Glutamic acid decarboxylase (GAD) catalyses the transformation of glutamate into γ-aminobutyric acid (GABA). Anti-GAD autoantibodies (GAD-Ab) have been associated with insulin-dependent diabetes mellitus (IDDM) and with other possibly immunomediated syndromes affecting the CNS including stiff-man syndrome (SPS),1 progressive encephalomyelitis with rigidity and myoclonus (PERM) and cerebellar ataxia,1 2 mostly in association with IDDM. These findings support the autoimmune origin of the neurological symptoms, possibly induced by an anti-GAD-Ab-mediated neuronal dysfunction. Manto et al3 induced cerebellar and spinal cord symptoms in rats, by intrathecal injection of IgG from anti-GAD-Ab positive patients affected by SPS or cerebellar ataxia, suggesting a pathogenetic mechanisms involving a change of balance between glutamate and GABA, causing glutamate excitotoxicity.

High-dose intravenous immunoglobulins and plasmapheresis have been suggested as possible therapies, but cerebellar symptoms have been rarely found to improve. Recently Lauria et al4 induced clinical improvement in a patient with anti-GAD-Ab cerebellar ataxia through high doses of methylprednisolone, suggesting that it should be considered as first-line therapy in these patients. We describe a 76-year-old man developing an anti-GAD associated subacute cerebellar syndrome that improved dramatically after steroid treatment.

CASE REPORT

A 76-year-old man was admitted to our clinic in January 2007 for the development, since June 2006, of a subacute progressive gait instability and loss of fluency of movement execution. Within 3 months, …