Polyhydramnios as a Clue for the Diagnosis of Congenital Myotonic Dystrophy

Abstract

In 40-50% of all polyhydramnios cases, no apparent cause can be identified and are classified as idiopathic. More than ten percent of babies with idiopathic polyhydramnios revealed certain anomalies after a course of clinical suffering. Congenital myotonic dystrophy (CMD) is one of them. Myotonic dystrophy is the most common form of neuromuscular disorder in adults. CMD is an autosomal dominantly inherited disease, inherited mostly from the mother. Severely affected CMD infants exhibit very critical respiratory failure, and the prognosis is unfavorable in up to 30% of cases. Polyhydramnios coexists with almost all CMD fetuses. A provisional diagnosis of CMD in a pregnancy complicated with polyhydramnios and maternal grip myotonia before birth may be helpful to the neonatology team for planning a thorough and prepared care for newborn patients. We report two cases to inform neonatologists as well as obstetricians that a provisional diagnosis of CMD can be made in a pregnancy complicated with polyhydramnios in a mother with grip myotonia or myotonic dystrophy.