Basic Anatomy and Evaluation
The ear is a remarkably complex structure that performs the dynamic functions of hearing and balance. Anatomically, it can be divided into three parts: outer, middle and inner ear.

Outer Ear
The outer ear is comprised of the “auricle” (the part that we see attached to the side of our head) and the ear canal. The outer ear’s purpose is for sound localization and to collect and direct sound waves to the eardrum, called the tympanic membrane, as part of the initial stage of sound processing/hearing.

Middle Ear
The middle ear is an air-containing space found behind the eardrum. The main function of the middle ear is to transmit and amplify sound waves from the eardrum through the three bones of hearing, called ossicles, to the inner ear, thereby converting sound waves to a nerve-impulse that can be transmitted to the brain for further processing.

To prevent the eardrum from rupturing due to differences in pressure between the middle and outer ear – for example, during scuba diving or air travel – the middle ear connects with the back of the throat through a channel called the Eustachian Tube.

Inner Ear
The inner ear has two functions: hearing and balance. First, as indicated above, the inner ear converts the mechanical energy of sound waves transmitted through the outer and middle ear into nerve impulses that are forwarded to the brain for auditory processing; this conversion of energy occurs in a snail-shaped chamber of the inner ear called the cochlea.

Second, the inner ear (along with our eyes and nerve receptors in our feet) enables our body to sense motion and balance. This is accomplished via three semi-circular canals which, like the cochlea, transmit nerve impulses to the brain. The nerve that transmits these impulses from both the cochlea (hearing) and semicircular canals (balance) is called the auditory nerve which enters the cranial cavity (the space occupied by the brain) via the internal auditory canal.

Hearing and Evaluation
With respect to hearing, most humans hear sounds in the range of 20 to 20,000 hertz with sounds in the middle frequencies being heard easiest. To understand further, a dog whistle is typically in the range of 16,000 to 22,000 hertz. Sounds below 20 hertz can often be felt although they may not be heard.

Evaluation of both of the ear’s functions of hearing and balance is performed by an Audiologist. In order to evaluate the organ of hearing, a hearing test, or Audiogram, is performed in a sound-proof booth by an Audiologist, hopefully with a cooperative patient. The standard testing includes Pure Tone Audiometry, Speech Audiometry and Immittance Audiometry.

Some additional tests that are useful for documenting hearing in uncooperative (e.g. infants and young children) or unresponsive (e.g. comatose) patients include Oto-Acoustic Emissions, Evoked Auditory Brainstem Responses and Electrocochleography.

With respect to balance, an Audiologist is able to assess disorders with an Electronystagmogram and Platform Posturography test.

Finally, the anatomy of the middle and inner ear and its relationship to the brain can be visualized with the assistance of x-rays, specifically CT and MRI scans, which provide detailed imagery of these hidden-from-view auditory mechanics.

Common Problems of the Outer, Inner and Middle Ear
In addition to simply looking at the outer ear, most doctors need a hand-held illuminated device called an “otoscope” to examine the ear canal and eardrum. Ear Specialists called Otolaryngologists will often use a special microscope to examine the ear. Complete evaluation of the ear includes assessment of hearing, balance and facial nerve function.

Outer Ear
Swimmer’s Ear [“Otitis Externa”]
This is an infection of the ear canal and patients may experience itchiness, foul-smelling drainage, throbbing pain and hearing loss. Swimmer’s Ear usually is caused by a combination of water exposure and abrasion of the ear canal (typically due to using cotton swabs).

Treatment typically requires antibiotic ear drops but may include referral to an Otolaryngologist for microscopic cleansing.

Eczema
This is an inflammatory condition of the ear canal and patients may experience itching, scaling, fissuring, crusting and secondary bacterial infections. Predisposing factors include skin conditions such as seborrheic dermatitis, atopic dermatitis, psoriasis and others.

Preferred treatment for this disorder is with steroid lotions and creams.

Middle Ear
Middle Ear Infection [“Acute Otitis Media”]
This is an infection of the middle ear that commonly occurs in young children, six months to 5 years, although it occasionally does occur in adults. This infection is associated with pain, irritability and, occasionally, foul-smelling drainage from the ear.

Treatment is with antibiotics and, occasionally, ear drops. When the patient has frequent infections, temporary tubes may be surgically inserted in the eardrum by an Otolaryngologist to decrease the infections.

Hole in the eardrum or Tympanic Membrane Perforation
This most commonly occurs due to ear infection or trauma (most commonly a cotton swab injury). Patients may experience pain, drainage and decreased hearing. The patient should be evaluated immediately by a medical professional and sometimes is referred to an Otolaryngologist for treatment.

Most perforations heal spontaneously and do not require any surgical repair.

Inner Ear
Some diseases of the inner ear include hearing loss, ringing (or Tinnitus), dizziness (or Vertigo) and facial paralysis. The causes for these problems are numerous and complicated. If you suspect you have any of the listed inner ear problems, seek immediate medical attention for evaluation.

Dr. David J. Malis is Brevard’s only fellowship-trained, board-certified Pediatric Otolaryngologist and is an active member of the American College of Surgeons (ACS), American Academy of Pediatrics (AAP), American Society of Pediatric Otolaryngology (ASPO), Society for Ear, Nose, Throat Advances in Children (SENTAC) and American Academy of Otolaryngology - Head & Neck Surgery (AAOHNS). Dr. Malis’ practice is located in Melbourne. For more information, visit online at www.MyKidsENT.com.