A case of congenital oblique retraction syndrome with upshoot in adduction

We treated a 27-year-old man who suffered from a congenital eye movement abnormality. The patient could not adduct the left eye, and showed exotropia, hypertropia and excyclotropia of the left eye. The range of abduction was also limited. The left eye showed marked upshoot on right gaze and eye globe retraction on right down gaze under conditions of right-eye viewing. The superior rectus muscle of the left eye was recessed and transposed nasally. The insertion of the superior oblique muscle was found to be defective. The upshoot and face turn improved after surgery. The globe retraction on right down gaze was no longer evident. We believe that the superior rectus muscle was innervated by an anomalous branch of the oculomotor nerve, which was originally destined to innervate the medial rectus, and that simultaneous contraction of the superior and inferior rectus muscles caused the globe retraction on right down gaze. This case also suggests the possibility that some part of the upshoot in adduction in Duane's syndrome is due to the co-contraction of the superior and medial rectus muscles due to this innervation anomaly.