Table 3.

Approach to diagnosing EA disorders in the clinic.

History of episodic spells	Onset age, triggers, duration, frequency Other attack symptoms? e.g. vertigo, tinnitus, confusion Medical history of other paroxysmal disorders? Migraine, seizures 3-generation family history Baseline between spells Response to treatment
Neurological examination	At baseline, during a spell, video of spell
Electroencephalogram	Routine EEG with provoked spell, video EEG
MRI brain with and without contrast	Normal, cerebellar atrophy, other brain lesions
Laboratory tests (secondary etiology suspected)	Thyroid function, thiamine, anti-seizure medication levels, ammonia, citrulline, lead, ETOH, anti-GQ1B antibodies, sedimentation rate, C-reactive protein, lupus anticoagulant, anticardiolipin antibodies IgG/IgM, anti-beta-2 glycoprotein antibodies IgG IgM CSF cell count, glucose, protein, oligoclonal bands, MS profile Paired serum/CSF: glucose, lactate, CASPR2, anti-NMDA-R, ANNA-1
Genetic testing	Single-gene if classical phenotype and family history (e.g. EA1, EA2) Episodic ataxia panels Next-generation sequencing Whole exome sequencing