General description

Anti-LGI1 antibody encephalitis is often seen in nonparaneoplastic encephalitis, but some cases are associated with tumors and should be screened for malignancy when these antibodies are seen.

Faciobrachial dystonic seizure (FBDS)

The characteristic clinical manifestation is known as faciobrachial dystonic seizure (FBDS), a very short, persistent dystonic seizure on the ipsilateral face and upper extremities. Typical FBDS is synchronized with involuntary movements of the ipsilateral face in one upper limb, lasting less than 3 seconds. Involuntary movements of the ipsilateral face occur synchronously with involuntary movements of the unilateral upper limb, with a high frequency of 10 to 360 attacks per day. Consciousness is usually preserved, but standing hair, sensory aura, speech arrest, and postictal fear or aggression may be present. About half of the patients develop cognitive dysfunction following FBDS.

Radiographic features

Typically, MRI reveals a limbic encephalitis pattern involving the temporal lobe, insula, and cingulate gyrus. Additionally, a characteristic finding of Anti-LGI1 antibody encephalitis is unilateral T1WI hyperintensity in the basal ganglia, frequently observed in patients exhibiting faciobrachial dystonic seizures (FBDS).