Anatomy of the neurovascular bundle: Is safe mobilization possible?

Purpose: We have previously defined the anatomy of the neurovascular bundle in the normal and hypospadiac penis. Historical experience suggests that mobilization of the neurovascular bundle is anatomically possible. We attempt to prove whether mobilization of the neurovascular bundle is safe and theoretically sound. Specific questions that will be addressed are does the neurovascular bundle send perforating branches into the corporal bodies; how far lateral does the dissection need to be before nerves are injured and exactly how deep into Buck's fascia must one go. Materials and Methods: A total of 35 normal human fetal penile specimens, gestational age 8 to 35 weeks, and 3 hypospadiac specimens, 33 to 41 weeks of gestation, were serially sectioned and stained with Mason's trichrome and the neuronal markers PGP 9.5 or S100. Computer reconstruction using commercial software and National Institutes of Health imaging allowed 3-dimensional analysis of the nerves, corporal bodies and glans. Results: Perforating nerves into the erectile bodies were not documented along the dorsal or lateral aspect of the tunica in any of the specimens studied. Only in the area of the crural bodies on the ventral lateral surface were nerves noted to pierce into erectile tissue. The neural network was extensive from the 11 and 1 to the 5 and 7 o'clock positions corresponding to the erectile tissue and urethral spongiosum junction. At this junction minor nerve branches were noted to perforate into the urethral spongiosum. A microscopic plane exists between the neurovascular bundle and tunica of the corporal bodies measuring 20 to 30 mu. in specimens greater than 30 weeks in gestation. Conclusions: Perforating branches from the dorsal lateral neurovascular bundle do not exist based on serial step sectioning and microscopic examination of male genital specimens. Surgically it is possible to elevate the neurovascular bundle but the dissection needs to remain directly on top of the tunica albuginea to prevent neuronal injury. Small perforating branches into the urethral spongiosum may be injured with unknown significance. We continue to advocate plication in the nerve-free zone at the 12 o'clock position for correction of penile curvature.