Dissociated eye movements in craniosynostosis: a hypothesis revived.

Abstract

A characteristic pattern of dissociated eye movements was observed in a large proportion of our patients with a variety of craniosynostosis syndromes. These anomalies simulate overaction of the inferior oblique and underaction of the superior oblique muscles which, however, cannot fully explain the abnormalities. In a number of cases, excyclorotation of the muscle cone was observed, with the upper pole of the eye tilted away from the midline. It is postulated that such excyclorotation of the eyes will lead to dissociated eye movements which can be explained on physiological grounds according to Hering's law. This paper presents a review of our patients and evidence to support this hypothesis.

Treatment of unilateral coronal synostosis by endoscopic strip craniectomy or fronto-orbital advancement: Ophthalmologic findings

“…The associated strabismus and ocular torticollis have been attributed to these orbital changes. [1][2][3][4][5][6][7][8] The majority of patients also develop aniso-astigmatism and, accordingly, may have an increased risk of amblyopia. 4,9 Although correction of unilateral coronal synostosis by fronto-orbital advancement (FOA) improves the orbital symmetry anterior to the axis of the globe, some posterior asymmetry may persist.…”

Manifested strabismus in a case of Apert syndrome

“…1,6 In addition to inferior oblique overaction and superior oblique under action, exocyclorotation of muscle cone with the upper pole of the eyeball tilted away from midline was also observed in such cases. 9 Under the hypothesis of exocyclorotation of muscle cone, Clement et al modeled the mechanics and proposed that not only the surgery of the rectus muscle but also the weakening of the oblique muscle should be performed to ensure effective result. 10 The strabismus patterns might change as the patients grow in such cases, which might be caused by progressive bone change and progressive exophthalmos.…”

Ocular Overelevation in Adduction in Craniosynostosis: Is It the Result of Excyclorotation of the Extraocular Muscles?

“…Excyclorotation of the globe is confirmed by the clinical finding of fundus extorsion as well as excyclorotated EOMs at strabismus surgery. 3,12 Suprisingly, there has been scant published radiological evidence to support a link between orbital and EOM excyclorotation and this type of horizontally incomitant vertical strabismus. 12,13,17 Current computed tomography (CT) and magnetic resonance imaging (MRI) techniques allow coronal views that can be used to assess for EOM excyclorotation around the orbit's anterior-posterior axis.…”

“…3,12 Suprisingly, there has been scant published radiological evidence to support a link between orbital and EOM excyclorotation and this type of horizontally incomitant vertical strabismus. 12,13,17 Current computed tomography (CT) and magnetic resonance imaging (MRI) techniques allow coronal views that can be used to assess for EOM excyclorotation around the orbit's anterior-posterior axis. Radiological evidence to confirm this pattern of rotated muscle position is sparse in the literature: Cheng et al 12 had just 5 coronal images in a series of 63 patients with craniosynostosis to support this theory.…”

“…11 Many authors, however, feel the upshoot on adduction can be explained by the finding of excyclorotated EOMs. 3,[12][13][14][15] The effect of the bony orbit on strabismus is well recognized 2,16 and the excyclorotation of the bony orbits seen in these conditions creates the excyclorotation of the EOMs. 3 This refers to the situation in which the positions of the vertical and horizontal rectus muscles have extorted out of the sagittal and horizontal planes.…”