Would otosclerosis (abnormal bone growth in the middle ear) on the left side result in absent ipsilateral (same side) and contralateral (opposite side) acoustic reflexes?

Acoustic Reflexes in Otosclerosis

In otosclerosis affecting the left ear, both ipsilateral and contralateral acoustic reflexes would typically be absent when the probe is placed in the affected (left) ear. 1, 2

Pathophysiology and Reflex Patterns in Otosclerosis

Otosclerosis is characterized by abnormal bone growth in the middle ear, most commonly affecting the stapes footplate and causing fixation that prevents normal vibration in response to sound. This directly impacts acoustic reflex testing in the following ways:

• Ipsilateral reflexes (probe in left ear): When testing the affected left ear with the probe in that ear, the acoustic reflex will be absent because the stapes fixation prevents the stapedius muscle contraction from changing middle ear impedance 2, 3

• Contralateral reflexes (probe in left ear): When stimulating the right ear but measuring in the affected left ear, reflexes will also be absent because even though the stapedius muscle on the right may contract normally, the fixed stapes in the left ear prevents detection of impedance changes 2, 4

• Contralateral reflexes (probe in right ear): When the probe is placed in the unaffected right ear and the stimulus is presented to the affected left ear, reflexes may still be present if the right middle ear system is normal 5

Diagnostic Value of Acoustic Reflex Testing

Acoustic reflex testing provides valuable diagnostic information in otosclerosis:

1. Reflex pattern specificity: The absence of both ipsilateral and contralateral reflexes when the probe is in the affected ear is highly characteristic of otosclerosis 2, 4

2. Inverted acoustic reflexes: In some cases of otosclerosis (approximately 90% in one study), an inverted acoustic reflex pattern may be observed when stimulating at high intensities (110 dB HL), which can help differentiate otosclerosis from other causes of ossicular chain fixation 4

3. Early detection: Acoustic reflex abnormalities may be present even in early stages of otosclerosis before significant conductive hearing loss develops 3, 5

Clinical Implications

• Temporal bone CT is the first-line imaging modality for suspected otosclerosis, providing excellent delineation of the ossicular chain and bony labyrinth 1

• The absence of acoustic reflexes in combination with normal otoacoustic emissions can help differentiate otosclerosis from auditory neuropathy/dys-synchrony 6

• Immittance measurements, including tympanograms and acoustic reflex testing, are recommended as part of the comprehensive audiological evaluation in patients with suspected hearing loss 1

Management Considerations

For patients diagnosed with otosclerosis:

• Surgical options include stapedectomy or stapedotomy to restore the mechanical function of the middle ear 1

• Amplification options for those with persistent hearing loss may include conventional hearing aids, CROS (contralateral routing of signal) systems, or BiCROS (bilateral contralateral routing of signals) systems 1, 7

• Bone conduction devices may be considered for patients who are not surgical candidates 7

• Cochlear implantation may be an option in cases of severe to profound hearing loss due to advanced otosclerosis 7

Remember that early diagnosis and intervention for otosclerosis can significantly improve outcomes and quality of life for patients with this progressive condition.