The impact of sleep-disordered breathing on early functional recovery in ischemic stroke

Abstract

The rehabilitation potential in ischemic stroke depends both on the localization and size of cerebral infarction and on many other factors ensuring the restoration of neuron function in the ischemic penumbra. Sleep-disordered breathing (SDB) appears as intermittent episodes of apnea and hypopnea, which are accompanied by hypoxemia and tissue hypoxia, and may slow early functional recovery in patients.Objective: to evaluate the impact of SDB on early neurological recovery in patients with ischemic stroke and to identify predictors of unfavorable functional outcome.Patients and methods. A total of 56 patients (24 men, 32 women; mean age 62±15 years) with ischemic stroke were examined. All the patients underwent brain magnetic resonance imaging. Neurological deficit was assessed using the National Institutes of Health Stroke Scale (NIHSS), modified Rankin Scale (mRS) on admission and at 3 weeks. To identify SDB, cardiorespiratory monitoring was performed on 2–5 days after the onset of the disease. The total number of episodes of SDB, apnea, hypopnea, apnea-hypopnea index (AHI), hypoxemia index, and the total time with arterial oxygen saturation < 90% (desaturation time < 90%) were recorded. Results and discussion. At baseline, the median NIHSS score was 6 (range 4–10) and the median mRS score was 3 (range 2–5). After 3 weeks, the median NIHSS score was 3 (range 1.5–5) and the median mRS score was 1 (range 0–3). According to the degree of achieved functional independence, the patients were divided into 2 groups: 1) 40 functionally independent patients (a mRS score of ≤2; 2) 16 patients in need of assistance/care (a mRS score of ≥3). The groups were matched for age, sex, localization of cerebral infarction, degree of cerebral atherosclerosis, and incidence of cardiac pathology. At the same time, at baseline Group 2 had a more severity of neurological deficit (p=0.001) and respiratory disorders (p<0.04) and more frequently large and medium-sized foci (p=0.01). Discriminant analysis with a model including the characteristics of patients who had a difference in the two groups was carried out to confirm the role of the factors considered as predictors for poor functional prognosis and to identify their specific contribution to outcome. The investigation showed the predictive value of the studied model as a whole with relation to early functional recovery in the patients. As this took place, the number of apnea episodes demonstrated the proper importance as a predictor of poor prognosis.Conclusion. It is established that the number of nocturnal apnea episodes >123 is associated with the worst functional recovery. The results of the comparative analysis can be taken as the threshold value associated with unfavorable functional recovery in the early stages (AHI≥25/hr-1). It is precisely these patients that can be considered as candidates for early CPAP therapy (Continuous Positive Airway Pressure) in order to improve early functional recovery.

Keywords

• ischemic stroke
• sleep-disordered breathing
• early rehabilitation