JM Lee, et al. ACUTE COMITANT ESOTROPIA WITH A CEREBELLAR TUMOR Fig. 1. Preoperative 9 cardinal photographs of a 3-year-old boy presenting with 50 PD of left esotropia without lateral incomitance secondary to a cerebellar astrocytoma. A B Fig. 2. Preoperative Brain MRI showing a 5 cm mass with an en- hanced peripheral rim at the midline of the cerebellum as well as hy- drocephalus (A: Low signal intensity on T1W1, B: High signal in- tensity on T2W1). was stopped due to lack of patient compliance. At the last follow -up examination, 2 years after eye muscle surgery, the patient’s angle of esodeviation remained 8PD at distant and near fixation (Fig. 3), and the corrected visual acuity was 20/40 with a glasses prescription of +0.75 diopters in both eyes. At this time, ocular motor fusion had not been reestablished following strabismus surgery. D iscussio n In most cases, the onset of acute acquired comitant esotropia occurs during infancy or childhood. Although comitancy is often thought to not be associated with neurologic disease,2 brain tumors and other intracranial processes in pediatric pa- tients may in fact present with comitant esotropia.3-7 William and Hoyt5 described six children with acute onset of comitant esotropia who were found to have tumors of the brain stem or cerebellum. Several reports have established that brain tumors such as cerebellar astrocytomas,5-7 medulloblastomas,5 pontine gliomas,5 astrocytoma of the corpous callosum (with hydro- cephalus),3 and Arnold Chiari malformation4,8 were associated with acute acquired comitant esotropia in childhood. Liu et al.9 reported 30 children with acquired esotropia resulting from known neurologic insults such as a brain tumor, meningitis, or pseudotumor cerebri. Of the 30 children reported, twelve (40%) of them had comitant esodeviation whereas the other 18 (60%) had incomitant esotropia. The authors concluded that comitant esodeviation can be common in children with identifiable neurologic insults. The exact mechanism responsible for acute comitant eso- tropia in patients with brain tumors is not clear. Lennerstrand,10 Hoyt and Good11 reasoned that comitant strabismus might result from involvement of supranuclear mesencephalic structures, which control vergence eye movement. Jampolsky12 and others13,14 have ascribed acquired comitant esotropia to infranuclear in- 229