White matter hyperintensities had a correlation with the cerebral perfusion level, but no correlation with the severity of large vessel stenosis in the anterior circulation

OBJECTIVE

The contribution of large vessel stenosis to the development of white matter hyperintensities (WMHs) has not been fully elucidated. This study aims to explore the correlation between ipsilateral white matter hyperintensities (WMHs) and the severity of large vessel stenosis in the anterior circulation and cerebral perfusion level, as well as analyze the factors influencing WMHs.

METHODS

A cross-sectional study of 150 patients with unilateral anterior circulation large vessel stenosis of ≥50% was conducted. The severity of ipsilateral WMHs was assessed by Fazekas scale on T2-weighted image and/or fluid-attenuated inversion recovery MR imaging, vascular stenosis severity was evaluated on computed tomography angiography images, and the level of cerebral perfusion was rated according to a staging system for abnormal cerebral perfusion based on CTP results. The relationships between the stenosis severity, cerebral perfusion level and ipsilateral WMHs severity were analyzed. A multivariate logistic regression analysis was performed to determine the factors independently influencing WMHs.

RESULTS

Among 150 patients (mean age, 63.12 ± 10.55 years), there was a statistically significant positive correlation between cerebral perfusion level and the severity of DWMHs and PWMHs (Gamma = 0.561, p < .001; Gamma = 0.600, p < .001), and a positive correlation between cerebral perfusion level and the severity of vascular stenosis (Gamma = 0.495, p < .001).While, there was no statistically significant correlation between the severity of vascular stenosis and the severity of DWMHs and PWMHs (Gamma = 0.188, p = .08; Gamma = 0.196, p = .06). The multivariate logistic regression analysis results demonstrated that age (OR = 1.047, 95% CI 1.003-1.093; p = .035), stroke/TIA history (OR = 2.880, 95% CI 1.154-7.190; p = .023) and stage II of cerebral perfusion (OR = 2.880, 95% CI 1.154-7.190; p = .023) were independent influencing factors on ipsilateral DWMHs. Age (OR = 1.051, 95% CI 1.009-1.094; p = .018), and stage II of cerebral perfusion (OR = 12.871, 95% CI 3.576-46.322; p < .001) were factors independently influencing ipsilateral PWMHs.

CONCLUSION

White matter hyperintensities may be attributed to cerebral hypoperfusion secondary to vascular stenosis but not directly to the severity of stenosis in the large vessels of anterior circulation. Moreover, longitudinal studies with sequential imaging exams may further reveal the impact of cerebral perfusion secondary to vascular stenosis on the development and progression of WMHs.

Multiple Factors Involved in the Pathogenesis of White Matter Lesions

White matter lesions (WMLs), also known as leukoaraiosis (LA) or white matter hyperintensities (WMHs), are characterized mainly by hyperintensities on T2-weighted or fluid-attenuated inversion recovery (FLAIR) images. With the aging of the population and the development of imaging technology, the morbidity and diagnostic rates of WMLs are increasing annually. WMLs are not a benign process. They clinically manifest as cognitive decline and the subsequent development of dementia. Although WMLs are important, their pathogenesis is still unclear. This review elaborates on the advances in the understanding of the pathogenesis of WMLs, focusing on anatomy, cerebral blood flow autoregulation, venous collagenosis, blood brain barrier disruption, and genetic factors. In particular, the attribution of WMLs to chronic ischemia secondary to venous collagenosis and cerebral blood flow autoregulation disruption seems reasonable. With the development of gene technology, the effect of genetic factors on the pathogenesis of WMLs is gaining gradual attention.

Preoperative white matter lesions are independent predictors of long-term survival after internal carotid endarterectomy

Background

Cerebral white matter lesions (WMLs) predict long-term survival of conservatively treated acute stroke patients with etiology other than carotid stenosis. In carotid endarterectomy patients, WMLs are associated with severe carotid stenosis and unstable plaques, with the risk of perioperative complications and with increased 30-day perioperative risk of death. However, no data exist on their effect on postoperative long-term survival, a factor important when considering the net benefit from carotid endarterectomy. Whether this effect is independent of classical risk factors and indications for surgery is not known either. We hypothesized that WMLs could be evaluated from preoperative routine computed tomography (CT) scans and are predictors of postoperative survival, independent of classical cardiovascular risk factors, indication category and degree of carotid stenosis.

Methods

A total of 353 of 481 (73.4%) consecutive patients subjected to carotid endarterectomy due to different indications, i.e. asymptomatic stenosis (n = 28, 7.9%), amaurosis fugax (n = 52, 14.7%), transient ischemic attack (n = 135, 38.2%) or ischemic stroke (n = 138, 39.1%), from prospective vascular registries during the years 2001-2010 with digital preoperative CT scans, were included in the study. WMLs were rated by a radiologist (Wahlund criteria) in a blinded fashion. Internal carotid artery (ICA) stenoses were angiographically graded (<50, 50-69, 70-99 and 100%). Odds ratios (ORs) and hazard ratios (HRs) are reported (ORs and HRs ≤1 indicate a beneficial effect). The median follow-up time was 67 months (interquartile range 45.5, range 0-129 months). Spearman's rho was used to estimate intraobserver agreement. Binary logistic regression was performed to analyze the association of risk factors with WMLs. Cox regression proportional hazards analysis was used to study the effect of different factors on survival.

Results

WML severity could be assessed with a substantial intraobserver agreement (Spearman's rho 0.843, p < 0.0001). Only age (OR 1.10, 95% CI 1.06-1.15; p < 0.0001 per year), degree of ipsilateral ICA stenosis (OR 2.22, 95% CI 1.08-4.55; p < 0.05 per stenosis grade) and indication category (OR 1.63, 95% CI 1.19-2.24; p < 0.01 per category) remained independently associated with WMLs. Age (HR 1.04, 95% CI 1.01-1.08; p < 0.05 per year), diabetes (HR 1.59, 95% CI 1.01-2.49; p < 0.05), peripheral arterial disease (HR 2.47, 95% CI 1.46-4.15; p < 0.01), degree of ipsilateral ICA stenosis (HR 2.56, 95% CI 1.12-5.87; p < 0.05 per stenosis grade) and WMLs (HR 3.83, 95% CI 1.17-12.5; p < 0.05) remained independently associated with increased long-term mortality.

Conclusions

WMLs in a preoperative CT scan provide a substantially reliable estimate of postoperative long-term survival of carotid endarterectomy patients independent of currently used criteria, i.e. cardiovascular risk factors, indication category and degree of ipsilateral ICA stenosis.

Carotid artery stenting improves cerebral hemodynamics regardless of the flow direction of ophthalmic artery

We enrolled 221 patients with elective carotid artery stenting (CAS). Patients with contralateral carotid stenosis exceeding 50%, insufficient vertebral artery (VA) flows, or angioplasty at subclavian artery were excluded. All patients underwent serial cerebral ultrasound studies. Of the 116 included patients, the direction of ophthalmic artery (OA) flow was forward in 74 patients while reversed in 42. The reversed flow group had worse ipsilateral stenosis, higher hemoglobin, and cardiac output. After CAS, the reversed flow group had an immediate recovery of ipsilateral internal carotid artery flow volume (FV; P < .0001), time average velocity (TAV) of middle cerebral artery (P = .02), and normalization of OA flow. The forward flow group had gradual decrement in TAV of contralateral anterior cerebral artery (P = .01) and total FV of VA (P = .001). Our results suggest CAS improves cerebral hemodynamics through different ways regardless of the direction of OA flow.

Cognitive Performance following Carotid Endarterectomy or Stenting in Asymptomatic Patients with Severe ICA Stenosis

Background. Endarterectomy (CEA) or stenting (CAS) of a stenotic carotid artery is currently undertaken to reduce stroke risk. In addition removal of the arterial narrowing has been hypothesized to improve cerebral hemodynamics and provide benefits in cognitive functions, by supposedly resolving a “hypoperfusion” condition. Methods. In this study we sought to test whether resolution of a carotid stenosis is followed by measurable changes in cognitive functions in 22 subjects with “asymptomatic” stenosis. Results. A main finding of the study was the statistically significant pre-post difference observed in the performance of phonological verbal fluency and Rey's 15-word immediate recall. Remarkably, there was a significant interaction between phonological verbal fluency performance and side of the carotid intervention, as the improvement in the verbal performance, a typical “lateralized” skill, was associated with resolution of the left carotid stenosis. Conclusion. The results reflect a substantial equivalence of the overall performance at the before- and after- CEA or CAS tests. In two domains, however, the postintervention performance resulted improved. The findings support the hypothesis that recanalization of a stenotic carotid could improve brain functions by resolving hypothetical “hypoperfusion” states, associated with the narrowing of the vessels.

Carotid stenting versus endarterectomy cognitive outcomes

BACKGROUND

The objectives are to analyze the impact of carotid revascularization on cognitive performance after a 3-month period in patients, who have undergone carotid artery stenting (CAS) or carotid endarterectomy (CEA), and to compare the cognitive outcomes between these 2 groups of patients. This a nonrandomized and prospective single-center experience.

METHODS

This study was performed in the University of Campinas Hospital from January 2010 to January 2012 and included 30 patients with carotid stenosis who received carotid interventions. Nineteen patients received CEA and 11 patients received CAS. Neuropsychologic evaluation included general cognitive, language, visuospatial, attentional, executive function, and memory tests.

RESULTS

After the follow-up period, there was improvement in episodic memory, encoding subitem (P = 0.02), and delayed recall (P = 0.02) for the CEA group. The CAS group improved in episodic memory, encoding subitem (P = 0.009), working memory (P = 0.04), and executive functions (P = 0.02). Comparing the techniques, the CAS group showed higher scores only in executive functions (P = 0.02).

CONCLUSIONS

Both groups had a similar performance in cognitive tests, comparing preoperative and postoperative results. However, patients who underwent CAS tended to achieve higher scores in executive function and operational memory/attention tests.