title: Environmental tilt illusion as the only symptom of a thalamic astrocytoma.
abstract: A 14-year-old girl experienced two episodes of environmental tilt illusion. During both episodes, which lasted less than 1 minute, she perceived all objects within view as rotated 45 degrees clockwise. There were no auras, accompanying symptoms, or sequelae. Neuro-ophthalmic examination findings were normal except for a right relative afferent pupil defect (RAPD). Imaging disclosed a cystic mass in the left posterior thalamus with compression of the brachium of the left superior colliculus. Stereotactic biopsy revealed a pilocytic astrocytoma. This is the first case documenting environmental tilt illusion as an isolated symptom of a thalamic lesion. Disruption of vestibular connections between the posterior thalamus and the posterior parietal cortex may be the cause of this visual perceptive disorder.
authors.affiliation: Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama, USA.
authors.forename: Aric J
authors.initials: AJ
authors.lastname: Aldridge
authors.forename: Lanning B
authors.initials: LB
authors.lastname: Kline
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Girkin
mesh_terms: D000293:Adolescent; D001254:Astrocytoma / Q000150:complications* / Q000175:diagnosis / Q000473:pathology; D001932:Brain Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000473:pathology; D005260:Female; D006801:Humans; D007499:Iris Diseases / Q000209:etiology; D008279:Magnetic Resonance Imaging; D010468:Perceptual Disorders / Q000209:etiology* / Q000503:physiopathology; D013028:Space Perception; D013788:Thalamus; D014796:Visual Perception