Research Methods / Techniques
Sacral neuromodulation(SNM) has become a viable and accepted treatment alternative for non-obstructive urinary retention. However, due to complexity of pathophysiology, different neurogenic deficits and unpredictability of affected neural network, the success rate may vary. Moreover, patients with sacral bone abnormalities and/or congenital spinal cord lesions may be poor candidates for proper placement of electrodes.
We aimed to describe a novel technique of selective placement of electrode over pudendal nerve (PN) with laparoscopic approach in a patient with urinary retention who previoulsy failed SNM treatment.
A 34 yrs-old woman with tethettered cord anomaly presented with urinary retention. She was on clean intermittent self catheterization (CIC) and history revelaed a previous failed SNM therapy (tined lead; Medtronic, Minneapolis, Minnesota, USA) trial in 2017. The electrode implanted to other S3 foramen did not continue to be succesfull after 7 month and patient reported resuming of urinary retention symptom and need for CIC again. A 3-D bone model was reconstructed and printed out to show virtual bone model. Because of the bone anomaly, a revision was not possible since there was no foraminal opening (Figure 1) and the patient was hospitalized for laparoscopic electrode implantation with an alternative technique.
Using 4 trocars, we dissected left side of urinary bladder and internal iliac vessels. After visual identification of pudendal nerve, artery and vein benath sacrospinous ligament (SSL), we selectively placed the electrode over the PN, as between pudendal nerve and SSL (Figure 2) and fixed the electrode using 3-0 Vicryl sutures to SSL for preventing dislocation. Proximal side of the electrode has been taken out from the body with left inguinal puncture for connection to the battery in the inguinal area.
Under magnified vision with laparoscopy, selective PN implantation of electrode yielded a high sensation by stimulation of only 0.3 V. After anesthesia recovery and at post-operative 8th hours, patient voided 680 ml without abdominal straining. Unilateral direct implantation on the nerve and stimulation of PN resulted in continous and high response. At post-operative day 1 the patient discharged and continued to use the same program. Her frequency volume chart revealed minimum 300 ml and maximum 740 ml voided volumes with 30 and 110 ml residual volumes measured by CIC.
Several alternative methods of neuromodulation of sacral roots have been described previously. To our knowledge, we describe laparoscopic PN neuromodulation for the first time in literature to treat urinary retention. It has previously been shown that unilateral electrical stimulation of PN afferents improved voiding efficiency by activating the augmenting reflex to produce efficient voiding. There is also evidence suggesting that by use of electrical stimulation to amplify the sensory feedback from PN, urethral afferents provide a means to enhance bladder emptying in persons with retention.
Our implantation technique is unique since under laparoscopic vision of the PN, selective stimulation resulted afferent transmission to sacral roots and restored voiding function in a woman with severe sacral bone anomaly who previously failed sacral nerve stimulation for treatment of urinary retention.