Robotics in the Management of Chronic Groin or Scrotal Content Pain
Chronic groin or scrotal content pain (CGSCP) is defined as a discomfort or pain lasting more than three months in the groin, scrotum, testis or epididymis.[39,40] Although some patients have a previous history of vasectomy, inguinal hernia repair, infection, and trauma, the exact mechanism of CGSCP is still unknown. There is no demonstrable etiological factor (idiopathic pain) in approximately 40 percent of the patients.[39–43]
The management of CGSCP begins with medical treatment including analgesics, anti-inflammatories and antibiotics. Neurotransmitter inhibitors (such as gabapentin) may also provide benefit especially in patients who have neuropathic pain.[40] Surgical treatment modalities such as microsurgical denervation of the spermatic cord (MDSC), epididymectomy and orchiectomy are employed only when all non-invasive medical options fail. Among available surgical options, MDSC appears to offer high success rates with the least amount of extirpative surgery.[43,44] Our group recently explored the anatomic basis of the MDSC procedure in men who had CGSCP. The study illustrated a unique distribution of Wallerian Degeneration in nerve bundles located at three specific areas in the spermatic cord: the cremasteric muscle area, the peri-vasal tissues and the posterior peri-arterial/lipomatous tissues.[45] Wallerian degeneration has been shown to cause chronic pain in peripheral nerves in other regions such as the arm or leg. This has helped us in developing a targeted approach to MDSC to further minimize or refine the amount of ligation performed during the procedure. The goal is just to ligate tissues in the spermatic cord that are likely to harbor the nerves with Wallerian degeneration, while preserving the bulk of the cord.
Laudano et al. recent performed an animal study (rat model) to illustrate the safety and efficacy of the MDSC procedure.[46] They showed a significant decrease in median number of nerve fibers remaining around the vas deferens after the MDSC procedure compared to the sham control (MDSC =3.5 nerves vs. sham =15.5 nerves, P=0.003). The animals were survived and then reassessed after two months. No deleterious effects on spermatogenesis or vas patency were seen in the experimental groups when compared with the sham rats.
Technique
Robotic assisted targeted microsurgical denervation (RTMDSC) was first described by our group in 2010.[14] Our technique differs from standard MDSC described by Levine[47] in that in includes a more conservative targeted ligation of tissues in the cord and also involves the use of the robotic platform. The standard MDSC technique involves ligation of the bulk of the spermatic cord except for the testicular arteries, vas deferens (in cases of previous vasectomy—this is ligated as well) and lymphatics. RTMDSC focuses and involves ligation of only three specific areas in the spermatic cord where we illustrated nerves with Wallerian Degeneration in our previous studies.[6,45,47] The bulk of the internal spermatic cord sheath and internal cord are preserved. A subinguinal approach is utilized. The spermatic cord is brought up to the skin. Medial, posterior and lateral cauterization of the peri-cord tissues is performed to ligate branches of the ilio-inguinal and genito-femoral nerves in the external inguinal ring area. The spermatic cord is now secured on a tongue-blade platform. The robot is now brought in from the right side of the patient (supine position). A black diamond micro-forceps is used in the right arm, micro-bipolar forceps in the left arm and a curved monopolar scissor is used in the fourth arm. The cremasteric muscle layer is carefully ligated using the curved monopolar scissors, the peri-vasal sheath is also carefully ligated while preserving the deferential artery and the vas deferens, and finally the posterior lipomatous/peri-arterial tissues are ligated. The internal spermatic sheath and inner cord are completely preserved.
After standard MDSC, there are some nerve fibers still left behind in the peri-vasal tissues as shown by Laudano et al..[46] Since this peri-vasal tissue area was shown in our previous study to be the one area with the highest density of nerves with Wallerian degeneration, we also perform hydrodissection of the vas deferens to further ligate any small diameter nerve fibers that may be in this tissue while preserving the vasa-vasorum (vascular plexus on the vas deferens). Previous animal studies have shown the efficacy of this technology for this application.[48]
In order to decrease the risk of neuroma formation and scarring around the spermatic cord, we also wrap the cord with a bio-inert matrix (AxoGuard, Axogen, Gainesville, FL, USA) at the completion of the RTMDSC.[49]
A recent modification of our technique has been the utilization of the flexible fiber-optic CO2 laser (OmniGuide, Cambridge, MA, USA) (Figure 5) to perform the ligation/ablation of the three key tissues mentioned above during RTMDSC. We recently performed a comparative study on a fresh human cadaver to assess the degree of peripheral thermal injury or damage to surrounding tissues when utilizing monopolar cautery versus CO2 laser ablation.[50] The study illustrated a significantly decreased amount of peripheral thermal damage with CO2 energy compared to standard monopolar electrocautery.[50] Thus, we have now instituted the use of this laser for the tissue ablation during RTMDSC for a more precise and controlled dissection.
Figure 5.
Peri-vasal tissue is being ablated using the flexible fiber optic CO2 laser (OmniGuide, Cambridge, MA, USA) during robotic assisted targeted microsurgical denervation (RTMDSC) procedure.
We have performed 546 RTMDSC procedures from October 2008 to October 2013 (546 spermatic cords in 463 patients). The median robotic operative duration was 15 minutes (range, 10–150 minutes). Pre-operative and post-operative pain was assessed using an externally validated pain assessment tool: PIQ-6 (Quality Metric Inc., Lincoln, RI, USA). 84.8% (463/546 cases) had a significant reduction (>50%) in pain after the RTMDSC procedure by six months postoperative. Within this group, 70.5% (385 cases) had complete resolution of pain and 14.3% (78 cases) had a greater than fifty percent reduction in their pain score. RTMDSC did not relieve any pain in 15.2% [83] testicular units. The complications were limited to one testicular ischemia, two testicular artery injuries (repaired intra-op with no long term sequel), one vasal injury (repaired intra-op with no long term sequel), ten hematomas, three seromas, and five wound infections.
Use of the robot for RTMDSC procedures offers some advantages to microsurgeons in terms of providing an additional instrument arm obviating the need for a skilled microsurgical assistant, allows for the easy integration of various imaging and sensing modalities at the surgeon console to improve surgical efficiency, and most importantly provides an ergonomic platform that eliminates tremor and reduced surgeon fatigue. The use of robotics for microsurgery at our institution has allowed us to improve our surgical throughput (decreased operative duration and ability to perform more procedures in the same amount of time) and thus has reduced the out-of-pocket costs to the patients to levels comparable to standard microsurgery. The caveat to this is of course the need for high volume to create such a situation. However, as the prices of robotic platforms fall in the future and as more platforms are developed, the use of these robots is likely to become less cost-prohibitive.
Vasectomy reversal is also a viable surgical treatment option in patients who have post-vasectomy pain.[51] The efficacy of robotic assisted vasectomy reversal for post-vasectomy pain has been explored by our group.[52] A total of 24 robotic vasectomy reversals [22 robotic assisted vasovasostomy (RAVV) and 2 RAVE] were performed in patients who had post-vasectomy pain. Eighty-five percent of the patients had a significant reduction in pain (>50% reduction in pain score). However, larger studies with long-term follow-up are needed to assess its clinical utility for this indication.
Transl Androl Urol. 2014;3(1):102-112. © 2014 AME Publishing Company
