Inclusion Criteria:

• Adults aged 18-75 years

• American Society of Anesthesiologists (ASA) physical status I-III

• Scheduled for elective spine surgery (cervical, thoracic, or lumbar) requiring intraoperative MEP monitoring

• Able to provide written informed consent

Exclusion Criteria:

• Known or suspected difficult airway (Mallampati class IV, history of difficult intubation, limited mouth opening < 3 cm, limited neck extension)

• Body mass index (BMI) > 40 kg/m2

• Known allergy or hypersensitivity to remifentanil, succinylcholine, rocuronium, sugammadex, or propofol

• Personal or family history of malignant hyperthermia • Known or suspected pseudocholinesterase deficiency

• Conditions predisposing to succinylcholine-induced hyperkalemia (e.g., major burns within the last year, denervation injuries or upper motor neuron lesions within 6 months, severe crush injuries, prolonged immobilization > 72 hours, known hyperkalemia > 5.5 mEq/L)

• Severe preoperative motor deficit (manual muscle testing ≤ 2/5 in monitored extremities)

• Neuromuscular disorders (e.g., myasthenia gravis, muscular dystrophy, Guillain-Barre syndrome, prior stroke with residual motor deficits)

• Severe cardiovascular disease (e.g., ejection fraction < 30%, unstable angina, myocardial infarction within 3 months)

• Severe bradycardia (heart rate < 50 bpm) or high-grade atrioventricular block without a pacemaker

• Current use of medications affecting neuromuscular function (aminoglycosides, magnesium infusion, certain antiepileptic meds, etc.)

• Emergency surgery

• High aspiration risk (e.g., uncontrolled gastroesophageal reflux disease)

• Pregnancy or breastfeeding

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 06/28/2026. Questions regarding updates should be directed to the study team contact.