Inguinal nerve block can be of diagnostic benefit and therapeutic value in patients with chronic groin pain. Pulsed radiofrequency treatment can be used for sustained pain relief in patients who get a positive response to the inguinal nerve block. However it is important to note that in some cases injection treatment may not provide the desired results or the pain relief may not be sustained. At Pain Spa Dr. Krishna performs inguinal nerve blocks under real time ultrasound guidance, using state of the art equipment. This ensures 100% accuracy and our complication rates are extremely low.
The ilioinguinal and iliohypogastric nerves are branches of the lumbar plexus originating from the ventral ramus of L1 with occasional contributing fibers from T12. They emerge from the lateral border of the psoas major muscle, travel around the abdominal wall, and penetrate the transverse abdominal and the internal oblique muscles to innervate the hypogastric and inguinal areas. The anterior cutaneous branch of the iliohypogastric nerve passes through the internal oblique muscle just medial to the anterior superior iliac spine (ASIS), to lie next to the external oblique muscle. It then passes through the external oblique above the superficial inguinal ring, and supplies the suprapubic area. The ilioinguinal nerve remains between the deeper two muscle layers, it travels through the inguinal canal and supplies the upper medial thigh and superior inguinal region.
The genitofemoral (L1–L2) nerve passes through and along the anterior surface of the psoas major muscle, and it divides into genital and femoral branches above the inguinal ligament. Its genital branch travels with the spermatic cord and innervates the genitalia inferior to the area supplied by the ilioinguinal nerve.
Injections are generally avoided in patients with systemic infection or skin infection over puncture site, bleeding disorders or coagulopathy, allergy to local anaesthetics or any of the medications to be administered. Pulsed radiofrequency ablation is contraindicated in patients with a cardiac pacemaker or any other neuromodulation implants.
The clinical application of pulsed radiofrequency (PRF) by interventional pain physicians for a variety of chronic pain syndromes, including ilioinguinal neuralgia, is growing. As a minimally invasive percutaneous technique with none to minimal neurodestruction and a favourable side effect profile, use of PRF as an interventional neuromodulatory chronic pain treatment is appealing.
The mechanism of action underlying the utility of PRF in interventional pain medicine is uncertain. Unlike conventional continuous radiofrequency ablation, whose pain relief effects are mediated through non-selective, temperature-dependent, neurodestruction, PRF is widely believed to act through a temperature- independent, neuromodulatory process, altering synaptic transmission and pain signaling via the emission of electric fields, with none to minimal resultant tissue destruction. Given the nondestructive nature of PRF, deafferentation pain—a feared complication of continuous radiofrequency ablation—is not a potential risk.
Patients who get temporary pain relief from ilioinguinal nerve blocks may be suitable for ilioinguinal nerve ablation procedure (pulsed radiofrequency treatment). This is likely to provide longer-term pain relief.
The procedure is done on an outpatient basis. The procedure is performed under ultrasound guidance to ensure the accuracy of needle placement. Specialized equipment including radiofrequency machine, probe, and RF needle is utilized to heat the nerve up to a temperature of 42°C. Generally local anaesthetic is injected around the nerve following nerve ablation. The local anaesthetic is responsible for immediate pain relief, whereas pulsed radiofrequency takes 4 to 6 weeks to provided sustained pain relief. Pain relief from pulsed radiofrequency ablation of the ilioinguinal nerve can last between 6 months to 24 months.
Complications are rare, particularly if the injections are performed using a precise needle-positioning technique. Possible complications include bruising, infection, hematoma, nerve injury and reaction to the injectates. Infection can be avoided with appropriate aseptic precautions. Severe allergic reactions to local anaesthetics are uncommon. Steroid injections may produce local reactions, occurring most often immediately after injection. These local reactions last for 24 to 48 hours and are relieved by application of ice packs. Post-procedural pain flare-up may occasionally occur and may be treated with painkillers. Neurological complications including paraesthesias and numbness have been described but are rare.