Tracing of proximal lumbosacral nerve conduction--a comparison of simultaneous magneto- and electroneurography.
OBJECTIVE
The reconstruction of nerve impulse conduction along proximal lumbosacral plexus and nerve roots is compared using simultaneous magneto- and electroneurography.


METHODS
In 3 healthy subjects the left tibial nerve was electrostimulated at the ankle. Evoked magnetic fields and electric surface potentials were measured simultaneously over the lumbosacral spine using a multichannel SQUID-detector with a planar measuring area and 25 surface electrodes covering a comparable area centered around L4. Based on either magnetic field or electric potential maps the depolarization front of the evoked compound action currents (CAC) was spatio-temporally reconstructed using a simple equivalent current dipole model in a half-space volume conductor.


RESULTS
The mean signal-to-noise ratio in the magnetic (electric) recordings was around 4 (8). Yet, the localization quality for the propagating CAC was lower for electric than magnetic recordings. The local nerve conduction velocity was around 47 m/s (calculated from magnetic data), but fluctuated unphysiologically for electric data.


CONCLUSIONS
In comparison to electroneurography, an anatomically reasonable localization of evoked compound action currents propagating in lumbosacral roots can be obtained by magnetoneurography.
Mackert
B M
BM
Neurophysics Group, Department of Neurology, Klinikum Benjamin Franklin, Freie Universität Berlin, Hindenburgdamm 30, 12203, Berlin, Germany. macbm@zedat.fu-berlin.de
Burghoff
M
M
Hiss
L H
LH
Trahms
L
L
Curio
G
G
D000328:Adult; D004594:Electrophysiology; D005071:Evoked Potentials; D006801:Humans; D008160:Lumbosacral Plexus / Q000502:physiology*; D008280:Magnetics; D009431:Neural Conduction / Q000502:physiology*; D013126:Spinal Nerve Roots / Q000502:physiology*