Faciobrachial dystonic seizures precede Lgi1 antibody limbic encephalitis

Ann Neurol. 2011 May;69(5):892-900. doi: 10.1002/ana.22307. Epub 2011 Mar 17.

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.

Interpretation: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Antibodies / blood*
  • Antibodies / therapeutic use
  • Anticonvulsants / therapeutic use
  • Brachial Plexus / physiopathology*
  • Disease Progression
  • Electroencephalography / methods
  • Face / physiopathology
  • Female
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Limbic Encephalitis / drug therapy
  • Limbic Encephalitis / immunology*
  • Limbic Encephalitis / physiopathology*
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Potassium Channels, Voltage-Gated / immunology
  • Proteins / immunology*
  • Seizures / etiology*
  • Seizures / pathology
  • Tomography, Emission-Computed, Single-Photon / methods
  • Treatment Outcome

Substances

  • Antibodies
  • Anticonvulsants
  • Intracellular Signaling Peptides and Proteins
  • LGI1 protein, human
  • Potassium Channels, Voltage-Gated
  • Proteins