Significance of EEG changes at carotid endarterectomy

Visually apparent EEG changes associated with clamping the internal carotid artery appeared in 55 of 176 consecutive patients (31%) undergoing carotid endarterectomy without shunt. Attenuation of higher frequency activity was the most common change. Changes were moderate in 33 patients (19%) and major in 22 (12.5%). Major changes usually commenced earlier than less severe alterations. EEG changes resolved within 10 minutes of clamp release in 36 of 55 patients (65%) after an average clamp time of 36.25 minutes. Changes occurred more commonly when pre-operative EEGs were abnormal contralateral to clamping and when the contralateral carotid artery was more than 90% stenosed. Of the inhalational anesthetics employed with nitrous oxide and oxygen, isoflurane was associated with the lowest incidence of clamp-associated EEG change. Post-operative strokes occurred in 2 of 22 patients (9%) with major clamp-associated EEG changes, none of 33 patients with moderate changes and none of 121 without changes. However, the mechanism of this relationship remains in doubt.     

显微颈动脉内膜切除术

目的评估显微颈动脉内膜切除的效果。方法回顾1998年至2004年4月施行的92例96侧显微颈动脉内膜切除的手术并发症,并分析其原因。结果与手术直接相关的并发症包括TIA1例、脑卒中2例、轻度颅神经损害3例、假性动脉瘤1例,但均非手术操作缺陷所致。死亡1例。结论颈动脉内膜切除的缺血性并发症多与手术操作不当相关,采用显微外科技术可以降低此类并发症率。显微外科技术还有助于远端颈内动脉显露和降低颅神经损伤发生率。     

Experiences with carotid endarterectomy at Sree Chitra Tirunal Institute

Background:

Atherosclerotic carotid artery disease poses a grave threat to cerebral circulation, leading to a stroke with its devastating sequelae, if left untreated. Carotid endarterectomy has a proven track record with compelling evidence in stroke prevention.

Objectives:

a) To confirm that carotid endarterectomy (CEA) is safe and effective in preventing stroke at both short and long term. b) to demonstrate long term patency of internal carotid artery when arteriotomy repair is performed using autologous saphenous vein patch.

Materials and Methods:

During ten years, from September 1997 to February 2008, thirty nine patients who underwent consecutive carotid endarterectomy at our institute, form the basis of this report. Their age ranged from thirty to seventy eight years, with a mean age of 56. There were four women in this cohort. Thirty seven patients were symptomatic with >70% stenosis and two were asymptomatic with >80% stenosis, incidentally detected. Imaging included Duplex scan and MRA for carotid territory and brain, and non-invasive cardiac assessment. Co-morbidities included smoking, hypertension, diabetes, and coronary artery disease. Carotid Endarterectomy was performed under general anaesthesia, using carotid shunt and vein patch arteriotomy repair.

Results:

All the patients made satisfactory recovery, without major adverse cerebral events in this series. Morbidities included Transient Ischemic Attack (TIA) in two, needing only medications in one, and carotid stenting in the other. Minor morbidities included neck hematoma in two and transient hypoglossal paresis in three patients. Yearly follow-up included duplex scan assessment for all the patients. Two patients died of contralateral stroke, two of myocardial events and two were lost to follow up. Thirty three patients are well and free of the disease during the follow up of three to 120 months.

Conclusion:

Carotid endarterectomy provided near total freedom from adverse cerebral events and its catastrophic sequelae, leading to excellent outcome, both short as well as long term.     

An audit of carotid endarterectomy for internal carotid artery disease at Dunedin Hospital

Carotid endarterectomy, mostly for symptomatic internal carotid artery stenosis, has been successfully performed in both the vascular and neurological surgery units at Dunedin Hospital. This study was performed to compare our results with those of the North American Symptomatic Carotid Endarterectomy Trial and the European Carotid Surgery Trial. The 30-day perioperative morbidity and mortality rate was 4.3% (1.2% < 95% Cl > 7.4%) which compares favourably with an estimated upper limit of 5.5% based on recent trial reports. The present study highlights the difficulty in modelling local clinical practice on results of major trials when standards of patient evaluation and surgical skill may differ from those of the large studies. To justify generalization of indications for intervention based on the multicentre trials, there must be continual monitoring of local surgical results, and standardized use of diagnostic investigations.     

Provincial carotid endarterectomy outcomes

BACKGROUND: Outcomes must be measured as a first step toward improving performance. We sought to measure the national and provincial outcomes from carotid endarterectomy (CE) and explain provincial differences. METHODS: We analyzed a large Canada-wide administrative hospital discharge database of all patients, except those in Quebec, receiving CE in 1994-1997 and used logistic regression for risk adjustment to measure adverse outcomes nationally and by province. Our main outcome measures were in-hospital stroke and/or death. RESULTS: A total of 14,268 patients underwent CE in the years 1994-1997. The overall death rate was 1.3% and the combined stroke and/or death rate was 4.1%. There was a trend towards improvement over the four years. The provinces of Saskatchewan and Newfoundland had significantly higher adverse event rates for the risk-adjusted combined outcome measure. CONCLUSIONS: The outcome of CE in Canada is good and showed improvement over four years. However, significant differences in provincial outcomes were found. This suggests that regionalization across provincial boundaries may be needed to promote higher surgeon and hospital case volumes and thus improve outcomes.     

Salivoma after carotid endarterectomy

Although the diagnosis and management of postoperative or traumatic fluid collections have been documented extensively in the literature, to our knowledge the occurrence of a salivoma after carotid endarterectomy has not been reported. We report an extra salivary glandular collection of saliva – a “salivoma” – in a 79-year-old patient who underwent a carotid endarterectomy with a high carotid bifurcation. He presented with serous watery drainage from the incision site that had started spontaneously 4 days after surgery. The patient was taken to the operating room for exploration and washout of the wound with presumption of an infectious source. As self-retaining retractors were placed under the platysma, a large release of serous fluid occurred. Copious irrigation allowed complete washout of the wound. On postoperative day 2, the patient re-exhibited neck wound fullness and a Penrose drain was placed in the incision with clear serous fluid flowing through the drain. The patient was given a scopolamine patch to decrease salivary secretions. Within 5 days, the drainage significantly decreased and the drain was removed. This diagnosis should be included in the differential diagnosis of an expanding neck mass following carotid endarterectomy to properly treat this complication.     

Transcranial Doppler in carotid endarterectomy.

PURPOSE: To evaluate the role of transcranial Doppler monitoring in reducing the complications of carotid endarterectomy, by analysing: (1) perioperative intracerebral blood flow velocity; (2) embolic load; and (3) effect of Dextran-40 therapy on patient outcome. DESIGN: Retrospective case series. METHODS: The study cohort consisted of 30 consecutive patients undergoing 32 carotid endarterectomy procedures. Continuous transcranial Doppler (TCD) monitoring of the ipsilateral middle cerebral artery (MCA) was performed to obtain flow velocities and embolic count. Flow velocity changes were analysed in relation to electroencephalographic (EEG) changes. A Dextran-40 infusion was instituted for patients who experienced a post-arteriotomy embolic load of >50 counts/hour. RESULTS: The average middle cerebral artery velocity (MCAvel) drop on cross clamping was 46+/-12.1%, expressed as a percentage of the individual's 24-hour pre-operative value. Clamping ischaemia developed in six cases (18.8%) of which three (9.4%) demonstrated TCD changes only, and three demonstrated both TCD and EEG changes (9.4%). The average increase in MCAvel at 60-120 minutes postarteriotomy, was 18+/-17.5%; six cases developed hyperaemia. Postoperative emboli were seen in 88% of cases with 31% of patients demonstrating embolic loads of >50/hour. CONCLUSIONS: Perioperative transcranial Doppler monitoring (1) is a useful adjunct to EEG assessment of cross clamping ischaemia, providing information in real time, on MCA blood velocity deterioration that may antecede irreversible change (2) detects postoperative hyperaemic response, and (3) allows quantification of microembolic loads that, when high, have been shown to be a precursor to localised cerebral ischaemia and can be effectively treated with Dextran-40 infusion.     

Neuropsychological functions after carotid endarterectomy

Summary Psychological testing was performed on 23 patients (mean age 60.7 years) with unilateral or bilateral stenoses of the carotid arteries prior to and 10 months after carotid endarterectomy. Intellectual functions were slightly improved, mnemic functions impaired, psychomotor functions and dimension of personality remained unchanged. Carotid endarterectomy, although improving neuropsychological functions in a few cases, on average does not cause a significant improvement. This underscores the preventive character of the surgical intervention.     

Hemodynamic effect of carotid endarterectomy

Cerebral blood flow was measured by the intravenous xenon-133 technique at rest and during cerebral vasodilation with acetazolamide in 32 patients before and after uncomplicated carotid endarterectomy. The results were compared with the internal carotid artery perfusion pressure measured during surgery. A significant improvement in side-to-side cerebral blood flow asymmetry occurred in 6 patients studied at baseline and in 11 patients during provoked cerebral vasodilation. These patients all belonged to a group of 14 patients who, in addition to a severe stenosis of the internal carotid artery, presented a reduction in cerebral perfusion pressure of at least 20%. No improvements occurred in 18 patients with no or only minor reduction in perfusion pressure, irrespective of the degree of stenosis. These findings indicate an improved perfusion reserve following carotid endarterectomy in most patients with marked reduction in perfusion pressure, whereas only some of these patients will experience an improvement in baseline cerebral blood flow.     

Neuropsychological changes after carotid endarterectomy

Carotid endarterectomy (CEA), performed to prevent stroke, could lead to changes in cognitive functions. Sixty-four patients with severe carotid stenosis undergoing CEA treatment were evaluated by means of a detailed neuropsychological assessment before (baseline), from one to two weeks (1st follow up) after and 3 months (2nd follow up) after surgical operation. A significant post-CEA improvement was found in verbal memory and attention (p<0.05), while other cognitive functions showed no significant changes.