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Eppstein AC, Munshi IA, Sakamoto B, Gwirtz K. Ultrasonography-Guided Identification With Methylene Blue Tattooing of the Ilioinguinal Nerve for Neurectomy for Chronic Pain: A Case Series. JAMA Surg. 2015;150(2):180–182. doi:10.1001/jamasurg.2014.1098
Chronic ilioinguinal pain is a common but morbid complication of inguinal herniorrhaphy for 12% to 62% of patients.1 Although pharmacologic options exist (such as nerve blocks), long-term pain relief is inferior to surgical neurectomy.2,3 We present our experience in ilioinguinal neurectomy with preoperative ultrasonography-guided identification and perineural injection of methylene blue to tattoo the nerve.
Four patients with inguinodynia who responded favorably to nerve blocks were referred for neurectomy. Three patients had pain from herniorrhaphy, and 1 patient had neuropathic pain. Before inducing anesthesia, a staff anesthesiologist localized the proximal nerve using ultrasonography above the anterior superior iliac spine, anterior to the midaxillary line, between the transversus abdominis and internal oblique muscle planes. A 21-gauge nerve stimulator needle reproduced preoperative pain. The intramuscular plane was hydrodissected with 0.5 to 5 mL of normal saline, followed by perineural tattooing with 0.3 to 0.5 mL of methylene blue and 2 to 5 mL of bupivacaine hydrochloride, 0.5%. The skin was marked to triangulate approximate nerve position. Under general anesthesia, a 3-cm transverse incision was made, and the external and internal oblique muscles were split in the direction of the fibers, allowing exposure of the transversus abdominis with self-retaining retractors. Within the blue-stained fibers of the transversus abdominis, we identified and dissected out the ilioinguinal nerve (Figure). The nerve was ligated proximally and distally, and a segment was sent for frozen section. All patients were discharged home without complications and were followed up for 4 weeks after surgery.
During surgery, the nerve was positively identified in all patients. The time from incision to localization was as short as 7 minutes. At follow-up, all patients had expected numbness over the distribution of the nerve. Three of the 4 patients experienced complete or near-complete resolution of pain, although 1 of the 3 patients had incisional hyperesthesia. The fourth patient experienced numbness but no pain relief. However, this patient’s pain was eventually relieved by the excision of an inguinal lymph node.
Ilioinguinal neurectomy is effective at reducing pain after inguinal herniorraphy.4 Traditionally, surgeons have relied on anatomic landmarks in the postoperative groin; success depends on finding the nerve within scarred and obliterated tissue planes. Dissection may be arduous, may damage surrounding structures, or may require mesh removal.5 Using stimulator needle localization with directed cutdown can improve detection, but this advantage is lost if the needle slips. These problems necessitated a more reproducible, efficient technique that permits the quick identification of the nerve without the aforementioned pitfalls.
Our technique is based on the transversus abdominis plane block, which is used in our facility for postoperative analgesia.6 A strong ultrasonographic experience is critical to identifying the nerve within the muscle but can be time-consuming. After confirmation of the nerve by stimulation, minimizing dye injection prevents tattooing too wide an area. Localization allows for a small, roughly 3-cm incision far from previous scar tissue, and dissection is similar to the Rocky-Davis approach to appendectomy. Within the transversus abdominis fibers, the nerve will be visible against blue-stained muscle, allowing for easier ligation and division. None of our patients required removal of mesh. The time required for identification of the nerve varies based on the learning curve and the depth of the subcutaneous tissues, and good retraction is critical for visualization. Overall, this procedure reduces morbidity while allowing the surgeon to more quickly and easily treat the patient’s inguinodynia.
Corresponding Author: Andrew Curtiss Eppstein, MD, Surgery Service, Section of General Surgery, Richard L. Roudebush VA Medical Center, 1481 W Tenth St, Indianapolis, IN 46202 (firstname.lastname@example.org).
Published Online: December 17, 2014. doi:10.1001/jamasurg.2014.1098.
Author Contributions: Drs Eppstein and Sakamoto had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Eppstein, Sakamoto, Gwirtz.
Acquisition, analysis, or interpretation of data: Munshi.
Drafting of the manuscript: Eppstein.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Eppstein.
Administrative, technical, or material support: All authors.
Study supervision: Eppstein, Munshi.
Conflict of Interest Disclosures: None reported.
Previous Presentation: This paper was presented at the 38th Annual Surgical Symposium of the Association of VA Surgeons; April 8, 2014; New Haven, Connecticut.
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