Local steroid injection: its effect on the recovery of nerve conduction in experimental neuropathy

This study was designed to investigate the effectiveness of local steroid injection on the recovery of nerve conduction in acute compression neuropathy. Experimental neuropathy with complete conduction block was produced by mechanical compression of the caudal nerves of 24 rats. Five days after compression, the compression site was injected with 0.2 mL Dexamethasone acetate (8 mg/mL suspension) in eight rats (group A), and 0.2 mL normal saline in another eight rats (group B). The remaining eight rats (group C) received no injection. Motor nerve conduction velocity (NCV) over the compressed segment, as well as amplitude of the evoked compound muscle action potential (CMAP) recorded from the segmental tail muscles, were measured before nerve compression and three times per week after nerve compression. The recovery rates of NCV of the caudal nerve were not significantly different among the three groups. The recovery rate of amplitude of CMAP in group A was significantly higher than that in groups B or C (p less than 0.01). However, there was no significant difference in recovery rate of the amplitude of CMAP between groups B and C. It is concluded that local steroid injection to the site of nerve compression may facilitate the recovery of nerve conduction block but not the recovery of demyelinative lesion.