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To educate folks about otitis media and
eustachian tube dysfunction, I typically employ a variety of crude drawings to
illustrate the concept. This is helpful for
patients or parents of children suffering from OM, but also goes a long way to
educate med students and residents.
Otitis media is a common infection of the
middle ear (ME) seen by both ENTs and primary care providers alike, and
particularly those treating children. This
also occurs in adults, though to a lesser extent.
OM is a disease of the middle ear and
eardrum (tympanic membrane, abbreviated TM). OM is different than other types of ear infections, which is important to know for
proper treatment.
Following is a recap or summary that I use to teach both patients and residents about the pathophysiology (how disease alters the body’s normal function) of otitis media and how it develops from a problem with the eustachian tube (ET). I found that I often had to open more than one screen to show the various stages, so I recapped it all on one page. Here it is in a super-concise nutshell.
Super-short
explanation of otitis media pathophysiology
1. You get a cold, URI (upper respiratory
infection, which includes colds), or you’re on an or travelling up and down through varying altitudes.
2. Eustachian tube (ET) closes shut due
to tissue swelling from your illness, or collapsed from atmospheric pressure
changes, or a combination of both. The
ET stays closed rather than opening and closing as it naturally does. The ET travels from the ME to the back of the
nose (nasopharynx). The ET does
not go down your neck, so rubbing the neck won’t do a thing.
3. Negative pressure in ME: air is absorbed by
the mucosa that lines the ME, causing negative pressure, or a vacuum effect. This can cause the TM to retract inwards.
4. Fluid traps n ME. The negative pressure (the “vacuum” effect)
in the ME pulls fluid from the mucosa lining the ME. Without an open ET, the fluid is trapped in
the ME.
5. Bacteria normally found in the ME multiply
like crazy in the fluid. The fluid acts
as a nice culture broth, great for bacteria reproduction.
6. Ear infection of the otitis media type. Bacteria in fluid forms pus. The ME mucosa and the TM become inflamed, red, swollen. The TM may bulge out due to pus under pressure, causing pain, hearing loss, fevers. Sometimes the TM ruptures and pus drains out.
Super-Sized
Explanation
OK, that ultrashort nutshell may be too
concise, even for med students and residents (who ought to know more of the details
anyway). For those hankering for more
misery, well, this is your lucky day.
Here’s a more complete picture, or as they say in the movies, The
Director’s Cut:
First of all, below is a simple diagram of the middle ear and a normally functioning eustachian tube. At the top is a barometer inserted into the middle ear. Take note this is only a graphical representation, you really can’t insert a device straight into the middle ear as pictured without killing the patient. So don’t go trying this at home (you’d need to go in from the brain above to do this anyway). Though it looks like a cooking thermometer sticking out of a turkey, it measures pressure inside the ME, relative to outside (or atmospheric) pressure outside the ear.
The following is a not-normally-functioning ET:
If the ET still acts like a rash, undisciplined child, and refuses to do its normal stick and re-open, then fluid gets sucked into the ME and OM occurs:
Treatment
Treatment with antibiotics to kill the bugs (bacteria), pain meds (Tylenol or ibuprofen), often helps. ET often recovers and opens back up. But if not, chronic OM with fluid persists. Avoid decongestants or antihistamines—they are ineffective for OM, and prior studies1 have demonstrated this and should be avoided, especially in kids.
One form of immediate treatment is the Toynbee Maneuver (note, this is not a Valsalva. A Valsalva is what you do to increase abdominal pressure, for instance, with a stubborn bowel movement when constipated).
The last tx is the tried-and-true myringotomy and ear tube:
OM occurs mainly in kids, since their ETs
easily close for longer time periods and don’t mature until after 4 years of
age. In adults, it’s another story. If OM persists and they need a tube, we often
must check the nasopharynx first, usually with a fiberoptic scope, to find any source of mechanical
blockage such as a tumor. Naturally, if
a tumor is found, this radically changes therapy.
That’s all folks, the pathophysiology in a nutshell, a big one at that, coconut size.
Reference
1. Griffin G, Flynn CA. Antihistamines and/or
decongestants for otitis media with effusion (OME) in children. Cochrane
Database Syst Rev. 2011 Sep 7;2011(9):CD003423. doi:
10.1002/14651858.CD003423.pub3. PMID: 21901683; PMCID: PMC7170417.
©Randall
S. Fong, M.D.
For more topics on
medicine, health and the weirdness of life in general, check out the rest of
the blog site at randallfong.blogspot.com
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