Hypothesis / aims of study
Pudendal nerve entrapment (PNE) is an uncommon source of chronic pelvic pain. The pudendal neurolisis is an accepted treatment for PNE  and for these patients the laparoscopic approach is feasible and suitable . One of the characteristics of the pudendal nerve (PN) is the variability of its anatomy. Up to 48,5% of the pudendal nerves may not be presented as a single trunk and 57.7% of the rectal nerve would not enter the Alcock’s canal .
This could make the surgical neurolysis challenging, but laparoscopic intraoperative neuronavigation (LIN) could help to identify the PN, in order to preserve it and ensure its integrity after the procedure.
Study design, materials and methods
Of 33 patients with a PNE diagnosis in our centre 11 women underwent a laparoscopic neurolysis of PN with LIN. The intraoperative neuro-monitorization was performed with electrodes in legs (adductor and gastrocnemius) feet, external anal sphincter, perineum, mayor labia and clitoris.
This allowed us to measure electromyography (EMG), nerve terminal motor latency with selective electrostimulation in order to localize the different pelvic nerves and the bulbocavernosus reflex, which was used to control the integrity of the distal integrity of the nerve. Also head sensors were allocated to measure sensory evoked potentials to ensure the proximal integrity of the nerve. No muscle relaxation was used during the surgeries to preserve the integrity of the muscle respond.
Laparoscopic complete neurolysis of the PN was performed and a laparoscopic bipolar neuro-stimulation was used to perform the neuronavigation.
The mean age was 49,9 years and the mean time from diagnosis to treatment was 5.5 years. All patients had pathologic neurophysiologic test, the most affected branch was the perineal one, which was affected in 9 cases (82%), in the other 2 patient a holw affection of the nerve was detected.
The surgical approach was performed with 5 trocars (3 5mm and 2 10mm trocars) in a 30º Trendelenburg position similar to other uro-oncological procedures. After performing an obturator lymphadenectomy, we first exposed the upper sacral roots and then the pudendal. The identification of the different pelvic roots and nerves was performed with the neuro-stimulator. After that we cut the Sacrospinous ligament over the nerve and continue the dissection towards the Alcock’s Canal. The upper part of the Canal was opened, until the hole nerve was liberated. During the procedure the bulbocavernosus reflex and the sensory evoked potential were controlled by a Neurophysiologist. At the end of the surgery, the integrity of the pudendal nerve was also checked. In all cases the PN could be completely founded. In two patients the response to the EMG increased and other two patients had a decrease of the response to the neurostimulation in the electromyography after the surgery, the rest responses to neurostimulation remain unchanged. We also founded in two cases better response of the EMG distally to the entrapment zone. The integrity of the PN could be assessed in all the cases after the surgery.
Interpretation of results
In 6 cases perineural fibrosis was founded between the sacrospinous and sacrotuberous ligament, in 3 cases at the entrance of the Alcock’s canal and in 2 cases was inside the canal. The mean surgical time was 154.4 minutes, the mean hospital stay was 5 days and there were 2 complications (1 Clavien III due to a bowel perforation and 1 Clavien I because of a urinary infection). Three months after the surgery 4 (36%) of the patients had a complete resolution of the pain, 5 (45%) a huge improve and 2 (18%) a mild improve of the pain. Any of the patient complaint about the section of the Sacrospinous ligament.