Treatment of anti-GAD65 antibody-positive epilepsy and cerebellar ataxia with efgartigimod: a case report and literature review.

BACKGROUND

Anti-glutamic acid decarboxylase 65 (GAD65) antibody-associated neurological syndrome is a rare autoimmune disorder with heterogeneous clinical manifestations, including epilepsy and cerebellar ataxia. Standard treatment strategies remain limited. This report aimed to describe a rare case presenting with combined epilepsy and cerebellar ataxia, and to evaluate the efficacy of efgartigimod followed by mycophenolate mofetil.

METHODS

We present a 62-year-old female with slowly progressive recurrent epileptic seizures and cerebellar ataxia. Clinical, neurological, neuroimaging (PET/CT, MRI), and laboratory examinations (serum and cerebrospinal fluid GAD65 antibodies) were analyzed. The patient was treated with efgartigimod (10 mg/kg weekly for 3 doses) plus maintenance mycophenolate mofetil. Clinical outcomes and follow-up data were assessed.

RESULTS

Neurological examination showed left-sided dysmetria, dysdiadochokinesia, and a positive Romberg sign. Brain PET/CT revealed hypometabolism in the bilateral temporal lobes, right hippocampus, and left frontoparietal regions, accompanied by mild right hippocampal atrophy. Serum and cerebrospinal fluid (CSF) examinations were positive for GAD65 antibodies at titers of 1:1000 and 1:100, respectively, confirming the diagnosis of GAD65 antibody-associated neurological syndrome. After treatment, seizures completely resolved, gait ataxia improved significantly, and daily activities were fully restored at 1-month follow-up. Antiseizure medications were gradually tapered. No clinical relapse occurred during the 1-year follow-up period.

CONCLUSIONS

This case demonstrates that anti-GAD65 antibody syndrome can present as concurrent refractory epilepsy and cerebellar ataxia. The sequential regimen of efgartigimod induction combined with mycophenolate mofetil maintenance appears effective and safe. This therapeutic strategy may provide a valuable reference for the clinical management of such rare autoimmune neurological disorders.