Obstructive and Central Sleep Apnea in First Ever Ischemic Stroke are Associated with Different Time Course and Autonomic Activation

INTRODUCTION: Sleep-related breathing disorders are highly prevalent in patients with ischemic stroke. Among sleep-disordered breathing disorders, obstructive sleep apnea is the most represented one, but central sleep apnea, isolated or in the context of a periodic breathing/Cheyne–Stokes respiration, is frequently reported in these patients. Altered baroreflex responses have been reported in the acute phases of a cerebral event. METHODS: We conducted, in a group of patients with ischemic stroke (n=60), a prospective 3-month follow-up physiological study to describe the breathing pattern during sleep and baroreflex sensitivity in the acute phase and in the recovery phase. RESULTS: In the acute phase, within 10 days from the onset of symptoms, 22.4% of patients had a normal breathing pattern, 40.3% had an obstructive pattern, 16.4% had a central pattern, and 29.9% showed a mixed pattern. Smaller variations in the Apnea–Hypopnea Index were found in normal breathing and obstructive groups (ΔAHI 2.1±4.1 and −2.8±11.6, respectively) in comparison with central and mixed patterns (ΔAHI −6.9±15.1 and −12.5±13.1, respectively; ANOVA p=0.01). The obstructive pattern became the most frequent pattern, in 38.3% of patients at baseline and 61.7% of patients at follow-up. Modification of baroreflex sensitivity over time was influenced by the site of the lesion and by the sleep disorder pattern in the acute phase (MANOVA p=0.005). CONCLUSION: We suggest that a down-regulation of autonomic activity, possibly related to reduced vagal modulation, may help the recovery after stroke, or a transitory disconnection from the cortical node that participates in the regulation of sympathetic outflow.