Two-Year Outcome after Intervention or Aggressive Medical Treatment for Severe Asymptomatic Carotid Stenosis

• Main Authors: Chun-Jen Lin, 林浚仁
• Other Authors: I-Hui Lee
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/ymh4yw

博士 === 國立陽明大學 === 腦科學研究所 === 105 === Backgroud: Asymptomatic severe carotid stenosis has been shown to increase the incidence of microembolism and/or chronic hypoperfusion, which may consequently result in cognitive impairment and white matter ischemic injury. However, the diagnosis and pathophysiology of such vascular cognitive impairment are largely unclear. Moreover, there is a lack of controlled evidence for cognitive benefits by either optimal medical treatment alone or combinatory carotid revascularization. Aims: We aim to investigate brain connectivity markers being used to aid early diagnosis of cognitive impairment in patients with asymptomatic severe carotid stenosis patients, and seek for the optimal treatment for long-term vascular and cognitive outcomes. Methods: We compared asymptomatic, ≧70% unilateral stenosis of the extracranial internal carotid artery with matched healthy controls with a battery of neuropsychological tests, neck and brain sonography, structural and magnetic resonance imaging (MRI) and angiography, brain-wise diffusion tensor imaging and seed-based analysis of resting-state functional MRI. These patients were treated with either optimal medical treatments alone or in combination with carotid artery stenting (CAS) and followed three months and two years after the treatments. Results: Compared to the healthy controls, the patients had worse dizziness, poorer verbal memory, executive function and complex visuospatial performance. 40% of these patients fulfilled the criteria of mild cognitive impairment. Their whole-brain mean fractional anisotropy (FA) was significantly reduced and regional functional connectivity (Fc) was impaired in the dorsal attention network (DAN), frontoparietal network, sensorimotor network and default mode network. In particular, the Fc strength at the insula of the DAN and the whole-brain mean FA were linearly related with attention performance and dizziness severity, respectively. After three-month treatments, compared to the medical group, the stenting group showed significant alleviation of dizziness and insignificant improvement in verbal memory and complex visuospatial performance, accompanied with increased FA at the posterior corpus callosum and the posterior periventricular white matter ipsilateral to CAS. At two-year follow-up, the ipsilateral stroke rate, the composite vascular event rate and the global cognitive performance (mini-mental status examination, MMSE) were similar between the groups. The volumes of grey, white matter as well as hippocampus were not significantly changed. However, compared to the medical group, the stenting group had significant improvement of delayed verbal memory in association with enhancement of cerebral perfusion and periventricular FA strength ipsilateral to CAS. Conclusions: Asymptomatic ≧70% carotid stenosis is associated with mild cognitive impairment. Optimal medical treatments and combinatory carotid revascularization for such patients may enhance verbal memory, brain perfusion and white matter connectivity particularly ipsilateral to stenosis. Verbal memory performance and advanced imaging such as cerebral perfusion and connectivity measures can serve as both objective markers for early diagnosing cases at risk and therapeutic targets for cognitive outcomes.