Researchers are expanding their understanding of the effectiveness of electric fields increasingly used in implants to stimulate and repair damaged nerves. Effective nerve stimulation is key to relieving debilitating conditions such as sciatica.
“From the soldier on the battlefield to people involved in road accidents, the long-term effects of nerve injuries can seriously affect sufferers,” said University of Adelaide Professor Giuseppe Tettamanzi, Senior Lecturer, School of Chemical Engineering.
“Transcutaneous electrical nerve stimulation (TENS) is a widely used method of electrical stimulation in implants. Many of today’s implants are quite invasive, so it is important to understand how to maximize their effectiveness.
“Simple electrical circuitry in an implant can be applied to damaged nerves to help repair and rebuild them.”
This technology was invented by Professor Antonio Lauto from UWS, Sydney. The implants are surgically placed under the skin around the damaged nerve with power in early versions supplied externally. Innovative wirelessly powered graft antenna implants are increasingly being used. They are minimally invasive devices that act as both a wireless stimulator and a structure around which nerves can be rebuilt. The implants use a gold band that produces an electric field around it.
The team used several sophisticated computational electromagnetic techniques incorporated into a mouse model to hypothetically examine the effect of the circuit implanted through patches inserted near affected nerves. They published their work in the journal Bioelectromagnetics.
Luke Smith, who is the lead author of this research, undertook an honors project in his final year of his degree at the University of Adelaide under the supervision of Professor Tettamanzi and Professor Christophe Fumeaux, to explain the microscopic nature of the effect of electrical stimulation. He is currently doing a PhD at the University’s Australian Institute for Machine Learning.
“Our work shows that when the simple metal circuit in the patch inserted near the neural material is irradiated with the commonly used transcranial magnetic stimulation (TMS), it acts as a focus for the electromagnetic signal that ultimately activates the neurons in the neural material. ” he said.
“This ultimately tremendously speeds up the process of repairing damaged neuronal material.
“The electrical stimulation of the nerves is mainly due to the electric fields created at the edge of the ring, which create high-intensity field gradients in a small area around it.
“Our computational model shows that direct contact between the ring and the nerve ensures neural activation.”
Nerve damage usually takes more than three months to repair, and sufferers are at increased risk of depression due to the debilitating effects of conditions such as sciatica.
People suffering from pain due to nerve damage may have to resort to opioids for pain relief with all the associated risks of addiction and additional burden on health systems.
“This work, which is currently in progress, could benefit people with injuries and neurodegenerative diseases. The knowledge we have generated can inform future research,” said Professor Tettamanzi.