Ultrasound Guided Intercostobrachial Nerve Blockade in Patients with Persistent Pain after Breast Cancer Surgery: A Pilot Study

Background: Persistent pain after breast cancer surgery (PPBCS) affects 25 – 60% of breastcancer survivors and damage to the intercostobrachial nerve (ICBN) has been implicated as thecause of this predominantly neuropathic pain. Local anesthetic blockade of the ICBN couldprovide clues to pathophysiological mechanisms as well as aiding diagnosis and treatment ofPPBCS but has never been attempted.Objectives: To assess the feasibility of ICBN blockade and assess its effects on pain and sensoryfunction in patients with PPBCS.Study Design: This prospective pilot study was performed in 2 parts: Part 1 determined thesonoanatomy of the ICBN and part 2 examined effects of the ultrasound-guided ICBN blockadein patients with PPBCS.Setting: Section for Surgical Pathophysiology at Rigshospitalet, Copenhagen, Denmark.Methods: Part 1: Sixteen unoperated, pain free breast cancer patients underwent systematicultrasonography to establish the sonoanatomy of the ICBN. Part 2: Six patients with PPBCSwho had pain in the axilla and upper arm were recruited for the study. Summed pain intensity(SPI) scores and sensory function were measured before and 30 minutes after the block wasadministered. SPI is a combined pain score of numerical rating scale (NRS) at rest, movement,and 100kPa pressure applied to the maximum point of pain using pressure algometry (max= 30). Sensory function was measured using quantitative sensory testing, which consisted ofsensory mapping, thermal thresholds, suprathreshold heat pain perception as well as heat andpressure pain thresholds. The ICBN block was performed under ultrasound guidance and 10 mL0.5% bupivacaine was injected.Outcome Assessment: The ability to perform the ICBN block and its analgesic and sensoryeffects.Results: Only the second intercostal space could be seen on ultrasound which was adequate toperform the ICBN block. The mean difference in SPI was -9 NRS points (95%CI: -14.1 to -3.9),P = 0.006. All patients had pre-existing areas of hypoesthesia which decreased in size in 4/6patients after the block.Limitations: The main limitation of this pilot study is its small sample size, but despite this, astatistically significant effect was observed.Conclusion: We have successfully managed to block the ICBN using ultrasound guidance anddemonstrated an analgesic effect in patients in PPBCS calling for placebo-controlled studies.Key words: Anesthesia, local; intercostobrachial nerve; mastectomy; nerve block; neuralgia