Obstructive sleep apnea (OSA) is highly prevalent but easily undiagnosed and is an independent risk factor for cognitive impairment. However, it remains unclear how OSA is linked to cognitive impairment. In the present study, we found the correlation between morphological changes of perivascular spaces (PVSs) and cognitive impairment in OSA patients. Moreover, we developed a novel set of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) methods to evaluate the fluid dynamics of glymphatic drainage system. We found that the inflow and outflow parameters of the glymphatic drainage system in patients with OSA were obviously changed, indicating impairment of glymphatic drainage due to excessive perfusion accompanied with deficient drainage in OSA patients. Moreover, parameters of the outflow were associated with the degree of cognitive impairment, as well as the hypoxia level. In addition, continuous positive airway pressure (CPAP) enhances performance of the glymphatic drainage system after 1 month treatment in OSA patients. We proposed that ventilation improvement might be a new strategy to ameliorate the impaired drainage of glymphatic drainage system due to OSA-induced chronic intermittent hypoxia, and consequently improved the cognitive decline.

Studies implicate that gut dysbiosis is related with many neurological diseases. However, the potential role of gut dysbiosis in cryptogenic stroke (CS) has not been elucidated yet. In this study, a high prevalence of gastrointestinal (GI) dysfunction and gut inflammation with increased intestinal permeability have been found in CS patients compared with normal controls (NCs). The systemic inflammation in CS patients was also identified by measuring the levels of plasma C-reactive protein (CRP), lipopolysaccharide (LPS), LPS-binding protein (LBP), and white blood cells (WBC) count. Using 16S rRNA sequencing, we found increased alpha diversity, accompanied by a higher abundance of Enterobacteriaceae, Streptococcaceae, and Lactobacillaceae at the family level and Escherichia–Shigella, Streptococcus, Lactobacillus, and Klebsilla at the genus level in the intestinal microbiota of CS patients compared to NCs. Our results showed that the abundance of Klebsilla was positively correlated with the systemic inflammation, the National Institutes of Health Stroke Scale (NIHSS) scores, and the infarct volumes. In conclusion, gut dysbiosis in CS patients was associated with the severity of CS and the systemic inflammation. Maintaining the intestinal homeostasis may be a potential strategy for the treatment of CS.

Hypertrophic olivary degeneration (HOD) is a transsynaptic degeneration characterized by the disruption of dentato-rubro-olivary tract, a region also known as the Guillain-Mollaret triangle (GMT), which often occurs because of posterior fossa or brainstem lesions. Infratentorial cerebrovascular diseases (ICVD) has been linked to HOD in previous studies. The underlying mechanism of ICVD patients developed HOD, however, remains undetermined. In this study, we analyzed clinical features of 334 patients with ICVD and the results showed that brainstem hemorrhage was most likely to develop HOD (43.5%) among four types of ICVD. In addition, multivariate regression analysis revealed that PSP-RS was an independent risk factor (OR = 6.69, 95% CI: 1.58–28.32) for ICVD-HOD, and the presence of HOD was obviously higher in PSP-RS patients complicated by ICVD (43.5%) than that in PSP-RS patients uncomplicated by ICVD (4.2%). Furthermore, DTI study showed that the PSP-RS, HOD, PSP-RS with HOD, and PSP-RS with ICVD-HOD groups displayed the impaired microstructural integrity of the GMT compared to iPD and HCs groups. Moreover, some DTI parameters of the GMT showed correlation with the Progressive Supranuclear Palsy Rating Scale (PSPRS) score in PSP-RS patients. Taken together, our study demonstrated that PSP-RS was an independent etiological factor for ICVD-HOD which might due to impaired microstructural integrity of the GMT. More importantly, these findings suggest that PSP-RS patients should aim for the prevention of ICVD to reduce the occurrence of HOD.