Medulloblastoma Presenting With Bilateral Internuclear Ophthalmoplegia of Abduction: A Case Report

Medulloblastoma is the most common paediatric high-grade central nervous system tumour. To our knowledge, this is the first case of medulloblastoma presenting with bilateral internuclear ophthalmoplegia (INO) of abduction. We describe a rare case of a 14-year-old girl presenting with bilateral abduction deficits and optic disc swelling. Neuroimaging revealed a midline posterior fossa tumour consistent with medulloblastoma compressing the dorsal pons and 4th ventricle. Following surgical resection and adjuvant therapy, ocular motility normalized. This case report highlights the features of a rare horizontal gaze palsy; bilateral posterior INO of abduction, resulting from the mass effect of a large medulloblastoma. Such a rare presentation requires a high index of suspicion and familiarity with neuroanatomy and neuro-ophthalmic examination in order to ensure correct diagnosis, prompt investigation, and treatment of the cause.