Capital Region Special Surgery Blog

If you go to any mall in America you will find a plethora of teenagers wearing the ubiquitous ipod or other personal music player. About a year ago I did a television segment on the dangers of these music players. This issue resurfaced last week in a New York Times article and deserves new discussion.

Using a portable sound meter we tested various earphones and devices such as the ipod, an old Sony Walkman (remember those?), and various other MP3 players. We found that the sound intensity was dependant on two things: the actual player and the earphones. Most of the players could deliver very loud sound. The ipod went up to about 115 dB. The maximal recommended level for earphones is about 80dB. The earphones were just as important. It turned out that the better the earphone, the more sound it could generate. So a more expensive earphone with a heavier magnet could generate more sound than a cheaper pair.

Exposure to any load sound can lead to permanent hearing loss. The loss usually occurs in the very high frequencies at first. The human ear has a resonance at 4000Hz. That means that any multifrequency sound is maximally amplified at that frequency and therefore selectively produces damage in the part of the inner ear responsible for sensing that frequency (see “How The Ear Works”). Very often ear noise or tinnitus accompanies this type of hearing loss.

The Occupational Safety and Health administration publishes the maximal noise exposure guidelines and can be found on their website.

Below are the guidelines. Notice that the allowable levels are time dependant.
|
Duration per day, hours | Sound level dBA slow response
____________________________|_________________________________
|
8………………………| 90
6………………………| 92
4………………………| 95
3………………………| 97
2………………………| 100
1 1/2 ………………….| 102
1………………………| 105
1/2 ……………………| 110
1/4 or less…………….| 115
____________________________|________________________________
Footnote(1) When the daily noise exposure is composed of two or
more periods of noise exposure of different levels, their combined
effect should be considered, rather than the individual effect of
each. If the sum of the following fractions: C(1)/T(1) + C(2)/T(2)
C(n)/T(n) exceeds unity, then, the mixed exposure should be
considered to exceed the limit value. Cn indicates the total time of
exposure at a specified noise level, and Tn indicates the total time
of exposure permitted at that level. Exposure to impulsive or impact
noise should not exceed 140 dB peak sound pressure level.

Moral of the story: turn down the volume and protect those ears!

Think way back to those college days. You went on a long night out with your friends at the local watering hole. You open your eyes at the first ray of light and all of a sudden the whole world is spinnning faster than Dorothy Gale’s house.

It turns out that there is a very real physiologic reason why this happens and it is directly related to a very common nonalchohol related problem called Benign Paraxysmal Positional Vertigo.

In order to understand why this occurs you must understand how your ear helps you maintain balance. Each ear has a set of three balance canals called the semicircular canals.

These three canals are set at right angles to one another corresponding to three dimensional space. They are made up of a hollow tube filled with a fluid. At one end of that tube is a dilated space that houses a pice of jellatenous material called the cupula that literally floats in its surrounding fluid. There is a delicate balance between the density (weight) of the cupula and the fluid. When we move our heads the cupula gets difflected by innertia which in tern triggers nerve endings. This “tells” our ears that our head is moving. This system is designed to be insensitive to gravity and only sense angular acceleration (how quickly you move your head in one plane). Any change in the density of the Cupula or surrounding will cause the jelly to float or sink in resonse to gravity.

Alchohol (ethanol) is lighter than water. During your night of revelry the ethanol that you drink quickly creeps into fluid within the balance canals. This causes a difference in the “weight” of the fluid relative to the cupula and causes the cupula to rise or sink relative to gravity. Over time (as you sleep) this process reverses. The ethanol leaves the fluid and creeps into the cupula. As you wake up the cupula is becoming lighter than it surrounding fluid due to the ethanol getting into it. When you roll over in bed the cupula starts to float up activating the nerve endings telling your brain that you are moving. All of a sudden your head is spinning.

Benign Paroxysmal Positional Vertigo is very similar but in reverse. In this disorder calcium particles get stuck within the semicircular canal disrupting the delicate balance of cupula and fluid. The same thing happens in this disorder as in a hangover, only in reverse. You roll over, the calcium pushes on the nerve endings causing a sensation of spinning.

Lyme disease is prevalent in the Capital Region. I recently saw several patients who came to me for dizziness and disequilibrium. As part of a routine work-up I send these patients for a Lyme titer. A Lyme titer looks for antibodies in the blood. These antibodies can mean that you have a current or past infection. The results can be positive, negative or equivocal, (which means borderline). An equivocal result should be repeated in two to four weeks to see if there is any change. Since antibodies to other infections may look similar to Lyme Disease antibodies a “false positive” result may occur.

Another test used is the Western Blot or Immunoblot. This test looks at the specific parts of the bacteria to which antibodies attach. This test is more specific and less affected by antibiotic treatment. These are also reported as positive, negative or equivocal. An equivocal result should be repeated in two to four weeks. This test is done along with the Lyme titer since to detect a “false positive” result from the titer.

I am not a Lyme / Infectious Disease specialist so I usually send my patients to one when they test positive. These patients I mentioned at the start of this post all had negative tests. One patient in particular went the extra mile and saw several specialists and was finally tested positive for the disease. He is now on long term intravenous therapy and is feeling much better.

Lyme has been called the great masquerader. The disease can manifest in many forms and symptoms. The classic finding is a “bulls-eye” rash that is centered on the tick bite mark. In my experience this finding seems to be not as common as published in the literature. I would not discount the diagnosis if there is no rash. There are several tests available and not all have the greatest sensitivity so I will be sending multiple Western Blott tests from now on.

Here is a link for a new documentary about Lyme Disease “Under Our Skin”
http://www.youtube.com/watch?v=sxWgS0XLVqw