Two Pediatric Patients with Acute Acquired Comitant Esotropia as the First Symptom of Brainstem Tumor: A Case Report

INTRODUCTION: Acute acquired comitant esotropia (AACE) is an acquired strabismus with uncrossed sudden-onset diplopia due to esodeviation, comitant esotropia without accommodation factor, or paretic eye movement. The diagnosis of AACE entails differentiation from incomitant esotropia caused by abnormalities in the central nervous system. We present 2 pediatric patients with AACE as the first symptom of brainstem tumor. CASE PRESENTATION: The 2 patients were aware of their diplopia and had no other neurological abnormalities. There were no special findings in the anterior segment, ocular media, or fundus. Esotropia with a difference of no more than 10Δ between distant and near fixations was observed. Eye movements were normal, and Hess red-green test under prism neutralization did not reveal abduction restriction. The presumed cause of AACE in both patients was excessive use of digital displays, and brain magnetic resonance imaging (MRI) was performed to confirm the absence of neurological abnormality. Using MRI, a definitive diagnosis of AACE was made based on comitant esotropia associated with diffuse median glioma and medullary pilocytic astrocytoma without abducens nerve palsy. CONCLUSION: Although the incidence of AACE caused by brainstem tumors may be low, it is necessary to perform head imaging to confirm etiology. Furthermore, Hess red-green test under prism neutralization is considered important for the differentiation of abducens nerve palsy.