title: Head position during resting modifies spontaneous daytime decrease of downbeat nystagmus.
abstract: BACKGROUND
  The intensity of downbeat nystagmus (DBN) decreases during the daytime when the head is in upright position.
  
  
  OBJECTIVE
  This prospective study investigated whether resting in different head positions (upright, supine, prone) modulates the intensity of DBN after resting.
  
  
  METHODS
  Eye movements of 9 patients with DBN due to cerebellar (n = 2) or unknown etiology (n = 7) were recorded with video-oculography. Mean slow-phase velocities (SPV) of DBN were determined in the upright position before resting at 9 am and then after 2 hours (11 am) and after 4 hours (1 pm) of resting. Whole-body positions during resting were upright, supine, or prone. The effects of all 3 resting positions were assessed on 3 separate days in each patient.
  
  
  RESULTS
  Before resting (9 am), the average SPV ranged from 3.05 °/s to 3.6 °/s on the separate days of measurement. After resting in an upright position, the average SPV at 11 am and 1 pm was 0.65 °/sec, which was less (p < 0.05) than after resting in supine (2.1 °/sec) or prone (2.22 °/sec) positions.
  
  
  CONCLUSIONS
  DBN measured during the daytime in an upright position becomes minimal after the patient has rested upright. The spontaneous decrease of DBN is less pronounced when patients lie down to rest. This indicates a modulation by otolithic input. We recommend that patients with DBN rest in an upright position during the daytime.
  
  
  METHODS
  This study provides Class II evidence that for patients with DBN 2 hours of rest in the upright position decreases nystagmus more than 2 hours of rest in the supine or prone positions (relative improvement 79% upright, 33% supine, and 38% prone: p < 0.05).
authors.affiliation: Department of Neurology and IFB, Ludwig-Maximilians-University, Campus Grosshadern, Marchioninistr. 15, 81377 Munich, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Spiegel
authors.forename: R
authors.initials: R
authors.lastname: Kalla
authors.forename: N
authors.initials: N
authors.lastname: Rettinger
authors.forename: E
authors.initials: E
authors.lastname: Schneider
authors.forename: D
authors.initials: D
authors.lastname: Straumann
authors.forename: S
authors.initials: S
authors.lastname: Marti
authors.forename: S
authors.initials: S
authors.lastname: Glasauer
authors.forename: T
authors.initials: T
authors.lastname: Brandt
authors.forename: M
authors.initials: M
authors.lastname: Strupp
mesh_terms: D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D005133:Eye Movements; D005260:Female; D006257:Head; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000503:physiopathology*; D011187:Posture; D016684:Prone Position; D011446:Prospective Studies; D012146:Rest; D016683:Supine Position; D013997:Time Factors