What could posturography tell us about balance in essential tremor?

Background: Essential tremor (ET) is a neurological disorder characterized primarily by action tremor. Balance impairments in ET patients were formerly considered to be uncommon and simply age-related. However quantitative assessment with posturography has revealed impairments in control of both static and dynamic balance.

Research question: The aim of the present study is to assess postural stability with different posturographic techniques in ET patients.

Methods: A prospective cross-sectional study conducted in two University Hospitals. Eleven patients diagnosed with essential tremor and twelve healthy controls were included. Balance assessment were performed with: sensory organization test (SOT) and limits of stability (LOS) of the computer dynamic posturography (CDP), results of free-field body sway analysis with mobile posturography (Vertiguard®), modified timed up and go test (TUG), Dizziness handicap inventory (DHI) and activities-specific balance confidence scale (ABC).

Results: Patients with ET showed poorer scores in the SOT than controls for composite balance and somatosensory input. They also performed worse in LOS tests and Vertiguard® device indicated a higher risk of falling. There were no differences in the modified TUG. The mean score of DHI was 15.64 and 85.16 for ABC.

Significance: Posturography assessment (CDP and Vertiguard®) is more accurate in showing balance impairment in ET patients than clinical evaluation (modified TUG). Balance impairment involves deteriorated processing of somatosensory input which could be explained by cerebellar dysfunction. Balance deficits could be included into future diagnostic criteria.