title: Subjective visual vertical in Pisa syndrome.
abstract: BACKGROUND
  Parkinson's Disease (PD) alters perception and somatosensory information integration, including visual dependency and judgment of body position in space. PD may be associated with Pisa syndrome (PS), a lateral deviation of the longitudinal body axis (LBA) of unknown origin. We tested whether this inclination is associated with an altered perception of the subjective visual vertical (SVV) and if these alterations are secondary effects of the LBA deviation or of a primary perceptual dysfunction. Furthermore, we investigated the contribution of different sensory modalities and dopaminergic medication.
  
  
  METHODS
  Seventeen PD patients (8 with PS, 9 without PS) and 18 healthy controls were tested. The SVV was assessed in a seated, in a lateral horizontal and - in PS patients - in a seated manually rectified position. Frame and moving-stimulus-patterns were used to test visual dependency. In PD and PS patients all trials were conducted in dopaminergic "on" and "off".
  
  
  RESULTS
  When seated, SVV values on PD in "on" and PS in "on" and "off" differed significantly from controls. This difference remained in PS patients after manual rectification in "off". The SVV in a lateral horizontal position was not significantly different between the three groups. When inclined, visual dependency was higher in PD "off" than in controls.
  
  
  CONCLUSIONS
  Both PS and PD patients showed SVV deviations compared to healthy controls. These cannot be explained by their intrinsic lateral deviation in PS patients. They must be secondary to either a primary perceptual dysfunction or alterations of internal models of verticality due to re-weighting of perceptual afferences.
authors.affiliation: Institute of Neuroscience, Favaloro University, Buenos Aires, Argentina; Institute of Cognitive Neurology (INECO), Buenos Aires, Argentina. Electronic address: dscocco@ffavaloro.org.
authors.forename: Darío H
authors.initials: DH
authors.lastname: Scocco
authors.affiliation: Department of Neurology, Ludwig-Maximilians University, Klinikum Grosshadern, Munich, Germany.
authors.forename: Judith N
authors.initials: JN
authors.lastname: Wagner
authors.affiliation: Institute of Neuroscience, Favaloro University, Buenos Aires, Argentina; Institute of Cognitive Neurology (INECO), Buenos Aires, Argentina.
authors.forename: Juan
authors.initials: J
authors.lastname: Racosta
authors.affiliation: Institute of Neuroscience, Favaloro University, Buenos Aires, Argentina; Institute of Cognitive Neurology (INECO), Buenos Aires, Argentina.
authors.forename: Anabel
authors.initials: A
authors.lastname: Chade
authors.affiliation: Institute of Neuroscience, Favaloro University, Buenos Aires, Argentina; Institute of Cognitive Neurology (INECO), Buenos Aires, Argentina.
authors.forename: Oscar S
authors.initials: OS
authors.lastname: Gershanik
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications* / Q000503:physiopathology*; D010468:Perceptual Disorders / Q000209:etiology* / Q000503:physiopathology*; D010469:Perceptual Distortion / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*
keywords: Lateral trunk flexion; Postural control; Vestibular disease; Visual vertical – Parkinson's disease