Does the trunk impairment scale discriminate between trunk motor performance in patients with Parkinson’s disease and age-matched controls?

Objective: To determine the ability of the Trunk Impairment Scale (TIS) to discriminate between PD and healthy controls and to investigate which clinical characteristics would predict the outcome on the TIS.Background: The TIS is an instrument originally developed to evaluate trunk function in stroke patients. As patients with Parkinson’s disease (PD) classically have axial symptoms, this study wanted to determine whether the TIS can be suitably applied to this population. Methods: The design involved a cross-sectional study on 26 subjects with PD. Participants were evaluated with the TIS to assess their static and dynamic sitting balance and trunk movement coordination. A spinal mouse was used to determine postural deformity in sitting and standing. Twentysix control subjects were selected from an existing database, matched for age and sex. Results: Patients consisted of 17 males and 9 females with a mean age of 65 years (SD9), a median Hoehn and Yahr stage of 2.5 (range 2-4) and median UPDRS III score of 25 (range 8-36). Controls had a mean age of 65 (SD12). Patients with PD scored significantly lower on the TIS (p.0001) compared to the healthy individuals. When analysing 14 patients from HY stage 2 separately, TIS-scores were also significantly different from controls (p0.0003) and from the 15 patients in HY stage 3 and 4 (p0.04). Overall patients scored a median of 18 between 11-23 of the total range of 0-23 on the TIS. Controls had a median of 22 (range 17-23). Multivariate linear regression analysis showed that disease severity (UPDRS III) (R20.54, p.0001) and age (added R20.09, p.03) were significant variables in predicting trunk impairment in PD. Spinal mouse results revealed that 38% of patients had thoracic kyphosis in stance and 12% in sitting. Patients with more pronounced thoracic kyphosis in sitting also had decreased TIS scores (Rs-0.56, p0.0027). Conclusion: Disease severity, age and degree of thoracic kyphosis in sitting are important determinants of trunk impairment in PD. The TIS is able to discriminate between trunk motor performance in persons with early PD and age-matched controls. Patients did not use the full range of the scale. Further reliability study is indicated to validate an adapted version of the TIS.