Do you have hearing loss? If so, you may be wondering how your hearing can be improved. For many, hearing aids are the recommended therapy for hearing loss, but many people have hearing loss that can be improved by surgery.
There are generally two types of hearing loss: sensorineural and conductive. When both types are present we call it mixed hearing loss. Sensorineural hearing loss is caused by a problem with either the cochlea (the organ of hearing in the inner ear) or the cochlear nerve, which transmits sound signals from the cochlea to the brain. This is the most common type of loss, often associated with aging, and most cases are compensated well by hearing aids. Conductive hearing loss is caused by a problem with sound waves getting from the air around us to the cochlea. A sound wave travels through the ear canal, eardrum, and middle ear bones before going to the cochlea. Any problem along that pathway will dampen the sound wave and cause hearing loss. A long list of problems can cause conductive hearing loss, ranging from earwax impaction in the ear canal to a tumor behind the eardrum. Two common problems that I will discuss specifically are cholesteatoma and otosclerosis.
A Cholesteatoma is a benign destructive skin cyst arising from the eardrum as a result of longstanding eustachian tube dysfunction.
When the eustachian tube fails to open and equalize pressure behind the eardrum, a vacuum effect sucks back on the eardrum and over time forms a retraction pocket (Figure 1).
As skin cells shed from the outer layer of the eardrum within this pocket, a cyst forms and progressively grows, potentially eroding the ear bones and possibly even eroding into the intracranial cavity. Symptoms of a cholesteatoma are typically hearing loss, purulent drainage from the ear canal, pain and, when advanced, facial paralysis and possibly meningitis or brain abscess. Surgical treatment, called tympanoplasty and mastoidectomy, involves removing the cyst from the ear and rebuilding the eardrum and possibly the hearing bones if they have been eroded. Rebuilding the hearing bones, called ossiculoplasty, is usually done using tiny artificial prostheses often made of titanium or artificial bone that reconnect the eroded bones to the eardrum (Figure 2). The most common cause of conductive hearing loss between the ages of 15 and 50, otosclerosis is twice as common in women than men and 50% of patients have affected family members. Otosclerosis is a disease of abnormal bone metabolism limited to the inner ear bone. Normally the stapes (stirrup bone) moves in and out of the inner ear bone like a piston, transmitting sound waves to the cochlea. Otosclerosis causes fixation or fusion of the stapes to the surrounding bone preventing sound wave transmission despite preserved mobility of the malleus and incus bones. Stapedotomy is a surgical procedure in which the stapes is separated from the incus, and a laser is used to remove the upper arch of the stapes bone. A 0.6 mm hole (stapedotomy) is made in the footplate of the stapes with a laser, minimizing trauma to the delicate inner ear structures beneath. Through this hole an artificial prosthesis called a stapes piston is inserted and connected to the incus, thus restoring the transmission of sound waves to the cochlea (Figure 3).
Lastly, as opposed to the above treatments for conductive hearing loss, cochlear implants restore hearing to people with severe to profound sensorineural hearing loss who do not achieve benefit from hearing aids. Cochlear implants are devices that have an external processor connected to a coil of electrodes (Figure 4), which are surgically implanted directly into the cochlea. The external processor converts sound waves into electrical impulses and sends them to the coil within the cochlea, thus directly stimulating the cochlear nerve and producing sound (Figure 5). 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 deafness 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 have hearing loss, please receive an evaluation by an otolaryngologist and audiologist to see if surgery can restore hearing to your life.