Analgesic Efficacy of Magnesium Sulphate versus Ketorolac when Added to Bupivacaine in Erector Spinae Plane Block for Acute and Chronic Postmastectomy Pain

Background: Breast cancer surgeries are always proceeded by pain. The erector spinae plane block (ESPB) is a new inter-fascial block that has been recently used to control chronic pain in thoracoscopic surgery.
Aim: This study aimed to compare the analgesic effect of adding magnesium sulphate (MgSO₄) vs. ketorolac as an adjuvant to bupivacaine (BVC) in preoperative ESPB in females scheduled for modified radical mastectomy (MRM).
Methods: Seventy-five females were allocated into three groups (25 each). Group A received U/S guided ESPB with an injection of 20 ml of BVC plus 2 ml normal saline, group B received an injection of 20 ml of BVC plus 2 ml of 10% MgSO₄ (200 mg) and group C received an injection of 20 ml of BVC plus 2 ml (30 mg) ketorolac. The Visual Analogue Scale (VAS) score was utilized for evaluating the acute pain severity while brief pain inventory-short form (BPI-SF) was utilized to assess the chronic pain severity. Results: Magnesium and ketorolac didn’t reduce the incidence of pain at 1, 2, 3 and 6 months. Magnesium group has lower BPI scores at 1 and 2 months than the ketorolac and control groups but not 3 and 6 months postoperatively. Magnesium & ketorolac groups had significantly lower acute pain postoperatively. Compared to the control group, magnesium and ketorolac groups showed significantly lower total morphine consumption and longer mean times to the first analgesic recall.
Conclusion: Adding magnesium sulfate or ketorolac to BVC in a preoperative single shot of ESPB didn’t decrease the chronic post-surgical pain (CPSP) incidence 6 months after surgery. However, they provided superior early postoperative analgesia and reduced postoperative analgesic requirements.