Tympanometry screening is a test that is used to evaluate problems in the middle ear by measuring how your eardrum reacts to air pressure. It can help confirm the presence of fluid in the middle ear and whether that is causing an ear infection, eardrum perforation, Eustachian tube blockage or some other problem.
How Tympanometry Screening Works
To test for fluid in the middle ear, the doctor will insert a handheld probe into your ear. This device changes the air pressure inside the ear while producing a distinct tone. How your eardrum responds to the combination of pressure and sound will be measured and recorded on graphs to determine whether fluid has built up.
Normally, the eardrum moves freely in response to this type of stimuli. When movement does not occur as it should, this signals the presence of fluids and can help guide your physician in recommending an appropriate treatment solution.
In addition to ear infections and perforated eardrums, tympanometry screening can uncover a variety of other disorders including otosclerosis, cholesteatoma, impacted earwax, tympanic membrane scarring and tumors in the middle ear. You may experience a slight discomfort when the tip of the probe is inserted into the ear, but the test is otherwise pain free and harmless.
Tympanoplasty with Ossicular (Bone) Reconstruction
If the bones of hearing are eroded, then ossicular reconstruction (reconstruction of the bones of hearing) may be necessary at the time of tympanoplasty. In some cases, this can be determined before the surgery. In other cases, it only becomes obvious at the time that the ear is completely opened and examined under the microscope.
The ear surgeon must decide whether the bones of hearing can be reconstructed at the time of the reconstruction of the ear drum. In most cases, this is possible if the ear is dry and not infected. The most common bone erosion occurs at the tip of the incus (anvil). This bone normally connects to the stapes (stirrup bone) and the connection is normally only 1.5 mm (1/24th of an inch–lead pencil’s lead width) in thickness. With prior infections, the circulation to the bone can become obstructed. Infection can gradually wear away the connection to the point where the bone is no longer in contact with the stapes bone. This is called ossicular discontinuity, a break in the bony connection. One can think of the incus as the player arm of a phonograph and the stapes as the needle. If the player arm is not in contact with the needle, sound will not be transmitted with the same force as it would with a good connection.
Reconstruction of this type of ossicular discontinuity can be performed at the time of tympanoplasty surgery. There are several options. If the gap is small, it can be bridged by inserting a small piece of bone or cartilage taken from the patient at another site (behind the ear or from the lobe of tissue called the tragus in front of the ear). If there is a larger gap, then the incus bone is removed and modelled into a tooth-like prosthesis, using the operating microscope. This is then reinserted between the stapes and the malleus in order to reestablish continuity of the ossicular chain.
Other options include the insertion of a strut made out of an artificial bone, called hydroxy apatite. This artificial bone is porous and allows for the ingrowth of blood vessels and the complete assimilation of the artificial bone into the individual’s middle ear. With the modern day use of hydroxy apatite, there has been a marked reduction in the rejection of ossicular reconstruction prostheses.
Prior prosthetic devices were made out of porous plastics which had a much higher rejection rate.
In other less common ossicular reconstructions, the malleus (hammer) can become fixated by scar tissue or bony ingrowth to the lateral wall of the ear. In this “malleus fixation,” the bone must be separated from the canal wall and remodeled. Silastic or a plastic type of sheeting is often placed against the wall to prevent regrowth of new bone. Reconstruction in this instance often requires that the stapes and incus be separated from their connection to stop the transmission of the drill’s vibration which would damage the inner ear.
Call Mid-Valley ENT & Allergy at (541) 967-0404 for more information or to schedule an appointment.