EXTERNAL AUDITORY CANAL

The ear canal is hard to keep dry and gets picked. "Ordinarily the canal cleans itself", with cerumen and keratin flowing outward very slowly due to the movements of chewing. This really doesn't work very well, and the external canals can get dirty.

Cerumen impaction is common and annoying, interferes with hearing, "and can cause tinnitus and vertigo". Even if earwax is not impacted, adults try to remove it from their ears and those of their children. Q-tips pack cerumen, making it less likely to come out naturally and creating a good culture medium underneath. You will learn the right ways to clean ears on rotations.

External otitis is a generic term for inflammatory disorders (infections, contact dermatitis, seborrhea, etc., etc.) of the external auditory canal.

Remember that the external auditory canal is very sensitive. Patients present with itching and pain, and later with a discharge. (If you see nothing with your otoscope, check the throat too; mild inflammation around the eustachian tube will be felt in the ear.)

Infected hairs are usually due to staphylococcus and are very painful.

Swimmer's ear, extremely common, results from swelling of wet keratin (as in dish-pan hands) which plugs the outlets of the little hair follicles and invites infection. Pseudomonas organisms are the usual offenders; think of candida in very hot weather.

Fungal otitis (aspergillus, candida) and actinomycosis can produce chronic, itchy infections.

Contact dermatitis results from ear drops, hair sprays, atopic dermatitis, or picking. Seborrhea (oily, scaly skin) of the canal and auricle is of unknown etiology. Both of these problems are familiar from general dermatology.

Malignant external otitis is a pseudomonas infection that affects diabetics and spreads into the skull Am. Fam. Phys. 309: 2003.

Keratosis obliterans ("canal cholesteatoma") is a mysterious condition in which keratin keeps accumulating in the canal and plugging it.

During your career, you will see many interesting foreign bodies in ear canals. Insects get stuck in the cerumen and make a person miserable. Beans swell up due to fluid in the canal, and are especially hard to remove.

Traumatic perforation of the eardrum results from diving, water skiing, fights, and instrumentation. This presents a problem for otolaryngologists and attorneys.

Tumors of the external auditory canal are rare.

Exostoses (bony overgrowths) sometimes occur in children with other birth defects and the resulting hearing impairment does not help the child's development. (Check for this in "profoundly retarded Downs' syndrome kids"). Acquired exostoses are most famous for occurring in people who swim/surf in cold water; it's clearly true (Otolaryngology 126: 499, 2002) and that tells me they're hyperplasias rather than real neoplasms. The histopathology is successive laying-down of bone layers just under the periosteum (Laryngoscope 108: 195, 1998). Treating them: J. Laryng. Ot. 108: 106, 1994.

Adenomas of cerumen-producing cells or sweat glands occur rarely.

Remember that a tiny fracture of the skull can produce cerebrospinal fluid otorrhea. Think of this whenever there is a discharge "from the external ear canal".

*Older people's pinnas really are relatively bigger, nobody knows why (Br. Med. J. 311: 1668, 1995).

MIDDLE EAR

Most middle ear problems result from problems opening and closing the eustachian tube. Many factors -- big tonsils, upper respiratory infections, allergy, cleft palate, deviated septum, paralysis of part of the palate, or just being a small kid -- can interfere with proper function.

Aerotitis media is the familiar pain caused by barotrauma, as when one's ears fail to pop while changing altitude in an airplane. Recurrent episodes can lead to middle ear deafness.

Acute catarrhal otitis media means tissue fluid in the ear in the absence of obvious infection.

The etiology is often obscure; it may be "serous" (the fluid is supposedly a transudate) or "mucous" (the fluid is supposedly an exudate).

Many of these children require tonsillectomy-adenoidectomy and/or myringotomy with placement of tympanostomy drains ("tubes").

Chronic catarrhal otitis media ("glue ear") is a permanent case of mucous otitis media, which usually leads to deafness.

Failure of the eustachian tube to close results in hearing one's own respirations and voice in the ear.

Otitis media, infection of the middle ear, is common and troublesome. Update Lancet 363: 465, 2004.

Viral otitis media is the full feeling in the ear that often accompanies a viral "cold". It seldom requires treatment. (* By contrast, the rare "bullous myringitis", a brief viral infection of the eardrum, is very painful.)

Acute bacterial otitis media (the common earache) is a among the most common complaints for which people seek medical attention.

This is primarily a pediatric disease. Most patients have their first attack between 6 and 36 months of age.

Poor eustachian tube function prevents proper drainage from the ear, and when infections supervenes, the resulting inflammatory edema further interferes with drainage.

The usual agents are Streptococcus viridans and pneumoniae, Hemophilus influenzae, Staphylococcus epidermidis and aureus, and Branhamella (a troublesome, penicillin-resistant organism).

* Pneumococcal vaccine against otitis media: NEJM 344: 403, 2001.

Acute bacterial otitis media is very painful, and inflammation and bulging of the drum are obvious on examination. Response to antibiotics is generally good, but some patients may require myringotomy for immediate relief.

Of course, this does not correct the underlying eustachian tube dysfunction. Today, children get tympanostomy "tubes" inserted into their eardrums to provide drainage; these are removed after several years, when the eustachian tubes are working better.

* Unfashionable for decades, it's now clear that taking out the adenoid tonsils at the time of tube placement greatly helps prevent middle ear problems for children (NEJM 344: 1188, 2001). This is now standard if the tubes don't help.

The dreaded complications of acute otitis media -- rupture of the tympanic membrane, and spread to the cochlea, labyrinth, mastoids, meninges, and the brain -- are seldom seen today. However, endotoxin occasionally produces permanent hearing and/or labyrinthine damage (J. Laryng. Ot. 108: 310, 1994).

The rare acute necrotizing otitis media is usually due to beta-hemolytic streptococci and results in necrosis of the bones. / surfing

*News: Xylitol chewing gum, which is already very popular in Scandinavia and which is a powerful cavity-preventer (un-stickies the oral cavity) seems to prevent otitis media as well (Br. Med. J. 313: 1180, 1996, the famous case in which optional participation in a grammar school kids' science-project supposedly violated the participants' human rights).

Chronic suppurative otitis media is a longstanding, smoldering bacterial infection that can eventually destroy the middle ear.

Cholesteatoma is a fancy name for a mass of keratin (like an epidermoid cyst) in the middle ear. It can be congenital, acquired from perforation of the eardrum, or develop from chronic suppurative otitis media. This is a major surgical problem.

With all the dead keratin around to act as a foreign body, hopefully it will not surprise you to learn that bacterial biofilms form in cholesteatomas and prevent antibiotics from working (Arch. Oto. 128: 1129, 2002).

The major true tumor of the middle ear is the glomus jugular tumor, which forms in the "glomus jugulare", a miniature version of the carotid body. The tumor recapitulates the normal structure. Patients complain first of pulsatile tinnitus; hearing loss develops as the tumor slowly enlarges. Surgery is challenging.

* A fossil mammal from China shows the transition of the ear ossicles from their earlier role as reptilian jaw bones: Science 294: 357; 2001. For decades, the absence / "impossibility" of such a fossil was a major arguing-point for pseudoscientists.

OTOSCLEROSIS

In this very common disease, new bony and fibrous tissue forms in the ear.

Calcification and ossification of the annular ligament of the stapes prevents transmission of sound impulses at the oval window. Surgery, with insertion of a plastic stapes, helps some of these patients.

If new bone formation distorts the bony portion of the cochlea, sensorineural deafness results.

Otosclerosis is a major cause of acquired hearing loss, though fortunately it is seldom severe. It is also blamed for much of the tinnitus that trouble the elderly.

The cause of otosclerosis is unknown, though there is a familial tendency, and non-Caucasians are seldom affected.

COCHLEA AND AUDITORY NERVE

We seldom examine cochleas at autopsy, but there have been a few studies of congenital and acquired sensorineural deafness. In most cases, the cochlear hair cells are damaged or missing.

Viral infections, notably congenital rubella, congenital or acquired CMV, Lyme disease, post-natal mumps, and Lassa fever can cause permanent deafness.

Presbycusis, the sensorineural hearing impairment that comes with advancing age, involves degeneration and loss of high-frequency hair cells. Some families are much more severely affected than others. The same changes occur in young people exposed to very loud sounds (industrial noise, rock music).

High-power cochlear pathologists distinguish four types: sensory (abrupt loss of high tones), strial (loss of tones more uniformly), neural (loss of word discrimination), and cochlear conductive (the only type without anatomic pathology). This is deep stuff; read about it in Ann. Ot. Rhin. Lar. 102: 1, 1993.

Cerebellopontine angle tumors (schwannomas, meningiomas) are common, usually lie on the eighth nerve, and produce cranial nerve palsies.

Autoimmunity is implicated in cases of sudden "idiopathic" deafness, but the autoantibodies remain elusive (Acta Oto-Laryngol. 121: 28, 2001). Keep listening.

Cogan's syndrome, with sudden hearing loss and systemic vasculitis, is caused by an autoantibody against auditory epithelium and endothelium (Lancet 360: 915, 2002).

Also remember Paget's disease of bone can compress the auditory nerves. (Notice the size and shape of Beethoven's head -- it has been suggested that he went deaf from Paget's disease.)

Cochlear implants: Nature 352: 236, 1991; update Ped. Clin. N.A. 50: 341, 2003.

Tinnitus (i.e., "ringing" and other odd noises in the ear) is complicated: Mayo Clin. Proc. 66: 614, 1991.

* Tune deafness ("tin ear"; you have trouble picking up off-notes in familiar tunes played poorly) seems to be hereditary: Science 291: 1879 & 1969, 2001. Around 5% of folks are affected. The anti-instrumentalist movement in ultraconservative Christianity was founded by a tune-deaf evangelist.

MEMBRANOUS LABYRINTH AND VESTIBULAR NERVE

Deaf, giddy, odious to my friends,
Now all my consolation ends...

-- Jonathan Swift


Suffered from a chronic inner-ear infection

Several distinct diseases affect the balance system, but these seldom are examined by pathologists. Problems here cause vertigo, the distinct sensation of spinning.

Ménière's disease is a poorly-understood illness featuring attacks of vertigo with hearing loss. Treatment: Otol. Clin. N.A. 17(4): 761, 1984.

Vestibular neuronitis (the old "labyrinthitis") is viral involvement of "the labyrinth" (actually, its first connection in the brainstem). Usually this follows a more conventional viral illness (remember Lyme disease too). Patients can walk again in only a few weeks, and finally recover, often with minor residual damage. (* This is how I got my stagger.)

* Anti-herpes-1 treatment doesn't help, but methylprednisolone does: NEJM 351: 354, 2004.

Bárány's benign positional vertigo is a frightening condition that results (??) from an otolith breaking loose from the utricle. When the patient's head tilts into a certain position, the little rock settles on the sensor, triggering a spectacular attack. The diagnosis is easy and reassurance is all that is required (Mayo Clin. Proc. 66: 596, 1991).

* The various benign positional vertigos are now extensively subclassified and my prediction about the broken-off otolith is supported. See Neurol. 57: 1085, 2001. There are even manipulation-type techniques ("canalith repositioning procedures") for treatment: J. Laryngoo. 115: 727, 2001.

DEAFNESS AND HEARING IMPAIRMENT

One person in 500 is prevocationally deaf, and about half of us will have at least some hearing impairment as we grow older. (This is a major quality-of-life problem in the elderly. See Ann. Int. Med. 113: 188, 1990). Conduction deafness (i.e., disease of the external and middle ear) causes loss of hearing at all frequencies, and is best treated with a hearing aid. Sensorineural deafness (i.e., disease of the inner ear or auditory nerve) often (not always) interferes more with ability to hear higher frequencies, and sounds are greatly distorted. Mere amplification of sounds does not correct the defect, so the older hearing aids were less helpful. Central deafness, due to disease in the brain, is very rare, since the hearing pathways are so diffuse.

The most common known cause of congenital deafness in today's older adults is rubella, though more than half of cases are "idiopathic". Many genetic syndromes produce profound sensorineural deafness.

* There are at least 5 loci for nonsyndromic autosomal deafness, and the proteins made by a few are now known (Lancet 358: 1082, 2001). Progressive adult deafness from a mutation in a transcription factor: Science 279: 1950, 1998). Connexin (on the hair cells of the cochlea) mutations are extremely common in familial and sporadic congenital deafness: Lancet 351: 394, 1998; NEJM 339: 1585, 1998; Lancet 353: 1298, 1999; Lancet 358: 1082, 2001. This is especially common because deaf people tend to marry one another: Lancet 356: 500, 2000. DFNA10 mutations produce a progressive deafness beginning in childhood (Ann. Otol. 110: 861, 2001). Usher syndrome, the commonest cause of combined blindness-deafness, with nerve deafness and retinitis pigmentosa both, is caused at least in some case by defective myosin VII-A, which anchors to the actin cytoskeleton and moves things around inside cells: Nature 374: 60, 1995; physics and a bunch more Proc. Nat. Acad. Sci. 93: 3232, 1996. At least one Waardenburg locus, a dominant which imparts variable deafness, different-colored eyes, and a white forelock, has been cloned -- Nature 355: 635 & 637, 1992; Am. J. Hum. Genet. 52: 455, 1993, stay tuned for more, homologous to drosophila homeobox. The known deafness genes (by now dozens): Nat. Med. 4: 1245, 1998.

Severe deafness may be acquired from meningitis, trauma, or a variety of less common problems, including aminoglycoside antibiotics.

Until recently, ideologies dominated education of the deaf in our country. Most educators emphasized "teaching normal speech and lip-reading" in the education of deaf children, often forbidding the sign language that the deaf community actually uses to communicate. This was a terrible disservice. Even after years of practice, "reading lips" is very difficult. (The Ameslan sign for "lip-reading" is a combination of the signs for "mouth" and "impossible".) And attempts by the prelingually deaf to speak usually result in ridicule.

In some places, deaf children are still "mainstreamed" in regular classes for hearing children. Again, this is really mostly done for ideological reasons. Deaf kids in a Nicaraguan school where this is practiced actually are developing a sign language from scratch so they could communicate with each other (Science 293: 1758, 2001).

The hearing community has recently begun to notice and study the Ameslan (American Sign Language) that the deaf use (Science 247: 1127, 1989). It is fascinating, and is as demanding to learn as any other foreign language. The best interpreters are hearing children who grew up with one or two deaf parents. Do not confuse Ameslan with finger-spelling, in which the words of English are spelled out using hand positions. The Soviet Union taught all deaf and hearing children to finger-spell (the Russian alphabet, of course), in the hopes of making communication easier.

Many of the deaf like to consider theirs a separate culture, while in communities where there are more deaf than usual (old-time Martha's Vineyard, birthplace of American Sign Language, was one example), deafness has not been considered a handicap because "everybody speaks sign language". How physicians communicate with the deaf: JAMA 273: 227, 1995. Cochlear implants have enabled many deaf children to hear. If the child is to understand spoken language, you need to place the implant while the chid is very young, and talk to the child (Lancet 356: 466, 2000). It usually works pretty well, though not always, and not surprisingly, the data now confirms it improves the quality of life and is a money-saver (Ped. Clin. N.A. 50: 341, 2003). Probably because cochlear implants are available, most states have passed laws mandating hearing checks for newborns. Parents still have considerable choice (Arch. Ped. Adol. Med. 157: 162, 2003) and having some good data will make the choices easier.

Cochlear implantation for babies has been "extremely controversial" becuase of multiculturalism. The "politically correct" attitude was that minority-group identity was more important than a child's ability to enjoy music, learn to read and write, talk to most of the people he/she meets, use an ordinary telephone, or do most kinds of jobs. In the late 1990's the discussion became extremely heated and bitter. All about "deaf culture values" from the most vocal opponent of cochlear implants: Otolaryngology 119: 297, 1998. Proponents (Hastings Center Report 28(4): 6, 1998) points out that separate equally-valid culture or not, the deaf are the beneficiaries of expensive services (interpreters, special schools, special communications equipment) that the much-maligned mainstream society works very hard to provide. It seems to me that (right or wrong) legislatures will balk at expensive entitlements for disabled people who refuse to accept effective treatment -- or especially, who demand that their children remain disabled for life. Also a movie "The Sound and the Fury", 2001. Well, times changed. Now the vast majority of parents of kids with cochlear implants agree they wish their kid had gotten it earlier (Arch. Oto. 130: 673, 2004; good update from Gallaudet).

* SLICE OF LIFE REVIEW

{04577} internal auditory canal, normal
{13128} tympanic membrane, normal
{13168} stapes, normal and abnormal
{15077} cochlea, inner ear section
{15078} cochlea, inner ear section
{15079} cochlea, normal
{15079} cochlea, normal
{15080} cochlea, normal
{15081} organ of corti, normal
{15082} organ of corti, normal
{16288} cochlea, normal
{16289} cochlea, normal
{16292} cochlea, normal
{16293} cochlea, normal
{16301} vestibulocochlear nerve, normal
{16320} cochlea, normal
{16322} cochlea and semicircular canal, normal
{16338} cochlea, normal
{16339} cochlea, normal
{16340} cochlea, normal
{16341} cochlea, normal
{16350} cochlea, normal
{16360} oval window, normal
{16361} oval window, normal
{20714} cochlea, normal
{44877} tympanic membrane, normal

Drop by and meet Ed

Ed says, "This world would be a sorry place if people like me who call ourselves Christians didn't try to act as good as other good people ." Prayer Request

Teaching Pathology

PathMax -- Shawn E. Cowper MD's pathology education links
Ed's Autopsy Page
Notes for Good Lecturers
Small Group Teaching
Socratic Teaching
Preventing "F"'s
Classroom Control
"I Hate Histology!"
Ed's Physiology Challenge
Pathology Identification Keys ("Kansas City Field Guide to Pathology")
Ed's Basic Science Trivia Quiz -- have a chuckle!
Rudolf Virchow on Pathology Education -- humor
Curriculum Position Paper -- humor
The Pathology Blues
Ed's Pathology Review for USMLE I
Part I
Part II