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CASE REPORT
Delayed LGI1 seropositivity in voltage-gated potassium channel (VGKC)-complex antibody limbic encephalitis
  1. Michael Sweeney1,
  2. Jonathan Galli1,
  3. Scott McNally2,
  4. Anne Tebo3,4,
  5. Thomas Haven4,
  6. Perla Thulin1,
  7. Stacey L Clardy1
  1. 1Department of Neurology, University of Utah, Salt Lake City, Utah, USA
  2. 2Department of Radiology, University of Utah, Salt Lake City, Utah, USA
  3. 3Department of Pathology, University of Utah, Salt Lake City, Utah, USA
  4. 4Associated and Regional and University Pathologists Laboratory®, Salt Lake City, Utah, USA
  1. Correspondence to Dr Stacey L Clardy; stacey.clardy{at}hsc.utah.edu

Summary

We utilise a clinical case to highlight why exclusion of voltage-gated potassium channel (VGKC)-complex autoantibody testing in serological evaluation of patients may delay or miss the diagnosis. A 68-year-old man presented with increasing involuntary movements consistent with faciobrachial dystonic seizures (FBDS). Initial evaluation demonstrated VGKC antibody seropositivity with leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) seronegativity. Aggressive immunotherapy with methylprednisolone and plasmapheresis was started early in the course of his presentation. Following treatment with immunotherapy, the patient demonstrated clinical improvement. Repeat serum evaluation 4 months posthospitalisation remained seropositive for VGKC-complex antibodies, with development of LGI1 autoantibody seropositivity. VGKC-complex and LGI1 antibodies remained positive 12 months posthospitalisation. Our findings suggest that clinical symptoms can predate the detection of the antibody. We conclude that when suspicion for autoimmune encephalitis is high in the setting of VGKC autoantibody positivity, regardless of LGI1 or CASPR2 seropositivity, early immunotherapy and repeat testing should be considered.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

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Footnotes

  • Contributors MS evaluated the patient, analysed and interpreted the data, and drafted and revised the manuscript. JG evaluated the patient, analysed and interpreted the data, and drafted and revised the manuscript. SMcN analysed and interpreted the data, and created imaging figures. SC clinically evaluated the patient, analysed and interpreted the data, and revised the manuscript.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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