Acute Acquired Comitant Esotropia Associated with Chiari I Malformation

Purpose: We report two cases of patients who were referred to our clinic with acute acquired comitant esotropia (RACE) and were then diagnosed with a Chiari I malformation. Case summary: A 15-year-old female presented with acute diplopia for one week. She complained of headache, dizziness, and nausea one week before the onset of diplopia. The angles of esodeviation were concomitant in all directions of gaze, and no limitation in abduction was observed. Fundus photographs showed bilateral papilledema and brain magnetic resonance imaging showed cerebellar tonsillar herniation. She was diagnosed with acute acquired comitant esotropia associated with Chiari I malformation and was referred to the Neurosurgery Department for consideration of decompression surgery. A 12-year-old male presented with an acute onset horizontal diplopia for one week. He had a history of dizziness with syncope three months prior to his visit. He had comitant esotropia in all directions of gaze without any limitation of ocular movement. Brain magnetic resonance imaging showed cerebellar tonsillar herniation and he was diagnosed with acute acquired comitant esotropia associated with Chiari type I malformation. He was treated with bilateral medial rectus muscle recession surgery to correct esotropia and he had no diplopia after the surgery. Conclusions: When a patient presents with RACE, especially in the presence of neurological symptoms/signs such as headache, syncope, or papilledema, a full neurological examination and prompt neuroimaging are warranted to rule out Chiari I malformation.