Hendler T, Squires N K, Emmerich D S
Department of Psychology, State University of New York, Stony Brook.
Ear Hear. 1990 Dec;11(6):403-16. doi: 10.1097/00003446-199012000-00002.
Central auditory function was assessed in 15 patients with multiple sclerosis (MS) to determine whether the demyelinating lesions resulted in disruption of temporal processing. Auditory evoked potential (AEP) recordings included all three latency regions: Auditory brain stem responses (ABRs), midlatency responses (MLRs), and long-latency responses (LLRs). Two psychophysical tasks thought to involve temporal processing were used: a monaural-processing task (gap-detection) and a binaural-processing task (masking level difference; MLD). Further, AEP abnormalities and psychophysical performance deficits were related to lesion location, based on magnetic resonance imaging (MRI) scans. Reduced MLDs were seen in six MS subjects. Abnormal MLDs were always accompanied by abnormal ABRs and MLRs, and compared to subjects with normal MLDs, the subjects with abnormal MLDs were more likely to have bilateral abnormalities in the AEPs. Further, MLR indices of abnormal binaural interaction appeared to be specifically related to the psychophysical measure of binaural processing. The MRI data of these patients indicated widespread involvement of the auditory pathway. MS subjects with abnormal MRI signals restricted to levels caudal to the lateral lemniscus did not have abnormal MLDs. Gap-detection thresholds were more resistant to the effects of the demyelinating lesions; only two subjects had abnormal gap-detection thresholds. These subjects had extensive AEP abnormalities (bilaterally, in all three latency regions). The gap-detection thresholds were most specifically related to abnormalities of the LLRs. In addition, the subjects with elevated gap-detection thresholds were the only ones with a prolonged interval between the ABRs and MLRs. Thus, efficient neural conduction between the upper brain stem and auditory cortex appears to be crucial for normal monaural temporal processing. The results indicate that demyelinating lesions can cause deficits in temporal processing in the central auditory pathway. However, auditory temporal processing is not a unitary phenomenon since abnormalities at different levels of the auditory system disrupt different types of temporal processing. Finally, abnormal psychophysical performance was not seen in all subjects with AEP and MRI evidence of involvement of the auditory pathway; rather, these psychophysical measures appeared to be sensitive to disruption only in specific portions of the auditory system.
对15例多发性硬化症（MS）患者的中枢听觉功能进行了评估，以确定脱髓鞘病变是否导致时间处理功能中断。听觉诱发电位（AEP）记录包括所有三个潜伏期区域：听觉脑干反应（ABR）、中潜伏期反应（MLR）和长潜伏期反应（LLR）。使用了两项被认为涉及时间处理的心理物理学任务：一项单耳处理任务（间隙检测）和一项双耳处理任务（掩蔽级差；MLD）。此外，根据磁共振成像（MRI）扫描结果，AEP异常和心理物理学表现缺陷与病变位置相关。6例MS患者出现MLD降低。异常的MLD总是伴有异常的ABR和MLR，与MLD正常的受试者相比，MLD异常的受试者更有可能在AEP中出现双侧异常。此外，异常双耳交互的MLR指标似乎与双耳处理的心理物理学测量有特定关系。这些患者的MRI数据表明听觉通路广泛受累。MRI信号异常仅限于外侧丘系尾侧水平的MS受试者没有异常的MLD。间隙检测阈值对脱髓鞘病变的影响更具抵抗力；只有两名受试者间隙检测阈值异常。这些受试者有广泛的AEP异常（双侧，在所有三个潜伏期区域）。间隙检测阈值与LLR异常最具特异性相关。此外，间隙检测阈值升高的受试者是ABR和MLR之间间隔延长的唯一受试者。因此，上脑干和听觉皮层之间有效的神经传导似乎对正常的单耳时间处理至关重要。结果表明，脱髓鞘病变可导致中枢听觉通路时间处理功能缺陷。然而，听觉时间处理不是一个单一的现象，因为听觉系统不同水平的异常会破坏不同类型的时间处理。最后，并非所有有AEP和MRI证据表明听觉通路受累的受试者都出现了异常的心理物理学表现；相反，这些心理物理学测量似乎仅对听觉系统特定部分的破坏敏感。
