Introduction

• Abdominal Cutaneous Nerve Entrapment Syndrome (ACNES) accounts for an estimated 2-3% of cases of chronic abdominal pain and up to 30% of those with idiopathic abdominal wall pain^1,2.
• ACNES is defined as a localized, sharp or burning abdominal wall pain that can be precisely pinpointed by the patient.
• ACNES results from the entrapment of the anterior or lateral cutaneous branches of the thoracoabdominal nerves (T7-T12) as they traverse the fibrous abdominal fascia.
• The Carnett’s sign remains a key physical exam finding and can distinguish ACNES from visceral pain³.
  • Abdominal tenderness persists or worsens during voluntary tensing of the abdominal.
• The External Oblique Intercostal Fascial Plane (EOIFP) block is a regional anesthetic technique which targets the anterior and lateral branches of the thoracoabdominal nerves⁵.
  •  Performed by depositing local anesthetic between the external oblique and intercostal muscles⁵.

Case report

• A 21-year-old female presented to the Emergency Department with a two-week history of abdominal pain.
• Past Medical history included asthma, celiac disease, hyperlipidemia, and polycystic ovarian syndrome.
• Abdominal pain described as constant, sharp pain in the right upper quadrant (RUQ) without radiation.
  • Pain different from previous celiac flares or corpus luteal cyst-related pain.
  • Exacerbated by activity and raising her arms above her head
  • Limited oral intake due to worsening pain and nausea 

• Physical exam:
  • Moderate tenderness to palpation in the RUQ without rebound or guarding
  • Positive Carnett’s sign (tenderness intensified when lifting head and shoulders off the examination table and contracting abdominal wall muscles)
• Lab values unremarkable
• A right External Oblique Intercostal Fascial Plane (EOIFP) block was performed (Fig. 1)
  • 20ml of 0.25% Bupivacaine with 4mg Dexamethasone
  • Procedure was well tolerated with no immediate complications
• Marked reduction in RUQ pain within one hour of procedure
• Improvement in ambulation and tolerating oral intake
• Patient was discharged home the following day
• At outpatient two-week follow-up and telephone three-month follow up, patient report sustained, complete resolution of RUQ abdominal pain

Discussion

• Conventional treatments for ACNES involve local anesthetic injections, chemical neurolysis, or surgical neurectomy with varying degrees of success¹.
• The EOIFP block specifically targets both the anterior and lateral cutaneous branches of the thoracoabdominal nerves (T7-T11), potentially providing broader coverage than the transversus abdominis plane (TAP) block, which primarily affects the anterior branches
• Broader implementation and prospective studies are needed to define the efficacy of EOIFP block and establish its place the treatment of ACNES