A quantitative investigation of the handwriting kinematics in response to STN-DBS in Parkinson's disease patients.

AIM

The aim of this manuscript was to investigate possible handwriting alterations focusing on micrographia in PD patients with STN-DBS in distinct stimulation conditions.

METHODS

All consecutive PD patients with STN-DBS therapy who visited our movement disorder center between October 2023 and December 2023 and agreed to participate in the study were enrolled. Extensive clinical assessments including various scales were performed. The MDS-UPDRS-III-stimulation-'off' and 'on' scores were evaluated. The handwriting parameters including letter area, writing time and pressure were measured on a digital graphic tablet using an electronic pen. In addition to these parameters, indices related to micrographia were measured under four stimulation conditions (bilateral, left, right, no stimulation).

RESULTS

Overall, we included 20 patients with a mean age of 56.7 ± 11.4 years (F/M = 7/13). The comparisons of the handwriting parameters did not reveal any significant differences between the distinct stimulation conditions. Writing duration showed strong correlations with the HAM-A score (CC = 0.662,  = 0.007) and the HDRS score (CC = 0.642,  = 0.005).

CONCLUSION

No stimulation-related dynamic changes were observed in handwriting kinematics in patients with STN-DBS. These findings might give perspectives regarding the pathophysiology of micrographia in PD as well as mechanisms underlying the efficacy of STN-DBS.