Masahito Sumitomo

Effectiveness of cervical sympathetic ganglia block on regeneration of the trigeminal nerve following transection in rats

Background and Objectives Stellate ganglion block (SGB) is one treatment option for human trigeminal nerve injury. The aim of this study was to evaluate the effectiveness of cervical sympathetic ganglia blocks (SB) by comparing the recovery of severed nerves in 2 rat models, treated or not treated by SB. Methods The infraorbital nerves (ION) were cut in 108 rats. Fifty-four of them were treated daily by SB for 30 days (SB group). The remainder were left untreated (Control group). The stages of recovery were evaluated neurophysiologically by measuring somatosensory evoked potentials (SEPs) and were histologically analyzed via microscopic observation. Results The neurophysiologic evaluation showed that SEP amplitude was detected 1 month after cutting the ION in the SB group, but not in the Control group. The average recovery after 8 months was almost 100% in the SB group and about 70% in the Control group. The histologic evaluation showed no significant difference in the number of myelinated nerve fibers per unit area between the 2 groups. However, in the SB group, the mean diameter and distribution of diameters of the myelinated fibers were greater, and myelinated fibers of large diameter were observed at an early stage. Conclusions The findings suggest that cervical sympathetic nerve block may accelerate the recovery and regeneration of severed ION. The clinical correlation in patients with peripheral trigeminal paralysis remains to be established.