对颅骨外侧轻敲所产生的前庭诱发肌源性电位取决于两种不同机制。

Vestibular evoked myogenic potentials in response to lateral skull taps are dependent on two different mechanisms.

作者信息

Brantberg Krister, Westin Magnus, Löfqvist Lennart, Verrecchia Luca, Tribukait Arne

机构信息

Department of Audiology, Karolinska Hospital, 171 76 Stockholm, Sweden.

出版信息

Clin Neurophysiol. 2009 May;120(5):974-9. doi: 10.1016/j.clinph.2009.03.008. Epub 2009 Apr 18.

DOI:10.1016/j.clinph.2009.03.008

PMID:19376744

Abstract

OBJECTIVE

To explore the mechanisms for skull tap induced vestibular evoked myogenic potentials (VEMP).

METHODS

The muscular responses were recorded over both sternocleidomastoid (SCM) muscles using skin electrodes. A skull tapper which provided a constant stimulus intensity was used to test cervical vestibular evoked myogenic potentials (VEMP) in response to lateral skull taps in healthy subjects (n=10) and in patients with severe unilateral loss of vestibular function (n=10).

RESULTS

Skull taps applied approximately 2 cm above the outer ear canal caused highly reproducible VEMP. There were differences in VEMP in both normals and patients depending on side of tapping. In normals, there was a positive-negative ("normal") VEMP on the side contra-lateral to the skull tapping, but no significant VEMP ipsi-laterally. In patients, skull taps above the lesioned ear caused a contra-lateral positive-negative VEMP (as it did in the normals), in addition there was an ipsi-lateral negative-positive ("inverted") VEMP. When skull taps were presented above the healthy ear there was only a small contra-lateral positive-negative VEMP but, similar to the normals, no VEMP ipsi-laterally.

CONCLUSIONS

The present data, in conjunction with earlier findings, support a theory that skull-tap VEMP responses are mediated by two different mechanisms. It is suggested that skull tapping causes both a purely ipsi-lateral stimulus side independent SCM response and a bilateral and of opposite polarity SCM response that is stimulus side dependent. Possibly, the skull tap induced VEMP responses are the sum of a stimulation of two species of vestibular receptors, one excited by vibration (which is rather stimulus site independent) and one excited by translation (which is more stimulus site dependent).

SIGNIFICANCE

Skull-tap VEMP probably have two different mechanisms. Separation of the two components might reveal the status of different labyrinthine functions.

摘要

目的

探讨颅骨轻敲诱发前庭诱发肌源性电位（VEMP）的机制。

方法

使用皮肤电极在双侧胸锁乳突肌（SCM）上记录肌肉反应。使用提供恒定刺激强度的颅骨敲击器，测试健康受试者（n = 10）和重度单侧前庭功能丧失患者（n = 10）对颅骨外侧轻敲的颈前庭诱发肌源性电位（VEMP）。

结果

在外耳道上方约2 cm处进行颅骨轻敲可引起高度可重复的VEMP。正常人和患者的VEMP根据轻敲侧不同而有所差异。在正常人中，颅骨轻敲对侧出现正负（“正常”）VEMP，同侧无明显VEMP。在患者中，病耳上方的颅骨轻敲引起对侧正负VEMP（与正常人相同），此外同侧还有负正（"倒置"）VEMP。当在健耳上方进行颅骨轻敲时，仅出现较小的对侧正负VEMP，但与正常人相似，同侧无VEMP。

结论

目前的数据与早期研究结果相结合，支持颅骨轻敲VEMP反应由两种不同机制介导的理论。提示颅骨轻敲既引起纯粹的同侧刺激侧独立的SCM反应，也引起双侧且极性相反的刺激侧依赖的SCM反应。颅骨轻敲诱发的VEMP反应可能是两种前庭感受器刺激的总和，一种由振动兴奋（刺激部位依赖性较小），另一种由平移兴奋（刺激部位依赖性较大）。