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Introduction: There are currently no effective treatments for primary orthostatic tremor (POT). An adequate disease-specific POT severity scale is a prerequisite to conduct clinical trials and monitor disease severity in clinical practice. Recently, the English OT-10 scale has been developed for this purpose. Here we aimed to obtain a scale to measure the severity of POT in Dutch speaking individuals. Methods: An established translation, adaptation and validation approach was employed to obtain a Dutch version of the OT-10 scale. Validation was performed in a Dutch POT cohort (n = 46). Results: A Dutch OT-10 scale was obtained which showed good internal consistency (Cronbach's alpha > 0.80), total score test-retest reliability (intraclass correlation coefficient > 0.80), and concurrent validity (Pearson correlation > 0.80). Item-to-total correlation was good (weighted kappa > 0.40) for all items, and item test-retest reliability was good (weighted kappa > 0.40) for eight out of ten items. Overall, the Dutch OT-10 scale demonstrated acceptable validity. Conclusions: We obtained and validated a Dutch version of the OT-10 scale, capturing POT severity. Next to its use in clinical practice, translation and validation of the OT-10 scale in more languages will help to find evidence-based treatments for POT.
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BACKGROUND: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an established treatment for disabling motor symptoms of Parkinson's disease (PD) that persist despite optimal pharmacological treatment. Currently, DBS is not performed if there is concomitant significant cognitive impairment based on concerns of cognitive deterioration, higher complication rate and less functional improvement. However, this has not been investigated so far. METHODS: A single center, prospective, randomized, open-label, blinded end-point (PROBE design) pilot clinical trial is being performed. Patients are eligible for the trial if they have PD dementia (PDD), are able to provide informed consent, and experience disabling motor response fluctuations, bradykinesia, dyskinesia, or painful dystonia, despite optimal pharmacological treatment. In total 44 patients will be randomized to either STN-DBS accompanied by best medical treatment (DBS group) or to best medical treatment alone (BMT group). The primary outcome measure is the change from baseline to 30 weeks on the Movement Disorder Society-Unified Parkinson's Disease Rating Scale part III score in a standardized off-drug phase. The main secondary outcome measures consist of scales assessing cognitive aspects of daily living, neuropsychiatric symptoms and impulsive compulsive disorders. Additional secondary outcome measures include motor signs during on-drug phase, dyskinesia, motor fluctuations, cognitive performance, (severe) adverse events, treatment satisfaction, and caregiver burden. Patients will be followed during 52 weeks after randomization. DISCUSSION: The Deep Brain Stimulation for MOtor symptoms in patients with Parkinson's disease DEmentia (DBS-MODE) trial directly compares the effectiveness and safety of DBS with BMT in patients with PDD. TRIAL REGISTRATION: The DBS-MODE trial has been registered in the International Clinical Trial Registry Platform (NL9361) on the 24th of March 2021 ( https://trialsearch.who.int/Trial2.aspx?TrialID=NL9361 ).
