Subclinical cochlear dysfunction in newly diagnosed relapsing-remitting multiple sclerosis.

Area of Science:

• Audiology
• Neuroscience
• Ophthalmology

Background:

• Hearing impairment in multiple sclerosis (MS) is often attributed to central auditory system damage.
• Emerging evidence suggests potential peripheral inner ear involvement in MS.
• Investigating subclinical cochlear dysfunction in early MS is crucial.

Purpose of the Study:

• To assess subclinical cochlear dysfunction in untreated, newly diagnosed MS patients.
• To explore the correlation between cochlear dysfunction and MS disease severity.
• To utilize transient-evoked and distortion-product otoacoustic emissions (TEOAEs and DPOAEs) for assessment.

Main Methods:

• Included 40 newly diagnosed relapsing-remitting MS patients with normal hearing and 40 matched controls.
• Conducted audiological evaluations: pure tone audiometry, acoustic immittance, auditory brainstem response (ABR), and OAEs.
• Used self-administered questionnaires for hearing disability self-perception.

Main Results:

• ABR and pure tone audiometry were within normal limits for all MS patients.
• TEOAE and DPOAE amplitudes were significantly reduced in MS patients compared to controls at key frequencies (1000-3000 Hz).

Conclusions:

• Untreated MS patients with clinically normal hearing exhibit decreased OAE amplitudes, indicating subclinical cochlear impairment.
• This suggests early peripheral hearing damage in MS, potentially detectable by OAEs.
• The findings hypothetically point to early subclinical outer hair cell involvement in MS, as ABR wave I was preserved.