These are tests that can and should be done by the specialist to ensure the correct diagnosis. This is a farily comprehensive list taken from several websites.
SCDS and PET have similar symptoms. The correct diagnosis is vital. There are also some notes on Hyperacusis, another condition with similar symptoms.
Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an instrument called an endoscope. Endoscopy can also refer to using a borescope in technical situations where direct line-of-sight observation is not feasible.
Measuring middle ear pressure with an electroacoustic impedance meter helps to assess eustachian tube function.
High negative middle ear pressure (> -100 daPa) indicates eustachian tube dysfunction. High negative pressures may be seen in individuals with normal hearing; however, a nearly normal middle ear pressure may be associated with hearing loss.
In the presence of tympanic membrane perforation, the air passes into the middle ear resulting in a large canal volume on tympanometry.
The Politzer test is performed by visual inspection of the tympanic membrane while compressing one naris into which the end of a rubber tube attached to an air bag has been inserted while the opposite naris is compressed with digital pressure. The patient is asked to repeat the letter K or to swallow while air is injected into the nasal cavity. When positive, the overpressure that develops in the nasopharynx is transmitted to the middle ear, and only indicates an anatomically patent ET tube.
Both the Politzer and Valsalva test may be beneficial as a temporary treatment of effusion or high negative middle ear pressure.
The Toynbee Test is performed by visual inspection of the tympanic membrane while the patient swallows with their nose manually occluded. This generates a positive pressure within the nasopharynx, followed by a negative pressure phase and is considered positive when there is an alteration in middle-ear pressure as assessed by pneumatic otoscopy before and after the maneuver. Negative middle-ear pressure or temporary negative middle ear pressure followed by return to ambient pressure after the Toynbee test usually is indicative of normal eustachian tube function. This is in contrast to the Politzer and Valsalva tests which only test patency. The results of this maneuver can often be equivocal, since several studies have shown that a significant portion of normal adults and children can not open their eustachian tubes with this maneuver, and patients with patulous eustachian tube often can not maintain a negative pressure within their middle ears.
Eustachian tube catheterization can be performed, and also can indicate eustachian tube patency.
Radiographic evaluation includes computed tomography, and magnetic resonance imaging. The use of contrast materials to evaluate patency has been described in the past, but is infrequently used today. Catheterization of the eustachian tube with a curved metal cannula via the transnasal approach has been used to assess tubal function for more than 100 years. It can be done blindly, with the help of a nasopharyngoscope, or transorally with a 90° telescope. The catheter is passed along the floor of the nose until it touches the posterior wall of the nasopharynx. The catheter is then rotated 90° medially and pulled forward until it impinges on the posterior free part of the nasal septum. The catheter is then rotated 180° laterally, so that its tip lies at the nasopharyngeal opening of the eustachian tube. A Politzer bag is attached to the outer end of the catheter, and an auscultation tube with 2 ear tips is used with one tip in the patient’s ear and the other in the examiner’s ear. Air is pushed into the catheter by means of the Politzer bag. The examiner hears the rush of air as it passes through the catheter into the eustachian tube and then into the middle ear. Successful transferring of applied positive pressure from the proximal end of the cannula into the middle ear suggests tubal patency. Normal blowing sounds mean a patent eustachian tube and bubbling indicates middle ear fluid. Whistling suggests partial eustachian tube obstruction while absence of sounds indicates complete obstruction or failed catheterization.
In the Lab:
There are several more complex methods of evaluating eustachian tube function that have been described and most involve the use of manometry, sonometry, of tympanometry. Besides tympanometry most of these tests require complex equipment, and are mainly used in a research setting.
Non-intact Tympanic Membrane Tests
• The Inflation-Deflation test
• Forced Response test
• clearance test
Intact Tympanic membrane tests
• pressure chamber technique
Permeatal examination of the tympanic membrane assesses the patency and perhaps the function of the tube. A normal appearing tympanic membrane usually indicates a normally functioning eustachian tube, although this does not preclude the possibility of a patulous tube.
Otoscopic evidence of tympanic membrane retraction or fluid in the middle ear indicates eustachian tube dysfunction but cannot be used to differentiate between functional impairment and mechanical obstruction of the tube. Normal tympanic membrane mobility on pneumatic otoscopy (siegalization) indicates good patency of the eustachian tube. Nasopharyngoscopy Nasopharyngoscopy by posterior rhinoscopic mirror examination or more accurately by fiberoptic endoscope helps visualization of any mass (eg, adenoids, soft tissue growth in the nasopharynx) that may be obstructing the pharyngeal end of the eustachian tube. Attempts have been made to assess eustachian tube function with the help of nasopharyngoscopy. Yagi and colleagues evaluated the patency of the eustachian tube using a fiberoptic endoscope and a photoelectric device (phototubometry). Using videoendoscopy of the ear, Poe and colleagues assessed tubal function in adults and observed various disease processes such as inflammation of the tube and patulous dysfunction. This method has been gaining popularity in the assessment of patients suspected to have eustachian tube dysfunction.
With the recent development of advanced imaging technology, studies have been used to better define the anatomy and pathology of the eustachian tube. MRI has been used to visualize the eustachian tube and to assess its anatomy and pathology in patients with nasopharyngeal carcinoma. Moreover, MRI has been used in experimental animal models to evaluate middle ear inflammation. It has more accurately been also used to assess the effect of experimentally induced functional obstruction of the eustachian tube by botulinum toxin A on the middle ear. CT has also been used to assess the tube in normal individuals, in patients with patulous eustachian tube, and in otitis media. It has also been used in studying eustachian tube clearance. Fluoroscopy with contrast provides dynamic evaluation of mucociliary clearance.
Other tests have been developed for assessment of eustachian tube function. A 9-step inflation-deflation tympanometric test is used to assess changes in resting middle ear pressure after applying positive and negative ear canal pressures while the patient is swallowing.
Other methods include microflow technique, impedance method, sonometry, forced response test, and videoendoscopy of the nasopharyngeal end of the eustachian tube.
A self-described method by patients with perforated tympanic membranes is the bitter taste of ear drops in the mouth when used topically. This indicates a patent eustachian tube.
A final testing mechanism is sonotubometery. The advantage of this diagnostic test is the ability to evaluate the eustachian tube function with or without an intact tympanic membrane under physiologic conditions. The ET in more detail ‘Patulous eustachian tube Yoshida et al. [36••] examined 20 temporal bone CTs of patients with patulous eustachian tube and 25 normal controls. In the patulous eustachian tube group, the tubal lumen was patent throughout the cartilaginous portion (P < 0.014). They also found that the soft tissue corresponding to glandular tissue and Ostmann’s fat was smaller in patients with a patulous eustachian tube. Kano et al. [37•] investigated the use of a novel audiometric test for assessing patulous eustachian tube. In this test, sound is presented to the nasopharynx and threshold testing is performed in the usual fashion. Threshold testing allows quantification of the severity of patulous eustachian tube and may be helpful to monitor patient progress. Orlandi and Shelton [38••] reported on eustachian tube occlusion in two patients with cerebrospinal fluid leak after lateral skull base or vestibular schwannoma surgery. Their endoscopic technique to cauterize the nasopharyngeal orifice and oversew it was successfully used on another cerebrospinal fluid leak case and one patulous eustachian tube case. Tube open? Not working together? Excess Mucosa? Not enough mucosa? - Endoscopy. ‘ SCDS Temporal bone CT scan, high resolution - this is the most conclusive test. (see below) x 2 (0.5 pref) The voxel dimension of the machine used in the present study was 0.5 mm. Conceivably less than 0.5 mm of otic capsular bone would be enough to form a protective barrier for the canal and prevent the diagnosis of superior semicircular canal dehiscence syndrome. The authors reason that if at least one-fifth of the pixel is filled with bone, the attenuation would still be high enough to be detectable by examining the actual attenuation measurements within a voxel, even if the image did not display the structure as the expected white line of bone. Even a small amount of bone would be detectable beside the substantially lower attenuation of the dura or against the fluid in the semicircular canal and the contiguous subarachnoid space. By measuring the attenuation values in each pixel, the authors changed the findings in their study for several temporalbones from false-positive to true-negative Temporal bone CT scans reformatted to Poschel and Stenver projections revealed a left-sided superior canal dehiscence A CT scan of the temporal bone should generally be obtained in persons with sound or pressure sensitivity. CT of the temporal bone is supposedly very accurate in identifying canal fistulae (Fuse et al, 1996), although as there is really no other good way to identify canal fistulae, it is hard to be sure that it is picking them all up. As SCD is a type of canal fistula and it is moderately common, the main reason for this procedure is to check for SCD. CT should be done of the temporal bone with at .6 mm resolution or better (lower is better). It may be impossible to get a CT scan with a resolution < 0.6 mm. This is generally OK, but don't accept higher resolution (i.e. 1 mm is not good enough). There is also a trade-off between radiation and resolution. One might argue that the tiny lesions that can be discovered with 0.1 mm cuts are not worth the radiation load. This issue is presently unclear. Direct coronal scans are the best protocol for SCD -- in our opinion, reformatted images are not nearly as good. At this writing (2006) all University hospitals should be able to do a direct coronal CT. It is very important to insist on this -- radiology technicians have been known to do reformatting, figuring that it doesn't matter. It does matter ! Usually you only get one shot at this, so make sure it is done right the first time. In our opinion, this is what your test prescription should say: CT scan of the temporal bone, with high resolution (0.6 mm or less). Please do direct coronals, using a bone dedicated window (width 1600 HU and center at 400 HU). Axial cuts are not necessary to diagnose SCD. Nevertheless the radiologists often do them anyway. We suspect that they do this largely because radiologists are more familiar with axial views and also because radiologists seem often to be fond of using 3D reconstructions. . One could also argue that without axial cuts, the very rare PCD syndrome might go undiagnosed. On the other hand, one could also argue that the axial cuts are generally not necessary, and add financal cost and biological cost (radiation) to the patient experience. Radiologists sometimes take matters into their own hands and, because they have some interest in the situation, add CT protocols that were not authorized by the treating physician. For temporal bone CT -- x-rays of the most dense bone in the body -- this seems to us to be a bad idea. We are paticularly perturbed by the radiation cost, as we think that it would be best for all concerned to just do the minimal procedure needed to confirm or rule out SCD. At this writing, Jan 2009, this issue is simply not resolved. An MRI is also a good idea to exclude potentially confounding entities such as cholesteatoma or tumor. MRI is not a test for dehiscence because it doesn't show the bone and resolution is not as good as CT scan. However, MRI is the best way of showing other possibly confounding problems such as acoustic tumors, cholesteatoma, or multiple sclerosis plaques. A temporal bone CT scan with true coronal cuts and reconstructions that specifically examine the superior canals should be obtained. Unfortunately, this cannot be performed in the majority of neuroradiology centers (yet). MRI scans with contrast are useful in the workup of dizziness and should be obtained to exclude a tumor but do not show SCD. will a standard head CT or low resolution temporal bone CT will show SCD? No. A typical SCD is 1 to 4 millimeters-the size of a pinhead or only slightly larger! Therefore, standard head CTs, low resolution temporal bone CTs and MRIs will not be able to detect SSCD reliably. The BEST imaging for SCDS is a high resolution 0.5 mm collimation or less CT of the temporal bones with images that are REFORMATTED to include cuts in the plane of (Poschel) and perpendicular (Stenver) to the superior canals. If surgery is considered as an option, we would recommend that the best possible imaging be obtained prior to undergoing a craniotomy procedure as negative explorations where no dehiscence was found have been reported in the clinical literature. RADIOLOGIC FINDINGS IN SCDS As stated above, conventional temporal bone CT scans may not identify small dehiscences of the superior canal. Although a recent study by the University of Pittsburgh demonstrated that an experienced neuroradiologist could identify SCD reliably in standard 0.5 collimation coronal temporal bone cuts (and these were compared with images reformatted in the planes parallel to (Poschel) and orthogonal (Stenver), negative surgical explorations have been reported and so we believe that reformatted images to examine superior canals should be standard of care ESPECIALLY if surgery is being considered. Valsalva test In SCD, positive pressure or Valsalva against pinched nostrils produces down beating nystagmus, with a torsional fast phase consistent with stimulation of the affected ear (CCW for right ear, CW for left ear). See example below. Negative pressure or Valsalva against a closed glottis may produce upbeating nystagmus and nystagmus beating with the torsional fast phase in the opposite direction (CW for right ear, CCW for left ear). Practically, we don't think that you can do this test without magnification -- i.e. a video-frenzel system with a good enough focus that you can see torsion. Another method is to use an examining microscope focused on the sclera. We are less enthused about this. The Tullio test Occasionally doctors will attempt a formal "Tullio's" test. In our practice in Chicago, we do this ourselves (in persons who complain of sound sensitivity), and think that this is rarely positive, but still worth the minimal effort that it takes to assess Tullio's. There are several methods of doing this. From a systems perspective, there are three potential variables in testing for tullio's: • Sound generation -- loudness, frequency • Person's sensitivity • Output measurement Tullio test: Sound generators Starting with sound generators, audiometers (hearing testing machines) are the most accessible to most clinicians. Here, Tullio's is noticed serendipitously by an observant audiologist. Because Tullio's is generally not elicited by soft sounds, the pitfall of this method is that in most persons, the stimulus is not loud enough to cause any problem. Another pitfall is that only one frequency is tested at a time. One might miss the sound that triggers symptoms. Fistula Testing A fistula test , which entails making a sensitive recording of eye movements while pressurizing each ear canal with a rubber bulb, is occasionally helpful. A positive test is good grounds for a temporal-bone CT. Fistula tests are little used because they are difficult to do and insensitive. Fistula tests are often not available or even thought of. However, if a patient complains of dizziness during tympanometry, this is a clue that the patient has a positive pressure test. A strong nystagmus (vertical and rotatory) may be produced by pressure in the external ear canal. However, we do not think that this is very sensitive. Simple observation of the patient's eyes with appropriate equipment (such as VNG) may also provide the diagnosis, as in some cases, there is a pulse-synchronous oscillation (Rambold, 2001; Hain et al, 2008), see video below.. The purpose of this test is to detect perilymphic fistula . If pressure sensitivity is found, fistula is highly likely. Pressure is applied to each ear in turn, and eye movements are recorded with a sensitive infrared recording device. For this reason, fistula testing in our laboratory is about 10 times more sensitive than conventional EOG based recordings. The picture above shows Dr. Hain using a Brunnings otososcope to deliver pressure. Fistula testing can also be done at the bedside as illustrated on the accompanying figure. Pressure is applied to the ear through one of the devices listed (1-hand bulb with typanometer tip, 2-Brunnings otoscope, 3-tympanometer), and eye movement is either directly observed or measured with a video-frenzel goggle device. Tympanometry Zodiac 901 tympanometer used at Chicago Dizziness and Hearing Tympanometry is a method of measuring the stiffness (or it's inverse, compliance) of the ear drum. It is a quick test that is part of most basic hearing assessments. A large amount of useful information about the middle ear can be gained from this brief short and easy test. Tympanometry is one of several tests that audiologists call "immittance" tests. The use of the term "immitance", which is not a normal English word, seems to be largely present for didactic reasons. Immittance = impedance+admittance. The other "immittance" test is acoustic reflexes.Typically, both types if "immitance tests" are done using the same machine. Tympanograms can also be done using hand-held devices that will not do reflexes. These are typically used at the bedside as a quick method of determining if there is a perforation of the ear drum or a middle ear infection. There is some overlap with AR (acoustic reflex) testing and tympanometry, and the AR technique is often used when one wants to look at pressure over time. Middle ear muscle testing Finally, tympanometry can be used to detect abnormal contractions of the stapedius and tensor tympani muscles. This requires a machine that can run the tympanogram over 30 seconds, at a single frequency, looking for blips in the trace. Usually this is done using the acoustic reflex mode of the tympanometer. Rhythmic changes in impedance of the middle ear. Each bump was correlated with a high-pitched "tic" that can be heard from the outside, due to stapedius myoclonus. Audiometry Audiometry is generally done as a preliminary test, and an alert audiologist who knows about SCD may make the diagnosis on the spot. In patients with SCD (see figure 3), audiometry may show bone conduction scores better than air (conductive hyperacusis). If there is a simultaneous sensorineural hearing loss in SCD, the overall picture may mimic the conductive hearing loss pattern of otosclerosis (Mikulec et al, 2004). However, as VEMP's are present in SCD, but absent in conductive hearing loss, it is easy to tell these two apart. A full audiogram should be performed for both ears. Specifically, BONE conduction should be performed at -5 and -10 dB to exclude supranormal thresholds that are common in SCDS patients. Additional tests that should be performed include a tympanogram, acoustic reflexes, and otoacoustic emissions are crucial to exclude otosclerosis or ossicular fixation, middle ear fluid, Eustachian tube dysfunction. Often, SCDS patients will have supranormal bone conduction or conductive hyperacusis with an air-bone gap and PRESENT acoustic reflexes and normal tympanograms (unless previous surgery or concurrent ear infection is present). Information taken from: http://emedicine.medscape.com/article/874348-overview
Hyperacusis (also spelled hyperacousis) is a health condition characterized by an over-sensitivity to certain frequency ranges of sound (a collapsed tolerance to normal environmental sound). A person with severe hyperacusis has difficulty tolerating everyday sounds, some of which may seem unpleasantly loud to that person but not to others. The most common sound to appear unpleasant in hyperacusis is people eating or clicking their fingers. It can be acquired as a result of damage sustained to the hearing apparatus, or inner ear. There is speculation that the efferent portion of the auditory nerve (olivocochlear bundle) has been affected (efferent meaning fibers that originate in the brain which serve to regulate sounds).
In cochlear hyperacusis (the most common form of hyperacusis), the symptoms are ear pain, annoyance, and general intolerance to any sounds that most people don’t notice or consider unpleasant. Crying spells or panic attacks may result from cochlear hyperacusis. As many as 86% of hyperacusis sufferers also have tinnitus. In vestibular hyperacusis, the sufferer may experience feelings of dizziness, nausea, or a loss of balance when certain pitched sounds are present. For instance, someone with vestibular hyperacusis may feel like they are falling and as a result involuntarily grimace and clutch for something to brace themselves with. Anxiety, stress, and/or phonophobia may be present in both types of hyperacusis. Someone with either form of hyperacusis may develop avoidant behavior in order to try to avoid a stressful sound situation or to avoid embarrassing themselves in a social situation that might involve noise. A person suffering from hyperacusis might be startled by very low sound levels. Everyday sounds like shutting doors, ringing phones, running water, cooking, normal conversation and many others will hurt his/her ears. In extreme situations even the use of earplugs fails to bring relief and the patient may spend his life trying to avoid all sounds and just stay at home.
The most common treatment for hyperacusis is retraining therapy which uses broadband noise. Tinnitus Retraining Therapy (TRT), a treatment originally used to treat tinnitus, uses broadband noise to treat hyperacusis. Pink noise can also be used to treat hyperacusis. By listening to broadband noise at soft levels for a disciplined period of time each day, patients can rebuild (i.e., re-establish) their tolerances to sound. When seeking treatment, it is important that the physician determine the patient’s Loudness Discomfort Levels (LDL) so that hearing tests (brainstem auditory evoke response) or other diagnostic tests which involve loud noise (MRI) do not worsen the patient’s tolerance to sound.