Factor structure, normative data and retest-reliability of a test of fine motor functions in patients with idiopathic Parkinson's disease

Abstract

The purpose of this study was to measure the stability of motor functions in patients with idiopathic Parkinson's disease (IPD). A test of fine motor skills was developed that allow objective repeated measures of momentary capability among this group of patients. The study included 114 right-handed IPD-patients (mean age: 67.0+/-9.4 years, mean duration of the disease: 6.1+/-4.9 years). Patients with dementia, pharmacogenic psychiatric side-effects, other neurological diseases and tremor-type IPD were excluded. All patients were tested with an apparative motor performance test ('Motorische Leistungsserie nach Schoppe') and 24 hr later, again with the identical test. The patients (all properly adjusted to medication) were receiving different drug combinations; there was no change in the medication between tests for patients included in the analysis. Seven factors were extracted: 'finger-tapping speed,' 'speeded manual dexterity,' 'speeded finger dexterity,' 'movement planning,' 'complex movement: right,' 'complex movement: left,' and 'steadiness.' The subtests proved to have acceptable test-retest reliability. It is thus possible to produce objective, statistically sound data which enable a confirmation of improvement via medication or of the illness' progression. The presentation of normative data permits intra- and inter-individual interpretations of a single patient's performance. In addition, the patients' performance can also be compared with that of healthy controls in similar age groups (cf. data in the literature).