Walsh & Hoyt: Congenital

Congenital absence of abduction as an isolated phenomenon is exceedingly rare but may occur from injury to the abducens nerve shortly before or during birth. In one study, abduction paresis was present in 35 of 6,360 newborns, and in all but one it disappeared by 6 weeks of age. Birth trauma was suspected. In another study of 6,886 neonates, 0.4% had abduction paresis, increasing progressively from 0% for deliveries by caesarean section to 0.1% for spontaneous vaginal delivery, 2.4% for forceps delivery, and 3.2% for vacuum extraction, again suggesting birth trauma as the cause.