Unexplained head tilt following surgical treatment of congenital esotropia: a postural manifestation of dissociated vertical divergence.

BACKGROUND Strabismus surgery for congenital esotropia can be complicated by the development of a postoperative head tilt. PURPOSE To determine the pathophysiology of acquired head tilting following horizontal realignment of the eyes in children with congenital esotropia. MATERIALS AND METHODS Retrospective analysis of nine children with congenital esotropia who developed unexplained head tilts following horizontal realignment of the eyes. RESULTS Shortly after strabismus surgery, each child developed a head tilt in association with asymmetrical dissociated vertical divergence (DVD). Five children maintained a head tilt toward the side of the fixing eye (group 1), which did not serve to control the DVD. Four children maintained a head tilt toward the side of the hyperdeviating eye, which served to control the DVD (group 2). Children in group 2 had earlier horizontal muscle surgery and developed better stereopsis than those in group 1, suggesting that the higher degree of single binocular vision and stereopsis in these children may have led to a compensatory torticollis to control an asymmetrical DVD. CONCLUSIONS The onset of an unexpected head tilt after congenital esotropia surgery is usually a postural manifestation of asymmetrical DVD. In this setting, a head tilt toward the side of the fixing eye corresponds with a postural manifestation of the underlying central vestibular imbalance that produces DVD, while a head tilt toward the side of the hyperdeviating eye serves to counteract the hyperdeviation and stabilise binocular vision.