Development of cerebral microbleeds in patients with cerebral hyperperfusion following carotid endarterectomy and its relation to postoperative cognitive decline

OBJECTIVE A primary cause of cognitive decline after carotid endarterectomy (CEA) is cerebral injury due to cerebral hyperperfusion. However, the mechanisms of how cerebral hyperperfusion induces cerebral cortex and white matter injury are not known. The presence of cerebral microbleeds (CMBs) on susceptibility-weighted imaging (SWI) is independently associated with a decline in global cognitive function. The purpose of this prospective observational study was to determine whether cerebral hyperperfusion following CEA leads to the development of CMBs and if postoperative cogni-tive decline is related to these developed CMBs. METHODS During the 27-month study period, patients who underwent CEA for ipsilateral internal carotid artery stenosis (>= 70%) also underwent SWI and neuropsychological testing before and 2 months after surgery, as well as quantitative brain perfusion SPECT prior to and immediately after surgery. RESULTS According to quantitative brain perfusion SPECT and SWI before and after surgery, 12 (16%) and 7 (9%) of 75 patients exhibited postoperative cerebral hyperperfusion and increased CMBs in the cerebral hemisphere ipsilateral to surgery, respectively. Cerebral hyperperfusion was associated with an increase in CMBs after surgery (logistic regres-sion analysis, 95% CI 5.08-31.25, p < 0.0001). According to neuropsychological assessments before and after surgery, 10 patients (13%) showed postoperative cognitive decline. Increased CMBs were associated with cognitive decline after surgery (logistic regression analysis, 95% CI 6.80-66.67, p < 0.0001). Among the patients with cerebral hyperperfusion after surgery, the incidence of postoperative cognitive decline was higher in those with increased CMBs (100%) than in those without (20%; p = 0.0101). CONCLUSIONS Cerebral hyperperfusion following CEA leads to the development of CMBs, and postoperative cogni-tive decline is related to these developed CMBs.