Post-carotid endarterectomy changes in cerebral glucose metabolism on 18F-fluorodeoxyglucose positron emission tomography associated with postoperative improvement or impairment in cognitive function

Abstract

. disclosure Dr. Ogasawara has received research funding (3,500,000 yen) from Nihon Medi-Physics Co., Ltd. This work was partly supported by Grant-in-Aid for Strategic Medical Science Research (S1491001, 2014-2018 obJect Cognitive function is often improved or impaired after carotid endarterectomy (CEA) for patients with cerebral hemodynamic impairment. Cerebral glucose metabolism measured using positron emission tomography (PET) with 18 Ffluorodeoxyglucose (FDG) correlates with cognitive function in patients with neurodegenerative diseases. The present study aimed to determine whether postoperative changes in cerebral glucose metabolism are associated with cognitive changes after CEA. methods In patients who were scheduled to undergo CEA for ipsilateral internal carotid artery (ICA) stenosis (≥ 70% narrowing), cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) to acetazolamide were assessed preoperatively using brain perfusion single-photon emission computed tomography (SPECT). CBF measurement using SPECT was also performed immediately after CEA. For patients with reduced preoperative CVR to acetazolamide in the cerebral hemisphere ipsilateral to surgery, cerebral glucose metabolism was assessed using FDG-PET before surgery and 3 months after surgery and was analyzed using 3D stereotactic surface projection. Neuropsychological testing was also performed preoperatively and 3 months postoperatively. results Twenty-two patients with reduced preoperative CVR to acetazolamide successfully underwent FDG-PET studies and neuropsychological testing before and after CEA. Seven, 9, and 6 patients were defined as showing improved, unchanged, and impaired postoperative cognition, respectively, based on the neuropsychological assessments. The cortical area with increased postoperative glucose metabolism was greater in patients with improved postoperative cognition than in those with unchanged (p < 0.001) or impaired (p < 0.001) postoperative cognition. The cortical area with decreased postoperative glucose metabolism was greater in patients with impaired postoperative cognition than in those with improved (p < 0.001) or unchanged (p < 0.001) postoperative cognition. All 7 patients with improved cognition exhibited postoperative hemispheric increases in glucose metabolism, while 5 of the 6 patients with impaired cognition exhibited postoperative hemispheric decreases in glucose metabolism. Brain perfusion SPECT revealed that the latter 6 patients experienced postoperative cerebral hyperperfusion, and 2 of the 6 patients exhibited cerebral hyperperfusion syndrome. The cortical area with decreased postoperative glucose metabolism in these 2 patients was greater than that in other patients. coNclusioNs Postoperative changes in cerebral glucose metabolism, as measured using FDG-PET, are associated with cognitive improvement and impairment after CEA.

Reduced Hypoxic Tissue and Cognitive Improvement after Revascularization Surgery for Chronic Cerebral Ischemia

“…This cognitive improvement is reportedly related to postoperative restoration of brain perfusion that was reduced before surgery [4]. Restoration of perfusion may lead to improvement in cerebral metabolism, resulting in cognitive improvement [4,5]. These findings suggest that functionally impaired but structurally intact tissue may exist in areas of chronic cerebral ischemia with reduced cerebral metabolism and that such tissue may be viable in hypoxic conditions [6].…”

“…This syndrome impairs cognitive function even when the cerebral tissue appears structurally intact on MR imaging [5]. To investigate the relationship between postoperative improved cognition and hypoxic neural tissue, patients with cerebral hyperperfusion syndrome were excluded from the present study.…”

“…When a focally or globally prominent increase in CBF was visually observed in the affected cerebral hemisphere on this brain SPECT, the patient was determined to have cerebral hyperperfusion syndrome [5].…”

“…When patients had abnormally reduced cerebral blood flow (CBF) in the affected cerebral hemispheres (see "Brain SPECT and PET Studies" section), they were finally included in the present study. Patients with cerebral hyperperfusion syndrome after surgery [5] (see "Brain SPECT and PET Studies" section) were excluded.…”

Maintaining unperturbed cerebral blood flow is key in the study of brain metastasis and its interactions with stress and inflammatory responses

“…Moreover, when using a micro-needle inoculation, which avoids occlusion of the CCA, these detrimental effects were circumvented. In humans, narrowing of an ICA (located downstream to the CCA) beyond 70% is associated with cognitive impairments, which are reversible by improving perfusion (Yoshida et al, 2015). These findings further support our claim that experimentally-related reduction in ICA blood flow may constitute a significant confound for extrapolating experimental findings regarding brain processes to the clinical setting.…”