Physical Examination and Clinical Evaluation of the Patient with Otosclerosis

The patient with otosclerosis usually suffers from a gradually progressive hearing loss. This is usually bilateral and may be asymmetrical. Age of presentation is usually in the third or fourth decade. The patient will most likely be female, and if the patient has a family history of conductive deafness, the diagnosis of otosclerosis will be more likely. Patients will likely be soft spoken because they hear their own voice as louder as a result of bone conduction (Emmett 1993). Similarly, patients will complain of worsening hearing disability while eating. For female patients, the hearing disability often worsens with the onset of pregnancy.

A history for previous ear surgery should be elicited.

PHYSICAL EXAMINATION

The entire auditory system should be evaluated thoroughly. The pinna and external auditory canals should be inspected, and any debris that might obscure the tympanic membrane should be carefully removed.

The tympanic membrane should be examined, preferably with the aid of the operating microscope. In particular, the tympanic membrane should be evaluated to rule out the presence of other disorders that could cause a conductive hearing loss. The presence of tympanosclerotic plaques on the tympanic membrane or thinning of the tympanic membrane could well point to tympanosclerosis as a cause of the conductive hearing loss, by causing fixation of the ossicular chain.

Fluid in the middle ear and barotrauma should be ruled out when eliciting a history as well as when conducting a physical exam. Chronic adhesive otitis media and tympanic membrane perforation, as well as cholesteatoma, if present, will be evident to the experienced otolaryngologist upon examination of the tympanic membrane under the microscope. On occasion a reddish blush will be evident. This is known as Schwartze’s sign. This reddish blush is due to abnormal vascular shunts between the otosclerotic focus and the vessels on the promontory. This is a sign of an active otosclerotic focus and could be a contraindication for surgery.

The pneumatic otoscope can help differentiate between malleus fixation and otosclerosis (Moon and Hahn 1978). If the malleus is fixed, the excursion of the tympanic membrane will be minimal when the bulb of the pneumatic otoscope is compressed. In otosclerosis, however, the excursion of the tympanic membrane may appear to be normal. This tool, though a subjective one, can in experienced hands identify the presence of malleus fixation.

Tuning Fork Tests

Although audiological tests are now freely available and the degree of hearing loss can be evaluated, it is still necessary for the otolaryngologist to perform tuning fork tests in order to arrive at a reasonable idea as to the nature of the hearing loss and its severity. It is also a quick and, again in experienced hands, reliable way of assessing the type and nature of the hearing loss and can help compare the findings of the tuning fork with those found on pure tone and impedance audiometry. It should be remembered that pure tone and speech audiometry are subjective tests that can vary from one audiological laboratory to another.

The tuning forks used are 256, 512, and 1024 Hz. The tuning fork tests should be performed with all three tuning forks by both the audiologist and the otolaryngologist.

Rinne’s test is a reliable method for ascertaining if the hearing loss is a conductive one. The tines of the tuning fork are placed 2 cm away from the external auditory canal, and the patient is asked to indicate when the sound of the vibrating tuning fork is no longer heard. This is evaluating air conduction of sound. When the patient indicates that he or she can no longer hear the tuning fork, the still vibrating fork is placed on the skin overlying the antral area of the mastoid. This evaluates bone conduction of sound. The patient is then asked if he or she can hear the sound of the vibrating tuning fork.

A Rinne’s test is positive if air conduction is greater (longer) than bone conduction. It is negative if bone conduction is greater than air conduction. A negative Rinne’s test indicates the presence of a conductive hearing loss. For a Rinne’s test to be negative with a 512 Hz tuning fork, an air-bone gap of at least 30 to 45 dB is needed.

Weber’s test is also useful in identifying the ear with the greater conductive hearing loss. When the tuning fork is placed on the middle of the forehead, the patient perceives the sound as louder in the ear with the greater conductive hearing loss. When a unilateral conductive hearing loss is present and the other ear is normal, the sound of the tuning fork will be heard (lateralizes) in the ear that has a conductive hearing loss. In situations of unilateral sensorineural hearing loss, the sound of the tuning fork is more audible in the normal ear than in the ear that has a sensorineural hearing loss.

False-Negative Rinne’s Test

Absolute Bone Conduction (ABC) Test