Transcranial Alternating Current Stimulation in Back Pain- Pilot Sudy

• XCSITE100 Stimulator Sham (Device), also known as Sham tACS: The participant will receive up to one minute of tACS stimulation until the stimulation fades. Sham stimulation mimics the skin sensations a participant would experience during a tACS session
• XCSITE100 Stimulator tACS (Device), also known as tACS: Transcranial alternating current stimulation (tACS) is a method of noninvasive brain stimulation in which weak electrical current are applied to the scalp in a sine wave pattern to induce cortical oscillations at the frequency at which they are applied

Primary outcomes

• Change in Heart Rate Variability Before and After 40-minute Stimulation [before and after 40-minute stimulation at each session]: Changes in parasympathetic tone, increase in high frequency band input via spectral analysis on EKG recordings between active and sham stimulation
• Change in Electroencephalogram Power in Alpha Band Before and After 40-minute Stimulation [5 minute recordings before and after each 40-minute stimulation at each session.]: Changes in the EEG power in the alpha (8-12 Hz) band before and after 40-minute stimulation

Secondary outcomes

• Change in Pain Rating on the Visual Analog Scale Before and After 40-minute Stimulation [before and after 40 minute stimulation session]: Self reported pain rating using a Visual Analog Scale (VAS) ranging from 0-10 done before and after stimulation with '0' being no pain and '10' as bad as it could be. Lower values represent a better outcome. (Pain difference was normalized using modulation index to account for ordinal scale)

Sex: All, ages: 18 Years to 65 Years

Inclusion Criteria:

* Male or female, aged 18-65
* Diagnosed with nonspecific chronic low back pain by clinician
* BMI is less than 30
* Suffered from chronic pain for > 6 months
* Self-report pain measures >4
* Meets criteria for low depression and suicide risk as defined by the Hamilton-Depression Rating Scale
* Capacity to understand all relevant risks and potential benefits of the study (informed consent)
* Not currently taking opioids, benzodiazepines, and anticonvulsant medications

Exclusion Criteria:

* Radicular Pain
* Traumatic brain injury, Any brain devices/implants, including cochlear implants and aneurysm clips
* History of major neurological or psychiatric illness, including epilepsy
* (For females) Pregnancy or breast feeding
* Diagnosis of eating disorder (current or within the past 6 months), Obsessive Compulsive Disorder (lifetime), or Attention-Deficit Hyperactivity Disorder (currently under treatment)

Participant flow

Outcome results

• Change in Heart Rate Variability Before and After 40-minute Stimulation (Primary), Mean, ms^2: Sham tACS 0.206 +/- 0.76; Active10 Hz tACS -0.01 +/- 0.56 (p .319)
• Change in Electroencephalogram Power in Alpha Band Before and After 40-minute Stimulation (Primary), Mean, square microvolts: Sham tACS 0.03 +/- 0.16; Active 10 Hz tACS 0.4 +/- 0.15
• Change in Pain Rating on the Visual Analog Scale Before and After 40-minute Stimulation (Secondary), Mean, units on a scale: Sham tACS -0.178 +/- 0.97; Active 10 Hz tACS 0.18 +/- 0.31 (p .0488)

Adverse events

Time frame: Study enrollment until 2 day followup after last session

Limitations and caveats: Limitations of the study include small sample size. Participants received only 1 session of Active 10 Hz tACS by design but there is likely an additive effect and future studies should investigate multiple sessions.

• Results publication: Prim JH, Ahn S, Davila MI, Alexander ML, McCulloch KL, Frohlich F. Targeting the Autonomic Nervous System Balance in Patients with Chronic Low Back Pain Using Transcranial Alternating Current Stimulation: A Randomized, Crossover, Double-Blind, Placebo-Controlled Pilot Study. J Pain Res. 2019 Dec 11;12:3265-3277. doi: 10.2147/JPR.S208030. eCollection 2019. PMID 31849514
• Results publication: Ahn S, Prim JH, Alexander ML, McCulloch KL, Frohlich F. Identifying and Engaging Neuronal Oscillations by Transcranial Alternating Current Stimulation in Patients With Chronic Low Back Pain: A Randomized, Crossover, Double-Blind, Sham-Controlled Pilot Study. J Pain. 2019 Mar;20(3):277.e1-277.e11. doi: 10.1016/j.jpain.2018.09.004. Epub 2018 Sep 27. PMID 30268803

• Study Protocol and Statistical Analysis Plan (PDF, 2017-03-29)

• Karen McCulloch, PhD, DPT, Principal investigator, University of North Carolina, Chapel Hill

NIH grants: R01MH101547