What kind of doctor should evaluate a hearing problem?
Neurotologists specialize in the ear, and are specially trained to treat diseases of the inner ear and ear brain interface,and in skull base and intracranial surgery for problems such as acoustic neuroma, glomus jugulare, intractable dizziness, total deafness, and traditionally unresectable tumors that may present with hearing loss. Neurotologists are distinct from otoneurologists whose background is in neurology who have a special interest in disorders affecting hearing and balance; but their perspective and background are different, and they are neurological diagnosticians only, and do not perform surgery on the ear and related structures.
Otolaryngologists (ear, nose and throat doctors) are specialists in ear problems, among other things. Otology is a sub-specialty of otolaryngology. It is practiced by physicians with special interest in and concentration on ear problems. Neurotology is a further sub-specialty of otology. Although the field is more than 30 years old, there are still relatively few of us with expereience and/or fellowship training beyond otolaryngology residency who qualify as neurotologists.
What should a patient expect from an otologist?
Like any other doctor, the first thing an ear doctor will want is a complete history of the hearing problem. This will include information on when it started, how fast it progressed, whether there were obviously related problems (illness, head injury, medication ingestion, toxic exposure, noise exposure, etc.), whether other members of the family have hearing loss, whether there have been ear infections, and other related matters. The ear doctor will also inquire about how many aspects of general health because of numerous systemic conditions that may cause hearing problems.
The ear doctor will also perform a physical examination. Ordinarily this includes a complete ear, nose and throat examination with special attention to the ears. The otologist usually includes an informal hearing assessment with a tuning fork, and sometimes other assessments of balance, sensation, and other functions. An audiogram (hearing test) will virtually always be obtained. Depending upon the results of the history, physical examination and hearing test, the doctor may order numerous other tests. Sometimes these seem overwhelming at first; but there is ordinarily a good reason for each of them.
What is an Audiogram?
An audiogram is a hearing test. It is generally performed in a soundproof room using sophisticated, calibrated equipment. The test is usually administered by a trained professional, most commonly a certified audiologist. Earphones are placed over the ears and tones are presented to each ear, one at a time. The softest level at which the sounds can be heard is recorded. Other tests are also performed, including ability to hear and understand speech. Numerous special hearing tests are also available to help determine the site of an abnormality in the hearing system.
What other kinds of tests might be ordered?
Because of the complexity of the hearing system and the many things that may affect it, a systematic evaluation involving various parts of the body is often required. This usually involves a variety of blood tests and imaging studies. Imaging studies may include an MRI scan (magnetic resonance imaging) with contrast injection to look at the inner ear nerves and brain, a CT scan without contrast injection to look at the bones of the ear, imaging of the blood vessels to the brain (MRA [magnetic resonance angiography], or occasionally angiography), imaging of the microscopic blood flow within the brain (SPECT or PET scan) and other less common studies. Not all such studies are necessary in every person, of course; but one should not be surprised to see them included in a comprehensive evaluation of a particularly significant or asymmetric hearing loss.
What is the otologist looking for with all these tests!
Essentially a comprehensive evaluation for hearing loss seeks to identify all potentially correctable or serious conditions that may be responsible for the hearing deficit. Although many doctors unfortunately still limit the examination to a hearing test, declaring “Well, you’re old, so you can’t hear very well,” this in insufficient and unfair. Otologists, and especially neurotologists, are most likely to be aggressive in searching for every possible condition that may be helped. Many such conditions are discussed below.
Specifically, what sort of things might an otologist be looking for?
The examination and testing described above are designed to detect diseases of the ear, nerve, brain, and other areas of the body that may cause hearing loss.
This sounds expensive. Is it cost effective?
Questions about cost effectiveness are difficult, and depend upon philosophy. I (Dr. Robert Sataloff) am biased, and it is important for my readers and patients to understand that bias. By most commonly applied standards (which which I disagree in general), I am one of the least cost effective physicians around. However, that refers to cost in terms of dollars spent by insurance companies, not cost in terms of patients’ health, quality of life, lost work time for multiple visits and tests ordered a few at a time over months, or the personal cost of delayed diagnoses. Some managed health care plans resist comprehensive evaluation such as I have prescribed for many patients, because the yield of positive test results is low. As a nation, we seem to be favoring this notion of cost effectiveness in an effort to control medical expenditures. However, it is important for everyone to recognize the value judgement implied. In order to allegedly keep costs down, we are accepting an increased number of missed or delayed diagnoses. Society is saying that this is acceptable.
What are some other common hearing tests?
Tympanometry is performed commonly. It involves placing a gentle pressure probe in the ear. This test allows assessment of the pressure in the middle ear, and it may help detect fluid, fixation of the middle ear bones, and other conditions. Other maneuvers with the same equipment can provide even more information.
Site of lesion testing involves the regular audiometer, using a variety of other test protocols to help determine where a problem lies. This kind of testing may involve comparison of hearing in one ear with the other, detection of small changes in signal intensity, testing ability to hear the presence of noise, testing the ability to hear sentences placed in both ears at the same time, and many other test scenarios.
Brainstem evoked response audiometry (BERA or ABR) involves sophisticated, computerized equipment. Sounds are placed in the ear, and the brainstem’s response is recorded from electrodes pasted to the patient (like electrocardiogram electrodes). This testing is extremely helpful in distinguishing sensory (inner ear) from neural (nerve) causes of hearing loss and for helping to localize problems in the brainstem auditory pathway. In selected cases, it is also helpful in determining hearing threshold (ability to hear soft sounds), and it is used commonly for that purpose in infants.
Otoacoustic emissions (OAE) testing detects sounds that are actualky generated within the cochlea. OAE may be helpful in defining the site of lesion in some and hearing loss in cases, and potentially for some tinnitus problem.
Tinnitus (ear noise) can be tested in several ways. Sometimes it is possible to measure the frequency and intensity of tinnitus. There are also tests that help determine whether it can be suppressed or masked.
Since the inner ear is divided into hearing and balance sections which are related, balance system testing is often appropriate when hearing problems are present. In addition to our routine audiogram (the hearing test with which most patients are familiar), there are numerous special tests of hearing including brainstem evoked response audiometry (ABR), tympanometry that measures middle ear pressure among other things, electrocochleography (ECoG), central auditory processing tests and their studies.
The inner ear controls not only hearing but also balance, and many tests are available to assess the balance system. Such testing may be useful even in patients who do not have obvious balance problems. The most common balance tests are electronystagmography (ENG) and computerized dynamic posturography (CDP). ENG involves eye movements that can be measured, now usually replaced by videonystagmography (VNG), and stimulating the vestibular pathways through visual and caloric stimuli. The caloric stimuli are usually cool and warm water placed in the ears. Additional related information can also be obtained from rotational testing, using a special rotating chair. This kind of testing is not widely available, but may be valuable for some patients. CDP tests overall balance function using a computerized testing platform. It provides invaluable information that is especially useful in combination with a VNG. Vestibular evoked myogenic potential testing (VEMP) also is valuable for evaluating selected middle ear structures such as the saccule, and for helping to determine whether there is absence of bone between the inner ear and the brain (superior semicircular canal dehiscence).
Facial nerve testing also may be part of otologic evaluation and might include several studies such as facial nerve electroneurography (ENoG or facial electromyography (EMG).
For example, this approach argues that you can’t order MRI’s on every patient with moderately asymmetric sensory hearing loss if only 1 in 100 or 200 will turn out to have an acoustic neuroma (ear-brain interface tumor). Rather, you should follow the person’s hearing and get the MRI in six months or a year or two years if the hearing is worse on one side. This delay in diagnosis will save the cost of 100 or more “unnecessary” MRI scans.
From my perspective as a tertiary care medical school professor, I think the personal cost of allowing one individual to go undiagnosed for a serious, treatable condition is greater than the money saved by not ordering tests that might prove normal. In general, the larger the tumor at the time of diagnosis, the less the chance of saving hearing, and the greater the chance of the patient suffering facial paralysis, stroke, or worse at the time of surgery. Personally, I think the most cost effective way to practice medicine is to be certain that no one leaves my office without a diagnosis, regardless of what tests may be medically necessary to establish that diagnosis. This approach used to be fairly universal, until the current emphasis on controlling medical costs became such a dominant force. Nevertheless, it is important for consumers of health care to understand the price they pay for “cost effectiveness”, and legitimate differences in philosophy among health care providers. Such understanding allows patients to position themselves so that they can get the kind of care they want and access to physicians whose approach is consistent with their needs.