Immunohistochemical study of the cavernous nerves in the periprostatic region

Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? The anatomy of the periprostatic tissues, in particular the fascial layers and neurovascular structures, remain a somewhat enigmatic and controversial area. Despite the considerable advances made in this area since the original dissections of Walsh and Donker almost thirty years ago, the precise location and function of these structures remains uncertain. The topic is of tremendous importance as we continue to refine surgical techniques to allow men the maximum opportunity to recover erectile function following radical prostatectomy. Yet many of these surgical refinements are not based on definitive knowledge of the relevant anatomy and clearly more knowledge is required. For the first time, we have not just characterized the quantitative nature of the periprostatic nerves, but we also offer some insight into the likely functional nature of these nerves by selectively staining the sympathetic and parasympathetic nerves using immunohistochemical methods.

• To characterize the immunohistochemical nature of sympathetic and parasympathetic nerves surrounding the prostate.

• Using serial sectioning, four male cadavers were investigated using a combination of haematoxylin and eosin staining and immunohistochemistry. Both the sympathetic and parasympathetic contributions to the autonomic nervous system in the periprostatic region were assessed by staining analysis, the number of nerves fibres was quantified, their position relative to the prostate recorded and their function inferred. • The fascial architecture of the neurovascular bundle (NVB) was also quantified.

• Approximately 27.8% of all nerve fibres identified were found on the anterior half of the prostate, above the 3 to 9 o'clock level. At the base, mid, and apex of prostate, parasympathetic fibres accounted for 4%, 5% and 6.8% of the nerves located on the anterolateral aspect of the prostate, respectively. • Sympathetic nerves found above the 3 to 9 o'clock level represented ≈15% of the total number of nerves. • When staining the periprostatic fascia, the classical NVB exhibited a distinct fascial architecture with three separate compartments.

• A tiny minority of nerves in the anterior periprostatic region are functionally significant parasympathetic nerves. • There is little anatomical evidence to support higher incisions in the lateral prostatic fascia to spare cavernous nerve fibres, although such approaches may reduce the risk of traction injury on the more posterolaterally located NVB. • The presence of distinct fascial compartments in the NVB is also confirmed.