Stroke & Sleep Apnea

Is There a Relationship Between Stroke and Sleep Apnea ?

 Meet Mrs Johnson, a case study:   

Mrs Johnson is a 60 year old lady who suffered a stroke 2 months ago. She was paralyzed on the left side and was moderately aphasic with difficulty expressing language.  Since then, Mrs Johnson has improved through the care of her physicians and nurses and by her perseverance with rehabilitation.

In the general population, stroke risk factors include: Hypertension, smoking, diabetes, cardiac arrhythmia (atrial fibrillation), prior history of stroke, carotid artery disease, physical inactivity and dyslipidemia.  Mrs Johnson had 3 of those risks (hypertension, diabetes and smoking). Her neurologist addressed those risk factors and she was started on the appropriate medications and lifestyle modifications to make sure she does not have another stroke: Her doctors put her on blood pressure pills and aspirin, her diabetes was more tightly controlled and she stopped smoking.

Her neurologist was concerned about one more risk that has yet to be addressed: obstructive sleep apnea syndrome (OSA). Mrs Johnson showed the clinical symptoms of OSA: She snored “like a chain saw”, made gasping sounds, tossed and turned a lot and felt tired and sleepy during the day. Her husband has been concerned about her sleep for while.

Her neurologist ordered a sleep study known as the polysomnogram. It showed that Mrs Johnson has 50 apneas and hypopneas an hour so her Apnea-Hypopnea Index (AHI) was 50, which is considered severe. An apnea or hypopnea refers to a process of intermittent relaxation of the throat muscles to the point of narrowing or blocking the passage of airflow. Mrs Johnson’s blood oxygen level also dropped to a low of 80% and 70% (normal is > 90%). Her sleep was quality was disrupted because of the OSA.

Her neurologists initiated the CPAP (continuous positive airway pressure) treatment for the OSA.  Mrs Johnson started to sleep better (so did her husband) and she felt more refreshed and energetic during the day. In fact, she was more alert on mornings when the physical therapist visits her home to work on her speech and strength. Her blood pressure began to improve as well.

Background on Stroke and Sleep Apnea

Mrs Johnson is among 700, 000 Americans who have a stroke each year. It is the leading cause of disability in the United States. OSA is associated with many conditions that increase the stroke risk: Hypertension, diabetes, cardiovascular disease and obesity. OSA also leads to cognitive impairment and may hider stroke recovery. OSA is often unrecognized and under diagnosed.

Is obstructive sleep apnea (OSA) a risk factor for stroke?

Yes it is. The Sleep Heart Health Study which was published in 2010 provides “compelling evidence based on 8 years of prospective data from a large, geographically diverse community-based cohort of middle-aged and older adults, that modest to severe levels of sleep apnea are associated with approximately three-fold increase risk of ischemic stroke in men.” In women, stroke risk was increased in those with obstructive AHI > 25 per hour (1).

Based on this study and other cross-sectional studies over the past decade, OSA is established as an independent risk factor for stroke

Does treating sleep apnea reduce the risk of stroke?

  1. A 2009 study by Martinez-Garcia from Spain found that CPAP treatment reduced mortality in patients with ischemic stroke and obstructive sleep apnea (2).
  2. A 2005 study by Martinez-Garcia looked at outcomes of CPAP treatment in stroke patients who also had sleep apnea with an AHI > 20 after 18 months: failure to use CPAP in individuals with AHI > 20 increased their probability of a new vascular event by five-fold (OR 5.09) (3).

What is the link between sleep apnea and stroke

Sleep apnea and stroke share common risk factors:

  • Hypertension: Sleep apnea is an independent risk factor for hypertension. The Wisconsin Sleep Cohort Study by Terry Young was the first to identify a dose response relationship between the apnea-hypopnea index (AHI) severity and risk of developing hypertension. Most importantly, treatment with CPAP reduces systemic hypertension in hypertensive patients (4,5).
  • Atrial fibrillation: Sleep Apnea is independently associated with (6). Recurrence of Atrial Fibrillation at 12 months in was higher (82%) in the OSA group that were not receiving CPAP therapy than the 42% recurrence in the treated OSA group (7).
  • Heart disease: Sleep Apnea is a risk factor for cardiovascular disease (8).
  • Carotid artery wall intima-media thickness is increased in patients with severe sleep apnea syndrome (9).
  • Diabetes: Sleep apnea increases the risk of developing diabetes, independent of other risk factors. Sleep Apnea is independently associated with the development of diabetes mellitus II and that treatment of sleep apnea with CPAP improves glycemic control (10,11).
  • Obesity increases the risk of developing sleep apnea (5).

Recommendation: Consensus statement by VA stroke task force:

  1. Neurologists are encouraged to screen their stroke patients for sleep apnea, with the recognition that it is an independent risk factor for stroke and it carries an increased risk for future vascular events such as stroke, atrial fibrillation and myocardial infarction.
  2. Treatment of sleep apnea in the general population is recommended because it confers benefits by reducing the vascular burden and improving daytime functioning (less sleepy, better cognitive function).

Future research is needed to establish whether treating sleep apnea reduces or delays stroke in people. Research can explore the use of oral appliance and positional therapy when CPAP is a challenge to use for stroke patients with motor disability.

 

STOP-Bang Sleep Apnea Questionnaire

Use this screening tool to test your risk for OSA.Answer yes or no to each of these questions:

  1. Do you snore loudly (louder than talking or loud enough to be heard through closed doors)?
  2. Do you often feel tired, fatigued, or sleepy during daytime?
  3. Has anyone observed you stop breathing during your sleep?
  4. Do you have or are you being treated for high blood pressure?
  5. BMI more than 35?
  6. Age over 50 years old?
  7. Neck circumference > 15.75 inches?
  8. Gender: Are you male?

If you answered YES to more than 3 answers: You have a High-risk for OSA
If you answered YES to less than 3 answers: You have a Low-risk for OSA

The more numbers of “yes”s, the more severe the sleep apnea. If you scored for a high risk for sleep apnea, please talk to your doctor to get properly evaluated, diagnosed and treated. Don’t take a chance on your health.

To check your BMI, go to google and put BMI for woman/man and it will calculate it for you (provide your weight and height).

To check your neck circumference, use a measuring tape around your neck.

References:

  1. Redline S, Yenokyan G, Gottlieb DJ, Shahar E, O’Connor GT, Resnick HE, Diener-West M, Sanders MH, Wolf PA, Geraghty EM, Ali T, Lebowitz M, Punjabi NM. Obstructive sleep apnea-hypopnea and incident stroke: the sleep heart health study.Am J Respir Crit Care Med. 2010 Jul 15;182(2):269-77.
  2. Martínez-García MA, Soler-Cataluña JJ, Ejarque-Martínez L, Soriano Y, Román-Sánchez P, Illa FB, Canal JM, Durán-Cantolla J. Continuous positive airway pressure treatment reduces mortality in patients with ischemic stroke and obstructive sleep apnea: a 5-year follow-up study. Am J Respir Crit Care Med. 2009 Jul 1;180(1):36-41. Epub 2009 Apr 30.
  3. Martínez-García MA, Galiano-Blancart R, Román-Sánchez P, Soler-Cataluña JJ, Cabero-Salt L, Salce ues E.Chest. Continuous positive airway pressure treatment in sleep apnea prevents new vascular events after ischemic stroke. 2005 Oct;128(4):2123-9.
  4. Logan AG, Tkacova R, Perlikowski SM, Leung RS, Tisler A, Floras JS, Bradley TD. Refractory hypertension and sleep apnoea: effect of CPAP on blood pressure and baroreflex. Eur Respir J. 2003 Feb;21(2):241-7.
  5. Young T, Peppard P, Palta M, Hla KM, Finn L, Morgan B, Skatrud J. Population-based study of sleep-disordered breathing as a risk factor for hypertension. Arch Intern Med. 1997 Aug 11-25;157(15):1746-52.
  6. Gami AS, Pressman G, Caples SM, Kanagala R, Gard JJ, Davison DE, Malouf JF, Ammash NM, Friedman PA, Somers VK.Association of atrial fibrillation and obstructive sleep apnea. Circulation. 2004 Jul 27;110(4):364-7. Epub 2004 Jul 12.
  7. Kanagala R, Murali NS, Friedman PA, Ammash NM, Gersh BJ, Ballman KV, Shamsuzzaman AS, Somers VK.Obstructive sleep apnea and the recurrence of atrial fibrillation. Circulation. 2003 May 27;107(20):2589-94. Epub 2003 May 12.
  8. Shahar E, Whitney CW, Redline S, Lee ET, Newman AB, Javier Nieto F, O’Connor GT, Boland LL, Schwartz JE, Samet JM. Sleep-disordered breathing and cardiovascular disease: cross-sectional results of the Sleep Heart Health Study. Am J Respir Crit Care Med. 2001 Jan;163(1):19-25.
  9. Silvestrini M, Rizzato B, Placidi F, Baruffaldi R, Bianconi A, Diomedi M. Carotid artery wall thickness in patients with obstructive sleep apnea syndrome. Stroke. 2002 Jul;33(7):1782-5.
  10. Botros N, Concato J, Mohsenin V, Selim B, Doctor K, Yaggi HK.  Obstructive sleep apnea as a risk factor for type 2 diabetes. Am J Med. 2009 Dec;122(12):1122-7.
  11. Babu AR, Herdegen J, Fogelfeld L, Shott S, Mazzone T. Type 2 diabetes, glycemic control, and continuous positive airway pressure in obstructive sleep apnea. Arch Intern Med. 2005 Feb 28;165(4):447-52.
  12. Chung F, Yegneswaran B, Liao P, Chung SA, Vairavanathan S, Islam S, Khajehdehi A, Shapiro CM. STOP questionnaire: a tool to screen patients for obstructive sleep apnea. Anesthesiology. 2008 May;108(5):812-21.