The objective of this study is to report the clinical characteristics and treatment of patients with progressive
cerebellar ataxia associated with anti-GAD
antibodies. We performed a retrospective review of all patients with anti-GAD
ataxia managed at the Sheffield
Ataxia Centre over the last 25 years. We identified 50 patients (62% females) with anti-GAD
ataxia. The prevalence was 2.5% amongst 2000 patients with progressive
ataxia of various causes. Mean age at onset was 55 and mean duration 8 years. Gaze-evoked nystagmus was present in 26%, cerebellar
dysarthria in 26%,
limb ataxia in 44% and
gait ataxia in 100%. Nine patients (18%) had severe, 12 (24%) moderate and 29 (58%) mild
ataxia. Ninety percent of patients had a history of additional
autoimmune diseases. Family history of
autoimmune diseases was seen in 52%. Baseline MR spectroscopy of the vermis was abnormal at presentation in 72%. Thirty-five patients (70%) had serological evidence of
gluten sensitivity. All 35 went on
gluten-free diet (GFD). Eighteen (51%) improved, 13 (37%) stabilised, 3 have started the GFD too recently to draw conclusions and one deteriorated. Mycophenolate was used in 16 patients, 7 (44%) improved, 2 stabilised, 6 have started the medication too recently to draw conclusions and one did not tolerate the
drug. There is considerable overlap between anti-GAD
ataxia and
gluten ataxia. For those patients with both, strict GFD alone can be an effective treatment. Patients with anti-GAD
ataxia and no
gluten sensitivity respond well to immunosuppression.