title: Wilbrand's knee: does it exist?
abstract: OBJECTIVE
  In 1904, Hermann Wilbrand reported that nasal ON fibers form a loop into the contralateral ON, subsequently referred to as Wilbrand's knee. He had further theorized that a lesion affecting Wilbrand's knee would develop a distinct visual field defect characterized by an ipsilateral central scotoma with a contralateral superotemporal visual field defect. We present clinical evidence that disputes the existence of Wilbrand's knee.
  
  
  METHODS
  A retrospective analysis of 3 patients whose ONs were divided at the ON-chiasm junction is presented. Two patients had an ONS meningioma and the other patient had sarcoidosis of the ON. Resection of the lesion and the ON up to the nerve-chiasm junction was done to prevent the disease from extending into the OC and the contralateral ON. The patients had detailed neuro-ophthalmologic evaluations preoperatively and postoperatively.
  
  
  RESULTS
  After the resection of the ON at the ON-chiasm junction in the 3 patients, junctional scotoma could not be detected by visual perimetry.
  
  
  CONCLUSIONS
  No clinical perimetric evidence was found to support the existence of Wilbrand's knee in the anterior visual pathway.
authors.affiliation: Department of Neurosurgery, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA. leej@ccf.org
authors.forename: Joung H
authors.initials: JH
authors.lastname: Lee
authors.forename: Samuel
authors.initials: S
authors.lastname: Tobias
authors.forename: Jeong-Taik
authors.initials: JT
authors.lastname: Kwon
authors.forename: Burak
authors.initials: B
authors.lastname: Sade
authors.forename: Gregory
authors.initials: G
authors.lastname: Kosmorsky
mesh_terms: D000328:Adult; D001284:Atrophy / Q000473:pathology / Q000503:physiopathology; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D018450:Disease Progression; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008579:Meningioma / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D008875:Middle Aged; D019635:Neurosurgical Procedures; D009897:Optic Chiasm / Q000473:pathology* / Q000503:physiopathology*; D009900:Optic Nerve / Q000033:anatomy & histology / Q000473:pathology* / Q000503:physiopathology*; D019574:Optic Nerve Neoplasms / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D012189:Retrospective Studies; D012507:Sarcoidosis / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D012607:Scotoma / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D016896:Treatment Outcome; D015354:Vision, Low / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*