Welgampola M S, Rosengren S M, Halmagyi G M, Colebatch J G
Institute of Neurological Sciences, Prince of Wales Hospital and UNSW Clinical School, Sydney, NSW, Australia.
J Neurol Neurosurg Psychiatry. 2003 Jun;74(6):771-8. doi: 10.1136/jnnp.74.6.771.
To examine the properties and potential clinical uses of myogenic potentials to bone conducted sound.
Myogenic potentials were recorded from normal volunteers, using bone conducted tone bursts of 7 ms duration and 250-2000 Hz frequencies delivered over the mastoid processes by a B 71 clinical bone vibrator. Biphasic positive-negative (p1n1) responses were recorded from both sternocleidomastoid (SCM) muscles using averaged unrectified EMG. The best location for stimulus delivery, optimum stimulus frequency, stimulus thresholds, and the effect of aging on evoked response amplitudes and thresholds were systematically examined. Subjects with specific lesions were studied. Vestibular evoked myogenic potentials (VEMP) to air conducted 0.1 ms clicks, 7 ms/250-2000 Hz tones, and forehead taps were measured for comparison.
Bone conducted sound evoked short latency p1n1 responses in both SCM muscles. Ipsilateral responses occurred earlier and were usually larger. Mean (SD) p1 and n1 latencies were 13.6 (1.8) and 22.3 (1.2) ms ipsilaterally and 14.9 (2.1) and 23.7 (2.7) ms contralaterally. Stimuli of 250 Hz delivered over the mastoid process, posterosuperior to the external acoustic meatus, yielded the largest amplitude responses. Like VEMP in response to air conducted clicks and tones, p1n1 responses were absent ipsilaterally in subjects with selective vestibular neurectomy and preserved in those with severe sensorineural hearing loss. However, p1n1 responses were preserved in conductive hearing loss, whereas VEMP to air conducted sound were abolished or attenuated. Bone conducted response thresholds were 97.5 (3.9) dB SPL/30.5 dB HL, significantly lower than thresholds to air conducted clicks (131.7 (4.9) dB SPL/86.7 dB HL) and tones (114.0 (5.3) dB SPL/106 dB HL).
Bone conducted sound evokes p1n1 responses (bone conducted VEMP) which are a useful measure of vestibular function, especially in the presence of conductive hearing loss. For a given perceptual intensity, bone conducted sound activates the vestibular apparatus more effectively than air conducted sound.
研究骨传导声音引发的肌源性电位的特性及其潜在的临床应用。
使用B 71临床骨振动器在乳突上施加持续时间为7毫秒、频率为250 - 2000赫兹的骨传导短音，记录正常志愿者的肌源性电位。使用平均未整流肌电图从双侧胸锁乳突肌（SCM）记录双相正负（p1n1）反应。系统研究刺激传递的最佳位置、最佳刺激频率、刺激阈值以及衰老对诱发反应幅度和阈值的影响。对有特定病变的受试者进行研究。测量前庭诱发肌源性电位（VEMP）对气导0.1毫秒点击声、7毫秒/250 - 2000赫兹短音以及前额轻拍的反应，以作比较。
骨传导声音在双侧SCM肌肉中诱发短潜伏期p1n1反应。同侧反应出现更早且通常更大。同侧p1和n1的平均（标准差）潜伏期分别为13.6（1.8）毫秒和22.3（1.2）毫秒，对侧分别为14.9（2.1）毫秒和23.7（2.7）毫秒。在乳突过程中，外耳道后上方施加250赫兹的刺激产生的反应幅度最大。与VEMP对气导点击声和短音的反应一样，选择性前庭神经切除术患者的同侧p1n1反应消失，而重度感音神经性听力损失患者的该反应保留。然而，p1n1反应在传导性听力损失患者中保留，而VEMP对气导声音的反应则消失或减弱。骨传导反应阈值为97.5（3.9）分贝声压级/30.5分贝听力级，显著低于气导点击声（131.7（4.9）分贝声压级/86.7分贝听力级）和短音（114.0（5.3）分贝声压级/106分贝听力级）的阈值。
骨传导声音诱发p1n1反应（骨传导VEMP），这是前庭功能的一项有用指标，尤其在存在传导性听力损失的情况下。对于给定的感知强度，骨传导声音比气导声音更有效地激活前庭装置。
