Comparison of resting tremor at the upper limb joints between patients with Parkinson's disease and scans without evidence of dopaminergic deficit

BACKGROUND

A representative symptom of Parkinson's disease (PD) is resting tremor. The clinical manifestation of scans without evidence of dopaminergic deficit (SWEDD) is similar to it of PD, though the phenomenology of SWEDD is not well known.

OBJECTIVE

In the present study, the resting tremor of 9 SWEDD patients was quantitatively compared with that of 11 PD patients.

METHODS

Four 3-axis gyro sensors were attached on the index finger, thumb, dorsum of the hand, and arm of the more tremulous side. Root mean square (RMS) angular speed and angular displacement as well as irregularity of angular speed and displacement were derived from the sensor data.

RESULTS

Although disease duration and Hoehn and Yahr stages were comparable, SWEDD patients exhibited different tremor features from PD patients. Significantly faster RMS angular speed and greater RMS angular displacement (p< 0.05) were observed in PD patients than in SWEDD patients. The irregularity of angular displacement of pitch direction at the dorsum of the hand was greater in SWEDD patients than in PD patients (p< 0.05).

CONCLUSION

These results indicate that quantitative indices obtained from resting tremor task could be important biomarkers for identifying potential patients with SWEDD among patients diagnosed with PD.

DIFFERENCES IN GAIT PATTERNS BETWEEN PATIENTS WITH SWEDD AND NORMAL SUBJECTS

Whether gait assessment can distinguish patients with scans without evidence of dopaminergic deficit (SWEDD) from normal individuals remains unclear. In the present study, the gait patterns in SWEDD patients and normal individuals were investigated. 10 patients with SWEDD and 10 healthy normal subjects were recruited. A GaitRite linear walkway was used to quantitatively assess level walking. Eight spatiotemporal variables were selected for comparison between two groups. For statistical analysis, independent sample [Formula: see text]-tests were performed to compare between normal individuals and SWEDD patients. Compared with normal individuals, SWEDD patients exhibited a shorter step length ([Formula: see text]). In addition, SWEDD patients showed a wider distribution of heel-to-heel (HH) base of support compared with normal individuals ([Formula: see text]). SWEDD patients had a tendency to deteriorated gait speed ([Formula: see text]) and double-limb support cycle ([Formula: see text]). These results indicate that SWEDD patients adopted a walking strategy that utilized increased step length and width to compensate for deteriorated dynamic balance. These results indicate that quantitative gait assessment could be useful for more accurate diagnosis of SWEDD patients. In addition, understanding clinical features of SWEDD patients might contribute to efficient interventions.

COMPARISON OF STATIC POSTURAL BALANCE IN PATIENTS WITH SWEDDS AND PARKINSON’S DISEASE

Differentiating scans without evidence of dopaminergic deficits (SWEDDs) from Parkinson’s disease (PD) is very important to avoid costly and inappropriate interventions. The postural balance strategy patients with SWEDDs are not clear. This study investigates the difference in static postural balance between patients with SWEDDs and PD. Twenty-two patients (11 SWEDDs and 11 PD groups) and 11 control groups were instructed to quietly stand on a custom-made force platform. The outcome measures were, mean distance, 95% confidence ellipse area, mean velocity, mean frequency, peak frequency and peak power derived from the center of pressure (COP) data in overall, medio-lateral (ML) and anterio-posterior (AP) directions. As statistical analysis, ANOVA and post hoc tests were conducted for comparison of patients with SWEDDs and PD. SWEDDs patients presented a smaller postural sway size and a more frequent postural sway mainly in the ML direction ([Formula: see text]). On the contrary, there were no significant differences in mean velocity and peak power. Also, no significant differences existed between SWEDDs and normal subjects ([Formula: see text]). The results reflect that a few COP-based outcome variables might be useful to distinguish SWEDDs patients from PD patients. This study suggests that a static postural balance test can be used for clinical screening and identification of potential SWEDDs.