Sleep Disordered Breathings in Patients with Stabilised Stroke – A Case Control Study

Abstract

Aim of the study: In order to characterise sleep disordered breathing (SDB) in patients with stable stroke, a prospective observational study is ongoing in Rome. We report the results of the first 55 cases studied.Methods: A consecutive series of patients with acute stroke, admitted to the stroke unit of two different Roman University Hospitals, were screened. Participants were submitted to both clinical and instrumental evaluations at stroke onset and then at 4 months. The diagnostic tests included polisomnographyc (PSG) study and brain MRI. SDB, either central or obstructive, was diagnosed in presence of an apnoea/hypopnoea index (AHI) value ≥5. Statistical analysis was performed with SPSS version 18.0 for Windows. Comparisons were done by ϰ2 tests or via Fisher’s exact test depending on which was more appropriate. Correlations were done with non-parametric tests (Spearman’s rho). Statistical significance was set at p<0.05.Results: Fifty-five PSG studies were performed. Forty-two cases (76.4 %) had a SDB. Twenty-eight out of the 42 (67 %) cases with an AHI ≥5 had an obstructive sleep apnoea-hypopnoea (OSAH) and 12 (29 %) cases had a central sleep apnoea-hypopnoea (CSAH). Patients affected by CSAH were significantly older than those affected by OSAH (p=0.052). In the group of patients affected by predominantly OSAH, the longer the time interval from stroke to PSG, the shorter both the total sleep period and the total sleep time. Patients with predominantly CSAH were more frequently arrhythmic and more frequently affected by increase in pharyngeal tissue and referred significantly more frequently inattention or unrefreshing sleep.Discussion and Conclusions: The hypothesis we postulate is that, in a subgroup of patients with stroke, stroke moves to worsen patients’ pre-existing breathing condition, causing ventilatory instability. In these cases, central apnoea may take precedence over the obstructive one, in a loop gain circuit over than one, that gives rise to alternating obstructive and central events (possible complex-sleep apnoeas). Multicentre studies, capable of enrolling larger cohorts, are needed to confirm this hypothesis.