| Popis: |
Background: Freezing of gait (FOG) is notoriously difficult to quantify, leading to multiple metrics utilized as outcomes for clinical trials. The instrumented timed up a go and the many parameters that can be derived from it are commonly used as objective markers of gait severity in FOG trials, however it is unknown if they represent FOG severity. Objective: To determine the specificity and responsiveness of objective surrogate markers of FOG severity commonly utilized in FOG studies. Methods: Markers compared included: velocity, step/stride length, step/stride length variability, TUG, and turn duration. Data was collected in four conditions (ON and OFF dopaminergic drugs, with and without a dual task). Unified Parkinson’s Disease rating scale (UPDRS) was administered in the ON and OFF states. Results: 33 subjects were recruited (17 PD subjects without FOG (PD-control), and 16 subjects with PD and dopa-responsive FOG PD-FOG). The UPDRS motor scores were: 24.9 for the PD-control group in the ON state, 24.8 for the FOG group in the ON state, 42.4 for the FOG group in the OFF state. Significant mean differences between the ON and OFF conditions were observed with all surrogate markers (p0.90) for all markers except standard deviations. Step length variability was the only marker to show an area under the ROC curve analysis >0.70 comparing ON-FOG vs. PD-control. Conclusions: Multiple candidate surrogate markers for FOG severity showed responsiveness to levodopa challenge, however, most were not specific for FOG severity. |
