Gaze-induced strabismus

A 20-year-old woman with a past history of a sinonasal undifferentiated carcinoma involving the skull base and cavernous sinus, previously treated with surgery and radiation therapy, presented with intermittent horizontal diplopia induced by gaze to the right side. The gaze in the direction of the action of the right VI nerve produced sustained contraction of the right lateral rectus and an exodeviation increasing on left gaze. Ocular neuromyotonia involving the right VI nerve was believed to be secondary to the patient's previous radiation therapy. The discussants review the prior literature regarding ocular neuromyotonia involving the III, IV and VI cranial nerves, its relationship to prior radiation therapy, and possible modes of therapy including the use of Carbamazepine.