Pharmacokinetics and Impact of Magnesium Sulfate on Neuromonitoring in Spinal Surgery
University of California, San Francisco
Summary
Intraoperative neurophysiologic monitoring (IONM) is commonly used during complex spinal surgery to monitor the integrity of neural structures and improve the perioperative safety profile. Transcranial Motor Evoked Potentials (TcMEPs) monitor the integrity of the motor pathways and are one of the most commonly used monitoring modalities in spinal surgery. Because inhaled anesthetics can negatively affect the ability to monitor TcMEPs, anesthesiologists commonly use a combination of propofol and opioids to maintain the anesthetic state. Additionally, anesthesiologists will frequently administer intravenous infusions of medications that can decrease postoperative pain and opioid use (called opioid-sparing adjuncts) because spinal surgeries result in significant postoperative pain. Despite the increasing use of these agents, there is scant clinical data about how they may affect the integrity of TcMEP monitoring. Magnesium (Mg), a N-methyl-d-aspartate receptors (NMDA) receptor antagonist, is one of the adjuncts with robust data supporting clinical efficacy to decrease pain and opioid use on TcMEPs. Mg has been used clinically for decades. The investigators commonly utilize intravenous magnesium as a component of our spinal anesthesia protocol. However, there is only a single case report that discusses the effects of Mg on TcMEPs. Here the investigators propose a prospective clinical trial to quantitatively assess the effects of various Mg plasma levels on TcMEPs. There is a lack of literature on the pharmacokinetics of magnesium in non-pregnant patients.
Description
Spinal surgeries continue to increase in frequency and complexity, with the potential to cause injury to neural structures. Intraoperative neurophysiologic monitoring (IONM) is a crucial tool in spinal surgery, offering real-time detection of adverse changes in the integrity of neural systems governing sensory and motor function. At the same time, the patient is anesthetized, which decreases the risk of permanent and severe neuronal injury. Transcranial Motor Evoked Potentials (TcMEPs), which involve nonspecific stimulation of pyramidal axons in the cerebral motor cortex while monitoring myoge…
Eligibility
- Age range
- 18+ years
- Sex
- All
- Healthy volunteers
- No
Inclusion Criteria: Adult patients (\>18 years of age) undergoing open thoracolumbar fusion with planned neuromonitoring Exclusion Criteria: 1. Patients with a history of significant cardiac disease (LVEF \<35%, 2nd/3rd-degree block without a pacemaker, or significant arrhythmia) 2. Patients with kidney disease (GFR \<30), or hepatic dysfunction (history of cirrhosis) 3. Allergy or sensitivity to magnesium 4. Patient with neuromuscular disease such as myasthenia graves
Interventions
- DrugMagnesium sulfate administration
A single intravenous bolus of Mg of 30mg/kg (based on ideal body weight) will be administered over a period of 10 minutes (min).
Location
- University of California San Francisco HospitalSan Francisco, California