electroencephalography is a sensitive detector of cerebral ischemia and a valuable tool for determination of need for shunting during CEA. Surgeons should consider routine use of electroencephalography and selective shunting for significant electroencephalographic changes with clamping.     

Comparison of simultaneous electroencephalographic and mental status monitoring during carotid endarterectomy with regional anesthesia

Purpose: This study examines the accuracy of intraoperative electroencephalographic (EEG) monitoring for the detection of cerebral ischemia by comparing EEG with simultaneous mental status evaluation (MSE) during carotid endarterectomy in awake patients. Methods: Between 1994 and 1997, 208 consecutive carotid endarterectomies were prospectively evaluated for cerebral function during surgery with simultaneous MSE and EEG monitoring. Regional anesthesia (RA), which consisted of superficial cervical block, was chosen preferentially in 75% of the cases, with general anesthesia (GA) reserved for the patients who did not fulfill the criteria for RA. When available, 8-channel EEG monitoring was performed (59% with RA and 55% with GA). Results: The EEG was a reliable predictor in comparison with MSE in most but not all cases of cerebral ischemia. Significant neurologic changes were noted using MSE in 4 of 89 patients (4.5%) that were not detected using EEG (false negative results). Conversely, 6 of 89 cases (6.7%) showed unilateral slowing without associated changes in MSE (false positive results). For the awake patients, 21 of 150 cases (14%) showed MSE changes that required a shunt. By contrast, 9 of 32 GA cases (28%) showed EEG changes that would have led to shunting (P = NS). In the RA group, there were no strokes versus 3 of 58 cases (5.2%) with strokes in the GA group. Two of 150 cases (0.1%) had transient ischemic attacks in the RA group. There was 1 myocardial infarction in the GA group; no deaths occurred in this series. Conclusion: EEG monitoring yielded a significant number of false positive (6.7%) and false negative (4.5%) results in the detection of neurologic deficits when compared with MSE in the awake patients. In this series, the preferential use of RA resulted in less shunt use and was possibly associated with a lower stroke rate. (J Vasc Surg 1998;28:1014-23.)     

Use of shunts with eversion carotid endarterectomy

PURPOSE: The purpose of this study was to examine the utility of carotid shunting in the context of eversion endarterectomy. A comparison of patients who underwent carotid endarterectomy by eversion with and without shunts was performed. METHODS: Over a 5-year period, 2724 eversion carotid endarterectomies were performed. In most of these operations patients were under cervical block anesthesia. A shunt was used in 112 eversion endarterectomies (4.1%). Cervical block anesthesia was used in 103 patients (92.0%), general anesthesia was used in 5 patients (4.5%), and 4 patients (3.6%) were converted from cervical block to general anesthesia intraoperatively. The indications for shunting were neurologic deterioration in 99 patients (88.4%) who were under cervical block anesthesia, procedures performed in neurologically unstable or otherwise compromised patients who were under general anesthesia, and the operator's discretion in the remaining eight patients. RESULTS: There was a combined stroke/death rate of 2.7% in the shunt group. These three cases included one death from myocardial infarction and one delayed death due to intracerebral hemorrhage after discharge. Shunt insertion was unrelated to the negative outcome in these two cases. One perioperative major stroke in the shunt group was identified. Follow-up averaged 12.3 months (range, 1-53 months). CONCLUSION: Carotid shunts can be used effectively in the context of eversion endarterectomy. Shunt insertion is not associated with an increased stroke/death rate in these patients.     

Correlation of contralateral stenosis and intraoperative electroencephalogram change with risk of stroke during carotid endarterectomy.

Two hundred ninety-three carotid endarterectomies were performed with electroencephalogram (EEG) monitoring and without the use of a shunt. Two hundred sixteen patients had contralateral carotid stenosis of less than 70%; 45 had contralateral stenosis of 70 to 99%; and 32 had contralateral occlusion. There were six perioperative strokes (2.0%) and two deaths (0.7%). Major EEG changes were seen in 11 of the 77 patients (14.3%) with significant contralateral stenosis or occlusion versus 11 of the 216 patients (5.1%) in those without (P less than 0.025). The risk of immediate postoperative deficit was significantly higher in the subgroup with major EEG changes (4 of 22, 18.2%) than in those without such changes (5 of 271, 1.8%) (P less than 0.005). The risk in patients with less than 70% contralateral stenosis (7 of 216, 3.2%) was not significantly different from those with greater contralateral stenosis or occlusion (2 of 77, 2.6%). Carotid endarterectomy can be safely performed without a temporary shunt. Contralateral stenosis or occlusion alone does not confer increased risk. Major EEG changes are infrequent, but they identify a subgroup with significantly higher risk of intraoperative stroke.     

Selective shunting with eversion carotid endarterectomy

PURPOSE: The consensus is that eversion carotid endarterectomy (CEA) is a safe, effective, and durable surgical technique. Concern remains, however, regarding insertion of a shunt during the procedure. We studied the advisability of shunting with eversion CEA by comparing patients who underwent eversion CEA with and without shunting. METHODS: Over 9 years, 624 primary eversion CEAs were performed in 580 selected patients to treat symptomatic (n = 398, 63.8%) and asymptomatic (n = 226, 36.2%) carotid lesions. All eversion CEAs were performed by the same surgeon (E.B.), with the patient under deep general anesthesia, with continuous electroencephalographic (EEG) monitoring for selective shunting, based exclusively on EEG changes consistent with cerebral ischemia. A Pruitt-Inahara shunt was used in 43 eversion CEAs (6.9%). All patients underwent postoperative duplex ultrasound scanning and clinical follow-up at 1, 6, and 12 months and once a year thereafter. Mean follow-up was 52 months (range, 3-91 months). The main end points were perioperative (30-day) stroke and death, and recurrent stenosis. RESULTS: No perioperative death occurred in this series. Overall, ischemic perioperative stroke occurred in 4 of 624 patients (0.6%). Two strokes were minor and two were major. Only one (major) stroke occurred in the group with shunt insertion (1 of 43, 2.3%; P = not significant); the everted internal carotid artery was patent. Long-term follow-up was performed in all living patients. There was no late recurrent stenosis (>50%), and one late asymptomatic occlusive event occurred in the group without shunt insertion. CONCLUSIONS: Shunt insertion can be safely performed during eversion CEA. Perioperative mortality and morbidity after eversion CEA are not statistically modified with shunting.     

Prospective evaluation of electroencephalography, carotid artery stump pressure, and neurologic changes during 314 consecutive carotid endarterectomies performed in awake patients

OBJECTIVE: This study attempted to correlate neurologic changes in awake patients undergoing carotid endarterectomy (CEA) under cervical block anesthesia (CBA) with electroencephalography (EEG) and measurement of carotid artery stump pressure (SP). METHODS: Continuous EEG and SP monitoring was measured prospectively in 314 consecutive patients undergoing CEA between April 1, 2003, and July 30, 2006, under CBA. Indications for CEA were asymptomatic 70% to 99% internal carotid artery stenosis in 242 (77.1%), transient ischemic attacks (including transient monocular blindness) in 45 (14.3%), and prior stroke in 27 (8.6%). Mean common carotid artery pressure before clamping, mean SP after carotid clamping, and intraarterial pressure were continuously monitored in all patients. An indwelling shunt was placed when neurologic events (contralateral motor weakness, aphasia, loss of consciousness, or seizures) occurred, regardless of SP or EEG changes. RESULTS: Shunt placement was necessary because of neurologic changes in 10% (32/314) of all CEAs performed under CBA. Only 3 patients (1.4%) of 216 required shunt placement if SP was 50 mm Hg or more, vs 29 (29.6%) of 98 if SP was less than 50 mm Hg (P < .00001; sensitivity, 29.8%; specificity, 98.6%). In patients with SP of 40 mm Hg or more, 7 (2.6%) of 270 required shunt placement, vs 25 (56.8%) of 44 if SP was less than 40 mm Hg (P < .00001; sensitivity, 56.8%; specificity, 97.4%). Ischemic EEG changes were observed in 19 (59.4%) of 32 patients (false-negative rate, 40.6%) requiring shunt placement under CBA. Three patients had false-positive EEG results and did not require shunt placement (false-positive rate, 1.0%). The perioperative stroke/death rate was 4 (1.2%) in 314. All strokes occurred after surgery and were unrelated to cerebral ischemia or lack of shunt placement. CONCLUSIONS: Ten percent of patients required a shunt placement during CEA under CBA. Shunt placement was necessary in 56.8% of patients with SP less than 40 mm Hg. EEG identified cerebral ischemia in only 59.4% of patients needing shunt placement, with a false-positive rate of 1.0% and a false-negative rate of 40.6%. Both SP and EEG as a guide to shunt placement have poor sensitivity. Intraoperative monitoring of the awake patients under regional anesthesia (CBA) is the most sensitive and specific method to identify patients requiring shunt placement.     

Carotid endarterectomy with local anesthesia: Results and advantages

In a collaborative prospective study from two institutions, we reviewed the clinical course of 969 consecutive patients who had 1200 carotid endarterectomies (CEs) for the treatment of occlusive arterial disease during the period 1977 to 1987. The indications for CE comprised transient ischemic attacks (TIAs) in 581 cases (48.4%), cerebral infarction (CI) in 170 (14.2%), monocular blindness in 166 (13.8%), and asymptomatic stenosis in 283 (23.6%). Neurologic monitoring of the awake patient provided more reliable indication of the need for brain protection during operative arterial clamping than did electroencephalography or carotid stump pressure measurement. Of the 1200 cases, 113 (9%) required a shunt as determined by this method. Patients with contralateral carotid occlusion or severe stenosis required shunting six times more frequently than those with a unilateral lesion. Among all procedures, there were nine cases of transient neurologic deficit (0.9%), 11 cases of permanent neurologic deficit (0.9%), and eight deaths (0.67%). Among 283 CEs performed to treat asymptomatic lesions, no strokes and only one death (0.4%) occurred. One hundred sixty-six cases with amaurosis fugax were operated on without stroke or death. In the age group of 70 to 90 years, 508 procedures were carried out with four deaths (0.8%) and three strokes (0.6%). We conclude that CE performed with the patient under local anesthesia is safe and effective and permits satisfactory management of old and high-risk patients. (J VASC SURG 1988;7:232-9.)     

Limitations of electroencephalographic monitoring in the detection of cerebral ischemia accompanying carotid endarterectomy

An analysis was undertaken of 458 consecutive carotid endarterectomies performed over 6 years with the patient under general anesthesia and with electroencephalographic monitoring. Seventy patients (15%) had electroencephalographic changes suggestive of ischemia with carotid clamping and had shunts placed. Ischemic encephalographic changes occurred in 26% of patients with an occluded contralateral carotid artery, 21% of patients with a prior stroke history, and 12% of patients with no stroke history and a patent contralateral carotid artery. Nineteen strokes (4.1%), nine transient deficits (2.0%), and one death (0.2%) occurred in the 458 endarterectomies in this experience. Ten of the 19 strokes and five of nine transient deficits were immediately apparent when patients awoke from anesthesia. Five of 10 patients with immediate strokes and all five patients with immediate transient deficits had no ischemic electroencephalographic changes during the procedure. Two other patients with immediate strokes initially had ischemic electroencephalographic changes after carotid clamping that reversed with increased blood pressure or shunting. Therefore 7 of 10 patients with immediate strokes and all 5 patients with immediate transient deficits had electroencephalographs unchanged from baseline at completion of the procedure, and thus deficits not manifest by operative electroencephalographic changes developed. Our data do not support the tenet that electroencephalographic monitoring will always predict neurologic deficits accompanying carotid endarterectomy.     

A comparison of computerized EEG with internal carotid artery stump pressure for detection of ischemia during carotid endarterectomy

Previous investigations appear to indicate that an ischemic EEG is not observed during carotid cross-clamping when the stump pressure is >/=60 mm Hg. In this report of 124 carotid endarterectomies (CEA) performed with selective shunting based on computerized EEG (CEEG), we compared the CEEG and this previously established critical stump pressure level of 60 mm Hg as methods of detecting cerebral ischemia during carotid clamping. A significant association between stump pressure and CEEG findings during clamping existed (p <0.05). Only 1 of 44 patients with a stump pressure >/=60 mm Hg received a shunt based on CEEG signs of cerebral ischemia. However, 62 of the remaining 80 patients did not receive a shunt and awoke neurologically intact despite a stump pressure <60 mm Hg. A highly significant association between the postoperative neurologic exam and the CEEG findings during carotid clamping was demonstrated (p <0.001). In contrast, for stump pressure, a correlation with the neurologic exam was not found. Compared to CEEG, these results appear to indicate that a critical stump pressure of 60 mm Hg is a sensitive but not specific indicator for the placement of a shunt selectively during CEA. The combined use of these two monitors should lead to reliable shunt selection, especially when stump pressure is <60 mm Hg.     

Continuous electroencephalographic monitoring during carotid endarterectomy

Four hundred and twenty-seven carotid endarteriectomies were performed on 377 patients. The electroencephalogram was used as the sole determinant for the use of a carotid shunt in 386 carotid endarterectomies. With clamping of the internal carotid artery, 51 (13%) had electroencephalographic changes. The most common electroencephalographic change (60%) was rapid, ipsilateral attenuation of background activity. In the 30 day follow up period there were 3 deaths (0.7%) and 11 strokes (2.5%). Two patients (0.5%) had intraoperative strokes. The combined morbidity and mortality was 2.8% (12 of 427). Neurologic complications increased significantly with contralateral carotid occlusion. The electroencephalogram correlated well with neurological deficits occurring in surgery, but stump pressures neither correlated with neurological deficits nor electroencephalographic changes. Continuous electroencephalographic monitoring during carotid endarterectomy is an effective method of determining significant cerebral ischemia and the need for a carotid shunt.     

Results of routine shunting and patch closure during carotid endarterectomy

BackgroundThe role of shunting and patching during carotid endarterectomy remains controversial.MethodsThis is a retrospective case series evaluating consecutive patients undergoing carotid endarterectomy with routine shunting and patching. The primary endpoints were perioperative stroke, arterial injury, and lesion recurrence by duplex.ResultsOf the 220 operations performed, 43% were for symptomatic disease. Successful shunt placement occurred in 98%, with no shunt-related injuries. There was 1 minor perioperative stroke and no major strokes. At a mean follow-up of 24 months (median = 12 months), there was 1 restenosis potentially related to shunt placement. The incidence of asymptomatic >50% stenosis in the patched segment was 8%.ConclusionsA combined policy of routine shunting and patching simplifies intraoperative decision making with results that rival or exceed those of trials in which their use was not standardized. Shunts need not be avoided because of concern of arterial injury.     

Prognostic value of computerized EEG analysis during carotid endarterectomy

A single-channel EEG, analyzed in real time to produce a density spectral array (DSA) display was recorded during 111 carotid endarterectomies. A simple protocol that emphasized loss of high frequency activity was used to identify serious ischemic EEG events. In 70 patients (78 operations) with no preoperative neurologic deficits, new postoperative neurologic deficits appeared only in the seven patients who had ischemic EEG events that lasted 10 min or longer. The EEG was not predictive in the 31 patients (33 operations) who had preoperative neurologic deficits: one patient with no intraoperative change in EEG developed a new postoperative deficit, and one patient with EEG changes lasting 13 min had no demonstrable new deficit postoperatively. This EEG monitoring technique was simple and convenient to use, and appears to be predictive of gross neurologic outcome following carotid endarterectomy in patients without preoperative neurologic deficits.