Understanding the Effects of Transcutaneous Auricular Neurostimulation for Treatment of Chronic Pain

Overview

The purpose of the study is to find out how a stimulation device worn on the ear works. This device is thought to stimulate nerves in the area around the ear to change the signals in the brain. The device has been shown to reduce pain and to reduce the symptoms of withdrawal. The investigator will also investigate changes in the way each participant perceive sensations of pressure and heat. The participant will be asked to reduce the amount of pain medication that they take. Then, the participant will spend several days and nights in the Clinical Research Center at UTMB (University of Texas Medical Branch) in Galveston. During that time, the participant will be monitored for withdrawal symptoms and will receive either active (e.g., "real") brain stimulation or sham (e.g., "fake") brain stimulation for two days (four hours each day). At two times over the course of the study (before and after ear stimulation treatment), the participant will complete questionnaires about their pain score and how they are feeling, sensory testing, and will undergo magnetic resonance imaging (MRI) of their brain. The investigator will collect the following information from the participant's medical record: age, gender, medication history, medical diagnoses, recent vital signs, past doctor visits or hospital stays, and results of urine drug tests. Participation in this study will last approximately four days, and the participant will stay in the Clinical Research Center.

Rationale and Aims The current project will build on the previous tAN (transcutaneous auricular neurostimulation) research and clinical studies on chronic pain and opioid withdrawal, ultimately providing a "neural blueprint" of how tAN therapy can mitigate pain and opioid withdrawal symptoms. The investigators will conduct a clinical mechanistic trial of tAN in chronic pain patients tapering from therapeutic opioids. The study will accomplish the following Aim and address the following hypotheses: Aim: Establish the functional MRI (fMRI) neurophysiological signature specifically underlying tAN-based analgesia in chronic pain participants undergoing an opioid taper. Hypothesis 1: Chronic pain participants who receive tAN stimulation will demonstrate increased fMRI signal activation in vagal afferents within the brainstem compared to sham treatment. Hypothesis 2: Chronic pain participants who receive tAN will demonstrate decreased fMRI signal activation in the cortical and subcortical pain network compared to sham treatment. Exploratory Hypothesis 1: tAN-based changes in brain activation will correlate with measures of pain, and the severity of depression and anxiety to specifically delineate the overlay and distinguishing factors between the brain signatures of analgesia, and discomfort. Study Summary On Day 1 at the CRC (Clinical Research Center), the investigators will review the consent and obtain consent. the investigators will reduce the amount of pain medication on the first day and continue for four days. The reduction in dose will be 10-20% of the participants daily pain medication dose. The participant will complete questionnaires, submit a UDS, MRI, and sensory testing. On Day 2, the participant will be randomly assigned to receive either active, (real) brain stimulation or sham (fake) brain stimulation. The participant have an equal chance of being assigned to either group (similar to flipping a coin). Sham brain stimulation will look and feel like active stimulation. The participant will not be able to tell which type of stimulation is received until the participant complete the study. Brain stimulation will be delivered on the second and third days of the study for approximately four hours each day (e.g., four sessions of stimulation for one hour each day). On Day 3, the participant will receive four hours of stimulation. On Days 2 and 3, the participant will have your heart rate, blood pressure, and breathing rate measured; and will complete withdrawal symptom questionnaires and will give a pain score every four hours from 8am to 8pm. The researchers will not disturb participants at night. On Day 4, the participant will complete questionnaires, MRI, and sensory testing. The stimulation device will be returned to study personnel at the end of the study. The participant's pain physician can contact Spark Biomedical and prescribe the stimulation device for continued use at home.