Irreversible cochlear damage in myasthenia gravis -- otoacoustic emission analysis.

Abstract

OBJECTIVE:

Acetyl choline (ACh) is the main neurotransmitter of the efferent auditory system. This study is aimed to evaluate cochlear function in myasthenia gravis (MG), a neuromuscular transmission disorder caused by ACh receptor autoantibodies.

METHODS:

This prospective study included 16 myasthenic patients, tested audiologically twice, first after improvement from myasthenic crisis or acute oropharyngeal dysfunction (1 week from admission) and then 2 months later. We detected the effect of contralateral acoustic stimulation (CAS) on patients' transient and distortion product otoacoustic emissions (TEOAE and DPOAE).

RESULTS:

Compared with controls, patients reported significant reduction in overall echo response and amplitude of TEOAEs at 1-2 kHz and at 1-6 kHz of DPOAE with marked reduction at 5 kHz. In the control group, CAS produced amplitude reduction in TEOAEs and DPOAEs at 1-4 kHz. Utilizing masking effect, patients reported amplitude reduction in TEOAEs at 1.5-4 kHz while DPOAEs did not reach significant level except at 1.5 and 5 kHz. After 2 months, no changes were observed compared with early assessment.

CONCLUSIONS:

It is clear that disease progression is associated with irreversible cochlear damage. Lack of improvement in patients' emissions despite partial non-audiometric improvement in relation to receptors needs to be considered.

• Authors: S A Hamed, A M Elattar, E A Hamed
• Journal: Acta neurologica Scandinavica (Acta Neurol Scand) Vol. 113 Issue 1 Pg. 46-54 (Jan 2006) ISSN: 0001-6314 [Print] Denmark
• PMID: 16367899 (Publication Type: Controlled Clinical Trial, Journal Article)

Topics

• Adolescent
• Adult
• Auditory Threshold
• Chronic Disease
• Cochlea (pathology, physiopathology)
• Diagnostic Techniques, Otological
• Female
• Follow-Up Studies
• Hearing Loss, Sensorineural (diagnosis, etiology, physiopathology)
• Humans
• Male
• Middle Aged
• Myasthenia Gravis (complications, physiopathology)
• Otoacoustic Emissions, Spontaneous
• Prospective Studies