Polyethylene Glycol Fusion Restores Axonal Continuity and Improves Return of Function in a Rat Median Nerve Denervation Model.

Abstract

Polyethylene glycol (PEG) can fuse severed closely-apposed axolemmas and restore axonal continuity. We evaluated the effects of PEG-fusion on functional recovery in a rodent forelimb model of peripheral nerve injury. The median nerves of male Lewis rats (n=5 per group) were transected and repaired with standard suture repair (SR), SR with PEG (PEG), or SR with PEG and 1% methylene blue (PEG+MB); a sham surgery group was also included. Proximal stimulation produced compound nerve (CAPS) and muscle (CMAPs) action potentials recorded distally. The contralateral limb of each animal acted as an internal control for grip strength measurements. CAPs and CMAPs immediately returned in all PEG and PEG+MB animals, but not in SR animals. PEG and PEG+MB groups demonstrated earlier return of function by post-operative day (POD) 7 (62.6 ±7.3% and 50.9 ±6.7% of contralateral limb grip strength, respectively) compared to SR group, in which minimal return of function was not measurable until POD 21. At POD 98, the PEG group grip strength recovered to 77.2 ±2.8% while the PEG+MB grip strength recovered to 79.9 ±4.4%, compared to 34.9 ±1.8% recovery in the SR group (p<0.05). The PEG and PEG+MB groups reached 50% of the Sham group grip strength on POD 3.8 and 6.3, respectively, whereas the SR group did not reach 50% grip strength recovery of the Sham group throughout the study period. PEG-fusion plus neurorrhaphy with or without methylene blue re-established axonal continuity, shortened recovery time, and augmented functional recovery compared to suture neurorrhaphy alone.