Elsevier

Gait & Posture

Volume 7, Issue 3, 1 May 1998, Pages 228-236
Gait & Posture

Postural responses to vibration of neck muscles in patients with uni- and bilateral vestibular loss

https://doi.org/10.1016/S0966-6362(98)00012-5Get rights and content

Abstract

Postural responses to vibration applied unilaterally to the dorsal neck muscles were recorded with a sway platform in 11 patients with bilateral vestibular loss (BLD), 13 patients with unilateral vestibular lesions (ULD) and 19 normal subjects. In the normals, the vibration induced a forward postural deviation. Vibration failed to induce postural sway in the BLD patients but induced a backwards head movement in 7 patients. In the ULD patients, vibration contralateral to the lesion induced normal forward sway, whereas ipsilateral vibration resulted in sway directed to the side of the lesion and backwards. The findings demonstrate the importance of concurrent vestibular signals in determining the behavioural response to neck afferent input. We propose that in normal subjects the intact vestibular signal gives no confirmation that a head movement has occurred so it is assumed that the lower body has tilted forwards which provokes a compensatory sway. In the total absence of vestibular function the neck signal may represent a real head movement so the preferential response is a head tilt to restore upright posture. The vestibular imbalance in the ULD patients is roughly equivalent to the asymmetrical signals obtained in a normal subject during head rotation to the intact side. The stretch signal induced by ipsi-lesional vibration confirms possible head rotation, thus provoking a compensatory postural sway.

Introduction

Recordings of muscle spindle afferents during the vibration of muscle in both animals [1]and in humans 2, 3have shown that vibration selectively activates muscle stretch receptors; particularly Ia spindle afferents giving rise to a false signal of stretch. In human subjects, the responses to such `artificial stretch' signals are plastic. Vibration applied to a relaxed muscle gives rise to a tonic muscular contraction (tonic vibration reflex; [4]) and an illusory motion about the respective joint 5, 6when the actual movement is frustrated by a mechanical restraint. For example, vibration applied to Achilles tendons in a seated subject induces a tonic contraction of the ankle extensors or illusory dorsiflexion of the feet. Whereas, in a standing subject, Achilles tendon vibration gives a whole body sway backwards 7, 8and illusory, whole-body tilt forwards when the torso is restrained 5, 8. These findings show that central processing of proprioceptive afference depends on the postural context; specifically what possible reference (e.g. feet, trunk, etc.) is taken to be stationary. The choice of a particular reference is of crucial importance for the central interpretation of proprioceptive signals as they carry information about relative motions of the body segments rather than their trajectories in external space.

In the example of the Achilles tendon vibration the likely reference is the ground (i.e. the foot support). Afferent signals from the apparent lengthening of the extensor tendon are interpreted by the brain as the whole body deviation forward with respect to stationary feet, thus giving rise to either illusory forward tilt and/or backwards body sway as a compensating postural adjustment.

A backwards sway deviation can also be observed when other postural muscles of the posterior body surface are stimulated by vibration; the only exception being that vibration of the neck region results in a body sway forwards 9, 10, 11. It has been hypothesised that this difference is due to the fact that proprioceptive signals from the neck are processed jointly with vestibular input with the head taken as a reference [12]. Since, with the neck vibration, there is no concomitant signal from the labyrinth of head tilt, the brain estimates the signal as a tilt of the body beneath the space-fixed head with the neck as axis of rotation. This `illusory' tilt gives rise to a forwards sway response which is directed to returning the body to the upright.

On this hypothesis, one could expect that vestibular dysfunction would lead to a misinterpretation of proprioceptive signals from the neck. This has been tested in the present study which examines sway responses to vibration of the neck muscles in patients with peripheral vestibular lesions. Bilateral vibration of the dorsal neck muscles has been reported to increase sway in patients with central vestibular lesions whereas patients with unilateral peripheral lesions were unaffected by vibration [13]. Alternatively, other authors [14]have reported a lateral component (directed to the lesioned side) in the body sway evoked by vibration of dorsal neck muscles in compensated patients with unilateral vestibular dysfunction. Our experiments differ in that the vibration was applied unilaterally, thus uncovering asymmetries of postural response in patients with unilateral vestibular lesions (ULDs).

Section snippets

Apparatus

Subjects stood on a 50 cm square sway platform 20 cm high above the ground. The centres of the heels were approximately 10 cm apart and the feet splayed out at approximately 35°. Subjects were allowed to wear their everyday shoes and fortunately none of the women tested had fashion heels.

An electromechanical vibrator, 6.0 cm long, 2.5 cm wide with a flat 6×3.5 cm rectangular contact surface was positioned over the medial and superior aspect of the right (or left) trapezius muscle and held in

General characteristics of responses

In normal subjects, vibration of the neck muscles resulted in a whole body sway forward which was usually visible and attained up to 10° of tilt of the long axis at maximum. The response recorded by the sway platform consisted of a small backwards torque, seen better on average, followed by a forward deviation (Fig. 1, Fig. 2). At the offset of vibration the body returned to the upright.

In BLD patients, neck vibration resulted in neither sway deviation nor a postural instability but it was

Mechanisms of postural responses to neck vibration

A quiet stance is usually not impaired in patients with compensated vestibular disorders 16, 17but may become unstable when other sensory inputs (e.g. visual, proprioceptive, somatosensory) are manipulated 18, 19, 20, when adopting unusual attitudes 17, 21or during movement of the head 22, 23or body [24]. The causes of this instability may be twofold; the more basic being the impairment of vestibulo-spinal reflexes 25, 26. The second, as hypothesised by Black et al. [18], is the instability

References (43)

  • J.C. Gilhodes et al.

    Perceptual and motor effects of agonist-antagonist muscle vibration in man

    Exp Brain Res

    (1986)
  • G. Eklund

    General features of vibration-induced effects on balance

    Upps J Med Sci

    (1972)
  • V.S. Gurfinkel et al.

    [A study of the upright stance regulation system by means of vibratory stimulation of the muscle spindles]

    Fiziol Cheloveka

    (1977)
  • S. Lund

    Postural effects of neck muscle vibration in man

    Experientia

    (1980)
  • T. Morizono

    [Influence of neck vibration on body sway]

    Nippon-Jibinkoka-Gakkai-Kaiho

    (1991)
  • B.N. Smetanin et al.

    Postural responses to vibrostimulation of neck muscle proprioceptors

    Neurophysiology

    (1993)
  • H. Lekhel et al.

    Postural responses to vibration of neck muscles in patients with idiopathic torticollis

    Brain

    (1997)
  • I. Pyykko et al.

    Effect of proprioceptor stimulation on postural stability in patients with peripheral or central vestibular lesion

    Acta Otolaryngol Stockh

    (1991)
  • Hatano G., Yagi T., Morizono T. [The role of the cervical input in vestibular compensation]. Equilibrium Res 1992;Suppl...
  • M. Ojala et al.

    Posturography and the dizzy patient: a neurological study of 133 patients

    Acta Neurol Scand

    (1989)
  • P.L. Ghilardi et al.

    La posturografia nei deficit unilaterali vestibolari periferici [Posturography in unilateral peripheral vestibular deficiency]

    Acta Otorhinolaryngol Italy

    (1990)
  • Cited by (32)

    • Physiology of dystonia: Human studies

      2023, International Review of Neurobiology
    • The effects of neck muscle vibration on postural orientation and spatial perception: A systematic review

      2020, Neurophysiologie Clinique
      Citation Excerpt :

      Similarly, vestibular patients are of particular interest, as their asymmetrical behaviors could be at least partially due to body misorientation in space in acute disorders, as a result of imbalance of left and right vestibular inputs [8]. For unilateral vestibular patients, unilateral NMV induces a body tilt either in the antero-posterior plane or towards the lesional side, translating into the misinterpretation of vestibular information, which is not corrected [45,67]. In the case of bilateral vestibular or compensated vestibular lesion, no effect was found.

    • The influence of neck pain on balance and gait parameters in community-dwelling elders

      2008, Manual Therapy
      Citation Excerpt :

      March et al. (1998) documented a neck pain prevalence of 40.5% in elderly women and 36.1% in elderly men living independently in the community. Cervical afferent input is an important contributor to balance (Karlberg et al., 1996a; Lekhel et al., 1998; Bove et al., 2002) and balance disturbances have been documented in young and middle aged individuals with neck pain of both insidious and traumatic onset (Michaelson et al., 2003; Treleaven et al., 2005a,b). Subsequent improvements in balance have been demonstrated following localised treatment to the cervical spine (Fattori et al., 1996; Karlberg et al., 1996a).

    • Standing balance: A comparison between idiopathic and whiplash-induced neck pain

      2008, Manual Therapy
      Citation Excerpt :

      A link between neck pain and impairment in balance is suggested in several studies, which have demonstrated improvements in standing balance following treatment localized to the cervical spine (Alund et al., 1993; Fattori et al., 1996; Karlberg et al., 1996b; Persson et al., 1996). The co-occurrence of neck pain and balance disturbances is not surprising as the abundant cervical receptors in the muscles and joints of the cervical spine as well as their central and reflex connections to the vestibular, visual and postural control systems suggest that they have an important role in providing information for general postural control (Karlberg et al., 1995; Lekhel et al., 1998; Bove et al., 2002; Peterson, 2004). The association between disturbances to cervical afferentation and disturbances to standing balance has been demonstrated in several ways.

    View all citing articles on Scopus
    View full text