Does infantile abduction deficit indicate duane retraction syndrome until disproven?

Duane retraction syndrome consists of abduction deficit and palpebral fissure narrowing, upshoots, or downshoots on adduction. Infants with abduction deficit should be considered to have Duane retraction syndrome until disproven, because congenital abducens nerve palsy is extremely rare. The abducens nerve on the affected side is absent in type 1 Duane retraction syndrome and in some type 3 patients. The authors present a 7-month-old girl who showed limitation of abduction simulating Duane retraction syndrome. High-resolution magnetic resonance imaging (MRI) revealed atrophic lateral rectus and present abducens nerve. This report is important because this case showed that congenital abducens nerve palsy exists, although it is extremely rare, and high-resolution MRI could be pivotal for the differentiation of Duane retraction syndrome and congenital abducens nerve palsy in infancy.