Chronic Pain in Post-Mastectomy Patients; The Difference Between Pectoral Nerve (PECS I-II) and Erector Spinal Plane (ESP) Blocks

Despite advancements in breast cancer treatment, chronic postoperative pain-known as post-mastectomy pain syndrome (PMPS)-remains a common complication, with reported rates between 40-50%. It is typically neuropathic in nature and linked to factors such as axillary lymph node dissection, radiotherapy, and high levels of acute postoperative pain. Younger patients are at higher risk, and early neuropathic symptoms may predict long-term pain. Regional anesthesia techniques, including PECS and erector spinae plane (ESP) blocks, are widely used to improve perioperative pain control and potentially reduce the incidence of chronic pain. These techniques are considered effective and low-risk adjuncts to general anesthesia. This prospective observational study compares the impact of PECS I-II and ESP blocks on chronic pain development in patients undergoing modified radical mastectomy (MRM). The primary outcome is the incidence of pain at 3 months postoperatively (NRS ≥1). Secondary outcomes include acute pain scores, intraoperative fentanyl use, postoperative morphine requirements, and time to first analgesic. The study also explores associations between chronic pain and variables such as lymph node dissection, radiotherapy. Findings aim to guide clinical practice in selecting regional anesthesia techniques that provide both immediate and long-term pain relief.