Anti-GAD antibodies and periodic alternating nystagmus.
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.
Tilikete
Caroline
C
Neuro-Ophthalmology Unit, Hôpital Neurologique, Hospices civils de Lyon, Bron, France. tilikete@lyon.inserm.fr
Vighetto
Alain
A
Trouillas
Paul
P
Honnorat
Jérome
J
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*
D001323:Autoantibodies; D018755:GABA Agonists; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; D001418:Baclofen