title: Anti-GAD antibodies and periodic alternating nystagmus.
abstract: BACKGROUND
  Autoantibodies directed against glutamic acid decarboxylase (GAD-Ab) have recently been described in a few patients with progressive cerebellar ataxia, suggesting an autoimmune physiopathologic mechanism.
  
  
  OBJECTIVE
  To determine the exact role of GAD-Ab and gamma-aminobutyric acid (GABA)-ergic neurotransmission in the pathogenesis of cerebellar ataxia.
  
  
  METHODS
  Case report.
  
  
  METHODS
  University neurological hospital.
  
  
  METHODS
  We report the case of a patient with subacute cerebellar ataxia associated with GAD-Ab showing periodic alternating nystagmus (PAN).
  
  
  METHODS
  Baclofen, a GABAergic medication, was given to the patient.
  
  
  METHODS
  Eye movement recording of spontaneous nystagmus and postrotatory vestibular responses.
  
  
  RESULTS
  Baclofen was effective in suppressing PAN and improving postrotatory vestibular responses but not for improving cerebellar ataxia.
  
  
  CONCLUSIONS
  The presence of PAN and the response to baclofen provide a unique opportunity to suggest a direct role of GAD-Ab in cerebellar dysfunction in this patient.
authors.affiliation: Neuro-Ophthalmology Unit, Hôpital Neurologique, Hospices civils de Lyon, Bron, France. tilikete@lyon.inserm.fr
authors.forename: Caroline
authors.initials: C
authors.lastname: Tilikete
authors.forename: Alain
authors.initials: A
authors.lastname: Vighetto
authors.forename: Paul
authors.initials: P
authors.lastname: Trouillas
authors.forename: Jérome
authors.initials: J
authors.lastname: Honnorat
mesh_terms: D000368:Aged; D001323:Autoantibodies / Q000276:immunology*; D001418:Baclofen / Q000627:therapeutic use; D002524:Cerebellar Ataxia / Q000188:drug therapy / Q000276:immunology* / Q000503:physiopathology; D002531:Cerebellum / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D018755:GABA Agonists / Q000627:therapeutic use; D005968:Glutamate Decarboxylase / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D008959:Models, Neurological; D009433:Neural Inhibition / Q000276:immunology; D009759:Nystagmus, Pathologic / Q000188:drug therapy / Q000276:immunology* / Q000503:physiopathology; D010507:Periodicity; D009435:Synaptic Transmission / Q000276:immunology; D016896:Treatment Outcome; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis*
chemical_list: D001323:Autoantibodies; D018755:GABA Agonists; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; D001418:Baclofen