Facial asymmetry in superior oblique muscle palsy and pulley heterotopy

Introduction: Some observers have considered facial asymmetry as characteri stic of congenital superior oblique muscle (SO) palsy. However, recent orbi tal imaging studies have determined that incomitant vertical strabismus res embling SO palsy can be caused by heterotopic rectus muscle pulleys. This f inding suggests that facial asymmetry may predict the presence of abnormal orbital anatomy rather than be secondary to ocular torticollis. Methods: Su bjects who underwent orbital computed tomography or magnetic resonance imag ing were divided into 5 groups based on clinical evaluation and previously established imaging criteria: (1) congenital SO palsy; (2) acquired SO pals y; (3) strabismus with pulley heterotopy; (4) strabismus without SO palsy o r pulley heterotopy; and (5) orthotropic subjects. Frontal photographs were digitized and the following 3 facial morphometric features recorded: (1) a ngle of inclination of each orbit; (2) relative facial size; and (3) facial angle. Results: The 79 subjects who underwent imaging were divided into th e 5 groups as follows: 6 with congenital SO palsy; 7 with acquired SO palsy ; 20 with pulley heterotopy; 26 with strabismus without SO palsy or pulley heterotopy; and 20 control subjects. All subjects with either congenital or acquired SO palsy had torticollis. Multivariate analysis demonstrated no s ignificant differences in any of the 3 facial morphometric features among a ny of the groups. Conclusion: Facial asymmetry as assessed by these 3 morph ometric features is not useful in distinguishing between congenital SO pals y or pulley heterotopy and other acquired forms of strabismus. This finding casts doubt on the relationship between ocular torticollis and facial asym metry.