Efficacy of Magnesium Sulfate as an Adjuvant to Local Anesthetic in Erector Spinae Plane Block for Postoperative Analgesia After Modified Radical Mastectomy

Why It Matters

The protocol cuts opioid requirements and prolongs analgesia, accelerating recovery and reducing opioid‑related complications in breast surgery patients.

Key Takeaways

• 200 mg MgSO₄ added to levobupivacaine reduces morphine use 33%
• Analgesia duration extended 2.8‑fold with MgSO₄
• Study enrolled 60 women undergoing unilateral modified radical mastectomy
• ESP block performed at T3 and T6 under ultrasound guidance
• MgSO₄ enhances block via NMDA antagonism and calcium‑channel blockade

Pulse Analysis

Modified radical mastectomy remains one of the most painful oncologic procedures, with extensive tissue dissection and nerve injury driving high postoperative opioid demand. Regional techniques such as the erector spinae plane (ESP) block have gained traction because they can be performed under ultrasound guidance and target the dorsal rami that supply the thoracic wall. Yet the duration of analgesia from a single‑shot ESP block can be limited, prompting clinicians to explore adjuvants that extend pain relief without adding systemic side effects.

Magnesium sulfate, a non‑competitive NMDA receptor antagonist and calcium‑channel blocker, offers a pharmacologic route to enhance local anesthetic performance. In a double‑blind, randomized study of 60 female patients scheduled for unilateral MRM, investigators added 200 mg of MgSO₄ to 0.25 % levobupivacaine administered at the T3 and T6 transverse processes. The magnesium group required 33 % less morphine in the first 24 hours, and the time to the first rescue analgesic was 2.8 times longer than the control arm, with pain scores dropping to statistically significant lower levels (p < 0.001).

These results translate into a clear opioid‑sparing benefit, which is especially valuable amid growing concerns about postoperative opioid exposure and its contribution to chronic use. By prolonging the analgesic window of the ESP block, magnesium sulfate can facilitate earlier mobilization, shorter hospital stays, and improved patient satisfaction. Future investigations should assess optimal dosing, cost‑effectiveness, and whether similar gains are observable in other thoracic or abdominal surgeries, positioning magnesium‑augmented ESP blocks as a low‑risk, high‑impact addition to enhanced recovery pathways.