Post-stroke cognitive impairment (PSCI) is a common complication following acute ischemic cerebrovascular events. It not only seriously affects the quality of life of stroke survivors,but also increases the mortality of the patients. Inflammatory response has been proven to participate in the development and progression of acute ischemic stroke,which injures neural cells to further activate the body's inflammatory response and release of inflammatory factors,destroy the integrity of neural circuits,and thereby lead to cognitive dysfunction in patients. Evidence on the relationship between inflammatory biomarkers and cognitive function is insufficient. Therefore,this paper focused on the changes in the levels of inflammatory biomarkers to discuss the role of inflammatory response in patients with PSCI.

Objective:To summarize the clinical, imaging, muscle pathological and gene mutational features of patients with late-onset mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS).Methods:Three patients with late-onset MELAS, admitted to Department of Neurology, Jiaozuo People's Hospital Affiliated of Xinxiang Medical University from January 1997 to December 2021 were chosen; all patients were screened for mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) mutations by second-generation gene sequencing. The clinical, imaging, muscle pathological and gene mutational features of patients with late-onset MELAS were analyzed retrospectively.Results:The main clinical manifestations of these late-onset MELAS patients included stroke-like attacks, headache, hearing and vision loss, cognitive decline and mental disorder. The muscle tension and muscle strength of both upper extremities in these 3 patients were normal. Increased muscle tension and active tendon reflexes, and positive pathological signs in both lower extremities were noted in 2 patients. Head MRI showed abnormal long T1 and long T2 signals in temporal occipital parietal cortex and subcortex in 3 patients, and CT showed calcification in bilateral globus pallidus in 1 patient. Ragged red fibers (RRF) and ragged blue fibers (RBF) were found in the muscle biopsies of 3 patients, and cytochrome oxidase (COX)-negative muscle fibers were found in 2 patients. MT-TL1 gene m.3243A>G mutation was detected in all 3 patients by genetic testing, among which mutation in the blood of 2 patients was 15% and 17%, respectively, and mutation in the muscle tissues of 1 patient was 73%. Conclusion:Muscle pathology indicates high RRF percentage in patients with late-onset MELAS; and m.3243A>G spot mutation is the most common mutation type in late-onset MELAS, and m.3243A>G mutation ratio in muscle tissues is obviously higher than that in blood.