Ear surgery

Anatomy or system affected: Bones, ears, musculoskeletal system, nervous system

Definition: An invasive procedure to correct structural problems of the ear that produce some degree of hearing loss.

Indications and Procedures

Humans are able to detect sound because of the interaction between the ears and the brain. When sound waves strike the tympanic membrane (eardrum), it vibrates. The movement of the tympanic membrane then causes the movement of the ossicles, the three tiny bones within the middle ear (malleus, incus, and stapes). These moving bones transfer the vibrations to the cochlea of the inner ear, which stimulates the auditory nerve and, eventually, the brain.

Hearing problems may result when any part of the ear is damaged. Hearing difficulties can be categorized into two main areas: conductive and sensorineural hearing loss. In conductive hearing loss, the ear loses its ability to transmit sound from the external ear to the cochlea. Common causes include earwax buildup in the outer ear canal; otosclerosis, in which the stapes loses mobility and cannot stimulate the cochlea effectively; and otitis media, in which the middle ear becomes infected, and a sticky fluid is produced, which causes the ossicles to become inflexible. Otitis media is the most common cause of conductive hearing loss and typically occurs in children. If antibiotics such as amoxicillin or ampicillin fail to clear the ear of infection, surgery may be required. Sensorineural hearing loss results from damage to the cochlea or auditory nerve. Common causes include loud noises, rubella (a type of viral infection) during embryonic development, and certain drugs such as gentamicin and streptomycin. Occasionally, a tumor (neuroma) of the auditory nerve may cause sensorineural hearing loss.

Myringotomy is a surgical procedure in which an incision is made in the tympanic membrane to allow drainage of fluid (effusion) from the middle ear to the external ear canal. The surgeon usually performs this operation to treat recurrent otitis media, a condition in which pressure builds in the middle ear and pushes outward on the tympanic membrane. The patient, usually a child, is given general anesthesia. An incision is made in the eardrum so that a small tube can be inserted to allow continuous drainage of the pus. The tube usually falls out in a few months, and the tympanic membrane heals rapidly.

Otosclerosis, the overgrowth of bone that impedes the movement of the stapes, can be treated by stapedectomy (surgical removal of the stapes). General anesthesia is used to prevent pain or movement when an incision is made in the ear canal, and the tympanic membrane is folded to access the ossicles. The stapes can then be removed, and a metal or plastic prosthesis inserted in its place. The eardrum is then repaired.

Tympanoplasty is an operation to repair the tympanic membrane or ossicles. Sudden pressure changes in an airplane or during deep-sea diving may perforate the tympanic membrane (barotrauma) and require tympanoplasty. The procedure is similar to stapedectomy. With the patient under general anesthesia, an incision is made next to the eardrum to provide access to the tympanic membrane and ossicles. The tympanic membrane may need to be repaired if the perforated eardrum does not heal on its own. An operating microscope is employed for optimal visualization of the middle ear. If the tympanoplasty involves the ossicles, microsurgical instruments are used to reposition, repair, or replace the damaged bones. They are then reset in their natural positions, and the eardrum is repaired.

Auditory neuromas are benign tumors of the supporting cells surrounding the auditory nerve. Although rare, these tumors can cause deafness. Once neuromas are confirmed by computed tomography (CT) scanning, surgical removal is necessary. With the patient under general anesthesia, the surgeon must make a hole in the skull and attempt to remove the tumor carefully without damaging the auditory nerve or adjacent nerves.

Uses and Complications

More than 90 percent of the patients undergoing stapedectomy experience improved hearing. Approximately 1 percent, however, show deterioration of hearing or total hearing loss postoperatively. For this reason, most surgeons perform stapedectomy on one ear at a time.

Occasionally, the surgical removal of auditory neuromas causes total deafness because of damage to the auditory nerve itself. In rare cases, damage to nearby nerves may cause weakness and/or numbness in that part of the face. Depending on the extent of nerve damage, the symptoms may or may not lessen with time.

Perspective and Prospects

Improvements in technology promise new methods of treating hearing loss. For example, cochlear implants have been developed for the treatment of total sensorineural hearing loss. These implants are surgically inserted into the inner ear. Electrodes in the cochlea receive sound signals transmitted to them from a miniature receiver implanted behind the skin of the ear. Directly over the implant, the patient wears an external transmitter that is connected to a sound processor and microphone. As the microphone picks up sound, the sound is eventually conducted to the electrodes within the cochlea. In the twenty-first century, technology continued to offer new solutions to hearing loss that transcended traditional ear surgery. Gene therapy used in the experimental trials of the reproduction of hair cells and stem cell research both promised new treatments for hearing loss. Though gene therapy remained pending in clinical trials, inner ear cell therapy that hoped to recover sensorineural hearing loss, specifically hearing loss caused by damage to the auditory nerves in the cochlea became a reality through the use of embryonic stem cells.

Bibliography

Brunicardi, F. Charles, et al., eds. Schwartz’s Principles of Surgery. 9th ed. New York: McGraw-Hill, 2010.

Ferrari, Mario. PDxMD Ear, Nose, and Throat Disorders. Philadelphia: PDxMD, 2003.

Jaslow, Ryan. “Scientists Regenerate Hair Cells that Enable Hearing.” Harvard Medical School, 19 Apr. 2023, hms.harvard.edu/news/scientists-regenerate-hair-cells-enable-hearing. Accessed 30 July 2023.

Kassir, Kari. "Myringotomy." Health Library, Sept. 10, 2012.

Leikin, Jerrold B., and Martin S. Lipsky, eds. American Medical Association Complete Medical Encyclopedia. New York: Random House Reference, 2003.

Nadol, Joseph B., Jr., and Michael J. McKenna. Surgery of the Ear and Temporal Bone. 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 2005.

O'Reilly, Robert C. "Middle Ear Infections and Ear Tube Surgery." KidsHealth. Nemours Foundation, Oct. 2011.

Pender, Daniel J. Practical Otology. Philadelphia: J. B. Lippincott, 1992.

Peter, Roohi Mariam. “Stem Cell therapy: a Potential Cure for Hearing Loss?” Labiotech.eu, 28 Mar. 2023, www.labiotech.eu/in-depth/stem-cell-therapy-hearing-disorders. Accessed 30 July 2023.

Schwartz, Seth, and David Zieve. "Ear Tube Insertion." MedlinePlus, July 30, 2012.

Tierney, Lawrence M., Stephen J. McPhee, and Maxine A. Papadakis, eds. Current Medical Diagnosis and Treatment 2007. New York: McGraw-Hill Medical, 2006