Magnesium Sulfate Infusion on Postoperative Pain in Lumbar Surgery

The Effects of Perioperative Low-dose Magnesium Sulfate Infusion on Postoperative Pain in Lumbar Surgery

Effective postoperative analgesia after lumbar spine surgery (e.g., laminectomy, vertebroplasty, lumbar stabilization) is associated with faster recovery and shorter hospital stay. Multimodal analgesia aims to reduce opioid consumption and related adverse effects by combining agents with complementary mechanisms of action at peripheral and central levels.

Magnesium is one of the agents used in this approach. Its analgesic effects are attributed to inhibition of neuropathic pain, potentiation of opioid analgesia, and attenuation of opioid tolerance. Mechanistically, magnesium acts as a non-competitive NMDA receptor antagonist and modulates intracellular calcium influx, thereby reducing central glutamate release and limiting hyperalgesia.

However, the clinical efficacy of perioperative magnesium remains controversial. Outcomes may vary depending on timing (intraoperative vs. postoperative), dosing strategies (bolus vs. infusion), and total administered dose. The optimal dosage, administration method, safety profile, and dose-response relationship of magnesium for analgesic purposes are not yet clearly established.

This study aims to evaluate the effectiveness of perioperative low-dose magnesium sulfate (MgSO₄) in this context.

Inclusion Criteria:

• aged 18 years and older,
• ASA (American Society of Anesthesiologists) physical status I-II,
• awaiting to undergo lumbar spinal surgery under general anesthesia.

Exclusion Criteria:

• the presence of cardiac conduction disorders and/or cardiac comorbidities
• use of Ca channel blockers,
• hepatic/renal failure and allergy to Mg.