Toronto (April 30, 2003) - Stroke patients who have sleep apnea spend much longer in rehabilitation and do not recover as well physically compared to stroke patients without the sleep disorder, a new study shows.
The findings, published today in the journal Sleep, suggest that sleep apnea - a common illness among stroke patients - plays a role in inhibiting recovery from stroke.
"These results are exciting because sleep apnea is a treatable condition," says the study's lead author Dr. Douglas Bradley, Director of the Sleep Research Laboratory at the Toronto Rehabilitation Institute. "Treating sleep apnea could prove to be a new way to improve recovery from stroke and reduce hospital stays.
"There is potential here to improve quality of life for many people who've had a stroke and to reduce the financial burden on the health care system." Stroke is one of the leading causes of death and long-term disability in North America.
Sleep apnea causes a person to stop breathing repeatedly during sleep because of recurrent collapse of the throat. It can be caused by weight gain and conditions related to aging. The most effective treatment is continuous positive airway pressure or CPAP. This controls sleep apnea by forcing air through a tube and into a mask worn over the nose at night. Air pressure is transmitted through the nose and into the throat where it props the throat open thereby preventing apneas and snoring.
Recent evidence has shown that sleep apnea is common among patients who have had a stroke. Dr. Bradley and his colleagues wanted to know whether this breathing disorder was adversely affecting recovery and length of hospital stay for these patients.
The study, which involved 61 patients in Toronto Rehab's stroke rehabilitation unit, found sleep apnea in 72 per cent of the patients - a prevalence 10 times higher than in the otherwise healthy population.
The study shows that stroke patients with sleep apnea have greater degrees of physical disability and spent 14 (or 40 per cent) more days in the hospital's stoke rehab unit than those without sleep apnea. In spite of their longer stay in hospital, the patients with sleep apnea continued to be significantly more incapacitated when tested for their walking, self-care and other functional abilities.
"These findings suggest that sleep apnea contributed to the patients' functional incapacity and length of rehabilitation," says Dr. Bradley. "The worse the sleep apnea, the more debilitated they were, even after taking into account the severity of their initial stroke."
A person with even moderate sleep apnea stops breathing roughly 200 times in the night and, during those episodes, the brain is deprived of oxygen. For stroke patients already suffering brain damage, "the recurrent episodes of oxygen deprivation at night may be preventing the brain from recovering function and may even make the situation worse," says Dr. Bradley.
"I'm not saying the brain damage that's already there is reversible. But the ongoing insult to the brain from sleep apnea theoretically should be reversible. And if so, some of the brain cells may in fact improve their function."
The next step is a randomized controlled clinical trial to find out whether stroke rehab patients whose sleep apnea is treated with a CPAP device show changes in functional capacity compared to patients whose sleep apnea is not treated. Dr. Bradley has already started a trial of this kind.
Donald Taylor, a retired business executive who had a serious stroke three years ago and has sleep apnea, says the CPAP device has made a big difference in his life.
"I used to get very tired in the afternoons," says the 68-year-old. "CPAP helps me have the energy to do all the things I want to do." He and his wife recently returned from a two-month trip around Africa.
The study published today was supported by a grant from the Toronto Rehabilitation Institute Research Department. Dr. Bradley is a Senior Investigator at Toronto Rehab. He also holds positions at the Toronto General Hospital/University Health Network, Mount Sinai Hospital and the University of Toronto. He is the recipient of a Senior Scientist Award from the Canadian Institutes of Health Research.
About Toronto Rehabilitation Institute
The Toronto Rehabilitation Institute is Canada's largest hospital that provides adult rehabilitation services and complex continuing care. As a fully affiliated teaching and research hospital of the University of Toronto, Toronto Rehab also is advancing rehabilitation knowledge and practice.
