This analysis aimed to expand understanding of the efficacy and safety of consecutive transcutaneous afferent patterned stimulation (TAPS) sessions in people with essential tremor (ET) or Parkinson's Disease (PD).

TAPS is a non-invasive neuromodulation therapy that can improve action tremor in people with ET or PD [Isaacson 2020]. While real world evidence has demonstrated that tremor improvement can persist over back-to-back (i.e. consecutive) sessions in real-world settings [Lu 2023], this has yet to be evaluated in a prospective study.

Eleven ET and 9 PD patients were instructed to perform 3 daily back-to-back 40-minute TAPS sessions at home for 2 weeks. Back-to-back sessions were defined as those that were at least 20 minutes in length and within 20 minutes of one another. Measures of tremor power were collected on-device before and after every session during remote patient visits. The tremor power improvement ratio (pre/post-stimulation power, TPIR) of each session was computed by comparing post-stimulation power to the pre-stimulation power of the first session. Median TPIR was then calculated for each patient. 

Of the 20 enrolled patients, 16 (8 ET, 8 PD) completed the study. Tremor power improved after the first TAPS session (3.00 ×/÷ 1.54, geometric mean and standard error), was maintained at a similar level after the second session (3.05 ×/÷ 1.56, p=0.782) and may have increased after the third session (9.34 ×/÷ 1.97, uncorrected p=0.039). Ten percent (2 out of 20) patients reported an adverse event of which both were for minor skin irritation.

These findings suggest that patients could perform consecutive therapy sessions to experience longer action hand tremor relief and that back-to-back sessions share a similar safety profile to that of a single TAPS session [Isaacson 2020]. Future work is warranted to identify the patient population that is most likely to benefit from consecutive sessions.