Hemispherotomy can cause post-operative strabismus

Hemispherotomy, which involves disconnecting hemispherical fibers, is a treatment option for medically intractable epilepsy. As various neurological disorders can cause strabismus, we hypothesized that hemispherotomy can cause post-operative strabismus in patients with medically intractable epilepsy. Nineteen patients underwent the Hirschberg test before and after hemispherical disconnection surgery. Among the 19 patients, 16 patients (six females and 10 males; mean age, 12.2 years; range, 0.17–43 years) who underwent hemispherotomy were included in this study. The difference in the angle between the left and right eyes was significantly widened (p = 0.025). Nine (56%) of 16 patients exhibited post-operative chronic strabismus as evaluated with the Hirschberg test. Intermittent strabismus was noticed by family members or caregivers in 10 (63%) of 16 patients. Patients older than 12 years did not show post-operative strabismus as evaluated by the Hirschberg test. Hemispherotomy can cause or worsen post-operative strabismus in pediatric patients.