LAUSR

Faciobrachial dystonic seizures (FBDS), a hallmark of autoimmune encephalitis with leucine-rich glioma inactivated-1 (LGI1) antibodies (anti-LGI1 encephalitis) usually present as brief dystonic contraction of unilateral face and ipsilateral arm lasting less than 3 seconds. Here, we report a case presenting as bilaterally synchronized FBDS mimicking generalized convulsive status epilepticus. A 75-year-old previously healthy Japanese woman presented with gradual onset of memory impairment and visual and auditory hallucinations over a month. One week before admission, she started having rhythmically synchronized bilateral dystonic posturing of her face and extremities 1 to 3 times a day (Supplementary Video S1). During the attacks, she initially remained awake but became unresponsive with generalization of the dystonic seizure, followed by postictal drowsiness with left gaze preference for 10 to 30 minutes. On admission (day 1), the patient was incoherent and kept talking to herself, without full recovery of consciousness. On neurologic examination she was disoriented to time and place and had left–right disorientation and ideomotor apraxia, but otherwise unremarkable. The laboratory tests were unremarkable except hyponatremia (129 mEq/L). Cerebrospinal fluid (CSF) examination revealed 1 white blood cell/μL with normal levels of protein and glucose; herpes simplex viruses polymerase chain reaction was negative. CSF-restricted oligoclonal bands were detected. Classical paraneoplastic antibodies against intracellular antigens (antineuronal nuclear antibody-type 1, antineuronal nuclear antibody-type 2, antineuronal nuclear antibody-type 3, amphiphysin, and collapsin response mediator protein 5) were negative in serum. Autoantibodies against neuronal cell-surface antigens or synaptic proteins in serum/CSF were negative for antibodies to dipeptidyl-peptidase-like protein 6, collapsin response mediator protein 5, contactin–associated protein 2, and receptors of N-methyl-D-aspartate, α-amino-3-hydroxy5-methyl-4-isoxazolepropionic acid, and gamma-aminobutyrate type A and B, but positive for antibodies to LGI1; the serum was weakly positive, whereas the CSF was strongly positive. These neuronal surface antibodies were measured with both cell-based assay and rat brain immunohistochemistry at the University of Barcelona. Brain magnetic resonance imaging showed right-side predominant increased T2/fluid-attenuated inversion recovery signals in the medial temporal lobes, fimbria, and insular cortex. Whole-body computed tomography and pelvic magnetic resonance imaging revealed no evidence of malignancy. A post-ictal electroencephalogram showed left-side predominant delta slowing without epileptiform discharges. She was treated with intravenous methylprednisolone (1000 mg, 3 days), followed by gradual tapering of prednisolone (1 mg/kg/day), resulting in dramatic improvement in her psychiatric symptoms. She was discharged on day 30 without neurologic deficits or seizures. The patient’s clinical features, including hallucination, hyponatremia, magnetic resonance imaging abnormalities, CSF findings, and steroid responsiveness, were all compatible with anti-LGI1 encephalitis. Interestingly, bilaterally synchronized FBDS mimicking generalized convulsive status epilepticus seen here are phenotypically different from classic LGI1-associated FBDS in terms of the duration and bilateral involvement. Although the mechanisms underlying classic FBDS remain unknown, involvement of the basal ganglia or cortico-basal ganglia network has recently been implicated. FBDS may resemble tonic epileptic spasms, but whether they are of epileptic