Colebatch J G, Halmagyi G M, Skuse N F
Department of Neurology, Prince of Wales Hospital, Randwick, Sydney, Australia.
J Neurol Neurosurg Psychiatry. 1994 Feb;57(2):190-7. doi: 10.1136/jnnp.57.2.190.
Electromyograms (EMGs) were recorded from surface electrodes over the sternomastoid muscles and averaged in response to brief (0.1 ms) clicks played through headphones. In normal subjects, clicks 85 to 100 dB above our reference (45 dB SPL: close to perceptual threshold for normal subjects for such clicks) evoked reproducible changes in the averaged EMG beginning at a mean latency of 8.2 ms. The earliest potential change, a biphasic positive-negativity (p13-n23), occurred in all subjects and the response recorded from over the muscle on each side was predominantly generated by afferents originating from the ipsilateral ear. Later potentials (n34, p44), present in most but not all subjects, were generated bilaterally after unilateral ear stimulation. The amplitude of the averaged responses increased in direct proportion to the mean level of tonic muscle activation during the recording period. The p13-n23 response was abolished in patients who had undergone selective section of the vestibular nerve but was preserved in subjects with severe sensorineural hearing loss. It is proposed that the p13-n23 response is generated by activation of vestibular afferents, possibly those arising from the saccule, and transmitted via a rapidly conducting oligosynaptic pathway to anterior neck muscles. Conversely, the n34 and p44 potentials do not depend on the integrity of the vestibular nerve and probably originate from cochlear afferents.
通过置于胸锁乳突肌上的表面电极记录肌电图（EMG），并对通过耳机播放的短暂（0.1毫秒）滴答声做出的反应进行平均处理。在正常受试者中，比我们的参考值（45分贝声压级：接近正常受试者对此类滴答声的感知阈值）高85至100分贝的滴答声，会在平均肌电图中引发可重复的变化，平均潜伏期为8.2毫秒。最早的电位变化，即双相正-负波（p13-n23），在所有受试者中均出现，并且从每侧肌肉上方记录到的反应主要由源自同侧耳朵的传入神经产生。后来的电位（n34、p44），在大多数但并非所有受试者中存在，是在单侧耳朵刺激后双侧产生的。平均反应的幅度与记录期间紧张性肌肉激活的平均水平成正比。p13-n23反应在接受前庭神经选择性切断术的患者中消失，但在严重感音神经性听力损失的受试者中保留。有人提出，p13-n23反应是由前庭传入神经的激活产生的，可能来自球囊，并通过一条快速传导的少突触通路传递到颈部前侧肌肉。相反，n34和p44电位不依赖于前庭神经的完整性，可能起源于耳蜗传入神经。
