Facial asymmetry and tendon laxity in superior oblique palsy

Both facial asymmetry and superior oblique tendon laxity are associated with congenital superior oblique muscle palsy (SOP). It is unknown whether facial asymmetry and tendon laxity are related to each other, perhaps even causally. We evaluated 29 patients with SOP for presence of facial symmetry, tendon laxity, or both, and correlated these findings with presence or absence of chronic head tilt. Sixteen of 21 (76%) unilateral congenital SOP patients had facial asymmetry and 17 (81%) had tendon asymmetry. Ninety-four percent had either or both abnormalities, but only 57% had tendon laxity (palsy) on the side opposite the facial hypoplasia. All patients with facial hypoplasia had a head tilt toward the hypoplastic side of the face, regardless of which side the palsy was on. These findings, along with previous studies of congenital muscular torticollis, infer that the two anatomic abnormalities associated with congenital SOP (facial asymmetry and tendon asymmetry) do not occur as part of the same developmental sequence, but the facial asymmetry develops as a consequence of a chronic head tilt from a young age.