Electrically stimulating the spinal cord can be an effective therapy for different kinds of treatment-resistant chronic pain. The exact mechanisms through which the stimulation suppresses pain are still not fully understood. In most systems currently used in patients, the electrodes are placed epidurally into the spinal cord canal.
There is evidence that the stimulation effects are mediated by the dorsal root ganglions (DRG), which are located just outside the vertebral canal in between the vertebrae. Since inserting foreign bodies into the spinal canal have has some risks, placing the electrodes directly onto a DRG seems like an attractive alternative. To come up with the best surgical procedures and stimulation strategies for DRG stimulation, however, more basic research is needed.
The most common experimental animal for such studies is the rat. Due to its size, systems for humans cannot be used. Most research studies up to now have been performed with improvised wire-tethered systems that were problematic in use. A research group at the School of Medicine of the Croatian University of Split has now developed a new system that could serve as an efficient and wireless tool for such research projects.
In conjunction with their own, wireless custom-made stimulator, the group used a 2-contact CorTec silicone strip electrode that was tailor-made to optimally match the dimensions of the rat’s L5 DRG.
The device turned out to be well tolerated by the animals. Through their custom-made software, the researchers could wirelessly elicit electrical impulses generated by the implanted device and applied through the electrode to the DRG. Stimulation successfully reduced pain reactions to several kinds of stimuli applied in a rat model of chronic pain. Autopsies after the experiments revealed that all electrodes safely remained at the implantation site and showed no signs of corrosion.
With this proof-of-concept study, the authors successfully established a novel wireless device as a tool for exploring novel neuromodulation therapies for chronic pain in rat models. The device offers an effective, cost-efficient solution for various research uses. It promises to be very flexible in use. Controlled by a graphical user interface (GUI), the software can generate a variety of stimulation patterns with different frequencies and waveforms.
Implantable, Programmable, and Wireless Device for Electrical Stimulation of the Dorsal Root Ganglion in Freely-Moving Rats: A Proof of Concept Study.
Vuka I, Marciuš T, Kovačić D, Šarolić A, Puljak L, Sapunar D. J Pain Res. 2021 Dec 9;14:3759-3772. doi: 10.2147/JPR.S332438.