title: The gait disorder in downbeat nystagmus syndrome.
abstract: BACKGROUND
  Downbeat nystagmus (DBN) is a common form of acquired fixation nystagmus with key symptoms of oscillopsia and gait disturbance. Gait disturbance could be a result of impaired visual feedback due to the involuntary ocular oscillations. Alternatively, a malfunction of cerebellar locomotor control might be involved, since DBN is considered a vestibulocerebellar disorder.
  
  
  METHODS
  Investigation of walking in 50 DBN patients (age 72 ± 11 years, 23 females) and 50 healthy controls (HS) (age 70 ± 11 years, 23 females) using a pressure sensitive carpet (GAITRite). The patient cohort comprised subjects with only ocular motor signs (DBN) and subjects with an additional limb ataxia (DBNCA). Gait investigation comprised different walking speeds and walking with eyes closed.
  
  
  RESULTS
  In DBN, gait velocity was reduced (p<0.001) with a reduced stride length (p<0.001), increased base of support (p<0.050), and increased double support (p<0.001). Walking with eyes closed led to significant gait changes in both HS and DBN. These changes were more pronounced in DBN patients (p<0.001). Speed-dependency of gait variability revealed significant differences between the subgroups of DBN and DBNCA (p<0.050).
  
  
  CONCLUSIONS
  (I) Impaired visual control caused by involuntary ocular oscillations cannot sufficiently explain the gait disorder. (II) The gait of patients with DBN is impaired in a speed dependent manner. (III) Analysis of gait variability allows distinguishing DBN from DBNCA: Patients with pure DBN show a speed dependency of gait variability similar to that of patients with afferent vestibular deficits. In DBNCA, gait variability resembles the pattern found in cerebellar ataxia.
authors.affiliation: Department of Neurology, University of Munich, Munich, Germany; German Center for Vertigo and Balance Disorders (DSGZ), University of Munich, Munich, Germany.
authors.forename: Roman
authors.initials: R
authors.lastname: Schniepp
authors.affiliation: German Center for Vertigo and Balance Disorders (DSGZ), University of Munich, Munich, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Wuehr
authors.affiliation: Department of Neurology, University of Munich, Munich, Germany; German Center for Vertigo and Balance Disorders (DSGZ), University of Munich, Munich, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Huth
authors.affiliation: German Center for Vertigo and Balance Disorders (DSGZ), University of Munich, Munich, Germany.
authors.forename: Cauchy
authors.initials: C
authors.lastname: Pradhan
authors.affiliation: German Center for Vertigo and Balance Disorders (DSGZ), University of Munich, Munich, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Schlick
authors.affiliation: German Center for Vertigo and Balance Disorders (DSGZ), University of Munich, Munich, Germany; Institute for Clinical Neurosciences, University of Munich, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Brandt
authors.affiliation: Department of Neurology, University of Munich, Munich, Germany; German Center for Vertigo and Balance Disorders (DSGZ), University of Munich, Munich, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Jahn
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000503:physiopathology*; D014785:Vision, Ocular