Strategies for minimizing 60 Hz pickup during evoked potential recording

Electrical interference at mains power supply frequency can adversely affect the recording of evoked potentials and can be especially destructive in an operating room setting. We investigated 60 Hz interference in electrode cables running from subject to preamplifier and further examined methods to eliminate such interference. We conclude that braiding electrode wires is highly efficacious in such interference reduction, presumably by reducing the magnetic flux enclosed by the wires. We further indicate that the use of flexible metal hose fabricated from Permalloy 80 may effect further interference reduction.