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 breast cancer survivors and damage to the intercostobrachial nerve (ICBN) has been implicated as the cause of this predominantly neuropathic pain. Local anesthetic blockade of the ICBN could provide clues to pathophysiological mechanisms as well as aiding diagnosis and treatment of PPBCS but has never been attempted. Objectives: To assess the feasibility of ICBN blockade and assess its effects on pain and sensory function in patients with PPBCS. Study Design: This prospective pilot study was performed in 2 parts: Part 1 determined the sonoanatomy of the ICBN and part 2 examined effects of the ultrasound-guided ICBN blockade in patients with PPBCS. Setting: Section for Surgical Pathophysiology at Rigshospitalet, Copenhagen, Denmark. Methods: Part 1: Sixteen unoperated, pain free breast cancer patients underwent systematic ultrasonography to establish the sonoanatomy of the ICBN. Part 2: Six patients with PPBCS who 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 was administered. 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 of sensory mapping, thermal thresholds, suprathreshold heat pain perception as well as heat and pressure pain thresholds. The ICBN block was performed under ultrasound guidance and 10 mL 0.5% bupivacaine was injected. Outcome Assessment: The ability to perform the ICBN block and its analgesic and sensory effects. Results: Only the second intercostal space could be seen on ultrasound which was adequate to perform 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 4/6 patients after the block. Limitations: The main limitation of this pilot study is its small sample size, but despite this, a statistically significant effect was observed. Conclusion: We have successfully managed to block the ICBN using ultrasound guidance and demonstrated an analgesic effect in patients in PPBCS calling for placebo-controlled studies.