Discussion
tremor, Tremor, PD
ADVERSE EVENT, ESSENTIAL TREMOR, SIDE EFFECT
TAPS provided safe and effective relief of PD-associated action tremor, similar to results of previously reported relief of ET-associated action tremor [The efficacy of TAPS for PD patients in this study was comparable to that observed in previous ET studies. During a 3-month longitudinal study of ET-associated action tremor relief, 21,806 sessions were recorded during home use of TAPS therapy. Based on the median TPIR per patient, 92% of patients demonstrated an improvement in tremor power; 54% of patients experienced ≥50% reduction in tremor power; and 25% of patients experienced at least 70% reduction in tremor power [Efficacy in this PD study and previous ET studies both used BF-ADLs and tremor power to measure action tremor. This PD study used MDS-UPDRS III for clinical ratings while previous ET studies used Tremor Research Group’s Essential Tremor Rating Assessment Scale (TETRAS) [Adverse events were predominantly mild and resolved with minimal intervention. This study demonstrated that TAPS in PD has a side effect profile comparable to previous studies of TAPS in ET, with a device-related AE rate of 18% in this study in PD patients and 18% in the longitudinal home use clinical trial in ET patients [Several limitations of this study should be considered while interpreting its results. First, this was an open-label study. The field would benefit from a double-blinded, randomized sham-controlled study. However, the observed responder rates in postural tremor of MDS-UPDRS III (64% to 72%) were larger than 47% of PD patients who responded to placebo in tremor [Furthermore, previous studies of TAPS in ET-associated action tremor have been randomized to sham [Second, this study controlled the timing of PD-related medication with respect to TAPS sessions during supervised stimulation sessions at study visits but not during unsupervised home use. While it is possible the tremor improvement during home use was confounded by medication dynamics, this design captured TAPS efficacy as anticipated for real-world usage. Future studies tracking the temporal dynamics and interactions between TAPS therapy and medication would provide valuable guidance to clinicians and patients on dosing TAPS therapy in patients taking PD-related medications.Finally, this study only enrolled PD patients with postural tremor and focused on upper limb motor tasks assessable by telemedicine. Furthermore, because postural holds were performed unsupervised at home, it is possible the postural hold measurements may have unintentionally captured re-emergent tremor, in addition to postural tremor. While this enabled conducting the study during the COVID-19 pandemic, future in-person assessments on the effect of TAPS in a broader PD population and on other PD symptoms would be valuable.