Auditory Tests

A. Tuning fork tests (Tible 11-1)

Table 11-1.

Tuning Fork Test Results

Table 11-1.

Tuning Fork Test Results

Otologic Finding

Weber Test

Rinne Test

Conduction deafness (left ear)

Lateralizes to left ear

BC > AC on left

AC > BC on right

Conduction deafness (right ear)

Lateralizes to right ear

BC > AC on right

AC > BC on left

Nerve deafness (left ear)

Lateralizes to right ear

AC > BC, both ears

Nerve deafness (right ear)

Lateralizes to left ear

AC > BC. both ears

Normal ears

No laterlization

AC > BC. both ears

Conduction deafness = middle ear deafness (e.g.. otosclerosis, otitis media): nerve deafness - sensorineural deafness (e.g., presbycusis; AC = air conduction: BC = bone conduction.

Conduction deafness = middle ear deafness (e.g.. otosclerosis, otitis media): nerve deafness - sensorineural deafness (e.g., presbycusis; AC = air conduction: BC = bone conduction.

1. Weber's test is performed by placing a vibrating tuning fork on the vertex of the skull. Normally, a patient hears equally on both sides.

a. A patient who has unilateral conduction deafness hears the vibration more loudly in the affected ear.

b. A patient who has unilateral partial nerve deafness hears the vibration more loudly in the normal ear.

2. The Rinne test compares air and bone conduction. It is performed by placing a vibrating tuning fork on the mastoid process until the vibration is no longer heard; then the fork is held in front of the ear. Normally, a patient hears the vibration in the air after bone conduction is gone.

a. A patient who has unilateral conduction deafness does not hear the vibration in the air after bone conduction is gone.

b. A patient who has unilateral partial nerve deafness hears the vibration in the air after bone conduction is gone.

B. Brain stem auditory evoked potentials (BAEPs)

1. Testing method. Clicks are presented to one ear, then to the other. Scalp electrodes and a computer generate a series of seven waves. The waves are associated with specific areas of the auditory pathway.

2. Diagnostic value. This method is valuable for diagnosing brain stem lesions (multiple sclerosis) and posterior fossa tumors (acoustic neuromas). It is also useful for assessing hearing in infants. Approximately 50% of patients with multiple sclerosis have abnormal BAEPs.

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