The tVNS-PP trial investigates the effects of transcutaneous vagus nerve stimulation (tVNS) on autonomic functions, immune responses, and disease severity in chronic pain and restless legs syndrome (RLS) patients as compared to healthy controls.
A pilot study with healthy participants will investigate whether transcutaneous vagus nerve stimulation at the inner tragus reduces heart rate variability and lowers blood pressure without causing undesirable, severe side effects. In addition, changes in immune markers will be analyzed in blood samples before and after the interventions. Patients with primary restless legs syndrome will undergo a similar experimental protocol, except that transcutaneous vagus nerve stimulation will be performed daily. The aim is to determine whether stimulation reduces disease severity and chronic pain while improving quality of life.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
80
Frequency of 30 Hz, biphasic, rectangular pulses with a pulse width of 250 µs and an intensity of 20 mA. Device: Easy Tens+ device (body clock, London, UK)
University Medical Center
Göttingen, Germany
International RLS Severity Scale
Numeric score quantifying disease severity. This numeric rating scale ranges from 0 to 40 points. The higher the achieved score, the higher is the RLS disease severity. 0 points: no symptoms, 1-10 points: mild symptoms, 11-20 points: moderate symptoms, 21-30 points: severe symptoms, 31-40 points: extreme symptoms
Time frame: Seven days
Time domain analysis of heart rate variability
The standard deviation of the RR intervals (SDNN) and the root mean square of successive differences (RMSSD) in milliseconds.
Time frame: Two days
Spectral analysis of heart rate variability
The normalized high frequency component of the RR intervals (HF-HRV) is expressed as a percentage.
Time frame: Two days
Spontaneous baroreceptor sensitivity
The average baroreceptor sensitivity in ms/mmHg.
Time frame: Two days
Serum cytokine concentrations
Interleukin-6, interleukin-8, interleukin-1ß and tumor necrosis factor alpha in pg/ml.
Time frame: Two days
Hospital Anxiety and Depression scale
This questionnaire has 14 items that evaluate depression and anxiety symptoms. Each item has four possible responses and is scored in a range from zero to three with higher scores representing more symptoms.
Time frame: Two days
Median nerve stimulation
Electrical nerve stimulation of the median nerve to assess its strength-duration time constant (SDTC) or chronaxie in milliseconds. The SDTC is a measure of axonal excitability and provides indirect information about the functionality of sodium ion channels.
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Time frame: Two days
Sudoscan
Measurement of electrochemical skin conductance
Time frame: Two days
Brief Pain Inventory
This questionnaire assesses pain severity, location of pain, and impact on daily functions in the past 24 hours. Pain severity is scored on a numeric scale from zero to ten, with zero being no pain and ten being the worst possible pain.
Time frame: Two days
Short Form 12 (SF-12)
This questionnaire assesses the quality of life using 12 items. Each item is scaled on a range between zero and a maximum of six. Weighted sums are calculated and transformed into a population-standardized score ranging between zero and 100. The higher the score, the better is the respective life quality compared to the average population.
Time frame: Two days