Impaired vestibular-neck interaction in cerebellar patients

Background: Vestibulospinal reflexes play an important role in postural and locomotor control. For appropriate functioning of these reflexes, vestibular and proprioceptive sensory signals must be integrated. Single unit recordings from the fastigial nucleus in rhesus monkeys indicate that the cerebellum is important for such vestibulo-proprioceptive interaction. This study examines if the integration of vestibular and proprioceptive signals is impaired in patients with cerebellar disease.

Methods: Vestibulo-proprioceptive interaction was investigated in patients with cerebellar disorders of various etiologies. Binaural, sinusoidal galvanic vestibular stimulation (0.16Hz) was applied, while static head-on-trunk position was systematically altered in the horizontal plane: (0° straight ahead; 30°, 45°, 60°, each left and right). In healthy controls, alteration of head position resulted in a compensatory rotation in the direction of reflectory body sway, keeping it aligned with the interaural axis. These compensatory changes in sway direction were greatly reduced or absent in cerebellar patients, particularly in those exhibiting prominent gait and stance ataxia.

Conclusion: These findings support data from animal experiments indicating an important role of the cerebellum in the integration of vestibular and proprioceptive signals. Impaired vestibulo-proprioceptive interaction may be a clinically important component of cerebellar stance and gait ataxia.