Stridor as a neonatal presentation of skeletal muscle sodium channelopathy.

OBJECTIVE: To describe stridor as the presenting feature in a neonate with the skeletal muscle sodium channelopathy paramyotonia congenita.
DESIGN: Case report.
SETTING: Outpatient neuromuscular clinics at Great Ormond Street Hospital for Children and the Medical Research Council Centre for Neuromuscular Disease at the National Hospital for Neurology and Neurosurgery, London, England. PATIENT: A child carrying the Thr1313Met SCN4A mutation associated with paramyotonia congenita. INTERVENTION: Supportive care in the neonatal period and administration of mexiletine hydrochloride at age 4 years. MAIN OUTCOME MEASURE: The association of stridor and paramyotonia congenita was made retrospectively following the diagnosis in the infant's mother; the child is now regularly reviewed at the pediatric outpatient clinic.
RESULTS: Persistent stridor was present for the first 6 months of life, and episodic stridor can still be exacerbated by intercurrent respiratory tract infection, cold, laughter, or crying. Common symptoms of paramyotonia congenita have been apparent from age 1 year and are beginning to respond to a recent trial of mexiletine.
CONCLUSIONS: To our knowledge, neonatal stridor has not previously been reported in skeletal muscle sodium channelopathies. The recognition that infants inheriting mutations known to cause paramyotonia congenita are inherently at risk for developing neonatal complications following an uneventful labor is important for all training neurologists so they can advise expectant mothers and pediatric and obstetric colleagues appropriately.