Effect of tetrabenazine on computerized dynamic posturography in Huntington disease patients

Background: Impairment in computerized dynamic posturography scores has been documented in Huntington disease patients. Tetrabenazine is approved to treat chorea in Huntington disease, but its effect on posturography scores, and balance in general, is unknown.

Materials and methods: We designed a study to test computerized dynamic posturography performance while taking tetrabenazine and after stopping tetrabenazine for at least three days.

Results: 10 Huntington disease patients were studied both ON and OFF tetrabenazine. The composite score was statistically different between ON and OFF conditions and both conditions were significantly worse than reference scores. There was no significant difference between ON and OFF trials in the number of falls. A significant improvement on sensory orientation test conditions 3 (sway-referenced vision) and 5 (sway-referenced motion of the support surface and eyes closed) was seen while ON tetrabenazine. Strategy scores 1-3 were also significantly different while ON tetrabenazine.

Conclusion: These findings suggest that tetrabenazine aided patients in gating out of abnormal visual cues when other sensory modalities were available, as well as in gating out abnormal kinesthetic cues when visual cues were not available. It could not help with gating out of simultaneous abnormal visual and somatosensory cues. Thus, tetrabenazine can improve postural stability when one sensory modality is irrelevant, but this effect is not sustained when multiple abnormal sensory modalities are present. This is the first study supporting the use of any medicine to treat balance problems in Huntington disease.