Cognitive impairment associated with intraoperative and postoperative hypoperfusion without neurologic deficits in a patient undergoing carotid endarterectomy

BACKGROUND: Neuropsychological testing detects cognitive impairment in 20% to 30% of patients after carotid endarterectomy (CEA). CASE DESCRIPTION: A 51-year-old man with asymptomatic right cervical internal carotid artery (ICA) stenosis underwent a CEA. Intraoperative transcranial regional cerebral oxygen saturation monitoring revealed ischemia in the right cerebral hemisphere during ICA clamping and transient hyperemia subsequent to ICA declamping. The patient recovered without the appearance of new neurologic deficits. Brain single-photon emission computed tomography performed immediately after CEA showed a decrease in cerebral blood flow in the right cerebral hemisphere. Diffusion-weighted magnetic resonance imaging showed no new abnormal findings. Positron emission tomography performed 2 months after surgery revealed decreased cerebral metabolic rate of oxygen in the right cerebral hemisphere, and neuropsychological testing demonstrated a decline in performance IQ relative to preoperative levels. CONCLUSIONS: Intraoperative ischemia and postischemic delayed hypoperfusion in CEA can impair cognition even in the absence of development of postoperative neurologic deficit.     

Carotid endarterectomy in patients with contralateral internal carotid artery occlusion without intraoperative shunting

BACKGROUND: Controversy about the optimal method of performing a carotid endarterectomy (CEA) exists despite its widespread application and support from various randomized clinical trials. Many surgeons selectively or routinely use electroencephalography (EEG) monitoring as well as shunting when performing this operation. ETHODS: We conducted this retrospective study to assess the maximum carotid clamp time without shunting or EEG monitoring during a CEA without the development of neurological deficits in an already compromised cerebral circulation. RESULTS: Fifteen consecutive patients who underwent CEAs between 1988 and 1999 met our criteria of angiographically documented ipsilateral internal carotid artery (ICA) stenosis with contralateral ICA occlusion. The patient presentations included asymptomatic (14%), transient ischemic attack (TIA) (50%), and stroke (36%). All patients were operated under general anesthesia without shunting and only 4 patients underwent EEG monitoring. On angiography, all 15 patients had ipsilateral ICA stenosis (70-99%) and contralateral occlusion. In 54% of patients, the vertebral arteries (VAs) were both patent, while in 46% of patients only 1 VA was patent. Eighty-five percent of patients had at least 1 patent anterior communicating (Pcomm) artery, while 15% had nonvisualized Pcomm arteries bilaterally. Of the 15 patients, 14 had a patent anterior communicating artery. The mean clamp time of the CCA was 18.5 minutes (range 14-30 minutes). None of the 15 patients had new neurological changes immediately postoperatively or during the 6 weeks of follow-up. CONCLUSION: We propose that shunting may not be necessary during CEA for high-grade stenosis with contralateral ICA occlusion, presumably because of adequate distal small vessel collaterals.     

Closure of the arteriotomy after carotid endarterectomy: patch type is related to intraoperative microemboli and restenosis rate

OBJECTIVE: Patch closure after carotid endarterectomy (CEA) improves clinical outcome compared with primary closure. Whether there are differences in outcome between various patch materials is still not clear. The objective of this retrospective study was to investigate whether a relationship exists between the patch type and the number of microemboli as registered during CEA by transcranial Doppler imaging, the clinical outcome (transient ischemic attack and cerebrovascular accident), and the occurrence of restenosis. METHODS: We included 319 patients who underwent CEA. Intraoperative microembolus registration was performed in 205 procedures. Microembolization was recorded during four different periods: dissection, shunting, clamp release, and wound closure. The decision to perform primary closure or to use a patch for the closure of the arteriotomy was made by the surgeon, and Dacron patches were used when venous material was insufficient. Cerebral events were recorded within the first month after CEA, and duplex scanning was performed at 3 months (n = 319) and 1 year (n = 166) after CEA. A diameter reduction of more than 70% was defined as restenosis. RESULTS: Primary, venous, and Dacron patch closures were performed in 83 (26.0%), 171 (53.6%), and 65 (20.4%) patients, respectively. Primary closure was significantly related to sex (Dacron patch, 35 men and 30 women; venous patch, 108 men and 63 women; primary closure, 72 men and 11 women; P < .001). The occurrence of microemboli during wound closure was also related to sex (women, 2.5 +/- 0.6; men, 1.0 +/- 0.2; P = .01). Additionally, during clamp release, Dacron patches were associated with significantly more microemboli than venous patches (11.1 +/- 3.4 vs 4.0 +/- 0.9; P < .01), and this difference was also noted during wound closure (3.1 +/- 0.9 vs 1.4 +/- 0.4; P < .05). Transient ischemic attacks and minor strokes after CEA occurred in 5 (2.4%) of 205 and 6 (2.9%) of 205 procedures, respectively, and the degree of microembolization during dissection was related to adverse cerebral events (P = .003). In contrast, the type of closure was not related to immediate clinical adverse events. However, primary closure and Dacron patches were associated with an increase in the restenosis rate compared with venous patches: after 400 days, the restenosis rate for Primary closure was 11%, Dacron patch 16%, and venous patch 7% (P = .05; Kaplan-Meier estimates). CONCLUSIONS: Microemboli are more prevalent during clamp releases and wound closure when Dacron patches are used. Additionally, the observed differences in embolization noted by patch type were mainly evident in women. However, the use of Dacron patches was not related to immediate ischemic cerebral events but was associated with a higher restenosis rate compared with venous patch closure. This suggests that venous patch closure may be preferred for CEA.     

Magnetic resonance imaging in patients with cerebral hyperperfusion and cognitive impairment after carotid endarterectomy

OBJECT: Cerebral hyperperfusion after carotid endarterectomy (CEA) impairs cognitive function and is often detected on cerebral blood flow (CBF) imaging. The purpose of the present study is to investigate structural brain damage seen on magnetic resonance (MR) images obtained in patients with cerebral hyperperfusion and cognitive impairment after CEA. METHODS: One hundred and fifty-eight patients with ipsilateral internal carotid artery stenosis (> or = 70%) underwent CEA. Neuropsychological testing was performed preoperatively and at the 1st postoperative month. Cerebral blood flow was measured using single-photon emission computed tomography before, immediately after, and 3 days after surgery. Magnetic resonance imaging was performed before and 1 day after surgery. In patients with post-CEA hyperperfusion (defined as a CBF increase > or = 100% compared with preoperative values) on CBF imaging, MR images were also obtained on the 3rd postoperative day, the day on which hyperperfusion syndrome developed, and 1 month after the operation. RESULTS: The incidence of postoperative cognitive impairment was significantly higher in patients with post-CEA hyperperfusion on CBF imaging (12 [75%] of 16 patients) than in those without (6 [4%] of 142 patients; p < 0.0001). Only 1 of 5 patients with cerebral hyperperfusion syndrome developed reversible brain edema in the cerebral hemisphere ipsilateral to the CEA on MR images obtained on the day hyperperfusion syndrome occurred. However, postoperative cognitive impairment developed in all 5 patients with cerebral hyperperfusion syndrome regardless of the presence or absence of new lesions on MR images. In addition, postoperative cognitive impairment developed in 5 (45%) of 11 patients with asymptomatic cerebral hyperperfusion on CBF imaging despite the absence of new lesions on any postoperative MR images. CONCLUSIONS: Although cerebral hyperperfusion syndrome after CEA sometimes results in reversible brain edema visible on MR imaging, postoperative cerebral hyperperfusion -- even when asymptomatic -- often results in impaired cognitive function without structural brain damage on MR imaging.     

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

STUDY OBJECTIVE: To evaluate the relationship between continuous noninvasive monitoring of cerebral saturation (regional cerebral oxygen saturation [rSo2]) and occurrence of clinical and electroencephalographic (EEG) signs of cerebral ischemia during carotid cross-clamping. DESIGN: Prospective clinical study. SETTING: University hospital. PATIENTS: Fifty ASA physical status II and III inpatients undergoing elective carotid endarterectomy with a cervical plexus block. INTERVENTIONS: rSo2 was continuously monitored throughout surgery, while an independent neurologist evaluated the occurrence of both clinical and EEG signs of cerebral ischemia induced during carotid cross-clamping. MEASUREMENTS AND MAIN RESULTS: rSo2 was recorded 1 and 3 minutes after clamping the carotid artery during a 3-minute clamping test. In 5 patients (10%), the carotid clamping test was associated with the occurrence of clinical and EEG signs of cerebral ischemia. All these patients were treated with the placement of a Javid shunt, which completely resolved the symptoms. In no patient was permanent neurological injury reported at hospital discharge. In 4 of these patients, EEG signs of cerebral ischemia were present at both observation times, and in one of them, the duration of cerebral ischemia was less than 2 minutes. The percentage rSo2 reduction from baseline during the carotid clamping test was 17% +/- 4% in patients requiring shunt placement and only 8% +/- 6% in those who did not require it (P = .01). A decrease in rSo2 15% or greater during the carotid clamping test was associated with a 20-fold increase in the odd for developing severe cerebral ischemia (odds ratio, 20; 95% confidence interval, 6.7-59.2) (P = .001); however, this threshold had a 44% sensitivity and 82% specificity, with only 94% negative predictive value. CONCLUSIONS: Continuous rSo2 monitoring is a simple and noninvasive method that correlates with the development of clinical and EEG signs of cerebral ischemia during carotid cross-clamping; however, we could not identify an rSo2 threshold that can be used alone to predict the need for shunt placement because of the low sensitivity and specificity.     

A comparison of the cerebral hemodynamic effects of sufentanil and isoflurane in humans undergoing carotid endarterectomy

Prompted by reports of potentially deleterious cerebral vasodilation by the synthetic opioid sufentanil, the authors compared the effects of either isoflurane/N2O and sufentanil/N2O on cerebral blood flow (CBF), arteriovenous difference in oxygen content (AVDO2), and CBF reactivity to changes in PaCO2 during carotid endarterectomy. Cerebral blood flow was measured using the iv method of 133-Xe CBF determination and AVDO2 was measured using systemic arterial-jugular venous oxygen content differences. Patients, age 68 +/- 1 yr (mean +/- SE), received either isoflurane (n = 10), 0.75% in O2 and N2O, 1:1; or sufentanil (n = 10), 1.5-2 micrograms/kg bolus and then 0.2-0.3 micrograms.kg-1.h-1 infusion in addition to O2 and N2O, 2:3. Measurements were made immediately before carotid occlusion, and then at two levels of PaCO2 (approximately 32 and 42 mmHg) after insertion of a temporary in-dwelling bypass shunt. Prior to carotid occlusion, there was no significant difference in CBF (ml.100 g-1.min-1) between patients receiving isoflurane (22 +/- 3) or sufentanil (20 +/- 2). Similarly, there was no difference in AVDO2 (vol-%) between isoflurane (4.5 +/- 0.7) and sufentanil (5.4 +/- 0.8) groups. Using a two-way ANOVA design with anesthetic as the between-group factor and elevation of PaCO2 as the within-group repeated measure, there was a significant effect of hypercarbia to increase CBF (P less than 0.0001) and decrease AVDO2 (P less than 0.001). The product of AVDO2 and CBF, which reflects cerebral metabolic oxygen consumption, remained constant (P = 0.364).(ABSTRACT TRUNCATED AT 250 WORDS)     

Successful carotid endarterectomy in a patient with an aberrant branch from the common carotid artery

We report a patient who had an 80% asymptomatic stenosis in the distal right common carotid artery with an incidental finding of an aberrant branch arising from the right common carotid artery. He underwent an elective right carotid endarterectomy with an uneventful recovery. This is the first case in the literature of a successful endarterectomy in a patient with a common carotid anomaly and it emphasises the importance of careful dissection for unexpected anatomy.     

Carotid endarterectomy in patients with contralateral carotid occlusion: review of a 10-year experience

A total of 116 carotid endarterectomies were performed in patients with a totally occluded opposite internal carotid artery over a 10-year period from 1983 until 1992. The average age of patients was 66.4 years; 75% were men and 25% were women. The average degree of stenosis on the operated side was 76.7%. Twenty-one patients (18.1%) had had a documented previous stroke referrable to the side of the occlusion; 22 had a neurologic deficit attributable to the occluded vessel at the time of preoperative evaluation. Indications for surgery included transient ischemic attacks in 35 (30.2%), ipsilateral stroke in 10 (8.6%). amaurosis fugax in 11 (9.5%), and high-grade asymptomatic stenosis in 60 (51.7%). Forty-eight percent of the procedures were performed using local anesthesia, with intraluminal shunts inserted in all except one patient. The combined 30-day mortality and stroke morbidity in this population was 4.3%, which is comparable with a combined stroke and death rate of 4.0% among 956 patients without contralateral carotid occlusion undergoing endarterectomy during this period. This experience suggests that endarterectomy can be performed safely in the patient with internal carotid occlusion and is an important mechanism for the prevention of stroke.     

Carotid endarterectomy in patients with contralateral carotid occlusion: Is the risk increased?

Many vascular surgeons believe the risk of carotid endarterectomy is greater if the patient has a contralateral carotid occlusion, and thus believe intraoperative shunting is mandatory. Five hundred and eleven carotid endarterectomies were performed over the last 11 years by two of us (JEM and RAL). Of these, 370 had charts available for detailed analysis. Twenty-seven of these patients had complete occlusion of the contralateral carotid artery. Eight of these 27 patients were asymptomatic and 16 patients had transient ischemic attacks prior to surgery. Two patients had strokes which were stable at the time of surgery. One patient with a previous stroke was operated upon emergently with a new stroke in evolution. All were operated upon under general anesthesia and only three had intraoperative shunting. Occlusion time averaged 17.1 minutes varying from 11 to 34 minutes. There were two deaths, one cardiac and one pulmonary, and no postoperative strokes either temporary or permanent. Of the 343 patients without contralateral occlusion, three patients (.87%) died, and there were 19 (5.5%) neurologic complications of which seven (2%) were present at the time of hospital discharge. It appears that contralateral carotid occlusion does not increase the risk of stroke after carotid endarterectomy even when intraoperative shunting is not used.     

Extracranial-intracranial bypass for internal carotid/middle cerebral atherosclerotic steno-occlusive diseases in conjunction with carotid endarterectomy for contralateral cervical carotid stenosis: clinical results and cognitive performance

Clinical results as well as cognitive performances after extracranial to intracranial (EC-IC) bypass in conjunction with contralateral carotid endarterectomy (CEA) are poorly understood. Data from 14 patients who underwent unilateral EC-IC bypass for atherosclerotic internal carotid artery (ICA)/middle cerebral artery (MCA) steno-occlusive disease in conjunction with CEA for contralateral cervical carotid stenosis were retrospectively reviewed. Postoperative results were evaluated by MRI imagings. Nine patients also underwent neuropsychological examinations (NPEs), including assessment by the Wechsler Adult Intelligence Scale-Third Edition and the Wechsler Memory Scale-Revised (WMS-R) before and about 6 months after bilateral surgeries. Postoperative MRI follow-up (median, 8 months; interquartile range, 7–8 months) confirmed successful bypass in all patients, with no additional ischemic lesions on T2WI when compared with preoperative imaging. Further, MRA showed patent bypass and contralateral smooth patency at CEA portion in all patients. In the group rate analysis, all five postoperative NPE scores (Verbal IQ, Performance IQ, WMS-memory, WMS-attention, and Average scores of all those four scores) were improved relative to preoperative NPE scores. Performance IQ and Average score improvements were statistically significant. Clinical results after EC-IC bypass in conjunction with contralateral CEA were feasible. Based on the group rate analysis, we conclude that successful unilateral EC-IC bypass and contralateral carotid endarterectomy does not adversely affect postoperative cognitive function.     

Large cerebral arteriovenous malformation presenting with venous ischemia in the contralateral hemisphere. Case report

The authors report a rare case in which a large cerebral arteriovenous malformation (AVM) located in the left parietooccipital region presented with venous ischemia in the contralateral hemisphere. A 74-year-old man was admitted to the hospital because he was experiencing a loss of appetite, disorientation, and left hemiparesis. Computerized tomography scans revealed a low-density area in the right temporal lobe. Angiography demonstrated a large AVM in the left parietooccipital lobe and dilation, stagnation, and meanders of cortical veins in the contralateral hemisphere. The authors speculated that the elevated sinus pressure caused by a huge venous return of blood from the AVM produced venous ischemia in the contralateral hemisphere.     

A case of intraoperative hyperkalemia probably due to preoperative feeding with a liquid enteral formulation

A 67-year-old man with no remarkable preanesthetic complications underwent esophagectomy. The patient was fed only with a liquid enteral formulation (Ensure Liquid) for 5 days immediately before the operative day. His serum potassium level before Ensure Liquid administration was 4.1 mEq x l(-1). The first blood analysis at 30 min after the initiation of the surgery revealed an increase in serum potassium level (5.9-6.1 mEq x l(-1)) without any conceivable cause during the anesthetic management. A glucose-insulin infusion treatment lowered the serum potassium level to the normal range. The serum potassium level re-increased to 6.4 mEq x l(-1) 4 days after the initiation of jejunal feeding with Ensure Liquid and then returned to the normal range after the termination of Ensure Liquid administration. The patient's perioperative course suggests that the preoperative Ensure Liquid administration is a probable cause of the intraoperative hyperkalemia in this case.     

Angiogenesis in carotid atherosclerotic lesions is associated with timing of ischemic neurological events and presence of computed tomographic cerebral infarction in the ipsilateral cerebral hemisphere

We studied the association between plaque vascularity, timing of neurological and ocular symptoms, and presence of cerebral infarction in the ipsilateral cerebral hemisphere on preoperative computed tomographic (CT) scan. Consecutive patients undergoing carotid endarterectomy for carotid stenosis were included. All patients underwent preoperative noncontrast cerebral CT. Histological sections were obtained from carotid endarterectomy specimens and stained with an endothelial cell marker (CD34). Microvessel counts were performed in CD34-stained sections and verified through computerized image analysis. Associations between microvessel density in carotid atherosclerotic plaques, preoperative ipsilateral CT evidence of cerebral infarction, and timing of ipsilateral neurological and ocular events were assessed. Seventy-three patients underwent carotid endarterectomy, of whom 17 were symptomatic within 30 days of carotid endarterectomy, 11 were asymptomatic, and a further 45 had a preoperative symptom-free interval of 31-540 days (median = 56). Eighteen patients (24.6%) had CT evidence of cerebral infarction. Significantly higher microvessel counts were observed in patients with CT evidence of cerebral infarction in the appropriate hemisphere compared with patients who did not (p = 0.02). There was an inverse relationship between the microvessel density in atherosclerotic lesions and the timing of ischemic neurological events (odds ratio [OR] = 4.63, 95% confidence interval [CI] 2.95-7.28, p < 0.001). This relationship was independent of patient age (OR = 1.03, 95% CI 0.55-1.99, p = 0.70), sex (OR = 1.18, 95% CI 0.47-2.05, p = 0.56), smoking (OR = 1.07, 95% CI 0.54-2.09, p = 0.84), diabetes (OR = 0.90, 95% CI 0.45-1.79, p = 0.76), and hypercholesterolemia (OR = 0.98, 95% CI 0.68-1.11, p = 0.88). This study confirms the relationship between angiogenesis in carotid atherosclerotic lesions and development and chronology of ipsilateral hemispheric neurological events.     

体感诱发电位联合运动诱发电位监测在颈动脉内膜剥脱术中的应用

目的评估在颈动脉内膜剥脱术中(carotid endarterectomy,CEA)中采用体感诱发电位(somatosensory evoked potential,SSEP)与运动诱发电位(motor evoked potential,MEP)联合监测的方案对于预防术中脑缺血发生的准确性。方法选择因颈动脉狭窄择期拟行CEA患者90例,男71例,女19例,年龄18~80岁,ASAⅡ或Ⅲ级。术中监测SSEP和MEP,记录颈内动脉阻断前、颈动脉阻断时、阻断期间及开放后直至术毕SSEP和MEP波幅和潜伏期。评估术后5d内神经功能缺失情况,以发生神经功能缺失作为评判术中脑缺血发生的金标准。结果本研究中14例(15.6%)患者发生术后神经功能缺失。SSEP预测脑缺血发生的灵敏度79%、特异度92%;MEP预测脑缺血发生的灵敏度86%、特异度89%、SSEP+MEP联合监测的灵敏度为79%、特异度99%。结论在颈动脉内膜剥脱术中,体感诱发电位预测脑缺血发生的特异度高,运动诱发电位灵敏度高;二者联合监测可提高监测的特异性,弥补单一监测的不足。