Smulders Y E, Welgampola M S, Burgess A M, McGarvie L A, Halmagyi G M, Curthoys I S
Vestibular Research Laboratory, School of Psychology, University of Sydney, NSW, Australia.
Clin Neurophysiol. 2009 Aug;120(8):1567-76. doi: 10.1016/j.clinph.2009.06.008. Epub 2009 Jul 24.
Bone-conducted vibration (BCV) in the midline at the hairline (Fz), results in short latency potentials recorded by surface electrodes beneath the eyes - the ocular vestibular-evoked myogenic potential (oVEMP). The early negative component of the oVEMP, n10, is due to vestibular stimulation, however it is similar to the early R1 component of the blink reflex. Here we seek to dissociate n10 from R1.
Surface potentials were recorded from the infraorbital electromyogram of 10 healthy subjects, 6 patients with bilateral vestibular loss, 2 with unilateral vestibular loss, 4 with facial palsy and 3 with facial and vestibular nerve lesions on the same side. BCV was delivered at Fz, the inion, the glabella or the supraorbital ridge using a tendon hammer or a bone-conduction vibrator.
Onset latencies of the n10 evoked by taps at Fz or inion were significantly shorter than the R1 components of blink responses to supraorbital and glabellar stimuli. Upward gaze increased the amplitude of n10 but not R1. The n10 was absent bilaterally in patients with bilateral vestibular loss and beneath the contralesional eye in patients with unilateral vestibular loss, but in both these groups of patients R1 was preserved. In severe facial palsy the R1 component was absent or delayed and attenuated ipsilesionally, but n10 was preserved bilaterally. In subjects with unilateral facial and vestibular nerve lesions (Herpes Zoster of the facial and vestibulocochlear nerves) the dissociation was complete - the ipsilesional R1 was absent or attenuated whereas the ipsilesional n10 was preserved.
n10 is distinguished from R1 by its earlier onset, laterality, modulation by gaze position and dissociation in patient groups.
The n10 component evoked by BCV at Fz is not the R1 component of the blink reflex.
在发际线中线（Fz）处进行骨传导振动（BCV），可在眼睛下方的表面电极记录到潜伏期短的电位——眼前庭诱发肌源性电位（oVEMP）。oVEMP的早期负向成分n10是由前庭刺激引起的，然而它与眨眼反射的早期R1成分相似。在此，我们试图将n10与R1区分开来。
记录了10名健康受试者、6名双侧前庭功能丧失患者、2名单侧前庭功能丧失患者、4名面神经麻痹患者以及3名同侧面部和前庭神经损伤患者的眶下肌电图表面电位。使用肌腱锤或骨传导振动器在Fz、枕外隆凸、眉间或眶上嵴处施加BCV。
在Fz或枕外隆凸处轻敲诱发的n10起始潜伏期明显短于对眶上和眉间刺激的眨眼反应的R1成分。向上注视可增加n10的幅度，但不增加R1的幅度。双侧前庭功能丧失患者双侧n10缺失，单侧前庭功能丧失患者患侧眼下方n10缺失，但在这两组患者中R1均保留。在严重面神经麻痹患者中，R1成分缺失或延迟且同侧减弱，但n10双侧保留。在单侧面部和前庭神经损伤（面和前庭蜗神经带状疱疹）的受试者中，区分是完全的——患侧R1缺失或减弱，而患侧n10保留。
n10通过其更早的起始、偏侧性、注视位置调节以及在患者群体中的区分与R1相区别。
在Fz处由BCV诱发的n10成分不是眨眼反射的R1成分。
