Nerve compound action current (NCAC) measurements and morphometric analysis in the proximal segment after nerve transection and repair in a rabbit model.
In the evaluation of nerve regeneration using magneto-neurography (MNG), the proximal segment showed a reproducible decrease in peak-peak amplitude of the nerve compound action current's (NCAC) of 60%. To explain these changes, morphometry of myelinated axons in the proximal segment is compared to the MNG signals. A standardised nerve transection and reconstruction was performed in rabbits. NCACs were measured approximately 5 cm proximal to the lesion from operated and control nerves after 12 weeks. Histological samples were taken from the same area of the nerve where the NCACs were obtained. Results showed a decrease of the peak-peak amplitude of the NCAC of 57% compared to the control. Conduction velocity decreased 15% (not significant). Morphometry elicited a decrease in larger (10-15 microm) axons (284 +/- 134 vs 82 +/- 55) and an increase in smaller (2-5 microm) axons (1445 +/- 360 vs 1921 +/- 393). A strong correlation existed between the decrease in amplitude and the decrease in larger axons (0.85). Peak-peak amplitude varies approximately with the square of the diameter axon. Therefore, because peak-peak amplitude is mainly dependent on the larger-diameter axons, the decrease in peak-peak amplitude of the NCACs may be explained by a decrease in numbers of 10-15-microm axons.
Walbeehm
Erik T
ET
Department of Plastic and Reconstructive Surgery, Ee 1591, UHR Dijkzigt and Erasmus University Rotterdam, Dr Molewaterplein 50, PO Box 1738, 3000 Dr Rotterdam, The Netherlands. erikwalbeehm@mac.com
Dudok van Heel
E B Michiel
EB
Kuypers
Paul D L
PD
Terenghi
Giorgio
G
Hovius
Steven E R
SE
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001369:Axons / Q000145:classification / Q000502:physiology; D048429:Cell Size / Q000502:physiology; D004594:Electrophysiology; D015225:Magnetoencephalography / Q000295:instrumentation / Q000379:methods; D009416:Nerve Regeneration / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology*; D010525:Peripheral Nerves / Q000502:physiology*; D011817:Rabbits; D011930:Reaction Time / Q000502:physiology; D012018:Reflex / Q000502:physiology; D012107:Research Design