Objective: This study was designed to determine the efficacy of the Tremor Detection and Suppression device (TDS) as a therapeutic option in PD patients with intractable tremor.

Background: As the pathophysiology of tremor in Parkinson’s disease (PD) involves a complex interaction between central and peripheral mechanisms. From our previous study, we proposed that modulation of peripheral reflex mechanism by electrical muscle stimulation (EMS) could improve tremor temporarily. This study, we explore the efficacy of EMS for tremor reduction by a well-fitted device in a controlled setting with sham stimulation.

Methods: This is a randomized, controlled, pilot study involving 17 PD patients who satisfy the criteria of intractable tremor (10 in the TDS device group and 7 with sham stimulation). The glove was worn in more affected hand with attached sensor placed in the proximal part of the index finger.Stimulation of affected hand muscle was delivered via the 1.5*1.5 inches self-adhering electrodes. For TDS device group, pulse amplitude was slowly increased until tetanic muscle contractions without pain were observed. Subjects with sham stimulation received a similar set-up to the TDS device but a series of LED flashes was designed to act as a set of stimulation instead of the EMS.

Results: There were no significant differences in demographic data and tremor parameters between two groups.

comparison of demographic data, tremor parameters, and tremor outcomes between 2 groups

Items	TDS device group	Sham stimulation group	p-value
Age (year)	64.00 +/- 12.88	63.43 +/- 13.30	0.887
Disease duration (year)	8.30 +/- 4.29	6.29 +/- 2.75	0.417
TMSE score	25.3 +/- 2.63	26.43 +/- 3.86	0.417
LED dosage	583.00 +/- 302.82	824.12 +/- 477.26	0.270
Hoehn and Yahr	2.75 +/- 0.75	2.5 +/- 0.91	0.536
OFF UPDRS tremor score	10.9 +/- 4.28	8.57 +/-3.41	0.23
ON UPDRS tremor	6.1 +/- 2.81	5.57 +/- 2.3	0.536
ON UPDRS tremor of most affected hand	2.20 +/- 0.63	2.29 +/- 0.5	0.887
ON UPDRS tremor the most affected hand during stimulation	0.80 +/- 0.63	2.14 +/- 0.70	0.003*
Pulse amplitude (mA)	9.10 +/- 4.04	0.00 +/- 0.00	<0.001*
RMS axis X before stimulation	1.94 +/- 1.91	2.02 +/- 2.55	0.669
RMS axis Y before stimulation	2.09 +/- 2.11	3.31 +/- 5.96	0.669
RMS axis Z before stimulation	1.28 +/- 1.25	3.47+/- 7.46	0.740
RMS axis X during stimulation	1.01 +/- 1.28	2.03 +/- 2.46	0.315
RMS axis Y during stimulation	0.71 +/- 0.68	3.57 +/- 6.75	0.315
RMS axis Z during stimulation	0.66 +/- 0.59	3.24 +/- 648	0.417
Reduction of RMS axis X	0.93 +/- 1.38	-0.01 +/- 0.33	0.010*
Reduction of RMS axis Y	1.39 +/- 1.62	-0.26 +/- 1.22	0.013*
Reduction of RMS axis Z	0.63 +/- 1.03	0.22 +/- 0.99	0.109
Percentage of tremor attenuation axis X	44.15 +/- 28.75	-13.96 +/- 30.20	0.001*
Percentage of tremor attenuation axis Y	49.41 +/- 29.27	-11.56 +/- 43.85	0.007*
Percentage of tremor attenuation axis Z	24.85 +/- 45.22	-41.93 +/- 55.69	0.055
Percentage of tremor attenuation from UPDRS tremor of the most affected hand	63.33 +/- 31.23	7.14 +/- 18.90	0.003*

all statistic analysis were performed by Mann-Whitney U test, RMS; the root mean square of angular velocity, Reduction of RMS; RMS before stimulation minus with RMS during stimulation, UPDRS tremor score; a sum score of the UPDRS tremor items 16,20, and 21 (maximum 32 points), UPDRS tremor of the most affected hand ; a score of the UPDRS tremor item 20 of the most affected hand (maximum 4 points)” During stimulation, significant reductions of RMS angular velocity in both X- and Y-axis were observed in TDS device group than those with sham stimulation (p=0.010, and p=0.013, respectively). Compared to before stimulation, EMS provided significant reductions of the RMS of the angular velocity in all axis (X:p=0.007,Y:p=0.007,Z: p=0.047), and significant reduction of UPDRS tremor score of the most affected hand (p=0.006), while tremor frequency remained unchanged during the stimulation.

comparison tremor parameters between before and during stimulation in both groups

Group	Parameters	Before stimulation	During stimulation	p-value
TDS device	UPDRS tremor of the most affected hand	2.20 +/- 0.63	0.80 +/- 0.63	0.006*
	RMS axis X	1.94 +/- 1.91	1.01 +/- 1.28	0.007*
	RMS axis Y	2.09 +/- 2.11	0.71 +/- 0.68	0.007*
	RMS axis Z	1.28 +/- 1.25	0.66 +/- 0.59	0.047*
	Frequency axis X	5 +/- 1.49	6.43 +/- 1.48	0.066
	Frequency axis Y	4.96 +/- 2.25	5.38 +/- 1.32	0.541
	Frequency axis Z	5.27 +/- 1.69	5.69 +/- 1.59	0.553
Sham stimulation	UPDRS tremor of the most affected hand	2.29 +/- 0.5	2.14 +/- 0.70	0.317
	RMS axis X	2.02 +/- 2.55	2.03 +/- 2.46	0.612
	RMS axis Y	3.31 +/- 5.96	3.57 +/- 6.75	0.310
	RMS axis Z	3.47 +/- 7.46	3.24 +/- 6.48	0.499
	Frequency axis X	5.31 +/- 1.55	5.75 +/- 1.03	0.352
	Frequency axis Y	5.98 +/- 0.73	5.14 +/- 1.54	0.269
	Frequency axis Z	5.03 +/- 1.56	5.92 +/- 0.66	0.236

All statistic analysis were performed by Wilcoxon Sign Rank Test, UPDRS; Unified Parkinson’s disease Rating scale, UPDRS tremor of the most affected hand; a score of the UPDRS tremor item 20 of the most affected hand (maximum 4 points), RMS; the root mean square of angular velocity“ However, there were no improved in any tremor modality in the sham stimulation. None of adverse events were reported.

Conclusions: We demonstrated the efficacy of TDS device in the suppression of intractable rest tremor in PD. The efficacy was observed in clinical tremor score, RMS angular velocity, but not tremor frequency. Our study provides the preliminary evidence of EMS in the reduction of Parkinsonian tremor. Larger studies are needed to explore the efficacy of EMS as a therapeutic option of Parkinsonian tremor.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-efficacy-of-tremor-detection-and-suppression-device-in-intractable-rest-tremor-in-patients-with-parkinsons-disease/