Wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) secondary to demyelinating brainstem lesion

Abstract

We report the case of a healthy 25-year-old man presenting with sudden onset dizziness, strabismus, and cloudy vision that improved when he closed one of his eyes. He denied pain with eye movement or color desaturation, as well as history of recent immunization or febrile illness. He did not present any other neurologic symptom, but he affirmed having had a limited episode of a discrete strabismus four months before. In his first assessment at the emergency room his neurologic examination revealed a 30° exotropia of the right eye on the primary gaze position along with adduction deficit and abduction nystagmus bilaterally on conjugated horizontal eye movement, characterizing an internuclear ophthalmoplegia on both eyes. He also presented with asymmetrical convergence deficit, with inability on completing adduction on his right eye. On the vertical upward gaze there was also a vertical nystagmus. Eye fundus examination did not show retinal and optic nerve alterations. Visual acuity was normal. This set of findings qualified a WEBINO (wall-eyed bilateral internuclear ophthalmoplegia). During investigation, lumbar puncture showed mild hyperproteinrachia, with absence of oligoclonal bands and normal CSF (cerebrospinal fluid GigG (immunoglobulin G) index. He was submitted to a course of pulse therapy with methylprednisolone. Neuroaxis magnetic resonance imaging evidenced a demyelinating periaqueductal lesion, involving medium longitudinal fasciculus, ponto-mesencephalic junction and mesencephalic tegmentum, without gadolinium enhancement. As he remained symptomatic, plasmapheresis was indicated, with complete remission of symptoms afterwards. Following his investigation the tests for both anti-aquaporin-4 and anti-MOG antibodies were negative, and until the conclusion of this report, a diagnosis of clinical isolated syndrome remained as the main hypothesis.