Hypoxic ischemic encephalopathy in a case of intranuclear rod myopathy without any prenatal sentinel event

Intranuclear rod myopathy (IRM), a variant of nemaline myopathy, is characterized by the presence of nemaline bodies in myonuclei. We report a case of IRM presenting with hypoxic ischemic encephalopathy (HIE). There were no prenatal complications caused by fetal brain injury. Although no nemaline bodies were observed in the cytoplasm, intranuclear rods were observed in some fibers under light and electron microscopy. Molecular analysis identified a heterozygous variant, c.449C>T (p.Thr150Ile), in ACTA1. On magnetic resonance imaging at 9 days of age, injuries to the basal ganglia, thalamus, and brainstem consistent with perinatal HIE were seen. Respiratory insufficiency at birth was strongly suspected to be the cause of HIE. Our case highlights that a patient with a congenital neuromuscular disorder who presents with severe respiratory dysfunction requiring substantial resuscitative efforts at birth can be complicated by HIE without any prenatal sentinel event. Prenatal detection of neuromuscular disorders, careful management of delivery, and neonatal resuscitation and adequate respiratory management are important in preventing irreversible brain injury in these patients.