Analysis of dysgraphia in advanced Parkinson’s disease patients following bilateral STN-DBS: a prospective study

BACKGROUND: Parkinson’s disease (PD) is characterized by varying intensities of bradykinesia, rigidity, and tremor leading to disturbances in writing skills of the patient. We undertook this study to evaluate dysgraphia features in advanced PD cases and changes in these features after bilateral subthalamic nucleus deep brain stimulation (DBS). METHODS: All idiopathic PD cases who underwent DBS at our center were included in this study. Patients were assessed preoperatively for dysgraphia by analysis of handwriting in “off” phase by a single investigator on bedside testing. For quantification of micrographia, vertical length of first letter and width of the word written were calculated. An analysis of legibility of handwriting was also done for all patients using Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS). Patients were analyzed for dysgraphia at 6 months post-surgery in drug ‘off’ phase, and outcomes were correlated with baseline parameters. RESULTS: There were a total of 51 patients who were included in our study. Significant reduction was noted in postoperative Unified Parkinson’s Disease Rating Scale part III (UPDRS III) scores (P = 0.0001). Age more than 65 years was associated with less improvement in FTMTRS grades. Prevalence of micrographia reduced in the postoperative period, but the difference was not statistically significant. Median FTMTRS grade in preoperative and postoperative “off” phase was 3 and 2, respectively. Difference in pre- and postsurgery FTMTRS grades was found to be statistically significant (P = 0.00001). CONCLUSION: Subthalamic nucleus DBS results in substantial improvement in legibility of handwriting of patients, particularly in cases with age less than 65 years.