title: Midbrain myasthenia: fatigable ptosis, 'lid twitch' sign, and ophthalmoparesis from a dorsal midbrain glioma.
abstract: A collection of symptoms and signs indistinguishable from ocular myasthenia can be caused by an intracranial mass. We illustrate this condition with the case of an adolescent girl with neurofibromatosis type 1 and a dorsal midbrain astrocytoma. At presentation, she had fatigable ptosis, upgaze paresis, and a positive "lid twitch" sign. Radiation therapy resulted in marked reduction of her signs, confirming that the muscle fatigue was central in origin. We discuss the possible mechanisms of this central fatigability.
authors.affiliation: Department of Neurological Surgery, School of Medicine, University of California, San Francisco 94122.
authors.forename: N K
authors.initials: NK
authors.lastname: Ragge
authors.forename: W F
authors.initials: WF
authors.lastname: Hoyt
mesh_terms: D000293:Adolescent; D001763:Blepharoptosis / Q000209:etiology* / Q000503:physiopathology; D001932:Brain Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000532:radiotherapy; D005260:Female; D005910:Glioma / Q000150:complications* / Q000175:diagnosis / Q000532:radiotherapy; D006801:Humans; D008279:Magnetic Resonance Imaging; D008636:Mesencephalon; D009135:Muscular Diseases / Q000209:etiology* / Q000503:physiopathology; D009886:Ophthalmoplegia / Q000209:etiology* / Q000503:physiopathology