Specializing in Diseases of the Ear, Nose, & Throat
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Can Surgery Improve Your Patient’s Hearing Loss?
By Bryan K. Wilcox, MD
A cholesteatoma, or more correctly “keratin cyst,” is a benign destructive skin cyst arising from the tympanic membrane as a result of longstanding eustachian tube dysfunction. One of the most personally gratifying aspects of otolaryngology is helping people hear well again. Although most hearing loss is sensorineural and can be improved only with hearing aids, many people have hearing loss that can be improved by surgery.
As a brief review, there are three types of hearing loss: sensorineural, conductive, and mixed. Sensorineural hearing loss is caused by malfunction of the cochlea or cochlear nerve, most commonly from presbycusis and noise trauma. Conductive hearing loss is caused by decreased sound conduction from the external auditory canal to the cochlea, manifest on audiometry as a disparity between air conduction and bone conduction thresholds, termed an air-bone gap. When both types are present we call it mixed hearing loss. In general conductive losses are amenable to surgery. A long list of problems can cause conductive hearing loss, ranging from the common cerumen impaction or middle ear effusion to the rarer glomus tympanicum tumor in the middle ear. The most common surgically correctable causes are tympanic membrane perforation, ossicular discontinuity, cholesteatoma and otosclerosis.
Tympanic membrane perforations arise most commonly from suppurative otitis media with rupture, trauma, or persist after extrusion of pressure equalizing tubes. The vast majority of infectious or traumatic perforations will heal spontaneously within a few days or weeks, as long as the perforation is less than half of the TM surface. A period of watchful waiting is indicated, perhaps with ototopical antibiotic therapy if from suppurative OM or if the traumatic injury appears contaminated. Evaluation of traumatic perforations by an otolaryngologist is recommended in particular due to the possibility of ossicular chain disruption at the time of injury, which may require ossiculoplasty even if the drum closes spontaneously. Any perforation that persists longer than 3 months will likely not close and will require intervention. The maximal conductive loss from perforation alone is 25-30 dB, and often is milder. Successful tympanoplasty typically eliminates the conductive loss.
A cholesteatoma, or more correctly “keratin cyst,” is a benign destructive skin cyst arising from the tympanic membrane as a result of longstanding eustachian tube dysfunction.
Physiologically when the eustachian tube fails to open and equalize middle ear pressure, chronic negative pressure pulls back on the drum, and over time forms a retraction pocket (Figure 1), usually in the posterosuperior quadrant known as the pars flaccida. As epithelium sheds within this pocket, an inclusion cyst forms and progressively grows, potentially eroding the ossicles, the otic capsule, and possibly even into the intracranial cavity. Symptoms of a cholesteatoma are typically hearing loss, chronic purulent otorrhea, and otalgia. Complications of advanced disease include facial paralysis, vertigo, anacusis, and with intracranial extension meningitis, septic thrombophlebitis of the sigmoid sinus or brain abscess. 
Surgical treatment, called tympanoplasty and mastoidectomy, involves removing the cholesteatoma from the middle ear and/or mastoid, reconstructing the tympanic membrane, and possibly the ossicles if they have been eroded. Ossicular chain reconstruction, called ossiculoplasty, is usually done using titanium or other synthetic prostheses, which either reconnect bone-to-bone or bone-to-tympanic membrane depending on the location of discontinuity (Figures 2 & 3).
Ossicular discontinuity may also arise independent of cholesteatoma from temporal bone fractures, transcanal impalement injury or chronic tympanic membrane retraction.
Otosclerosis is the most common cause of conductive hearing loss between the ages of 15 and 50, is twice as common in women as men, and 50% of patients have affected family members. Otosclerosis is a disease of abnormal bone metabolism limited to the otic capsule. Otosclerosis causes fixation of the stapes footplate to the surrounding oval window, impeding sound wave conduction. Stapedectomy, in which the stapes footplate is totally or partially removed, has largely been replaced by stapedotomy, in which a small fenestration is made in the footplate, resulting in less post-op vertigo and reduced incidence of post-op anacusis (< 1% incidence). In stapedotomy the stapes superstructure is removed and a 0.7 mm hole is made in Figure 2 Figure 3 the footplate using an argon laser, minimizing trauma to the delicate vestibular saccule below. Through this hole a 0.6 mm stapes piston prosthesis is inserted and crimped to the long process of the incus, thus restoring the transmission of sound waves to the cochlea (Figures 4 & 5). In over 90% of stapedotomies the air-bone gap is closed to less than 10 dB, often with “over closure,” or better post-op air conduction than pre-op bone conduction on audiometry. The typical result is an overjoyed patient.
Lastly, as opposed to the above treatments for conductive hearing losses, cochlear implants restore hearing to people with severe to profound sensorineural hearing loss who do not achieve benefit from hearing aids. Cochlear implants have an internal processor connected to a coil of electrodes which are surgically implanted directly into the cochlea. An external processor processes sound into a digital signal, sends it to the internal implant which converts the digital signal to an electrical signal, and sends it to the coil within the cochlea, thus directly stimulating the cochlear nerve and producing sound perception (Figure 6). This is the device that restored hearing to Rush Limbaugh. 
Cochlear implantation can be performed in patients ranging from adults down to children as young as 1 year of age. Candidacy criteria for cochlear implantation include severe to profound bilateral sensorineural hearing loss, with little or no benefit from appropriately fitted hearing aids, defined by several quantitative audiometric tests. This exciting technology has provided hearing to children who have never heard before, and restored hearing to adults who thought they might never hear again.
If you suspect your patient has hearing loss, please have them evaluated to see if surgery can restore hearing to their life.