July 20, 2011
Here’s an attention-grabbing headline in Time Magazine—that exposure to second hand smoke significantly increases a teen’s chances of nerve deafness by almost two-fold. It’s already been shown that smoking can cause hearing loss in adults, but the fact that second hand smoke can affect teens’ hearing was quite a surprise.
It’s already known that cigarette smoke can aggravate middle ear infections in teens, leading to reversible hearing loss, but this study reported sensorineural hearing loss, which is generally nonreversible.
The authors of the study from NYU don’t give clear explanations for this finding, so let me put forth a few possible reasons:
- Teens probably listen to music at loud levels, which is known to cause nerve deafness, especially at higher frequencies (this study showed hearing loss at the mid to high frequencies).
- The teenage years are a period of massive change in the upper airway. These relative changes will destabilize breathing at night, leading to more frequent partial to total obstructions and arousals. Some teens (especially those with dental crowding and small jaws) will be more susceptible than others. Lack of deep, quality sleep has been shown to have detrimental effects on brain development and repair.
- Parents of the teens that smoke probably have a higher chance of snoring or having obstructive sleep apnea. Not sleeping well can predispose to increased stress and addictive activities that can stimulate and calm at the same time (such as alcohol and smoking).
- Intermittent brain hypoxia has been shown to cause major neurologic damage in multiple parts of the brain, including memory, executive function, autonomic control, and hearing centers
- Delayed sleep phase syndrome is more common in teens, contributing to poor sleep.
It’s conceivable that if you have mild degrees of nerve damage from loud music, the body will have the reserve to reverse or minimize any nerve damage. However, if you add all the other variables such as poor sleep and intermittent hypoxia from breathing pauses, then it’s likely that you’ll be more susceptible to inner ear nerve deafness.
So the next time your teenager seems to be ignoring you, it may be due to hearing loss.
February 16, 2011
There are a number of studies that associate an increased risk of deafness to sleep apnea, and an increased rate of dementia with sleep apnea, so why can’t deafness and dementia be linked, with sleep apnea being the main cause for both conditions? A study that was recently published in Neurology showed that for every 10 dBL hearing loss, after 12 years, the risk of dementia from all causes rose 27%. I’ve written numerous times about how sleep apnea can cause damage to the auditory cortex areas of the brain, as well as to the inner ear. The same process from sleep apnea that causes brain damage can injure areas that control memory, executive function, autonomic function, and hearing.
The next time someone you love can’t seem to hear you, it could be because he or she can’t process your words properly? Do you know someone who’s severely hard of hearing, and has possible dementia?
January 22, 2011
I’ve always suspected that nerve deafness may be one of the consequences of obstructive sleep apnea, but there’s been little research in this area. However, a new study out of Korea shows that in the elderly, having obstructive sleep apnea significantly increases your chances of have nerve deafness, particularly due to a problem in the central nervous system.
This finding is not surprising, since sleep apnea causes a hyper-coagulable state, with blood being more stagnant and tending to clot, in addition to additional inflammatory factors that can cause damage. It’s also been shown that blood is thicker and more viscous in people with sleep apnea. In fact, a recent study showed that people with obstructive sleep apnea had thicker blood than normal, and by diluting the blood concentration with saline, auditory brainstem reflexes improved to the point of being normal. Placing these people on CPAP also normalized hearing reflexes.
Recent brain imaging studies have shown that hypoxia in the brain from sleep apnea can cause major vascular and tissue damage, affecting critical areas of the brain, including the brainstem. The risk of stroke is also increased by more than 3 times if you have sleep apnea. Knowing all this, it’s not surprising that you can have either brainstem damage or peripheral inner ear vascular damage from untreated obstructive sleep apnea. One study showed that people with sudden one sided hearing loss from nerve damage have a higher risk of having sleep apnea.
I think that nerve deafness is part of the cardiovascular-metabolic process, going along with hypertension, diabetes, hypertension, high cholesterol, and heart disease. What you you think? If you have sleep apnea, do you have any hearing loss?
November 22, 2010
More than a handful of times, whenever someone comes to me with sudden hearing loss on one ear, there’s usually a precipitating event, such as an infection, stressful event, or trauma. Here’s a sequence of events where an underlying sleep-breathing problem clearly caused hearing loss.
A middle aged man with known severe hearing loss in both ears came to see me with sudden worsened hearing loss in his left ear 4 weeks ago. He normally uses hearing aids, but now he can’t understands people as well, even with his hearing aid. It turns out that exactly 4 weeks ago, while lifting something from his driveway, he pulled his back, with resulting severe back pain. He went to see his doctor, who prescribed a strong narcotic, which didn’t help that much. He’s usually a stomach sleeper, but due to his back pain, he had to sleep on his back. The night after he took his pain medication, he woke up and noticed his hearing loss on his left ear. His recent hearing test showed significantly diminished hearing in his left ear.
When I examined him, he had the classic anatomy of someone who has obstructive sleep apnea: small jaws, high arched hard palate, and very narrow posterior airway space (space behind the tongue), especially when on his back. All throughout his life, he naturally preferred to sleep on his stomach, but when suddenly forced to sleep on his back, wasn’t able to sleep efficiently (due to gravity’s effect on his tongue). But when he took his pain medication, his muscles relaxed even further, and he probably stopped breathing much more often. This caused a major and sudden stress response which probably caused either major inflammation or a mini-stroke in his inner ear blood vessels. Studies have shown that the area in the brainstem that controls the ear, as well as blood vessels that supply the inner ear are much more susceptible to damage. In particular, the area that’s responsible for the high frequencies is more prone to injury.
His exam only reinforced my observation that people who suffer from sudden nerve deafness all have very similar upper airway breathing passageways.
The traditional thing to do in this situation is to give oral steroids, but since it’s been about 4 weeks, the evidence for improving his condition is poor. Instead, I ordered a formal sleep study.