title: A novel CT-guided transpsoas approach to diagnostic genitofemoral nerve block and ablation.
abstract: BACKGROUND
  Inguinal hernia repair is associated with a high incidence of chronic postsurgical pain. This pain may be caused by injury to the iliohypogastric, ilioinguinal, or genitofemoral nerves. It is often difficult to identify the specific source of the pain, in part, because these nerves are derived from overlapping nerve roots and closely colocalize in the area of surgery. It is therefore technically difficult to selectively block these nerves individually proximal to the site of surgical injury. In particular, the genitofemoral nerve is retroperitoneal before entering the inguinal canal, a position that puts anterior approaches to the proximal nerve at risk of transgressing into the peritoneum. We report a computed tomography (CT)-guided transpsoas technique to selectively block the genitofemoral nerve for both diagnostic and therapeutic purposes while avoiding injury to the nearby ureter and intestines.
  
  
  METHODS
  A 39-year-old woman with chronic lancinating right groin pain after inguinal hernia repair underwent multiple pharmacologic interventions and invasive procedures without relief. Using CT and Stimuplex nerve stimulator guidance, the genitofemoral nerve was localized on the anterior surface of the psoas muscle and a diagnostic block with local anesthetic block was performed. The patient had immediate relief of her symptoms for 36 hours, confirming the diagnosis of genitofemoral neuralgia. She subsequently underwent CT-guided radiofrequency and phenol ablation of the genitofemoral nerve but has not achieved long-term analgesia.
  
  
  CONCLUSIONS
  CT-guided transpsoas genitofemoral nerve block is a viable option for safely and selectively blocking the genitofemoral nerve for diagnostic or therapeutic purposes proximal to injury caused by inguinal surgery.
authors.affiliation: Department of Anesthesiology and Pain Management, Stanford University Medical Center, Stanford, California 94304, USA.
authors.forename: David
authors.initials: D
authors.lastname: Parris
authors.forename: Nancy
authors.initials: N
authors.lastname: Fischbein
authors.forename: Sean
authors.initials: S
authors.lastname: Mackey
authors.forename: Ian
authors.initials: I
authors.lastname: Carroll
mesh_terms: D000328:Adult; D005260:Female; D006552:Hernia, Inguinal / Q000601:surgery; D006801:Humans; D007264:Inguinal Canal / Q000294:innervation*; D009407:Nerve Block / Q000379:methods*; D009437:Neuralgia / Q000175:diagnosis / Q000601:surgery; D010149:Postoperative Pain / Q000175:diagnosis / Q000601:surgery*; D016658:Psoas Muscles / Q000033:anatomy & histology*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome