Table 2

Patients with high-titre GAD65 antibodies and hyperkinetic movement disorders

Patient
no
Clinical descriptionSustained response to immunotherapy?Features supportive of immune-mediated aetiologySystemic autoimmunity?*Serum anti-GAD65 titre
(nmol/L)
CSF anti-GAD65 titre
(nmol/L)
1Older 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 disease38.1NA
2Child 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 disease3847NA
3Young 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 disease78029.6
  • 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.