Magnetoneurography: recording biomagnetic fields for quantitative evaluation of isolated rat sciatic nerves.

Magnetoneurography (MNG) is a technique to record the biomagnetic action fields of peripheral nerves. The benefits of MNG in contrast to electroneurography include the decreased signal disturbance caused by surrounding biological tissues and the use of a calibration pulse, both of which contribute to high reproducibility. MNG has proven to be a valuable tool to quantitate peripheral nerve regeneration in rabbits. However, the most commonly used model to study the peripheral nervous system is the rat sciatic nerve. Until now, the small size of the nerve impeded accurate MNG measurements in rat. This report describes a custom made recording chamber that allows accurate control of conduction distances and temperature and enables adequate MNG measurements of isolated sciatic nerves of Wistar rats. We applied biphasic stimulation with optimized grounding to reduce the stimulus artefact. A high reproducibility of signals was demonstrated. 'Ex vivo' nerve viability was assured for at least 2 h after dissection. In conclusion, MNG is a powerful tool to quantitatively evaluate the function of rat sciatic nerves and will be used for the early assessment of nerve regeneration.