Tympanomastoidectomy
		The ability to hear sound relies on the ear's ability to "feel" sound vibrations in the air and to change this mechanical vibration to nerve impulses. Vibration of air that is heard as sound travels down the outer ear and vibrates the eardrum. The vibration of the eardrum is transmitted through the middle ear by movement of the 3 bones of hearing. The 3 bones, malleus, incus and stapes, are called the ossicular chain. The stapes sits on a "window" to the inner ear. Movement of the stapes creates vibration of fluid in the inner ear. The vibration of the fluid creates movement of "hair cells" of the inner ear. The hair cells then generate an electrical signal that travels up the auditory nerve to the brain. The eardrum and bones of the middle ear must be able to move freely for the vibrations of sound waves to be transmitted to the fluid of the inner ear. Ear pressure on both sides of the eardrum needs to be equal for the eardrum and ear bones to move efficiently. The middle ear space exchanges air through the eustachian tube to equalize the air pressure relative to the outside air pressure. The eustachian tube is a muscular tube which connects the middle ear space to an opening behind the back of the nose. Movement of air through the eustachian tube allows equalization of air pressure behind the eardrum. Dysfunction of the eustachian tube can result in loss of air pressure exchange. The air in the middle ear space is absorbed by the body. Unless the middle ear space can exchange air, a negative middle ear pressure or partial vacuum of the middle ear space develops compared to the outside air. A lifelong history of eustachian tube dysfunction can result in a gradual collapse of the eardrum into the middle ear space. Collapse of the eardrum may create a deep pocket trapping the skin of the outer surface of the eardrum deep into the middle ear space. The skin of the outer surface of the eardrum needs to flake just like skin does in other parts of the body. This flaking is normally carried out of the ear canal with wax produced in the ear canal. If the collapse of the eardrum creates a deep pocket into the middle ear space, the skin is no longer able to migrate. The collection of skin flakes creates a cyst or cholesteatoma. When the cholesteatoma grows and pushes against the bony walls and structures of the middle ear space, the bone will give way, creating a larger and larger cyst pocket. The cyst may also cause repeated ear infections and drainage. This type of cholesteatoma is called an "Acquired" cholesteatoma that can develop over a lifetime of chronic ear problems. In a more unusual case, "Congenital" cholesteatoma can develop in infants because of skin pockets that are left behind in the middle ear space during fetal development. "Congenital" cholesteatomas develop behind a normal eardrum. "Acquired" cholesteatomas result from the lifelong history of chronic ear infection. "Acquired" cholesteatomas are typically associated with a hole or pocket in the eardrum. The gradual expansion of the cyst and repeated ear infections can lead to destruction of the bones of the middle ear resulting in hearing loss. Cholesteatoma will frequently grow into the opening of the mastoid, which is a cave-like air space in the bone of the skull that communicates with the middle ear. Treatment of cholesteatoma requires complete surgical removal of the sac of the cholesteatoma. Extremely small cholesteatomas might be able to be removed through the eardrum by doing a "Tympanoplasty". Many cholesteatomas also involve the mastoid, requiring surgical removal from the mastoid, called a "Mastoidectomy". These approaches are typically combined in a tympanomastoidectomy. If the bones of the middle ear space are involved with cholesteatoma, this may require removal and repair of the bones of the middle ear space. The bones of the middle ear space create the ossicular chain. Repair of the ossicular chain is called "ossiculoplasty". Tympanomastoidectomies are typically done under general anesthesia as an outpatient procedure at the hospital or surgery center. The mastoid portion requires an incision behind the ear to "drill out" the honeycombed bone of the mastoid. The "tympano" portion refers to removal of cholesteatoma from under the eardrum. Under microscopic visualization, the sac of the cholesteatoma is meticulously elevated from the nooks and crannies of the middle ear space and mastoid cavity. If the bones of the ossicular chain have been eroded by cholesteatoma or require removal because of involvement with cholesteatoma, the bones of the middle ear space may be able to be repaired. Sometimes the natural bones can be reshaped and replaced to reconstruct the ossicular chain or, in other cases, artificial pieces are used to reconstruct the ossicular chain. The facial nerve and Chorda Tympani nerve course through the middle ear and mastoid cavity. The facial nerve goes to the muscle of the face. The Chorda Tympani nerve gives a sensation of taste to the anterior part of the tongue. Surgery on the middle ear and mastoid require working around these nerves. The facial nerve is typically well protected in a bony canal, however, this bone covering may be absent or may have been eroded by the cholesteatoma or the bone cover may be removed in surgery making the facial nerve vulnerable. Ear surgeries are designed to avoid injury to these nerves. A facial monitor might be used during the surgery to provide warning of impending injury to the facial nerve. The Chorda Tympani nerve runs without a bony covering over the top of the ossicular chain in the middle ear space. This nerve is vulnerable to drying or direct injury during ear surgery. After surgery, patients may experience a metallic taste in the mouth due to injury to the nerve. The tongue is also supplied with sensation of taste by other nerves which are not at risk during surgery. The sensation of alteration of taste typically resolves within three months if there has been injury to the Chorda Tympani nerve. Other potential problems of ear surgery include possible persistence or increase of hearing loss if a successful ossicular chain reconstruction cannot be accomplished. If the bone has already been destroyed by cholesteatoma, however, reconstruction of the ossicular chain may result in better hearing after surgery. If hearing loss persists after surgery, hearing may still be improved by revision surgeries. Despite meticulous surgery, tiny portions of the cholesteatoma sac may be left behind, allowing for recurrence of the cholesteatoma. The ear needs to be followed closely for several years following the surgery. A "second look" procedure to evaluate for recurrent cholesteatoma may be advised within several months of the original procedure. This can allow finding a recurrence of cholesteatoma when it is in a small stage, allowing for easier removal. Following ear surgery, fluid and blood will fill the middle ear space causing a temporary hearing loss, which may last four to six weeks. As the fluid and old blood are absorbed from the ear, the hearing will improve. A postoperative hearing test will frequently be done six weeks after surgery. Back to top
		Kenneth G. Condon M.D. N4 W22370 Bluemound Road Ste. 202 Waukesha, Wisconsin 53186 Phone: (262) 521-1954