Awake malignant hyperthermia–spectrum presentation in a preterm neonate

Background: Malignant hyperthermia (MH) is a life-threatening pharmacogenetic disorder of skeletal muscle calcium regulation, classically triggered by volatile anesthetics or succinylcholine. Increasing evidence suggests that MH susceptibility may manifest outside the operating room under specific physiological stress conditions. Case presentation: We report a 35+6-week preterm neonate who developed an abrupt hyper-metabolic crisis characterized by hyperthermia, generalized muscle rigidity, severe hypercapnia, metabolic acidosis, hyperkalemia, and elevated creatine kinase levels temporally associated with nebulized beta-adrenergic stimulation, in the absence of known anesthetic triggers. Infectious, venti-latory, and environmental causes were systematically excluded. Serial laboratory analysis showed an initial lactate rise with rapid normalization and a progressive decline in creatine kinase levels. The Malignant Hyperthermia Clinical Grading Scale yielded a raw score of 56 (almost certain MH). The infant improved with supportive treatment without dantrolene and recovered fully. Conclusions: MH-compatible hypermetabolic crises can occur in preterm neonates outside anesthetic settings. Unexplained hypercapnia with hyperthermia and metabolic instability should prompt early consideration of MH in NICUs, even when no anesthetic triggers are present.