Spinal Implant Shows Promise for Muscle Disease Treatment

Researchers recently reported new evidence from a study of a medical device placed inside the body, a spine-stimulating implant.

Three people with a muscle-destroying disease got a little stronger after using the implant. They were able to stand and walk more easily because of electrical stimulation to their spinal cord.

Marco Capogrosso is an assistant professor at the University of Pittsburg, or Pitt, who led the research. "These people were definitely not expecting an improvement," he said. Capogrosso said, "They were getting better and better," over the study that lasted one month.

Returning muscle function

The implant was able to return some muscle function, at least temporarily. The implant was already being tested to treat paralysis in other patients. This new evidence suggests it might also aid diseases of the nervous system like spinal muscle atrophy, or SMA.

SMA is a genetic disease that slowly destroys motor neurons, nerve cells in the spinal cord that control muscles. That leads muscles to waste away, especially in the legs, hips, and shoulders and sometimes those involved with breathing and swallowing. There is no cure. A gene therapy can save the lives of very young children with a severe form of the disease, and there are some medicines to slow the disease in older patients.

Stimulating the spinal cord with low levels of electricity has long been used to treat chronic, or long-term, pain. Capogrosso's team also has tested it to help people paralyzed by strokes or spinal cord injury move their arms and legs with assistance. The system sends electrical signals to nerves that have stopped reacting. This has the effect of activating the muscles.

Capogrosso wondered if that same technology might help patients with SMA by stimulating sensory nerves to signal damaged muscle cells causing them to move. The researchers at the University of Pittsburgh published their study in Nature Medicine.

They implanted electrodes over the lower spinal cord of the three adults with SMA. Using the device did not return normal movement but with a few hours of spinal stimulation a week, all soon experienced improvements in muscle strength and function, the researchers wrote.

"You never get better"

Fifty-seven-year-old Doug McCullough took part in the study. "With a progressive disease you never get any better," he said, adding, “So having any improvement is just a really surreal and very exciting benefit."

All three subjects increased how far they could walk in six minutes by the study's end.

Capogrosso said they could walk farther because they got less tired and “even a person this many years into the disease can improve."

Researchers found the improvements did not disappear as soon as the stimulator was turned off. But they did decrease a few months after the study ended.

Neuroscientist Susan Harkema led similar studies of stimulation for spinal cord injuries while at the University of Louisville. She warned that the new study is small and did not last very long but said it was an important test of the device. She said it should be tested next with other muscle-degenerating diseases.

Capogrosso said some small but longer studies are beginning.