News from The Sleep Surgery Centre
Autumn 2009
SNORING AND CAROTID ARTERY ATHEROSCLEROSIS
Should we be listening to more necks ?
Carotid artery atherosclerosis (CAS) is a leading cause of ischemic stroke, which itself is the leading cause of disability in our North America(1). Studies have linked nocturnal hypoxemia and obstructive sleep apnea (OSA) with endothelial damage and arteriosclerosis(2,3). Until now snoring has not been studied as a possible factor.
In 1994, Dr. Hedner et al.(4) proposed a link between snoring vibrations and carotid artery endothelial damage causing carotid artery atherosclerosis. Snoring vibrations have been shown to be transmitted to the carotid artery lumen of rabbits, and rat tail blood vessels are denuded by 60 Hz. vibrations (approximately the snoring frequency)(5).
A recent study from Australia(6) has shown that heavy snorers, as quantified on polysomnogram as snoring for more than half the night, are 7.4 times more likely to have carotid artery atherosclerosis than mild or non-snorers, independent of other risk factors such as age, sex, hypertension and smoking. Femoral artery atherosclerosis in the same patients was not significantly increased. Nor was there a relationship between the severity of OSA (by Apnea-Hypopnea Index) and CAS.
For some time we have been aware of substantial evidence relating obstructive sleep apnea to stroke. In one study(7), 72% of stroke patients were found to have OSA (apnea hypopnea index greater than 10), and both the length of the hospital stay and the degree of permanent functional impairment increased proportionately with the severity of the OSA found. Since heavy snoring is one of the major symptoms of OSA, it may be that at least part of this relationship is due to snoring. While OSA has a prevalence of 4% in middle-aged men, and 2% in middle-aged women(8), snoring has a prevalence of 15-54% in the middle-aged population(8,9). If the association observed in the study is causal, the significantly raised risk of carotid artery atherosclerosis in heavy snorers, coupled with the high prevalence of snoring in the community, has substantial public health implications for the prevention of stroke.
Dr. Richard R.J.Smyth, MBBS, FRCS, FRCSC.
References:
(1)American Heart Assoc. Stats (www.americanheart.org)
(2)Kato et al, Circulation 2000;102:2607-2610
(3)Phillips BG et al, J Hypertens.1999;17:61-66
(4)Hedner J et al, in Saunders NA, Sullivan C. Sleep and Breathing. New York: Dekker;1994,823-846
(5)Amatoury J et al, J Appl Physiol 2006;100:1547-53
(6)Lee SA et al, Heavy Snoring as a Cause of Carotid Artery Atherosclerosis. Sleep, Sept.2008,31;9:1207-1213
(7)Kaneko et al, Sleep apnea in stroke patients predicts worse functional status and longer hospitalization. Annual Meeting of American Heart Assoc., Nov 11,2001; Anaheim, California
(8)Young T, New Engl J Med1193;328:1230-5
(9)Hiestand DM et al, Chest 2006;130:780-6
Past Articles
Doctors Patients and Sleep - A survey of family practitioners in the United States has shown that doctors in general do not ask their patients about sleep. More>>
New Surgical Procedures for Snoring and Obstructive Sleep Apnea - Fall 2006 newsletter from the Sleep Surgery Centre. More>>
Sleep Apnea Often Goes Undetected - Dec 2004 From the Publishers of the New England Journal of Medicine
Sleep apnea, a common and debilitating disorder signaled by loud snoring, often goes unrecognized, according to researchers who say better diagnosis and treatment would cut the risk of accidents, heart attacks, and strokes. More>>
Integrated Care for Sleep Disordered Breathing - Summer 2003 newsletter from the Sleep Surgery Centre
The condition of sleep disordered breathing covers a wide range of clinical variability from mild snoring to severe sleep apnoea. Many patients, and their clinicians, are unaware where exactly on that continuum they stand. Moreover once accurately diagnosed, the morass of available treatment is confusing, and the advice given on management may depend more on the perspective of the consultant than on the optimal treatment for a particular patient. More>>
Laser or Radio-Frequency: Which is better for snoring? - Fall 2002 newsletter from the Sleep Surgery Centre
At the Sleep Surgery Centre patients are encouraged to become thoroughly informed about all forms of treatment for snoring and obstructive sleep apnea and to engage fully in the decision process concerning the best treatment for them. Not surprisingly, then, the question of whether the laser assisted uvulopalatoplasty (LAUP) or radio-frequency palatal myoplasty (RPM) is the best treatment often comes up. More>>