Patients with high-titre GAD65 antibodies and hyperkinetic movement disorders
| Patient no | Clinical description | Sustained response to immunotherapy? | Features supportive of immune-mediated aetiology | Systemic autoimmunity?* | Serum anti-GAD65 titre (nmol/L) | CSF anti-GAD65 titre (nmol/L) |
| 1 | Older adult with involuntary movements of the left arm more than left leg that developed over 2 months; characterised as hemichorea on examination. | No trial, treated symptomatically with risperidone which reduced chorea but led to drug-induced parkinsonism. | Subacute onset, no alternative aetiology identified. | Yes, thyroid disease | 38.1 | NA |
| 2 | Child who always walked ‘gingerly’ on right side as per mother; turning in of right foot with ‘pulling sensation’ noticeable over 6 months; characterised as hemidystonia on examination. | Yes, reported 90% improvement of dystonia with intravenous IG intermittently over 9 months; intravenous IG discontinued due to headache with recurrence of dystonia after 7–8 weeks, but less severe than it was initially. | Response to immunotherapy, no alternative aetiology identified. | Yes, T1DM, thyroid disease | 3847 | NA |
| 3 | Young adult with clumsiness/tightness of left limbs and difficulty walking that developed over 6 years; characterised as hemidystonia on examination. | No trial, intravenous IG recommended but no follow-up available. | No alternative aetiology identified. | Yes, thyroid disease | 780 | 29.6 |
Age stratification is as follows: child, less than 12 years of age; adolescent, 13–18 years of age; young adult, 19–45 years of age; middle-aged adult, 46–65 years of age; older adult, greater than 65 years of age.
*Systemic autoimmunity refers to presence of T1DM, thyroid disease, pernicious anaemia, adrenal insufficiency, vitiligo or coeliac disease.
GAD65, glutamic acid decarboxylase-65; NA, not available; T1DM, type 1 diabetes mellitus.