Testing directly for LGI1 and contactin-associated protein 2 (CASPR2) antibodies should be undertaken in patients with clinical features suggestive of faciobrachial dystonic seizures, limbic encephalitis, Morvan syndrome, and neuromyotonia. LGI1-antibody seropositivity is most commonly associated with limbic encephalitis, with a high incidence of seizures and cognitive impairment. There is significant overlap in clinical manifestations with CASPR2 seropositivity, with neuromyotonia, pain, and sleep disturbance occurring across both clinical entities, albeit at different frequencies.
Jul. 16, 2021