Treating obstructive sleep apnea in stroke patients improves recovery from stroke

A new study shows that patients in stroke rehabilitation treated for their co-existing obstructive sleep apnea (OSA) recovered better from stroke than those whose OSA was not treated.

The study, published in the April edition of the journal Stroke, found "significant improvements" in functional and motor outcomes as well as mood of stroke rehabilitation patients who received continuous positive airway pressure (CPAP), a small mask placed over the patient's nose during sleep that alleviates OSA.

"These new findings are important because functional and motor impairments are often the most disabling features of stroke, limiting people's mobility and participation in daily activities," says Dr. Clodagh Ryan, lead author of the Toronto Rehab study. Dr. Ryan is assistant director of Toronto Rehab's Sleep Research Laboratory and an adjunct scientist.

"If stroke patients get greater improvement in motor and functional outcomes, such as the ability to walk, dress and bathe themselves without assistance, they are going to be more independent and will function better at home."

Stroke is a leading cause of disability in Canada. Only 10 per cent of people who have a stroke recover completely. The rest are left with permanent or long-lasting disability. The impact for stroke survivors, and for their families, can be enormous.

OSA is a disorder that causes a person to stop breathing repeatedly during sleep because of recurrent collapse of the throat. About five to 10 per cent of otherwise healthy people are believed to have OSA―but as many as 70 per cent of stroke patients have the disorder. Stroke patients with OSA have greater functional impairment and higher death rates than stroke survivors without OSA.

The new study involved 44 inpatients in Toronto Rehab's stroke rehabilitation service. All were diagnosed with OSA. Half of the patients were treated with CPAP, while the other half did not receive CPAP.

"The impact on patients' mobility, which is the major problem for most of our stroke patients, was quite dramatic," says study co-author Dr. Douglas Bradley, a Toronto Rehab senior investigator who heads the hospital's Sleep Research Laboratory.

During the four-week trial, he says, patients treated with CPAP showed "a markedly greater improvement in walking distance within six minutes, a test used to determine walking ability, compared to those not treated for sleep apnea."

Impaired motor function of the leg is a major limitation to stroke recovery because it limits functional independence, the authors note. CPAP usage "could improve functional independence and hasten return to community living."

How CPAP treatment produced these benefits is not clear. It could be due to increased brain blood flow and oxygen delivery, which alleviates adverse cardiovascular effects of sleep apnea, and possibly through enhanced 'neuroplasticity,' the authors suggest. Notably, CPAP treatment had marginal, if any, effects on cognitive outcomes in the new study.

The new study builds on previous research by Dr. Bradley that showed OSA plays a role in inhibiting recovery from stroke. His earlier studies found that stroke patients who have OSA spend much longer in rehabilitation and do not recover as well physically compared to stroke patients without the sleep disorder.

"With this study, we've moved forward to actually treat obstructive sleep apnea in these patients, and the results are exciting," says Dr. Bradley. "These findings have implications for people's independence and quality of life, and for reducing the burden on caregivers and the healthcare system."

Although the findings are encouraging, several study limitations, including the small sample size, make it difficult to know whether the results apply to the general stroke population, the authors say. Also, larger, longer-term trials are needed to determine whether such improvements persist over longer periods.