Absence of microemboli on transcranial Doppler identifies low-risk patients with asymptomatic carotid stenosis

Stroke Prevention & Atherosclerosis Research Centre, Robarts Research Institute, University of Western Ontario, London, Canada.
Stroke (Impact Factor: 6.02). 12/2005; 36(11):2373-8. DOI: 10.1161/01.STR.0000185922.49809.46
Source: PubMed

ABSTRACT Carotid endarterectomy clearly benefits patients with symptomatic severe stenosis (SCS), but the risk of stroke is so low for asymptomatic patients (ACS) that the number needed to treat is very high. We studied transcranial Doppler (TCD) embolus detection as a method for identifying patients at higher risk who would have a lower number needed to treat.
Patients with carotid stenosis of > or =60% by Doppler ultrasound who had never been symptomatic (81%) or had been asymptomatic for at least 18 months (19%) were studied with TCD embolus detection for up to 1 hour on 2 occasions a week apart; patients were followed for 2 years.
319 patients were studied, age (standard deviation) 69.68 (9.12) years; 32 (10%) had microemboli at baseline (TCD+). Events were more likely to occur in the first year. Patients with microemboli were much more likely to have microemboli 1 year later (34.4 versus 1.4%; P<0.0001) and were more likely to have a stroke during the first year of follow-up (15.6%, 95% CI, 4.1 to 79; versus 1%, 95% CI, 1.01 to 1.36; P<0.0001).
Our findings indicate that TCD- ACS will not benefit from endarterectomy or stenting unless it can be done with a risk <1%; TCD+ may benefit as much as SCS if their surgical risk is not higher. These findings suggest that ACS should be managed medically with delay of surgery or stenting until the occurrence of symptoms or emboli.

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    ABSTRACT: In contemporary medical publications the term "delirium" designates an acute global impairment of consciousness of any level and genesis. Acute insufficiency of cerebral cortex with clinical symptoms of delirium is a sign of severe neurological and/or internal disorder in older patients. Diagnosis of consciousness disturbances implicates urgent diagnostic evaluation and treatment. Knowledge of etiology and pathophysiology of postoperative delirium is very important, as only the former may direct researchers and practicians in the development and application of effective preventive technologies. Here we present the data of contemporary studies, including our own data, evidencing that intraoperative microembolic load is a primary etiology of postoperative delirium, whereas adverse effects of cerebral hypoperfusion and system inflammation syndrome are secondary to microembolic damage of brain and internal organs. It was consistently demonstrated that adverse effects of microemboli are dose dependent in young patients, whereas even relatively small amount of microemboli may be disastrous in elderly ones. The neurological mechanisms of postoperative psychotic symptoms are analyzed in the present chapter as well. Experimental studies showed, that excessive microembolism may induce ischemic damage of cholinergic pathways to neocortex and, therefore, stabilizing effects of acetylcholine on cognitive activity may be impaired in a proportion of surgical patients. Postoperative hyperactivation of monoaminergic systems with consequent blockade of prefrontal cortex control over posterior brain, facilitates intrusions of inappropriate internal memories and associations appearing as hallucinatory and illusion experiences in predisposed patients. Concomitant microembolic damage of posterior cortical regions (temporal, parietal and/or occipital) or preoperative chronic cortex insufficiency contribute to incorrect interpretations of actual sensory input leading to delusional thinking in postoperative delirium. Therefore, reduction of microemboli is the most important strategy in prevention of postoperative neurological complications.
  • Stroke 10/2014; 45(12). DOI:10.1161/STROKEAHA.114.006912 · 6.02 Impact Factor
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    ABSTRACT: Background Both pathophysiology and treatments of carotid atherosclerotic plaque stenosis represent two interesting fields of strong scientific investigation. Among different drugs, safety and efficacy of statin treatment have been widely investigated and proved. Materials and methodsThis narrative review is based on the material searched for and obtained via MEDLINE and PubMed up to March 2014. The search terms we used were: carotid plaque, intima-media thickness, plaque burden, stroke' in combination with statins, pleiotropic effects, HMG-CoA reductase inhibitors, lipid-lowering drugs'. ResultsCarotid stenosis represents both a useful parameter to evaluate the atherosclerotic burden and a target for therapeutic (medical or surgical) decisions. Statins do not only improve the lipid profile, but also induce some pleiotropic' anti-inflammatory activities that contribute to carotid plaque stabilization. Statin-mediated protective activities are under active investigation at subclinical levels with the potential benefit of advanced imaging techniques. However, considering that some new techniques (excepted B-mode ultrasound) remain quite expensive, they can have for the moment an important role in research, but not in the clinical field. Conclusions Emerging evidence suggests that statin treatment improves carotid atherosclerosis, inducing a partial regression of plaque inflammation and size. Innovative imaging techniques might also ameliorate the identification of patients at high risk of cerebrovascular and coronary events, for which preventive statin treatments might be essential.
    European Journal of Clinical Investigation 09/2014; 44(11). DOI:10.1111/eci.12340 · 2.83 Impact Factor

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