Multiphoton imaging and laser ablation of rodent spermatic cord nerves: potential treatment for patients with chronic orchialgia.

ABSTRACT

PURPOSE: Microsurgical denervation of the spermatic cord has been done to treat chronic orchialgia. However, identifying the site of spermatic cord nerves is not feasible with an operating microscope or robotic stereoscope. We used multiphoton microscopy, a novel laser imaging technology, to identify and selectively ablate spermatic cord nerves in the rat. MATERIALS AND METHODS: The spermatic cords of adult male Sprague-Dawley® rats were initially imaged in vivo under a low power multiphoton microscopy laser. After assessing the number, diameter and site (vasal vs perivasal) of the nerves a higher power laser using the same objective was used to ablate the nerves. The precision of nerve ablation and the preservation of surrounding structures were determined by histological analysis. We assessed the heterogeneity of the number of nerves with the Wilcoxon signed rank test. RESULTS: The average number of nerves per spermatic cord was 10, which was similar bilaterally (p = 0.13). The vas and perivasal structures had a similar number of nerves (p = 0.4). The median diameter of all nerves was 32 µm. Confirmation of nerve ablation, and preservation of the vas deferens and vasculature were anatomically validated by histological analysis. CONCLUSIONS: Multiphoton microscopy can identify and ablate nerves selectively in vivo in the rat. It can potentially be used for spermatic cord denervation to treat chronic orchialgia. Such imaging may increase the efficacy of nerve ablation and can avoid the potential risks of testicular atrophy and hydrocele associated with spermatic cord microsurgical denervation.