title: Faciobrachial dystonic seizures precede Lgi1 antibody limbic encephalitis.
abstract: OBJECTIVE
  To describe a distinctive seizure semiology that closely associates with voltage-gated potassium channel (VGKC)-complex/Lgi1 antibodies and commonly precedes the onset of limbic encephalitis (LE).
  
  
  METHODS
  Twenty-nine patients were identified by the authors (n = 15) or referring clinicians (n = 14). The temporal progression of clinical features and serum sodium, brain magnetic resonance imaging (MRI), positron emission tomography/single photon emission computed tomography, and VGKC-complex antibodies was studied.
  
  
  RESULTS
  Videos and still images showed a distinctive adult-onset, frequent, brief dystonic seizure semiology that predominantly affected the arm and ipsilateral face. We have termed these faciobrachial dystonic seizures (FBDS). All patients tested during their illness had antibodies to VGKC complexes; the specific antigenic target was Lgi1 in 89%. Whereas 3 patients never developed LE, 20 of the remaining 26 (77%) experienced FBDS prior to the development of the amnesia and confusion that characterize LE. During the prodrome of FBDS alone, patients had normal sodium and brain MRIs, but electroencephalography demonstrated ictal epileptiform activity in 7 patients (24%). Following development of LE, the patients often developed other seizure semiologies, including typical mesial temporal lobe seizures. At this stage, investigations commonly showed hyponatremia and MRI hippocampal high T2 signal; functional brain imaging showed evidence of basal ganglia involvement in 5/8. Antiepileptic drugs (AEDs) were generally ineffective and in 41% were associated with cutaneous reactions that were often severe. By contrast, immunotherapies produced a clear, and often dramatic, reduction in FBDS frequency.
  
  
  CONCLUSIONS
  Recognition of FBDS should prompt testing for VGKC-complex/Lgi1 antibodies. AEDs often produce adverse effects; treatment with immunotherapies may prevent the development of LE with its potential for cerebral atrophy and cognitive impairment.
authors.affiliation: Department of Clinical Neurology, Oxford University, Oxford, UK.
authors.forename: Sarosh R
authors.initials: SR
authors.lastname: Irani
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Michell
authors.forename: Bethan
authors.initials: B
authors.lastname: Lang
authors.forename: Philippa
authors.initials: P
authors.lastname: Pettingill
authors.forename: Patrick
authors.initials: P
authors.lastname: Waters
authors.forename: Michael R
authors.initials: MR
authors.lastname: Johnson
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Schott
authors.forename: Richard J E
authors.initials: RJ
authors.lastname: Armstrong
authors.forename: Alessandro
authors.initials: A
authors.lastname: S Zagami
authors.forename: Andrew
authors.initials: A
authors.lastname: Bleasel
authors.forename: Ernest R
authors.initials: ER
authors.lastname: Somerville
authors.forename: Shelagh M J
authors.initials: SM
authors.lastname: Smith
authors.forename: Angela
authors.initials: A
authors.lastname: Vincent
mesh_terms: D000328:Adult; D000368:Aged; D000906:Antibodies / Q000097:blood* / Q000627:therapeutic use; D000927:Anticonvulsants / Q000627:therapeutic use; D001917:Brachial Plexus / Q000503:physiopathology*; D018450:Disease Progression; D004569:Electroencephalography / Q000379:methods; D005145:Face / Q000503:physiopathology; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D020363:Limbic Encephalitis / Q000188:drug therapy / Q000276:immunology* / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D024642:Potassium Channels, Voltage-Gated / Q000276:immunology; D011506:Proteins / Q000276:immunology*; D012640:Seizures / Q000209:etiology* / Q000473:pathology; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D016896:Treatment Outcome
chemical_list: D000906:Antibodies; D000927:Anticonvulsants; D047908:Intracellular Signaling Peptides and Proteins; C116499:LGI1 protein, human; D024642:Potassium Channels, Voltage-Gated; D011506:Proteins