LAUSR

Glutamic acid decarboxylase (GAD) antibodies (ab) have been associated with rare disorders, such as Stiff-person syndrome, limbic encephalitis, cerebellar ataxia, and temporal lobe epilepsy. Other systemic autoimmune disorders have been linked to antiGAD ab, among them, diabetes mellitus (DM). A 38-year-old woman presented with a 4-month history of involuntary movements of the left hand, slurred speech, and gait instability. There was no relevant medical or family history, namely diabetes, sleep disorders, exposure to neuroleptics, or any other medication. Neurological examination showed a bilateral gaze–evoked torsional nystagmus in both vertical and horizontal gazes and an apparent “round the houses” sign with a leftwardguided horizontal vector (Supporting Information Video 1); hypometric or hypermetric saccades, features of saccadic lateropulsion (hyper/hypometria of horizontal saccades), broken smooth pursuit, and positional nystagmus were absent. There was moderate dysarthria and mild broad-based gait ataxia. Bilateral orofacial dyskinesia predominantly involved the left lower hemiface, lips, and forehead. There was right laterocollis and right-shoulder elevation and proximal dystonia of the left arm and forearm. Muscular tone of the neck and limbs were normal. Superficial and deep sensory examination were normal. Distal chorea involved the left fingers and thumb, occasionally the right thumb, and toes and big toes asymmetrically (Supporting Information Video 2). Formal neuropsychological assessment showed a marked deficit in anterograde episodic verbal memory, a slight deficit in anterograde episodic visual memory, marked slowness in processing speed, and moderate dysfunction in working memory. Blood tests were normal; infectious agents and autoimmune abs were negative, and cerebrospinal fluid (CSF) cytochemical and bacteriological examinations were normal (Supporting Information File 1). T2/Fluid attenuation inversion recovery (FLAIR)-weighted brain magnetic resonance imaging (MRI) showed a left mesial temporal hyperintensity (Fig. 1) without Diffusion-weighted imaging (DWI) restriction or gadolinium enhancement. The electroencephalogram (EEG) disclosed 9 electrographic seizures of left temporal ictal onset (T7) in 30 minutes, which showed no temporal correlation with the aforementioned involuntary movements nor other clinical manifestations (Fig. 2). Jerk-locked back-average analysis of the facial movements showed no cortical correlate. Anti-GAD titre was positive in blood (1/3200) and CSF (1/320) using indirect immunofluorescence with monkey cerebellum tissue sample; screening for anti-Hu, CV2, LGI1, N-methyl-Daspartate receptor, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, γ-aminobutyric acid-A-receptor, and γ-aminobutyric acid-B-receptor in both the serum and CSF was negative. Treatment with sodium valproate (1800 mg/day) stopped the electrographic seizures. A subsequent 5-day intravenous methylprednisolone course was followed by intravenous immunoglobulin (IVIg) and oral prednisolone (1 mg/Kg of body weight/day) as a result of the partial initial response of dyskinesias. Improvement occurred after this cycle of immunotherapy, especially regarding distal chorea, having maintained significant bilateral orofacial dyskinesia (Supporting Information Video 3). Search for an occult neoplasm (body computed tomography scan, body positron emission tomography, and endovaginal ultrasound) was negative. Two months after the first IVIg treatment, anti-GAD titres declined in the CSF (1/100), and the involuntary movements