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Background: Cognitive and motor performance can be supported, especially in older subjects, by different types of brain activations, which can be accurately studied by functional magnetic resonance imaging (fMRI). Vascular risk factors (VRFs) are extremely important in the development of cognitive impairment, but few studies have focused on the fMRI cortical activation characteristics of healthy subjects with and without silent cerebrovascular disease including white matter hyperintensities (WMH) and carotid stenosis (CS) performing cognitive tasks. Methods: Thirty-five volunteers with and without asymptomatic unilateral carotid stenosis above 70% and variable degrees of WMH underwent performance of a simple motor and cognitive task during an fMRI session. Results: While the performance of the motor task resulted in a cortical activation dependent of age but not of WMH and carotid stenosis, performance of the cognitive task was accompanied by a significantly increased activation independently correlated with age, presence of WMH as well as of carotid stenosis. Conclusions: in this study, cognitive domains regulating attention and working memory appear to be activated with a pattern influenced by the presence of carotid stenosis as well as by white matter hyperintensities. The impairment of these cognitive abilities is of high relevance in Alzheimer’s disease pathology. The fMRI pattern shown in patients with asymptomatic but significant carotid stenosis might be related to chronic cerebrovascular hypoperfusion, a critical pathophysiological mechanisms in AD. In these patients, carotid endoarterectomy should be considered also for AD prevention and might be recommended.

Objective to relate changes in somatosensory-evoked potentials (SEPs) with onset of neurological deficits in patients having carotid endarterectomy (CEA) under locoregional anaesthesia. Methods a prospective study of 50 consecutive patients. Results SEPs yielded an accuracy of 98%, specificity 100%, and sensitivity 89%. In all concordant cases the onset of a neurological deficit in awake patients corresponded to a 30–40% reduction in amplitude of N20-P25 waveforms. After shunting, the N20-P25 took 2–3 min to return to normal. Conclusions SEPs are associated with a 2% false negative rate. Their threshold for detecting cerebral ischaemia is lower than the currently reported value for patients under general anaesthesia. The time needed for evoked potentials (2–3 min) to return to normal after shunting limits their usefulness in verifying effective shunting. Copyright 2001 Harcourt Publishers Limited

Objectivesto determine the impact of the extracranial internal carotid stenosis on cerebral perfusion during aortoiliac surgery. Designprospective study. Material and methodsof 432 consecutive patients undergoing aortoiliac reconstruction, 16/86 (18%) with >70% internal carotid artery stenosis, underwent inverted surgical timing (aortic reconstruction first and carotid endarterectomy second). Preoperative Transcranial Doppler (TCD) with and without acetazolamide was used to evaluate cerebrovascular reserve capacity (CRC). Intraoperatively, middle cerebral artery flow velocity (mean MCAv) and systemic blood pressure (SBP) were recorded. Resultspreoperatively, all 16 patients had good CRC (increase in mean MCAv: 66% right and 72% left). Intraoperatively, the mean MCAv (from 49±13 to 45±14 cm/s p=0.0249) and SBP decreased (from 127±25 to 113±22 mmHgp=0.0016). In patients with unilateral carotid disease, declamping had no effect on left mean MCAv despite a significant decrease of SBP (129±44 to 113±21 mmHg p=0.0211). In those with bilateral disease, declamping decreased both mean MCAv: from (48±12 to 39±10 cm/s p=0.011) and SBP (123±26 to 111±25 mmHg p=0.0479). No perioperative neurological deficit occurred. Conclusionsif CRC is normal or still effective, aortoiliac reconstruction does not impair cerebral perfusion.

Objectives:: Studies comparing transcranial Doppler ultrasonography (TCD) with other intraoperative monitoring techniques for detecting clamping ischaemia during carotid endarterectomy under general anaesthesia suggest that a reduction of > two-thirds in the mean middle cerebral artery velocity (mMCAv) or a reduction of > 0.4 in the preclamping mMCAv: clamping mMCAv ratio warrants cerebral protection. Our aim was to study the relationship between mMCAvs and clamping ischaemia during carotid endarterectomy in awake patients. Materials and methods:: In a consecutive series of 57 patients undergoing carotid endarterectomy under locoregional anaesthesia 51 were monitored by intraoperative TCD, continuous EEG, and neurologic awake testing. Results:: Five of the 51 (9.8%) patients had transient clamping ischaemia, which carotid shunting reversed. TCD showed that these five patients had significant lower mean mMCAvs than the other 46 patients, who had no deficits (1.8 +/- 1.1 cm/s vs. 26.2 +/- 8.5, p = 0.0003). Current TCD criteria indicated that four other patients (7.8%) should have been shunted. All four had significantly higher clamping mMCAvs than the five shunted patients (11.5 +/- 1.9 vs. 1.8 +/- 1.1, p = 0.0012). Conclusions:: Intraoperative TCD detected cerebral ischaemia and yielded no false-negative. An mMCAv of 10 cm/s or less may indicate the risk of clamping ischaemia better than the higher threshold currently proposed. This would avoid unnecessary shunting due to false-positives.

Purpose:: To compare the influence of anaesthetic technique on perioperative complications in patients undergoing carotid endarterectomy. Material and methods:: In a retrospective study of 1020 consecutive patients who underwent carotid artery surgery over 10 years, perioperative neurologic and cardiologic complications and the use of an internal carotid artery shunt were compared in 337 patients (33%) treated under general anaesthesia and 683 (67%) under cervical block. The two groups had similar characteristics. The most frequent surgical indication was symptomatic carotid artery disease (91.5%). The remaining patients had asymptomatic severe internal carotid lesions (> 70%). Results:: The overall perioperative stroke rate was 1.9%, the death-stroke rate 0.7% and the cardiac complication rate 0.8%. The perioperative stroke rate was higher in the general anaesthesia group than in the cervical block group (3.2% vs 1.3%, p = 0.01). Cardiac complication rates were similar in the two groups. A carotid artery shunt was used in 75 patients (22%) receiving general anaesthesia and in 92 patients (13%) receiving cervical block (p = 0.0004). The causes of stroke in the cervical block group were intraoperative embolism (4 cases, 26%), perioperative thromboembolism (7 cases, 58%) and clamping ischaemia (1 case, 16%). Mechanisms causing stroke in the general anaesthesia group remained unidentified or uncertain. Conclusions:: Cervical block anaesthesia yields better perioperative results than general anaesthesia probably because it allows more reliable cerebral monitoring, reducing or even eliminating perioperative strokes related to clamping ischaemia. It facilitates detection of the mechanism underlying intraoperative stroke allowing surgical techniques and intraoperative management to be modified accordingly. Cervical block anaesthesia significantly reduces the need for internal carotid artery shunting.

Objectives:: In a retrospective non-randomised study we assessed the outcome after in situ replacement of infected knitted Dacron abdominal aortic grafts in patients without septicaemia or retroperitoneal abscesses. We also assessed whether the specific bacterial infection influenced outcome. Materials and methods:: Over the 5 years studied, 18 patients (9 with perigraft infection and 9 with aortoenteric erosion) underwent in situ replacement of aortofemoral grafts. All patients were haemodynamically stable, none required emergency treatment. Preoperative assessment included CT, MRI, leukocyte-labelled scintigraphy, and bacterial cultures whenever possible. Infected grafts were totally excised and replaced in situ with standard PTFE prostheses. Bacterial diagnosis included intraoperative Gram-staining and postoperative graft cultures. None of the patients had retroperitoneal collections or proximal anastomotic dehiscence. All patients had 6 week intravenous antibiotic therapy. Results:: One patient died of myocardial infarction, and another of haemorrhagic shock from proximal anastomotic dehiscence, accounting for a graft-related mortality of 6%. Dehiscence resulted from a polymicrobial infection. Mean 37 month surveillance showed no amputations and no graft-related infections. Conclusions:: In clinically and bacteriologically selected patients, total in situ replacement of infected abdominal aortic grafts offers an excellent outcome.

To investigate the clinical significance of intraoperative cultures in elective abdominal aortic aneurysmectomy, we cultured the aneuryrymml wall and contents in 90 patients undergoing vascular graft surgery. Prosthetic graft infection was documented in 1 out of 62 patients with negative cultures and in none of 28 patients with positive cultures (x2 = 0.4, p > 0.1). Bacterial growth was seen in neither of 2 inflammatory aneurysms, 3 of 14 atherosclerotic aneurysms and 2 of 5 aneurysms without specific features. A retrospective analysis of patients' charts aimed at finding possible risk factors failed to identify any correlation between results of cultures and length of hospitalization before surgery, time interval between angiography and surgery, route of angiography procedure or minutes of surgery before sample collection. We conclude that positive cultures may not imply clinical infection at the time of surgery and that prolonged post-operative organism-specific antibiotic therapy does not appear necessary to prevent graft contamination in patients undergoing elective abdominal aortic aneurysmectomy.