title: Progressive Multifocal Leukoencephalopathy: Recent Advances and a Neuro-Ophthalmological Review.
abstract: BACKGROUND
  Progressive multifocal leukoencephalopathy (PML) is a severe often fatal opportunistic infection of the central nervous system caused by reactivation of a ubiquitous polyoma virus, JC virus. Although typically characterized by multifocal asymmetric subcortical white matter lesions, it may be monofocal and affect the cortical gray matter. Among the broad spectrum of clinical manifestations that occurs with PML, visual complaints are common.
  
  
  METHODS
  Combination of representative personally observed cases of PML and comprehensive review of case series of PML from 1958 through 2014.
  
  
  RESULTS
  Neuro-ophthalmic signs and symptoms were reported in approximately 20%-50% of patients with PML and can be the presenting manifestation in half of these. A majority of these presentations occur from damage to cerebral visual pathways resulting in visual field defects, cortical blindness, and other disorders of visual association. Given the decreased frequency of infratentorial and cerebellar involvement, ocular motility disorders are less common.
  
  
  CONCLUSIONS
  Visual complaints occur in patients with PML and are often the presenting sign. Awareness of this condition is helpful in avoiding unnecessary delays in the diagnosis of PML and management of the underlying condition. Recent guidelines have established criteria for diagnosis of PML in the high-risk patient population and strategies to mitigate the risk in these populations.
authors.affiliation: Departments of Neurology (PS), University of Kentucky College of Medicine, Lexington, Kentucky; Departments of Ophthalmology (DMB), and Radiology (ASM), Washington Hospital Center, Washington, District of Columbia; Department of Neurology (JRB), Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and Department of Neurological Sciences and Ophthalmology (SK), University of Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Padmaja
authors.initials: P
authors.lastname: Sudhakar
authors.forename: David M
authors.initials: DM
authors.lastname: Bachman
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Mark
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Berger
authors.forename: Sachin
authors.initials: S
authors.lastname: Kedar
mesh_terms: D000328:Adult; D001921:Brain; D005260:Female; D006801:Humans; D007968:Leukoencephalopathy, Progressive Multifocal / Q000175:diagnosis* / Q000453:epidemiology / Q000628:therapy*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009462:Neurology / Q000379:methods*; D009885:Ophthalmology / Q000379:methods*; D014795:Visual Pathways / Q000473:pathology