Aktuelle Neurologie 2007; 34 - P722
DOI: 10.1055/s-2007-987992

Assessment of motor phenotype in Multiple Sclerosis using a force plate – a new biomarker for clinical studies?

F Holtbernd 1, M Wansing 1, R Bachmann 1, M Deppe 1, EB Ringelstein 1, R Reilmann 1
  • 1Münster

Background: Assessment of severity of symptoms in patients with Multiple Sclerosis (MS) in the setting of clinical studies is usually performed using categorical clinical scales such as the EDSS. Objective measures of disease phenotype are desirable to quantitatively and sensitively assess the progression of MS. Assessment of motor phenotype dysfunction may serve as a useful surrogate marker in MS that is easy to assess even in out-patient settings.

Objective: To investigate whether patients with MS (1) exhibit impairments in the stability of stance compared to controls that can quantitatively be assessed using a force plate and (2) to assess whether these measures correlate to the severity of disease as assessed clinically by the EDSS.

Subjects and methods: Patients with MS (n=28) and age-and-sex-matched controls (n=23) were standing on a force plate (Satel, France) with eyes open and eyes closed for 30 seconds. Subjects were instructed to stand still without moving. Stability of center of mass (COM) location was assessed by the variables “surface“, “distance“, and “velocity“ reflecting COM mobility. All subjects were assessed using the EDSS. Statistics were performed using ANOVA, t-tests, and Spearman correlations (SPSS 13.0).

Results: The measures surface, velocity and distance were significantly increased in patients with MS compared to controls (p<0.001 for all conditions with eyes open and closed). All three measures correlated to the severity of clinical symptoms in the patients as assessed by the EDSS (results for eyes open/closed, surface: r=0.659, p<0.001/r=0.664, p<0.001; velocity: r=0.730, p<0.001/r=0.789, p<0.001; distance: r=0.730, p<0.001/r=0.810, p<0.001). Loss of visual feedback severely deteriorated stability of COM in all measures in the patients (surface p<0.05, velocity p<0.01, distance p<0.01), in an EDSS dependent manner(surface r=0.468, p<0.05; velocity r=0.499, p<0.05; distance r=0.503, p<0.05). Controls showed deterioration in one measure only (distance p<0.05).

Conclusion: Assessment of stability of stance using a force plate provides objective and quantitative readouts of motor phenotype dysfunction in MS. The measures of COM dislocation were correlated to the severity of MS as expressed in the EDSS and deterioration after loss of visual feedback was EDSS dependent. A possible use of the force plate as a surrogate marker for clincial trials in MS warrants further exploration, e.g., in a blinded multicenter follow-up study.