Obstructive sleep apnea (OSA) is the most common type of sleep disordered breathing.  It involves repeated narrowing or collapse of the upper airway during sleep despite ongoing respiratory effort.  OSA is a risk factor for stroke and may also be a consequence of a stroke.  OSA is frequently found in patients who have had a stroke, and in this setting is often undiagnosed. It should be noted that many patients may have had their stroke because of this undiagnosed condition.
A recent report from the Cleveland Clinic indicates that up to two-thirds of patients who have had a stroke had obstructive sleep apnea.  These patients have poorer outcomes that those patient without OSA, in terms of functional and cognitive recovery, as well as short and long term mortality rates.  The Clinic points out physicians should consider an evaluation for OSA following stroke because of the high prevalence in this population. They also point out that the typical clinical features of OSA may not be present in the average stroke patient.
Making a diagnosis in stroke patients presents challenges.  Many are unable to communicate and may have neurologic deficits, which make it difficult to comply with a sleep study.  It may also be difficult for the stroke patient to comply with the standard CPAP therapy for OSA.  The ability to handle secretions, aspiration risk, and the ability to put on or remove the CPAP mask are all limiting factors.  However, the evidence for treatment benefit is mixed.