A little background on hearing:
Cholesteatoma is frequently associated with hearing loss. Normal hearing is considered to be 0 to 20 dB across frequencies, so in medical articles the level of hearing loss may be characterized as >30 dB, or >45 dB etc. Also, there are two types of hearing loss, sensorineuronal and conductive hearing loss. Sensorineuronal hearing loss is when nerves and inner ear structures such as the cochlea are implicated; sound is able to travel along the ossicles (hearing bones) to the nerves but is not processed correctly. These types of losses are rarely associated with cholesteatoma.
Conductive hearing loss refers to the inability of sound to travel along the bones to the inner ear structures, and is common when anything dampens the path along the bones which should normally be surrounded by air. Conductive hearing loss can occur due to situations like fluid in the ear, an ear infection, glue ear, bone deformities, and cholesteatoma. Conductive hearing loss is typically what is being assessed when a child has a hearing test prior or subsequent to a myringotomy or ear tube surgery, for example. Conductive hearing loss is linked to cholesteatoma both prior to surgery, because the growth can surround and erode the bones, as well as after surgery if the surgeon has removed parts of the hearing bone chain. It is fairly common for one of the first signs of a congenital cholesteatoma to be a hearing loss detected in early education screening programs, at which point a pediatrician or otolaryngologist may visually identify the cholesteatoma. Acquired cholesteatomas are usually found because of discharge from the ear, a related ear infection, or hearing loss.
Although congenital cholesteatomas in both ears are possible (bilateral), this is very rare. Because congenital cholesteatoma is essentially a developmental fluke, it usually only affects one ear (unilateral), and the related hearing loss also is in one ear. Nonetheless, single-sided hearing loss can still be a challenge, especially for a young child in school. If hearing impairment is total in one ear, this is called single sided deafness (SSD).
Acquired cholesteatomas may more commonly occur on both sides, leading to hearing loss in both ears.
As a final background point, it is important to understand that the primary objectives of initial surgery are cholesteatoma removal. Hearing considerations factor in, but are a longer term goal only after it is the surgeon is certain the cholesteatoma has been eradicated. As such, it is possible some kids with cholesteatoma will be temporarily or permanently hearing impaired in the affected ear(s).
How is hearing assessed?
Hearing tests are done by audiologists, people who have a Master’s or PhD in Audiology (soon all audiologists will be required to have a PhD). Audiologists assess hearing in patients of all ages, as well as assess balance issues. Audiologists are also able to help patients identify the right types of hearing aids and ensure hearing aids are functioning properly.
In a very young child (toddler age), hearing tests often cannot appropriately identify hearing issues by individual ear. The typical way of doing this requires tones/noises in each ear to which the patient responds. Small children do not usually tolerate the ear wires/inserts that must be worn to get information about each ear. Instead, these tests will be administered with sound coming out of a speaker. Often there is some sort of toy or light that reacts when the child should hear the sound. I cannot appreciate all the nuances an audiologist is looking for, but in general it is to see if the child reacts to the sound by looking in the direction of the toy. Other factors can influence the success of this: is the toddler tired, hungry, or annoyed? If so the difficulty in gaining an accurate assessment increases.
As a child gets older, if he or she can respond to instructions, as well as leave the in-ear wires in place, this makes the audiologist’s assessment much more accurate, and a per-ear assessment may be possible as well.
Finally, an audiologist may use a machine that directs a puff of air into the ear, and measures how well the eardrum is moving (it should be responsive to permit sound waves to pass through). This test will not be done in the event of suspected ear drum trauma or while an ear drum is healing from a surgical procedure.
Cholesteatoma hearing loss:
Hearing loss as a result of cholesteatoma can range from no discernible loss to complete deafness in the cholesteatoma affected ear (for example after the hearing bones have been removed). In the no to minimal loss category, it is usually not necessary for further hearing interventions. However, if hearing is more greatly affected, several approaches in conjunction with the otologist or otolaryngologist may be useful.
For example, if the hearing bones have been removed, a reconstruction with a titanium prosthetic device may be attempted once the middle ear is free from signs of cholesteatoma. These are called PORP or TORP (partial or total ossicular replacement prosthesis, respectively) devices. If these fail to improve hearing, or move out of the desired position, a variety of hearing aid technologies are available. Some of these are even implant devices (such as the BAHA or Bone Anchored Hearing Aid). The goal of hearing aids for conductive hearing loss are to get the sound to the same side or opposite side cochlea, which still function properly.
The type of surgery can also influence hearing outcomes. In general, there is a better outcome with less intrusive surgeries. For example, if the stapes hearing bone is left intact, this usually is a positive factor in better hearing outcomes. Likewise, if a canal wall down procedure with removal of the hearing bones occurs, placement of a prosthetic device may be more difficult, and a patient may be more limited in hearing aid options.
Success associated to extent of disease and surgery:
In general (remembering that “in general” with cholesteatoma may not exist), canal wall up procedures are believed to have a better hearing outcome, because much of the middle ear remains intact. Canal wall up procedures are often used where the extent of the disease is fairly constrained (page on congenital cholesteatoma staging). Canal wall down procedures are used when the disease is more extensive or difficult to eradicate due to placement in the ear. Canal wall down procedures significantly alter the middle ear space, so usually also require attempts at hearing reconstruction. Several studies have examined the long term outcome of impacts on hearing pre and post surgery, and in some cases post surgical hearing may improve, in some cases it may remain the same, and in some cases, it may be diminished. Much depends on the hearing abilities of the patient before surgery. (17097434)
Stapleton et al. also conclude this, and note:(22431873)
This brings us again to the benefit of early intervention when cholesteatoma is suspected.
Hearing Aids and Implants
One type of hearing aid is a device that goes into the ear canal, however for many people with cholesteatoma this is not a recommended type of hearing aid. The ear canal must be kept dry to minimize chances for infection, and anything that closes off air passing along the external ear canal for prolonged time periods can cause the ear canal to remain damp.
Likewise, patients who have had a canal wall down procedure with a meatoplasty (enlarged ear canal) may find that certain devices do not fit well in or around the ear.
CROS behind-the-ear (BTE) hearing aids are one possible solution, particularly for single sided hearing loss. A small device is worn behind the ear with a microphone tube near the ear canal. Any sounds are then routed wirelessly to another device on the better hearing ear, and then transmitted to the cochlea.
BAHA devices are surgically implanted to bypass the middle ear bones, and transmit to the cochlea through the skull bone.
Hearing aid technology is rapidly advancing, which is terrific news for children affected by cholesteatoma.
Two newer devices on the market also use bone conduction: Sophono is an implanted device very similar to the BAHA, but with no exterior visible anchor when the conducting plate is not worn (the conducting plate and anchor use low strength magnets), and a faster healing/turn on time. The SoundBite system, also designed for single sided hearing loss, is non-surgical and uses the bone of the teeth to transmit sound to the cochlea. It uses a mouth device similar to a retainer, and is said to work for children as young as 5 years old.Last updated: August 11, 2012 at 23:00 pm