Prolonged T 1 values of the crushed nerve are not exclusively attributable to Wallerian degeneration or endoneurial edema

Abstract

Axonotmesis of the left sciatic nerve was performed on adult male Wistar rats. T₁ values of the crushed nerve samples were determined with proton magnetic resonance spectroscopy. Denervation changes of the dependent hind plantar flexor muscles were assessed with proton magnetic resonance imaging of their cross-sectional area and muscle force measurements. However, T_l relaxation time of the crushed nerve samples remained prolonged implying the absence of nerve regeneration. This would be in contradiction with what is known about regeneration after simple crash and the muscle force and magnetic resonance imaging measurements of the dependent plantar flexor muscles. These studies indicated that sufficient nerve regeneration had taken place to restore their muscle force and volume. A model is suggested to explain the persistence of prolonged T_l values in the presence of muscle force recovery.