Cerebellar ataxia associated to anti-glutamic acid decarboxylase autoantibody (anti-GAD): partial improvement with intravenous immunoglobulin therapy.

CASE A 51 year-old man presented to our hospital with nine-years history of progressive gait instability, difficulty walking and insulin dependent diabetes. Family history was unremarkable. On examination, there was ataxic gait, severe limb and trunk ataxia, and dysarthria. He scored 65 in International Cooperative Ataxia Rating Scale (ICARS) and 20 in Scale for Assessment and Rating of Ataxia (SARA), an objective toll for evaluating ataxia severity. Electroneuromyography was normal. Blood tests, thyroid function, antibodies and serologic tests were normal, except for high serum anti-GAD: 3.2 U/ mL (normal range: <1.0 U/mL). Brain magnetic resonance imaging (MRI) disclosed mild cerebellar atrophy. Genetic tests for spinocerebellar ataxias type 1, 2, 3 and 6 were negative. Immunoglobulin therapy was started, 0.4 g/Kg daily, for five consecutive days every month, during three months. Partial improvement of motor symptoms was observed four months after the beginning of treatment: he scored 37 in ICARS and 16 in SARA.