From the Research
The genital branch of the genitofemoral nerve should be blocked below the inguinal ligament. This approach is preferred because below the ligament, the genital branch has already separated from the femoral branch and travels through the inguinal canal, making it more accessible and allowing for a more targeted block. The block is typically performed at the level of the external inguinal ring or within the inguinal canal. To perform this block, a local anesthetic such as 5-10 mL of 0.25-0.5% bupivacaine or 1-2% lidocaine is injected. Anatomically, the genital branch innervates the cremaster muscle and provides sensory innervation to the scrotum in males or the labia majora in females. Blocking above the inguinal ligament would be less specific as the nerve is deeper and still joined with the femoral branch in many cases, potentially resulting in unwanted blockade of the femoral branch which supplies the anterior thigh skin and would require a deeper injection with higher volumes of anesthetic.
Some key points to consider when performing this block include:
- The use of ultrasound guidance to improve the efficacy and reduce morbidity of the block, as seen in a case report of a successful cryoablation of the femoral component of the genitofemoral nerve using ultrasound guidance 1.
- The potential for variation in the distribution of the genitofemoral nerve, with some studies suggesting that the terms "medial branch" and "lateral branch" may be more practical for describing the proximal branches of the genitofemoral nerve 2.
- The effectiveness of peripheral nerve stimulation of the cutaneous branch of the ilioinguinal and genital branch of the genitofemoral nerves in treating testicular pain, as demonstrated in a case report of a 30-year-old man with chronic testicular pain following scrotal hydrocele surgery 3.
- The importance of considering the anatomy of the genitofemoral nerve and its branches when performing the block, as well as the potential risks and benefits of the procedure, as discussed in a study on the use of CT-guided transpsoas approach to diagnostic genitofemoral nerve block and ablation 4.
- The potential benefits of combining the genitofemoral nerve block with other blocks, such as the ilioinguinal/iliohypogastric nerve block, in improving the quality of perioperative anesthesia and analgesia, as seen in a randomized controlled pilot study 5.