Turning Down the Sting of Neurotherapy Treatment

One of the most persistent problems in neurotherapy treatment is making brain stimulation accessible enough for everyday clinical use. The most effective currently available solutions require complex and costly surgery, which are only available to a small fraction of patients that could benefit from them. Carnegie Mellon researchers, in collaboration with the Neuroscience Institute and the University of Pittsburgh Anesthesiology and Perioperative Medicine department, are working toward this goal by improving a currently available nonsurgical therapeutic technology.

Pulsed Transcranial Electrical Stimulation (pTES) is a noninvasive neuromodulation treatment, which does not require surgery, and could be an effective treatment for depression, anxiety, and cognitive issues; however, it can be extremely painful. It requires high-amplitude pulses to reach brain structures, so it often causes a sharp stinging sensation on the scalp.

"In the scientific community, pTES is thought to be essentially unusable for therapeutic applications because of the pain it causes," explains Rabira Tusi, a Ph.D. student in Carnegie Mellon’s Neuroscience Institute and lead author on the study. "The only clinical application so far is with anesthetized patients, where pain isn't an issue."

Tusi and Mats Forssell, a research scientist in the electrical and computer engineering department, set out to solve this "electric sting" by applying the principles of peripheral nerve stimulation. They hypothesized that they could dull the scalp’s pain receptors using an electrical conduction block. This “block” is an additional layer of high-frequency stimulation added to the therapeutic pulses. These high-frequency signals, which they call “background hums”, prevent scalp pain signals from reaching the brain while allowing the therapeutic brain pulses to pass through.

Their paper, “Reducing scalp pain for pTES of motor cortex using background hums,” was recently published in Brain Stimulation, the premier journal for publishing research in the field of neuromodulation.

Tusi and Forssell stimulated the brains of patients with fibromyalgia, a condition characterized by extreme pain sensitivity, without causing extreme discomfort. A subset of participants with reduced pain scores demonstrated the success of this method, highlighting the potential of pTES as a therapeutic treatment of chronic pain.

"We think that this technique has a lot of potential to improve the lives of patients. The first step to being able to run clinical trials was to make the technique easily tolerable," says Pulkit Grover, professor of electrical and computer engineering and Tusi's advisor. "The critical advance is that not only is this modality more direct in its stimulation mechanisms than other noninvasive stimulation modalities, but it is also portable. Now the hard work of testing this for various clinical indications can begin."

The team is already looking at how this new modality of stimulation can help other populations, including treatments for osteoarthritis and depression.

"Our findings suggest that the relationship between brain stimulation and pain is more nuanced than a simple one-to-one relationship,” says Dr. Ben Alter, an anesthesiologist at the University of Pittsburgh, Director of Translational Pain Research, and co-author of the paper. “If we can address the pain barrier, pain-optimized electrical stimulation could become an important alternative or complement to existing neuromodulation approaches.”

By silencing the pain of pTES, the researchers are opening a new door for neurotherapy. Their work brings us closer to a future where non-invasive deep-brain stimulation could be a therapy as accessible and routine as a standard medical checkup.

Additional authors on the paper include Carnegie Mellon researchers Jeehyun Kim, Maxwell Murphy, Jonathan Shulgach, Prakarsh Yadav, Alonso Buitano Tang, Vishal Jain, and Douglas Weber. As well as University of Pittsburgh researchers Maya Maurer.