Magnetometry of injury currents from human nerve and muscle specimens using superconducting quantum interferences devices

Acute lesions of polarized membranes lead to slowly decaying ('near-DC') in jury currents driven by the transmembrane resting potential gradient. Here we report the first recordings of injury-related near-DC magnetic fields fr om human nerve and muscle specimens in vitro using Superconducting Quantum interference Devices (SQUIDs) operated in a conventional magnetically shiel ded room in a clinical environment. The specimen position was modulated sin usoidally beneath the sensor array by a non-magnetically fabricated scissor s lift to improve the signal-to-noise ratio for near-DC fields. Depending o n the specimen geometry the field patterns showed dipolar or quadrupolar as pects. The slow decay of human nerve and muscle injury currents was monitor ed for several hours from a distance of a few centimeters. Thus DC-magnetom etry provides a sensitivity which might allow the remote detection of injur y currents also in vivo. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.