Assessment of association of ischemic stroke and sleep disorders ( respiratory- related sleep disorders and others) on cognition in the patients under 55 years old

Introduction: Sleep-related respiratory disorders, especially obstructive sleep apnea syndrome (OSAS) , are common in the majority of stroke patients. OSAS is considered as a risk factor for stroke as well as a post-stroke complication. Both OSAS and stroke alter cognitive function. There are a few studies evaluating the effects of OSAS on cognitive function in stroke patients. In the studies conducted, the presence of OSAS in patients with stroke was associated with severe cognitive dysfunction. There are no studies evaluating the effect of association of OSAS with young stroke on cognition in the literature. Methods: Sixty patients with stroke below 55 years of age were included in the study. The patients' histories, demographic characteristics, habits, background and family history were recorded. Physical examination was done for OSAS. Routine laboratory and radiological investigations were performed. Stroke etiology was evaluated with TOAST classification. NIH Stroke Score (NIHSS) and Modified Rankin Scale were used to evaluate functionality. Epworth Sleepiness Scale was performed to assess daytime sleepiness and patients were admitted to sleep service for over-night polysomnography investigatioın. Clock drawing test, Montreal cognitive assessment scale (MOCA test), Stroop test, Audiovisual Number Sequences Test; Lawton and Brody's Instrumental Daily Living Activities Index (FFA) were used to assess daily living activity, and Beck's depression scale was used to assess depression. Findings: According to polysomnography (PSG) results, 7 subjects were considered to be normal while 10 subjects were diagnosed as having primary snoring, 14 subjects as mild OSAS, 11 subjects as moderate OSAS, and 18 subjects as severe OSAS. Demographic data showed no significant difference between the groups. When evaluating the neck structure, physical examination revealed a significant difference between the groups, especially in the severe OSAS group. Atherosclerotic diseases were common in patients and their relatives. Among the sub-parameters of NIHS score, especially facial asymmetry and dysarthria were more frequent in severe the patients with OSAS. When the relationship between stroke localization and the groups was evaluated, it was observed that brain stem involvement was more frequent in the patients with severe OSAS. All parameters of executive function, i.e., attention, language, delayed recall and MOCA test, Stroop Test, many parameters of the auditory number sequences test were found to be significant when compared with control group, especially severe OSAS. As OSAS increased, Daily Living Activity score decreased and Beck Depression Test score increased. Significant deterioration in Stropp Test sections 2 through 5 were found to be statistically significant in the group with severe OSAS and stroke compared to the group with isolated severe OSAS. Similarly, subjects with moderate and mild OSAS with stroke association were affected in all parts of the Stroop Test compared to isolated moderate and mild OSAS group. Cognitive parameters were found to correlate with both the NIHS Scale and the Epworth Sleepiness Score when groups evaluated separately. Conclusions: Since patients aged 18 to 55 years were included in our study, the importance of investigating the effects of sleep disorders, sleep-related breathing disorder and stroke-OSAS on cognition, especially in young stroke patients, was emphasized for the first time in the literature. Since sleep related diseases -which are one of the causes of stroke etiology- can appear under 55 years old, attention should be paid to this issue as much as the other risk factors. The presence of accompanying atherosclerotic diseases as well as respiratory disorders during sleep makes the issue even more important.