Deep brain stimulation (DBS) therapy has been one of the few therapeutic options available to those who suffer from advanced Parkinson’s disease. The procedure is invasive, expensive and comes with potential side effects, let alone reluctant patients afraid of getting anything implanted into their brains. Now a laboratory study out of Duke, that tested the effectiveness of using electrical signals to stimulate the dorsal column in the spinal cord of mice, has achieved surprising results.
From the press statement issued by the Duke University press office:
The device was attached to the surface of the spinal cord in mice and rats with depleted levels of the chemical dopamine — mimicking the biologic characteristics of someone with Parkinson’s disease along with the impaired motor skills seen in advanced stages of the disease.
When the device was turned on, the dopamine-depleted animals’ slow, stiff movements were replaced with the active behaviors of healthy mice and rats. Improved movement was typically observed within 3.35 seconds after stimulation.
Researchers tested mice and rats with acute and chronic dopamine deficit using varying levels of electrical stimulation and in combination with different doses of dopamine replacement therapy, also known as 3,4-dihydroxy-L-phenylalanine or L-DOPA, to determine the most effective pairing.
When the device was used without additional medication, Parkinsonian animals were 26 times more active. When stimulation was coupled with medication, only two L-DOPA doses were needed to produce movement compared to five doses when the medication was used by itself.
While deep brain stimulation (DBS) and other experimental treatments attack the disease at its origin — in the brain — Nicolelis and team took a different approach. The concept for the device began when researchers made a surprising connection with another neurological condition.
The rhythmic brain activity in the animals with Parkinson’s disease resembled the mild, continuous, low-frequency seizures that are seen in those with epilepsy.
One effective therapy for treating epilepsy involves stimulating the peripheral nerves, which facilitate communication between the spinal cord and the body. Researchers took that concept and developed a modified approach for a Parkinson’s disease model.
In a healthy body, neurons fire at varying rates as information is transmitted between the brain and the body to initiate normal movement. This process breaks down in someone with Parkinson’s disease.
“Our device works as an interface with the brain to produce a neural state permissive for locomotion, facilitating immediate and dramatic recovery of movement,” says Per Petersson, co-author of the study.
“Following stimulation, the neurons desynchronize, similar to the firing pattern that you would see when a healthy mouse is continuously moving.”
Small leads are implanted over the spinal cord and then connected to a portable generator, a small device capable of producing mild electrical currents. During the trial period, the generator is external, while for permanent treatment it would be implanted below the skin.
Press release: Novel Spinal Cord Stimulator Sparks Hope for Parkinson’s Disease Treatment
Image: A recording of the brain activity of a rat with Parkinson’s symptoms before (above) and after (below) spinal cord electrical stimulation.