Electrophysiological measurements of peripheral nerves in rats using the Qtrac approach

Abstract

IntroductionThe aim of this study was to build an implant and benchmark it for further improvement, specifically aimed to measure periphery nerves in rats. The nerve algorithm was based on the Qtrac approach for measurements of excitability measurements on motor and sensory nerves. This design was designed for enhanced measurements of nerve function related to diabetic neuropathy; a common and sometime a debilitating condition that eventually may result in foot ulcers and limb amputation. In order to better treat and prevent complications it is of great importance to recognize the sensory and autonomic dysfunction as early as possible. At the moment, it is unclear how and when the autonomic changes develop in relation to the somatosensory signs. The pathology of DN is primarily characterized by loss of nerve fibers. A typical course of the disease often starts with small‐fiber neuropathy/dysfunction in toes and feet, pain and paresthesia. Development of the proposed device addresses this problem.MethodsWe created a working pre‐amp and filter prototype and used conventional Qtrac algorithms. The performance consisted of multiple iterations to determine the best configuration for the amplification, signal‐to‐noise, filtration, space occupied on the PCB and battery use. The Qtrac package includes an automated stimulation<−>response threshold tracking software and hardware setup with specialized algorithms to determine multiple variables in nerve excitability studies. The device was measured in the nerves: sciatic, ulna and tail.ResultsEight rats were examined in 3 nerves (Fig 1A–1C). These data showed no significant difference between a regular Qtrac setup and the newly‐designed Qtrac setup. We showed a measurable difference between the nerves in question as shown in Figure 1D, showing 5 different variables obtained from the Qtrac protocol from the different nerves. The data is shown as a mean value of all rats in the study. At the same time, the difficulty in precisely measure in the same spot on different rats, became clear. Especially the Ulnar nerve proved too hard to use for this purpose, and we are reluctant to use this nerve in further studies.ConclusionThe study demonstrated a novel Qtrac design for measurements of periphery nerves in rats. The study revealed reliable data, showing significant difference in several excitability parameters for the three nerves. Potentially, explained by different amounts of fibers in the examined nerves, different fiber sizes and compositions. Further studies should include telemetric add‐on and measurements in rats suffering from DN. .needle placement in rats. A. Sciatic, B. Ulna, C. Tail. Graphs (D) show 5 different variables obtained from the Qtrac protocol from the different nerves.Figure 1