Permanent Hearing Loss From Noise May Depend on Time of Day!

Research out of Sweden have discovered that noise-induced hearing loss sustained at night is more likely to become permanent than if it occurred during the day... at least in mice.

Apparently, there are certain genes found to cycle in the cochlea of mice in a pattern that followed the hours of the day. By measuring the auditory nerve activity, they found that mice exposed to moderate noise levels during the night suffered from permanent hearing loss while mice exposed to similar noise levels during the day did not. The ability to heal after noise-induced hearing loss (temporary threshold shift) was linked to the circadian rhythm due to levels of BDNF (brain derived neurotrophic factor).

Specifically, concentration of BDNF increases in the cochlea during the day which protected hearing from permanent damage whereas levels were absent at night. Furthermore, researchers were able to artificially increase BDNF levels at night when normally absent and confer hearing protection with noise exposure.

What does this mean for humans?

IF human ears also have a biologic clock similar to mice, than researchers MIGHT be able to develop a specific way to reverse (or prevent) noise-induced hearing loss. Currently, the only way to treat acute noise-induced hearing loss is high doses of steroids whether orally or by injection directly into the ear.

Also, humans should probably avoid listening to loud music at night (i.e. concerts, night-clubs, restaurants, etc) which elevates risk of permanent hearing loss (compared to during the day).

Reference:
TrkB-Mediated Protection against Circadian Sensitivity to Noise Trauma in the Murine Cochlea. Current Biology, 27 February 2014. 10.1016/j.cub.2014.01.047

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Cicadas Can Cause Permanent Hearing Loss!

Cicadas are pretty darn ugly... But beyond their ugliness and making cars look pretty messed up... the sound they make is not only irritating, but potentially harmful.

Sometime the end of this April 2013, billions of large flying insects called cicadas will make their appearance along with their characteristic stridorous noise. The male cicadas are the ones making this mating noise with "tymbal" soundmakers amplified by large resonance chambers found on body.

Occurring every 17 years, this year's swarm is known as Brood II and has not been seen since 1996. Expected to cover much of the East Coast, the buzz created by these insects can reach 90 decibels... about as loud as a jackhammer. If one is right next to your ear, the sound can reach 120 decibels are equivalent to sandblasting or a loud rock concert. [see noise chart]

At 90 decibels, possible hearing damage may occur if a human ear is exposed to this level noise for more than 8 hours a day. At 120 decibels, less than 15 minutes of exposure can induce possible permanent hearing loss.

So... keep a pair of ear plugs in your purse or pants pocket and use them if the sound starts to get too loud.... or too irritating.

Sources:
17 years in the making, this spring's cicada invasion generates early buzz. NBC News 4/10/13.

Cicada. Wikipedia

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ER Doc Found Negligent in Bell's Palsy Case

This case is not quite what you might think...

Here's the background... The Wisconsin State Supreme Court  found an ER physician negligent for failing to offer a carotid ultrasound for a patient who presented with an isolated facial paralysis (patient did not exhibit paralysis anywhere else in the body) and upheld a $2 million jury award to the patient in 2008. Not only that, the Wisconsin Medical Board reprimanded the ER physician and fined her $300. [link]

Hmmmm... After all, it is not considered routine nor standard of care to obtain a carotid ultrasound for an isolated facial paralysis known as Bell's palsy. I should also mention that the ER physician was NOT found negligent in the diagnosis of Bell's palsy.

Well, here's the other part of the story... The patient did have a CT scan of the brain in the ER which was normal. A diagnosis of Bell's palsy was appropriately made by the ER physician and the patient sent home. Eleven days later, the patient suffered a stroke with irreversible damage. A stroke workup at that time revealed a carotid artery with 95% obstruction.

For those uninitiated, paralysis due to a blocked carotid artery would cause lack of blood flow to one entire half of the brain resulting in not only facial paralysis, but also paralysis of half the body too. Furthermore, a stroke causing facial paralysis would have forehead sparing (more on this).

The court's feeling was that the patient should have been offered a carotid ultrasound at the time of the initial ER visit for Bell's palsy... in essence, the court was stating a stroke workup should have been offered/done for a Bell's Palsy. I should also mention that most ER's do not have carotid ultrasound capabilities outside of business hours.

To reiterate, a carotid ultrasound is NOT a test that a physician would or should normally order for a Bell's Palsy workup. By the court stating a carotid ultrasound should have been performed, it has turned a medical condition of Bell's palsy which is not a stroke concern into a diagnosis of possible stroke.

Does that now mean that whenever a patient presents with a Bell's palsy, a stroke protocol should also be pursued which would include:

1) Stroke rapid response by the ER
2) Hospital admission
3) Stroke workup which would include:
  • Carotid ultrasound
  • MRI Head
  • Cardiac workup for arrhythmias (atrial fibrillation which can cause embolic stroke)
  • Pulmonary and vascular workup for deep venous thrombosis (can also cause embolic stroke)
etc, etc, etc

Medically speaking, Bell's palsy is NOT a stroke nor a concern for possible stroke nor increased risk of stroke. Bell's palsy is an isolated inflammation of the facial nerve that has nothing to do with the brain.

ER physicians have a hard enough job as it is now, but to be responsible for pursuing workups for totally unrelated diagnosis separate from the main presenting concern should be cause for concern.

Perhaps there is more to this case that was absent from what has been reported in the media...

Source:
State board reprimands doctor who was found negligent by high court. Wisconsin State Journal 3/21/13

Health Sense: How much should doctor tell you? Wisconsin State Journal 7/9/12

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People DO Suffer Hearing Loss After a Loud Concert

Almost everybody at some point in their lives have attended a loud concert or loud nightclub.

Almost everybody will also recall a temporary reduction in their hearing with or without ringing afterwards for a short period of time.

This phenomenon is called temporary threshold shift (TTS) whereby the affected person has a temporary hearing loss that may last hours to days due to temporary damage of the outer hair cells of the cochlea.

If loud nose exposure happens enough times, permanent hearing loss can occur.

For some, permanent hearing loss may occur after attending numerous loud concerts whereas in other more "susceptible" individuals, it can happen after a single loud concert.

It doesn't even have to be a loud music concert. ANY loud noise exposure can do including shooting guns, listening to a portable music player like the iPod, fireworks, playing in an orchestra/band, etc.

However, loud concerts are of particular interest given how many individuals are exposed all at once and provided a unique research opportunity which was presented on May 21, 2012 at the American Otologic Society Meeting in Los Angeles.

The researchers (led by Dr. Jennifer Derebery of the House Ear Institute) essentially took hearing test before and after the concert of 29 teenagers.

72% suffered objective hearing loss after the concert though only 53% reported subjective hearing loss. 25% reported new onset tinnitus after the concert.

Of note, hearing ear plugs were offered to the study subjects, but only 3 accepted them.

Adult researchers who sat with the teenagers under investigation measured sound levels throughout the concert. During the 26 songs played during the three hour concert, sound levels ranged from 82 to 110 decibels with an average of 98.5 decibels. The mean level was greater than 100 decibels for 10 of the 26 songs.

As a reference, ear pain occurs at 125dB. Jet engine noise is at 140dB. Sustained loud noise exposure of 90-95dB can result in permanent hearing loss.

OSHA (Office of Safety and Health Administration) mandates workers to never be exposed to sound levels of 100dB for more than 2 hours per day (no more than 4 hours per day at 95dB).

Clearly something more needs to be done to protect teenagers' hearing, especially given how few accepted hearing ear plugs. A fundamental cultural shift would most likely have to occur with encouragement from not only the musicians but also parents and teachers...

OR, the music volume at concerts should be turned down... No boos please.


Reference:
Teenagers Hear Worse After Attending Concert. LiveScience 5/21/12

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Kissing the Ear Can Cause Permanent Hearing Loss

MSNBC reported 3/29/12 about a phenomenon called cochlear ear-kiss injury. This condition is when hearing loss occurs after a person kisses someone else over the ear, usually a mom over a baby's or child's ear.

Right after the kiss, a person can suffer from immediate and potentially permanent hearing loss along with other symptoms including ringing, sensitivity to sound, sound distortion, and aural fullness.

How or why does this occur?

With a kiss, a strong suction is created within the ear canal that pulls on the eardrum which tugs on the middle ear bones that can lead to turbulence within the inner ear.

Infants are particularly susceptible to this condition given their ear canals are SO small and the suction created by an adult kiss over the ear can be so strong.

There are other variations of this type of ear/hearing injury.

Barotrauma of the ear can lead to similar type issues due to sudden pressure changes from flying, parachute jumping, diving into water, SCUBA, snorkeling, etc.

Getting slapped over the ear can do the same thing as cochlear ear-kiss injury, but in reverse. Rather than suction from a kiss creating strong negative pressure within the ear canal, a slap over the ear creates sudden strong positive pressure.

At times, such pressure changes can get so severe that the eardrum can rupture.

Source:
Innocent 'kiss of deaf' can cause permanent hearing loss. MSNBC 3/29/12

The kiss of deaf: Four-year-old's big smooch left her mom with partial hearing loss. Newsday. June 7, 2008

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