Beyond acrodynia: infantile mercury vapor poisoning presenting with refractory hypoglycemia and persistent neurological damage

Infantile elemental mercury poisoning is clinically rare and poses a severe long-term health threat. This report describes a rare case of non-accidental infantile elemental mercury poisoning, in which the infant was continuously exposed to mercury vapor for 20 days starting from postnatal day 15. The infant initially presented with feeding difficulties and respiratory symptoms, which rapidly progressed to respiratory distress and seizure-like episodes at 5 months of age; laboratory tests revealed severe hypoglycemia and metabolic acidosis. Despite 5 days of intravenous glucose infusion and comprehensive support involving mechanical ventilation, sedation, and corticosteroids, hypoglycemia and epileptic symptoms persisted. The diagnosis of mercury poisoning was confirmed by a blood mercury test and governmental investigation, followed by two courses of dimercaptopropane sulfonate (DMPS) chelation therapy, after which hypoglycemia, respiratory symptoms, and epilepsy were effectively managed. The patient was discharged 25 days after admission. CT images revealed no abnormalities in the head at admission, but subsequent MRI at discharge and thereafter indicated persistent brain damage, including signal abnormalities and cerebral atrophy. This case suggests that severe hypoglycemia can be a critical component of infantile elemental mercury poisoning and contributes to persistent neurological injury. It also highlights that the efficacy of chelation therapy is severely limited when treatment is delayed after prolonged exposure. Current chelators such as DMPS have poor blood-brain barrier penetration and cannot effectively remove accumulated inorganic mercury from the CNS, underscoring the urgent need for novel CNS-penetrating therapeutic strategies in delayed presentations.