Influence of vibration to the neck, trunk and lower extremity muscles on equilibrium in normal subjects and patients with unilateral labyrinthine dysfunction

To investigate the role of proprioceptors of different skeletal muscles in postural control, in normal subjects and patients with unilateral labyrinth ine dysfunction (ULD), the effect of vibration on these muscles was studied by postulography. The subjects comprised 59 normal subjects and 12 patient s with ULD due to resection of acoustic tumours. Sagittal body sway was obs erved during vibration to the triceps surae, tibialis anterior and upper do rsal neck muscles. No significant change in sway was observed in the fronta l plane in normal subjects. Significant differences between normal subjects and patients were found on stimulation of the muscle groups of triceps sur ae and biceps femoris during vibration. In patients with ULD, vibration to the dorsal neck muscles caused a deviation towards the diseased side. It ca n be speculated that the upper dorsal neck muscle plays an important role i n maintaining the body balance in the frontal plane in patients with ULD. O n the other hand, the lower extremity muscles, especially the muscles on th e dorsal side of the body, play a significant role in adjusting the standin g posture in the sagittal plane.