Can carotid endarterectomy improve metabolic status in patients with asymptomatic internal carotid artery flow lesion? Studies with localized in vivo proton magnetic resonance spectroscopy

PURPOSE: Carotid endarterectomy (CEA) has proven to be effective in the prevention of stroke in patients with significant internal carotid artery (ICA) stenosis. However, whether increased cerebral blood flow after CEA improves the cerebral metabolism in patients with asymptomatic ICA flow lesions is unknown. Localized in vivo proton magnetic resonance spectroscopy ((1)H-MRS) has been used to measure the metabolic status of the human brain in a totally noninvasive manner. The aim of this study was to investigate the cerebral metabolism after CEA in patients with asymptomatic ICA flow lesions and no visible infarction on magnetic resonance imaging (MRI). MATERIALS AND METHODS: We designed a prospective study to investigate the metabolic changes in the middle cerebral artery (MCA) territory with (1)H-MRS for 18 consecutive patients with asymptomatic severe stenosis of the ICA (>70% reduction in diameter) and for 16 healthy control subjects. The 18 patients with ICA flow lesion and no visible infarction on MRI who underwent CEA were evaluated before and 7 days after surgery (CEA group). The 16 control subjects had never had a cerebral event, and brain MRI and carotid duplex scan study results were normal in all (control group). RESULTS: Preoperative ICA volume flow was severely decreased to less than 150 mL/min in all 18 patients, in comparison with our laboratory normal value of matched age group of 250 to 300 mL/min. After CEA, ICA volume flow was increased to greater than 300 mL/min in all patients (P =.00). For patients in the CEA group, preoperative N-acetylaspartate/creatine and choline/creatine ratios in the MCA territory were slightly decreased compared with the healthy subjects in the control group but were within normal limits. However, the postoperative values of N-acetylaspartate/creatine and choline/creatine ratios in the ipsilateral MCA territory were significantly increased as compared with the preoperative values (P <.05). In the contralateral side, the postoperative increase of choline/creatine ratio and the decrease of myo-inositol/creatine ratio were statistically significant as compared with the preoperative values (P <.05). CONCLUSION: CEA seems to improve the cerebral metabolic status in patients with asymptomatic ICA flow lesions and no visible infarction on MRI.     

Ischemic events due to intraoperative microemboli developing in the cerebral hemisphere contralateral to carotid endarterectomy in a patient with preoperative cerebral hemodynamic impairment

A 74-year-old man with a history of asymptomatic right internal carotid artery (ICA) occlusion experienced amaurosis fugax in the left eye. Angiography showed left cervical ICA stenosis in addition to right cervical ICA occlusion. The right anterior and middle cerebral artery (MCA) territories were perfused from the left ICA via the anterior communicating artery. Brain perfusion single-photon emission computed tomography revealed reduced cerebral blood flow and reduced cerebrovascular reactivity to acetazolamide only in the right cerebral hemisphere. The patient underwent left carotid endarterectomy (CEA). Transcranial Doppler monitoring showed microembolic signals in the left MCA during dissection of the left ICA, but intraoperative monitoring suggested absence of global hypoperfusion or ischemia in the bilateral cerebral hemispheres during left ICA clamping. Transient and slight motor weakness of the left upper extremity was noted on recovery from anesthesia. Diffusion-weighted magnetic resonance imaging demonstrated the development of new spotty ischemic lesions only in the right cerebral hemisphere. The present case suggests that intraoperative cerebral embolism causing postoperative neurological deficits can develop exclusively in the cerebral hemisphere contralateral to CEA if the hemisphere has preoperative hemodynamic impairment and collateral circulation via the anterior communicating artery from the ICA ipsilateral to CEA.     

Decreased transcranial Doppler carbon dioxide reactivity is associated with disordered cerebral metabolism in patients with internal carotid artery stenosis.

PURPOSE: The hemodynamic effect of stenosis of the internal carotid artery (ICA) can be assessed by measuring, with transcranial Doppler (TCD), the carbon dioxide (CO(2)) reactivity of the cerebral vessels. The aim of this study was to determine whether a decreased CO(2) reactivity is associated with a compromised cerebral metabolism, as evaluated with (1)H magnetic resonance spectroscopy (MRS). METHODS: Sixty-six patients with unilateral or bilateral stenosis of the ICA, who were scheduled for carotid endarterectomy (CEA) and who had undergone both a TCD CO(2) reactivity test and a MRS examination, were included in this study. The ICA stenosis on one side (CEA side) was always more than 70%, and the extent of the stenosis on the contralateral side varied. RESULTS: The CO(2) reactivity and the N-acetyl aspartate (NAA)/choline ratio were correlated in both hemispheres (r =.43; P <.001). Patients with an ICA occlusion contralateral to the CEA side are especially at risk for disordered cerebral hemodynamics and metabolism; in the contralateral hemisphere, the mean CO(2) reactivity and NAA/choline ratio were abnormal (18% and 1.52, respectively), and lactate was present in 85% of the patients. Changes indicative of disordered hemodynamics were found more often in symptomatic than in asymptomatic patients. CONCLUSION: A decreased CO(2) reactivity appears to be associated with a disordered cerebral metabolism. Patients with severe bilateral ICA stenosis are at risk for disordered cerebral metabolism and hemodynamics. Therefore, the indication for CEA based on the degree of ICA stenosis and clinical grounds might be refined with an additional test, such as the TCD CO(2) reactivity test.     

Improved cerebral perfusion after simultaneous stenting for tandem stenoses of the internal carotid artery--two case reports

Two patients with extracranial internal carotid artery (ICA) stenosis and tandem stenosis of the ipsilateral intracranial ICA were treated simultaneously by angioplasty with stenting. A 68-year-old man who presented with neovascular glaucoma had 90% stenosis of the right cervical ICA and 80% stenosis of the ipsilateral petrous ICA. A 74-year-old man who suffered from transient ischemic attack had 75% stenosis of the left cervical ICA and 90% stenosis of the ipsilateral cavernous ICA. Hemodynamic compromise was confirmed in both patients. Tandem stenting of both extracranial and intracranial ICA stenoses was performed simultaneously in both patients without complications. Poststenting angiography demonstrated excellent dilation of both lesions and normalization of cerebral perfusion. Simultaneous tandem stenting for extracranial ICA stenosis with intracranial tandem stenosis is less invasive than open surgery in high-risk patients with hemodynamic compromise, especially if the major lesion responsible for cerebral hypoperfusion is difficult to determine.     

Hemodynamic effect of carotid stenting and carotid endarterectomy

BACKGROUND: Carotid angioplasty with stent placement (CAS) may offer an alternative treatment to carotid endarterectomy (CEA). However, in contrast to CEA, which has been shown to normalize impaired cerebral hemodynamics, the effects of CAS remain unclear. To investigate alterations in cerebral hemodynamics, we prospectively studied patients undergoing CAS and compared them with a group of similar patients undergoing CEA. METHODS: Twenty-three patients undergoing CAS for recently symptomatic internal carotid artery (ICA) stenosis were prospectively studied. Volume flow in the ICAs and basilar artery (BA) were measured with magnetic resonance volume flow quantification before CAS and 1 month after. The results were compared with those in 13 similar patients undergoing CEA and 40 control subjects without ICA stenosis. RESULTS: After CAS, volume flow in the ipsilateral ICA increased from 114 +/- 17 to 231 +/- 17 mL/min (P < .001), and total volume flow (ICAs plus BA) increased from 495 +/- 24 to 552 +/- 28 mL/min (P < .05). No significant changes were seen in the contralateral ICA and BA after CAS. Total volume flow and flow in the stenosed ICA normalized after CAS compared with control subjects. Volume flow values similarly improved after CEA. CONCLUSIONS: CAS results in a normalization of impaired cerebral hemodynamics, as assessed by magnetic resonance volume flow measurements. The degree of improvement is similar to that seen after CEA.     

Local haemodynamic changes during carotid endarterectomy--the influence on cerebral oxygenation.

OBJECTIVES: To characterize carotid bifurcation haemodynamics and cerebral oxygenation during clamping and at reperfusion after carotid endarterectomy (CEA). MATERIALS AND METHODS: Sixty-two patients with a symptomatic high-grade stenosis of the internal carotid artery (ICA), who underwent CEA under general anaesthesia, were studied prospectively. Measurements of stump-pressure, volume flow (transit time flowmetry) and changes in cerebral oxygenation (near-infrared spectroscopy (NIRS)) were performed. Selective shunting was based on stump pressure only. RESULTS: Stump pressure correlated with both ICA flow before clamping (r=0.45; p=0.03) and changes in cerebral oxygenation (rSO2) during clamping (r=0.61; p=0.002), the latter was reversed by shunt placement. ICA flow before clamping also correlated with changes in rSO2 during clamping (r=0.41; p=0.01). CONCLUSION: Measurements with transit time flowmetry and cerebral oximetry are technically easy and help to determine the need for selective shunting during CEA. High ICA flow before clamping in combination with a low stump pressure usually indicates the need for a shunt. Volume flow measurements may also be useful in the quality assessment of the CEA.     

Effects of the free radical scavenger, edaravone, on the development of postoperative cognitive impairment in patients undergoing carotid endarterectomy

BACKGROUND: Some patients undergoing carotid endarterectomy (CEA) experience postoperative cognitive impairment. The purpose of the present case cohort study with historical control was to determine whether pretreatment with a novel free radical scavenger, edaravone, could prevent development of cognitive impairment after CEA. METHODS: Fifty-five patients with ipsilateral internal carotid artery (ICA) stenosis (> or =70%) underwent CEA with administration of edaravone before ICA clamping. Neuropsychological testing was performed preoperatively and at the first postoperative month. Cerebral blood flow was also measured using single-photon emission computed tomography before and immediately after CEA and on the third postoperative day. RESULTS: Postoperative cognitive impairment was observed in only 1 (2%) patient, who exhibited postoperative cerebral hyperperfusion (cerebral blood flow increase > or =100% compared with preoperative values). Incidence of postoperative cognitive impairment in the control group (92 CEA patients without administration of edaravone) was significantly higher (12%) (P = .0298, control vs treatment group). Logistic regression analysis demonstrated that postoperative cerebral hyperperfusion and absence of pretreatment with edaravone were significant independent predictors of postoperative cognitive impairment. CONCLUSION: Pretreatment with edaravone can prevent development of cognitive impairment after CEA.     

Carotid endarterectomy and intracranial thrombolysis: simultaneous and staged procedures in ischemic stroke

PURPOSE: The feasibility and safety of combining carotid surgery and thrombolysis for occlusions of the internal carotid artery (ICA) and the middle cerebral artery (MCA), either as a simultaneous or as a staged procedure in acute ischemic strokes, was studied. METHODS: A nonrandomized clinical pilot study, which included patients who had severe hemispheric carotid-related ischemic strokes and acute occlusions of the MCA, was performed between January 1994 and January 1998. Exclusion criteria were cerebral coma and major infarction established by means of cerebral computed tomography scan. Clinical outcome was assessed with the modified Rankin scale. RESULTS: Carotid reconstruction and thrombolysis was performed in 14 of 845 patients (1.7%). The ICA was occluded in 11 patients; occlusions of the MCA (mainstem/major branches/distal branch) or the anterior cerebral artery (ACA) were found in 14 patients. In three of the 14 patients, thrombolysis was performed first, followed by carotid enarterectomy (CEA) after clinical improvement (6 to 21 days). In 11 of 14 patients, 0.15 to 1 mIU urokinase was administered intraoperatively, ie, emergency CEA for acute ischemic stroke (n = 5) or surgical reexploration after elective CEA complicated by perioperative intracerebral embolism (n = 6). Thirteen of 14 intracranial embolic occlusions and 10 of 11 ICA occlusions were recanalized successfully (confirmed with angiography or transcranial Doppler studies). Four patients recovered completely (Rankin 0), six patients sustained a minor stroke (Rankin 2/3), two patients had a major stroke (Rankin 4/5), and two patients died. In one patient, hemorrhagic transformation of an ischemic infarction was detectable postoperatively. CONCLUSION: Combining carotid surgery with thrombolysis (simultaneous or staged procedure) offers a new therapeutic approach in the emergency management of an acute carotid-related stroke. Its efficacy should be evaluated in interdisciplinary studies.     

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.     

症状性颈内动脉闭塞的术前评估及手术治疗

目的:探讨症状性颈内动脉(ICA)闭塞患者手术治疗的效果和术前评价方法。方法:选择海南省人民医院血管外科2010年1月—2016年3月手术治疗的11例ICA闭塞的患者,2例行颈动脉内膜剥脱术(CEA),9例行CEA加取栓术。术前均行头颈联合CTA和颈部血管彩超,部分患者行脑CT灌注成像、经颅彩色多普勒超声以及脑血管造影等检查,观察患者围术期与长期疗效。结果:所有患者ICA闭塞均为单侧,其中4例对侧ICA有50%的狭窄。闭塞主要位于ICA起始端,8例闭塞段延至颅底,闭塞长度16~85 mm。术前颈动脉彩超均在可在颅底探及ICA血流。10例手术再通成功,1例失败。术后10例脑缺血症状明显改善,其中3例出现过度灌注综合征。随访期,1例患者ICA在术后3个月闭塞。1例在术后18个月死亡。结论:手术治疗ICA闭塞具有满意安全的围手术期效果和较好的中远期效果。术前精确的评估是手术成功的关键。     

Progression of atherosclerosis in asymptomatic carotid arteries after contralateral endarterectomy: a 10-year prospective study

OBJECTIVE: The best way to manage both symptomatic and asymptomatic severe carotid stenoses has been thoroughly demonstrated by large randomized clinical trials, but less is known about the natural history and management of the contralateral asymptomatic internal carotid artery (ICA). This prospective study was undertaken to determine whether disease progressed in the contralateral ICA of patients who had undergone carotid endarterectomy (CEA) and were followed up clinically and by duplex ultrasound (US) scan. METHODS: The contralateral asymptomatic ICAs of 599 patients who had undergone CEA for severe carotid disease over a 10-year period were followed up clinically and with duplex US scan at 1 month and then every 6 months. ICA stenosis was classified as mild (30%-49%), moderate (50%-69%), severe (70%-99%), or occlusion. Progression was defined as an increase in ICA stenosis of 50% or more for ICAs with a less than 50% baseline lesion or as an increase to a higher category if the baseline stenosis was 50% or more. End points of the study were the incidence of contralateral disease progression and late neurologic events. Kaplan-Meier analysis was used to estimate freedom from disease progression and from neurologic events. The relationship between progression and risk factors was also analyzed. RESULTS: Overall, disease progressed in 25.2% of patients (151/599) after a mean follow-up of 4.1 years. Disease progressed in 34.3% of patients (101/294) with mild stenosis vs 47.9% of patients with moderate stenosis (47/98; P = .016). Three additional patients with mild lesions at baseline progressed to severe lesions. The median time to progression was 29.8 months for mild and 18.5 months for moderate stenoses (P = .033). The rate of late neurologic events referable to the contralateral ICA was 3.2% (19/599) for the entire series and 4.8% (19/392) for patients with a 30% or greater ICA stenosis: these included 4 (0.7%) strokes and 15 (2.5%) transient ischemic attacks. All but 3 events (16.3%; 16/98) occurred in patients with disease progression from moderate to severe stenosis. Overall, 53 late CEAs were performed. CONCLUSIONS: This prospective analysis has shown that disease progression in contralateral asymptomatic ICAs after CEA is relatively common in patients with a diseased ICA at the baseline and strongly supports duplex US surveillance, approximately every 6 months, in patients with more than mild disease. A baseline lesion is significantly predictive of progression to severe stenosis, and progression from moderate to severe stenosis is strongly associated with neurologic clinical events. No demographic or clinical factor proved useful in identifying patients likely to experience disease progression.     

Medullary streaks in a patient with atherosclerotic internal carotid artery occlusion: case report

BACKGROUND: Magnetic resonance imaging (MRI) of a patient with atherosclerotic internal carotid artery (ICA) occlusion demonstrated medullary streaks in the deep white matter, which were previously observed only in moyamoya disease and may indicate decreased cerebral blood flow. Cerebral perfusion and metabolism were evaluated using positron emission tomography (PET). CASE DESCRIPTION: A 46-year-old man presented with right hemiparesis and motor aphasia. Cerebral angiography showed left cervical ICA occlusion. MRI showed medullary streaks in the deep white matter of the left middle cerebral artery (MCA) territory. PET imaging of this region revealed decreased cerebral blood flow and increased oxygen extraction fraction and cerebral blood volume. MRI after superficial temporal artery-MCA anastomosis revealed decreased intensity of the medullary streaks. CONCLUSIONS: Medullary streaks in patients with atherosclerotic ICA occlusion may indicate reduced perfusion pressure and increased risk of recurrent stroke.     

Impact of external carotid artery occlusion at declamping of the external and common carotid arteries during carotid endarterectomy on development of new postoperative ischemic cerebral lesions

Objective

The external carotid artery (ECA) is inadvertently occluded during carotid endarterectomy (CEA). The importance of ECA occlusion has been emphasized as a loss of extracranial to intracranial collaterals, a source of chronic embolization, or a site for extended thrombosis during wound closure. This study aimed to determine whether ECA occlusion that inadvertently developed during endarterectomy and that was eventually detected using blood flow measurement of the ECA after declamping of all carotid arteries is a risk factor for development of new postoperative ischemic lesions at declamping of the ECA and common carotid artery (CCA) while clamping the internal carotid artery (ICA). This study also aimed to determine whether intraoperative transcranial Doppler (TCD) monitoring predicts the risk for development of such lesions.

Combined therapeutic approach of intra-arterial thrombolysis and carotid endarterectomy in selected patients with acute thrombotic carotid occlusion

PURPOSE: The feasibility and clinical outcome of intra-arterial thrombolysis followed by carotid endarterectomy (CEA) for acute thrombotic occlusion of the internal carotid artery (ICA) were evaluated. METHODS: Intra-arterial thrombolysis and CEA were performed in four patients with acute thrombotic ICA occlusion. Computed tomography scans, cerebral angiograms, and the severity of carotid plaques were examined, and the patients' clinical outcome was evaluated. RESULTS: All 4 patients had severe hemiparesis; 3 patients were alert, and 1 patient was lethargic at the time of hospital admission. New lesions were not shown by means of the initial computed tomography scan. ICA occlusion was indicated in all four patients by means of cerebral angiograms; in three patients, middle cerebral artery occlusion was noted. Collateral circulation was manifested in all patients. Partial recanalization of the occluded ICA was obtained in all patients. Two patients with severe residual ICA stenosis underwent an emergency CEA soon after thrombolysis; the other two patients were treated by means of CEA in the subacute or chromic stage. Plaque rupture and intraplaque hemorrhage were seen in all four patients. All four patients recovered completely, and restenosis of the ICA was not shown by means of follow-up angiograms. CONCLUSION: Intra-arterial thrombolysis followed by CEA may be an effective therapeutic approach for treating acute thrombotic ICA occlusion. The optimal timing of CEA remains controversial.     

Outcome of carotid stent-assisted angioplasty versus open surgical repair of recurrent carotid stenosis

PURPOSE: We compared outcome and durability of carotid stent-assisted angioplasty (CAS) with open surgical repair (ie, repeat carotid endarterectomy [CEA]) to treat recurrent carotid stenosis (RCS). METHODS: A retrospective review of anatomic and neurologic outcomes was carried out after 27 repeat CEA procedures (1993-2002) and 52 CAS procedures (1997-2002) performed to treat high-grade internal carotid artery (ICA) RCS after CEA. The incidence of intervention because of symptomatic RCS was similar (repeat CEA, 63%; CAS, 60%), but the interval from primary CEA to repeat intervention was greater (P <.05) in the repeat CEA group (83 +/- 15 months) compared with the CAS group (50 +/- 8 months). In the CAS group, 17 of 52 arteries (33%) were judged not to be surgical candidates because of surgically inaccessible high lesions (n = 8), medical comorbid conditions (n = 4), neck irradiation (n = 3), or previous surgery with cranial nerve deficit or stroke (n = 2). Three patients who underwent repeat CEA had lesions not appropriate for treatment with CAS. RESULTS: Overall 30-day morbidity was similar after CAS (12%; death due to ipsilateral intracranial hemorrhage, 1; nondisabling stroke, 1; reversible neurologic deficits or transient ischemic attack, 2; access site complication, 2). and repeat CEA (11%; no death; nondisabling stroke, 1; reversible cranial nerve injury, 1; cervical hematoma, 1). Combined stroke and death rate was 3.7% for repeat CEA and 5.7% for CAS (P >.1). All duplex ultrasound scans obtained within 3 months after CEA and CAS demonstrated patent ICA and velocity spectra of less than 50% stenosis. During follow-up, no repeat CEA (mean, 39 months) or CAS (mean, 26 months) repair demonstrated ICA occlusion, but two patients (8%) who underwent repeat CEA and 4 patients (8%) who underwent CAS required balloon or stent angioplasty because of 80% RCS. At last follow-up, no patient had ipsilateral stroke and all ICA remain patent. At duplex scanning, stenosis-free (<50% diameter reduction) ICA patency at 36 months was 75% after repeat CEA and 57% after CAS (P =.26, log-rank test). CONCLUSIONS: Carotid angioplasty for treatment of high-grade stenotic ICA after CEA resulted in similar anatomic and neurologic outcomes compared with open surgical repair. Most lesions are amenable to endovascular therapy, and CAS enabled treatment in patients judged not to be suitable surgical candidates. Duplex scanning surveillance after repeat CEA or CAS is recommended, because stenosis can recur after either secondary procedure.     

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.     

Frequency, clinical significance and course of cerebral ischemic events after carotid endarterectomy evaluated by serial diffusion weighted imaging.

OBJECTIVES: Neurological deficit defines the outcome of Carotid Endarterectomy (CEA) that is mainly caused by cerebral ischemia. Diffusion-weighted imaging (DWI) is a sensitive method for demonstrating even small ischemic lesions. The aim of this study was to evaluate the frequency, clinical significance and course of ischemic lesions after CEA using serial DWI. METHODS: DWI was performed within 1 day before and after CEA in 88 patients. Postoperative lesions were analyzed by their quantity, volume and distribution. To differentiate temporary ischemia from definite cerebral infarction (blood brain barrier disruption) all patients with a positive postoperative DWI were reexamined with contrast-enhanced T1-MRI 7-10 days after the procedure. All patients were examined by a neurologist within 2 days before and after CEA. RESULTS: Two patients showed a postoperative neurological deficit. Postoperative DWI revealed ipsilateral ischemic lesions in 15 patients. In seven of these patients a brain infarction was diagnosed on the T1-MRI during follow-up. A significant correlation between the number of DWI lesions (p=0.031) as well as the volume of DWI lesions (p=0.023) and definite infarction was found. Symptomatic patients preoperatively showed significantly more DWI lesions (p=0.036) and cerebral infarcts (p=0.003). CONCLUSION: DWI is a sensitive method of demonstrating ischemic events after CEA. The number and volume of DWI lesions after CEA are highly predictive of brain infarction.     

EEG bispectral index during carotid endarterectomy

PURPOSE: Carotid endarterectomy (CEA) is an established surgical procedure for the treatment of internal carotid artery stenosis. Stroke is the commonest risk factor during CEA, therefore, cerebral monitoring became essential. Currently the EEG bispectral index (BIS) is used as a monitor of depth of anesthesia and it has showed decreasing trend during cerebral ischemia. We conducted this study to document the changes of the BIS variable during CEA under anesthesia. METHODS: Ten patients who underwent CEA under general anesthesia were studied. The EEG BIS was measured during the perioperative period where five phases were identified: (A) before induction of anesthesia, (B) before clamping of ICA, (C) during clamping of ICA, (D) after declamping of ICA and (E) during the recovery from anesthesia. RESULTS: The age ranged between 53-69 yr. The mean values of the BIS were 91.4 +/- 5.6, 59.6 +/- 18.7, 44.3 +/- 6.8, 54.7 +/- 8.3 and 72.1 +/- 12.4 during A, B, C, D and E phases respectively with statistical significant low values during B, C, D and E phases versus phase A. CONCLUSION: The decreasing trend of the EEG BIS was shown during ICA clamping and whether this is an important quantitative variable to determine the adequacy of cerebral perfusion during CEA yet to be further studied.     

Magnetic resonance angiography of collateral compensation in asymptomatic and symptomatic internal carotid artery stenosis

OBJECTIVE: In patients with stenosis of the internal carotid artery (ICA), the presence of collateral circulatory pathways may be crucial to maintain cerebral perfusion pressure, metabolism, and function. The purpose of the present study was to determine whether patients with asymptomatic stenosis of the ICA have a better collateral ability of the circle of Willis when compared with patients with symptomatic ICA stenosis. METHOD: Magnetic resonance angiography consisting of the circle of Willis was performed in 19 patients with severe asymptomatic ICA stenosis and in 21 patients with severe symptomatic ICA stenosis prior to carotid endarterectomy and in 53 control subjects. Between group comparisons were made for function (directional flow) and anatomy (diameter). RESULTS: In patients with asymptomatic ICA stenosis, the prevalence of collateral flow via the anterior communicating artery was significantly increased (37%, 7 of 19) compared with symptomatic patients (10%, 2 of 21) and control subjects (0%; P <.001). Patients with asymptomatic ICA stenosis demonstrated the largest mean diameter of the anterior communicating artery (1.33 +/- 0.18 mm) compared with patients with symptomatic ICA stenosis (1.22 +/- 0.18 mm) and control subjects (1.06 +/- 0.10 mm, P <.05). No differences in collateral flow pattern or diameter were found for the posterior communicating artery between the groups. CONCLUSIONS: The present cross-sectional study demonstrates the importance of an adequate hemodynamic compensation via the circle of Willis in patients with ICA stenosis. Whether differences in collateral compensation can be used to select patients for CEA has yet to be determined.     

Cerebral Ischaemic Changes in Association With the Severity of ICA Lesions and Cerebropetal Flow

OBJECTIVES: To study the effect of the severity of internal carotid artery (ICA) lesions on cerebral haemodynamics. DESIGN: Cross-sectional study. MATERIALS AND METHODS: Magnetic resonance (MR) imaging, angiography (MRA) and spectroscopy (MRS) were used to study the prevalence of (border-zone) infarctions, volume flow in the main cerebropetal and middle cerebral arteries (MCA) and metabolic changes in the MCA territories in 170 patients with symptomatic ICA stenoses or occlusions and 25 control subjects. RESULTS: No significant correlation was found between severity of the carotid lesion and the prevalence of border-zone infarctions. Also, no significant correlation was found with changes in the N -acetyl-aspartate/choline ratio nor with the prevalence of cerebral lactate. In patients with at least one severe ICA lesion, flow in the basilar artery was increased. Flow in the MCA on the symptomatic and asymptomatic side was decreased when at least one ICA was occluded. Total cerebropetal flow (flow through the ICAs plus basilar artery) was decreased when at least one ICA was occluded. No significant correlation was found between changes in cerebropetal flow and the N -acetyl-aspartate/choline ratio nor with the prevalence of border-zone infarctions. CONCLUSION: Border-zone infarctions and ischaemic metabolic changes are not directly the result of cerebral hypoperfusion caused by severe ICA lesions.