Spinal implant inflates like a tiny air mattress to block severe pain

By targeting the same mechanisms through which epidural anesthesia controls pain during child birth, engineers at the University of Cambridge have demonstrated a new medical implant that could offer relief from other types of severe pain. Administered with a needle and inflated like a tiny air mattress once in position, the device works by subjecting the spinal cord to mild electrical currents, and could negate the need for invasive surgeries.

The new implant is essentially a type of advanced spinal cord stimulator, which are devices that sit in between the spinal cord and the vertebrate and emit electrical pulses that disrupt pain signals. These are typically shaped like paddles and require skilled surgeons to implant via complex procedures. Another type can be implanted with a needle and requires only a local anesthetic, but isn't nearly as effective as it targets a smaller area.

“Spinal cord stimulation (SCS) is a treatment of last resort, for those whose pain has become so severe that it prevents them from carrying out everyday activities,” said Dr Damiano Barone one of the paper’s senior authors. “However, the two main types of SCS devices both have flaws, which may be one reason their use is limited, even though millions struggle with chronic pain every day.”

The University of Cambridge researchers are attempting to find a sweet spot in between these two treatment options, by combining soft robotics, miniaturized electronics and microfluidics. Their solution is an ultra-thin device around the width of a human hair, that is fitted with a set of electrodes. It can be rolled up into a cylinder and placed in a needle, for implantation into the epidural space of the spinal column.

From there, the device is pumped with either water or air, which causes it to unfurl like a miniature air mattress and cover a sizable section of the spinal cord. Connected to a pulse generator, the electrodes then start emitting mild electrical currents into the spinal cord, which disrupts the signals of severe pain.

“Our goal was to make something that’s the best of both worlds – a device that’s clinically effective but that doesn’t require complex and risky surgery,” said Dr Christopher Proctor, senior author of the study. “This could help bring this life-changing treatment option to many more people.”

The scientists have only demonstrated their device in vitro and on human cadaver models, so there is a lot of work to do before it enters clinical use. Down the track, it could be used to treat severe pain in regions including the legs and back, but also tackle conditions like paralysis and Parkinson's disease. The team hopes to explore these possibilities through further testing and then clinical trials.

“The way we make the device means that we can also incorporate additional components – we could add more electrodes or make it bigger in order to cover larger areas of the spine with increased accuracy,” said Barone. “This adaptability could make our SCS device a potential treatment for paralysis following spinal cord injury or stroke or movement disorders such as Parkinson’s disease. An effective device that doesn’t require invasive surgery could bring relief to so many people.”

The research was published in the journal Science Advances.

Source: University of Cambridge