An injury in which a nerve is cut can involve a long period of convalescence for the patient. Doctors at the hand and plastic surgery clinic at Linköping University Hospital has together with RISE and Linköping University, has started investigating whether continuous nerve stimulation is able to improve regeneration of damaged nerves.
If your hand is cut so deeply that a nerve is cut, a hand surgeon will reconnect the ends so that the nerve has the potential to regrow. It is a very slow process, however, with regrowth of approximately one centimetre a month. But research is now being carried out which may radically alter this regrowth time.
– “When it comes to recovery from nerve injuries, you become ‘old’ relatively quickly, and the possibility of regaining full function in damaged nerves already begins to diminish at the age of 16,” explains Simon Farnebo, Hand Surgeon at Linköping University Hospital. “The faster the convalescence, the greater the chances are of regaining function, so we are continuously trying to find ways to speed up the healing process.”
Electrical pulses promote nerve growth
Studies from other universities have shown that regrowth of a damaged nerve is stimulated by an electrical pulse in conjunction with surgery. It is an established fact that electrical pulses promote nerve growth, but there have been very few long-term experiments.
– “First and foremost, we need to create a device that will enable us to determine whether long-term nerve stimulation has produced the positive effects we’re hoping for. And, if so, create an implant capable of stimulation over time,” says Roman Lassnig, Researcher at RISE.
Implant for stimulation over time
The team at Linköping University Hospital had previously conducted experiments with implantable interfaces which were able to communicate via NFC. Flexible, biocompatible electrodes are wound around the nerve, and the patient can then initiate nerve stimulation via a smartphone app.
– “We want to implant a device in the damaged nerve able to provide continuous pulse stimulation for one, or perhaps as long as two, years. We believe the results will be twofold. Firstly, that regeneration of the damaged nerve is sped up substantially, and, secondly, that stagnation in the region of the brain that responds to the nerve impulse, which has always been the case, is prevented,” says Lassnig.
Greater patient involvement
The app also provides direct feedback from the implant so that the patient can follow the healing process, which is conducive to greater patient involvement.
– “The patient’s own involvement is an important factor,” says Farnebo. “It’s difficult and frustrating for patients to just hope and wait for treatment to produce results. With this solution, the patient is partly able to administer their own treatment by controlling the electrical pulses, and then see the results and get feedback on the healing process.”
Great interest in nerve stimulation
Different types of nerve stimulation have become a hot topic, and although this project focuses on the nerves of the hand, the same technique can be applied to all cut nerve fibres. Simon Farnebo sees a number of potential uses for the implants:
– “The form factor of the printed implants in combination with their biocompatibility means that this technique can also be used in, for example, the treatment of chronic nerve injuries and pain alleviation, or even to control biomechanical prostheses.”
Participants in project have included clinicians and engineers from Linköping University Hospital, experts in organic electronics, electrical circuits and systems from Linköping University, and printed electronics researchers at RISE.
– “The fact that this project has been requested, initiated and carried out in close partnership with the surgeons is an important reason RISE became interested in the project and in how we could bring together our respective expertise. The incentive for the surgeons was the opportunity to truly improve the quality of life for their patients, and it’s fantastic that we and the technology can contribute to this,” concludes Lassnig.
