Spontaneous remission without progression to limbic encephalitis in a patient with LGi1 seropositive faciobrachial dystonic seizure

Faciobrachial dystonic seizures are pathognomonic of leucine-rich glioma inactivated-1 (LGi1) antibody, non-paraneoplastic limbic encephalitis. Faciobrachial dystonic seizures usually precede limbic encephalitis by about a month. It is unknown whether, if untreated, faciobrachial dystonic seizures inevitably progress to limbic encephalitis. We present an LGi1 seropositive patient with a year’s history of faciobrachial dystonic seizures, who achieved remission spontaneously without immunotherapy or antiepileptic drug treatment, and did not develop evidence of limbic encephalitis over a three-year follow-up. Neurology Asia 2016; 21(2) : 191 – 193 Address correspondence to: Dr. Sherrini Bazir Ahmad, Address: Neurology Laboratory, 6th Floor, Menara Selatan, University Malaya Medical Center, 59100 Kuala Lumpur, Malaysia. Telephone number: +6 0127085977, Email: [email protected] INTRODUCTION Antibodies against the voltage-gated potassium channel (VGKC) principally bind with leucinerich glioma-inactivated protein 1 (LGI1) or with contactin associated protein-like2 (CASPR2) in the central and peripheral nervous systems. While these antibodies are characterized by amnesia, behavioural and psychiatric disturbances and hyponatraemia, CASPR2 antibodies are typically associated with peripheral motor excitability and Morvan syndrome while LGi1 are more often associated with limbic encephalitis and epilepsy which may be drug resistant. A stereotypical seizure associated with LGi1 antibodies is the faciobrachial dystonic seizure (FBDS), which precedes the onset of limbic encephalitis by about a month. These seizures are brief (< 3 seconds) with frequent dystonic posturing (up to > 50 times/day) almost always affecting the arm (unilateral or bilateral), frequently associated with ipsilateral facial grimacing and may involve the leg. They are almost always refractory to antiepileptic drugs (AEDs), but are responsive to immunotherapy. In a series of 29 patients with FBDS, 3 were treated with immunotherapy and did not progress to limbic encephalitis. The authors commented that it was not yet clear if untreated, FBDS would inevitably proceed to limbic encephalitis. We describe a case of LGi1 seropositive FBDS, without cognitive impairment, who achieved spontaneous remission without immunotherapy or AED treatment. Subsequent follow-up did not show any progression of the disease.