A study of brachial plexus potentials using a 3-dimensional electrode array

Brachial plexus potentials were investigated with a three-dimensional orthogonal electrode array. The array was simulated using an ideal, infinitely homogeneous model. The model was verified by testing human subjects with the arm abducted at three different angles to determine whether changes in nerve orientation would alter the potential waveforms. Potentials were recorded for both ulnar and median nerves. Results show qualitative correlation between the simulation and test results. Differences between the median and ulnar nerve waveforms were consistently measurable, and the change in shoulder position was shown to the statistically correlated with changes in waveform latencies. The results suggest that observed differences and changes are due to the change in dipole orientation rather than the change in current density that occurs when the nerve enters the torso from the arm.<>