title: Longitudinal assessment of reflexive and volitional saccades in Niemann-Pick Type C disease during treatment with miglustat.
abstract: BACKGROUND
  Niemann-Pick Type C disease (NPC), is an autosomal recessive neurovisceral disorder of lipid metabolism. One characteristic feature of NPC is a vertical supranuclear gaze palsy particularly affecting saccades. However, horizontal saccades are also impaired and as a consequence a parameter related to horizontal peak saccadic velocity was used as an outcome measure in the clinical trial of miglustat, the first drug approved in several jurisdictions for the treatment of NPC. As NPC-related neuropathology is widespread in the brain we examined a wider range of horizontal saccade parameters and to determine whether these showed treatment-related improvement and, if so, if this was maintained over time.
  
  
  METHODS
  Nine adult NPC patients participated in the study; 8 were treated with miglustat for periods between 33 and 61 months. Data were available for 2 patients before their treatment commenced and 1 patient was untreated. Tasks included reflexive saccades, antisaccades and self-paced saccades, with eye movements recorded by an infrared reflectance eye tracker. Parameters analysed were reflexive saccade gain and latency, asymptotic peak saccadic velocity, HSEM-α (the slope of the peak duration-amplitude regression line), antisaccade error percentage, self-paced saccade count and time between refixations on the self-paced task. Data were analysed by plotting the change from baseline as a proportion of the baseline value at each test time and, where multiple data values were available at each session, by linear mixed effects (LME) analysis.
  
  
  RESULTS
  Examination of change plots suggested some modest sustained improvement in gain, no consistent changes in asymptotic peak velocity or HSEM-α, deterioration in the already poor antisaccade error rate and sustained improvement in self-paced saccade rate. LME analysis showed statistically significant improvement in gain and the interval between self-paced saccades, with differences over time between treated and untreated patients.
  
  
  CONCLUSIONS
  Both qualitative examination of change scores and statistical evaluation with LME analysis support the idea that some saccadic parameters are robust indicators of efficacy, and that the variability observed across measures may indicate locally different effects of neurodegeneration and of drug actions.
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia. label@unimelb.edu.au.
authors.forename: Larry A
authors.initials: LA
authors.lastname: Abel
authors.affiliation: Melbourne Neuropsychiatry Centre, University of Melbourne, Melbourne, Australia. mark.walterfang@mh.org.au.|Neuropsychiatry Unit, Royal Melbourne Hospital, Melbourne, Australia. mark.walterfang@mh.org.au.
authors.forename: Mark
authors.initials: M
authors.lastname: Walterfang
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia. matthew.stainer@abdn.ac.uk.|Active Vision Lab, School of Psychology, The University of Aberdeen, Aberdeen, Scotland. matthew.stainer@abdn.ac.uk.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Stainer
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia. ea_bowman@hotmail.com.|Melbourne Neuropsychiatry Centre, University of Melbourne, Melbourne, Australia. ea_bowman@hotmail.com.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Bowman
authors.affiliation: Melbourne Neuropsychiatry Centre, University of Melbourne, Melbourne, Australia. dvelakou@bigpond.net.au.|Neuropsychiatry Unit, Royal Melbourne Hospital, Melbourne, Australia. dvelakou@bigpond.net.au.
authors.forename: Dennis
authors.initials: D
authors.lastname: Velakoulis
mesh_terms: D017485:1-Deoxynojirimycin / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000328:Adult; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D006801:Humans; D008137:Longitudinal Studies; D052556:Niemann-Pick Disease, Type C / Q000188:drug therapy / Q000503:physiopathology*; D012438:Saccades / Q000502:physiology*; D055815:Young Adult
chemical_list: D004791:Enzyme Inhibitors; D017485:1-Deoxynojirimycin; C059896:miglustat