Somatosensory shift of postural control in dizzy patients.

CONCLUSIONS

Postural control is dependent on the visual system in normal conditions. Shift from visual to somatosensory dependence in dizzy patients suggests that utilizing the stable visual references is recommended for the rehabilitation of dizzy patients.

OBJECTIVES

To investigate which of the visual or somatosensory system is mainly used for substitution of the impaired spatial orientation in dizzy patients.

METHODS

We recruited 189 consecutive patients with or without dizziness and vestibular dysfunction. Dizzy patients were divided into three groups: acute, episodic, and chronic dizziness. Vestibular function was assessed by caloric test, traditional head impulse test, and head shaking nystagmus. Visual or somatosensory dependence of spatial orientation was assessed by posturography on a solid surface or on foam in eyes open or closed condition. The foam ratio (posturography with/without foam) when eyes were closed was indicative of somatosensory dependence of postural control, whereas the Romberg ratio on foam showed visual dependence. (Romberg ratio on foam)/(foam ratio with eyes closed) was calculated and used as an index of the visual/somatosensory dependence of postural control.

RESULTS

The visual/somatosensory ratio of postural control was significantly lower in dizzy patients as well as patients with vestibular dysfunction, however, no differences were found between acute, episodic, and chronic dizziness.