Spinal anesthesia for urgent cesarean section in a parturient with RYR1 mutation-associated malignant hyperthermia susceptibility: a case report

INTRODUCTION: Malignant hyperthermia (MH) is a rare pharmacogenetic disorder triggered by volatile anesthetics and succinylcholine. MH susceptibility in pregnancy requires prospective anesthetic planning to ensure maternal and fetal safety. This case reports the successful management of an urgent cesarean section under spinal anesthesia in a parturient with pre-pregnancy genetic confirmation of MH susceptibility. MAIN SYMPTOMS AND CLINICAL FINDINGS: A 27-year-old primigravida (G1P0) at 38 weeks gestation presented with labor pain. She had a known pathogenic RYR1 variant (c.10561G > A) identified before pregnancy due to significant family history (grandfather's intraoperative death). Labor failed to progress in the first stage, necessitating an urgent (Category 2) lower segment cesarean section. Preoperative physical and neuromuscular examinations were normal. MAIN DIAGNOSES, THERAPEUTIC INTERVENTIONS, AND OUTCOMES: The patient had autosomal dominant MH susceptibility confirmed by whole exome sequencing. Regional anesthesia was selected as the preferred trigger-free technique; a single-shot spinal anesthetic with 12 mg of 0.5% hyperbaric bupivacaine at L4-L5 achieved a T4 sensory level. Strict MH precautions were implemented: anesthesia machine flushed with 100% oxygen, vaporizers removed, activated charcoal filters applied, CO₂ absorbent replaced, and succinylcholine and volatile agents excluded. Dantrolene was immediately available. Hemodynamics were maintained with left uterine displacement, crystalloid colloid, and phenylephrine infusion. The decision-to-incision interval was 40 min and decision-to-delivery interval 45 min. The intraoperative and 48-hour postoperative course was uneventful, with stable end-tidal CO₂ (32-36 mmHg), normothermia (36.5-37.0 °C), heart rate 80-95 bpm, and no muscle rigidity. A healthy neonate (birth weight 3.1 kg, Apgar 8/9) was delivered. The patient was discharged on postoperative day three in stable condition. CONCLUSION: This case demonstrates that spinal anesthesia is a safe and effective trigger-free technique for urgent cesarean section in MH-susceptible parturient when strict precautions are followed. Pre-pregnancy genetic diagnosis enabled prospective multidisciplinary planning and contributed to excellent maternal and neonatal outcomes.