Hamed S A, Elattar A M, Hamed E A
Department of Neurology, Assiut University Hospital, Assiut, Egypt.
Acta Neurol Scand. 2006 Jan;113(1):46-54. doi: 10.1111/j.1600-0404.2005.00541.x.
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.
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).
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.
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.
乙酰胆碱（ACh）是传出听觉系统的主要神经递质。本研究旨在评估重症肌无力（MG）患者的耳蜗功能，MG是一种由ACh受体自身抗体引起的神经肌肉传递障碍疾病。
这项前瞻性研究纳入了16例重症肌无力患者，进行了两次听力学测试，第一次是在重症肌无力危象或急性口咽功能障碍病情改善后（入院1周后），第二次是在2个月后。我们检测了对侧声刺激（CAS）对患者瞬态和畸变产物耳声发射（TEOAE和DPOAE）的影响。
与对照组相比，患者报告TEOAE在1-2kHz以及DPOAE在1-6kHz的整体回声反应和幅度显著降低，在5kHz时明显降低。在对照组中，CAS使TEOAE和DPOAE在1-4kHz的幅度降低。利用掩蔽效应，患者报告TEOAE在1.5-4kHz的幅度降低，而DPOAE除了在1.5kHz和5kHz外未达到显著水平。2个月后，与早期评估相比未观察到变化。
显然，疾病进展与不可逆的耳蜗损伤有关。尽管患者在受体相关的部分非听力测量方面有所改善，但耳声发射缺乏改善这一情况仍需加以考虑。
