Abstract

Acute confusion and hyponatraemia are common presentations in acute medicine. We report two cases of anti-voltage gated potassium channel (VGKC) antibody-related limbic encephalitis highlighting the variable presentation of this condition. Both patients were thoroughly investigated with MRI scan of brain, lumbar puncture, EEG as well as infective and autoimmune screens for encephalitis. Anti-VGKC antibodies were positive for both patients and prompt treatment with immunotherapy yielded good recovery. Patients presenting with confusion and seizures who have no demonstrable infectious or metabolic cause should have investigation for an autoimmune cause expedited. In addition, psychiatric presentations with atypical features such as drowsiness should prompt similar investigations. The outcome of anti-VGKCrelated limbic encephalitis is improved with early treatment employing steroids or immunotherapy.

[download-attachments container="div" style="list" display_icon="1" display_count="1" display__size="0"]

References

1. The Guidelines and Audit Implementation Network (GAIN) (Northern Ireland) Guidance on hyponatraemia in adults (on or after 16th birthday) February 2010. Available at: http://www.gainni.org/Publications/Guidelines/Hyponatraemia_guideline.pdf (last accessed 15 March, 2014).
2. Denes E, Labach C, Durox H, et al. Intrathecal synthesis of specific antibodies as a marker of herpes simplex encephalitis in patients with negative PCR. Swiss Med Wkly 2010; 140:w13107.
3. Solomon T, Michael BD, Smith PE, et al. Management of suspected viral encephalitis in adults-Association of British Neurologists and British Infection Association National Guidelines. J Infect 2012; 64(4):347-373.
4. Lennox BR, Coles AJ, Vincent A. Antibody-mediated encephalitis: a treatable cause of schizophrenia. Br J Psychiatry 2012 Feb;200(2):92-94.
5. Buckley C, Oger J, Clover L, et al. Potassium channel antibodies in two patients with reversible limbic encephalitis. Ann Neurol 2001;0(1):73-78.
6. Parthasarathi UD, Harrower T, Tempest M, et al. Psychiatric presentation of voltage-gated potassium channel antibodyassociated encephalopathy. Case report. Br J Psychiatry 2006; 189:182-183.
7. Ambrose HE, Granerod J, Clewley JP, et al. Diagnostic strategy used to establish etiologies of encephalitis in a prospective cohort of patients in England. J Clin Microbiol 2011; 49(10):3576-3583.
8.  Klein CJ, Lennon VA, Aston PA, et al. Insights from LGI1and CASPR2 potassium channel complex autoantibody subtyping. JAMA Neurol 2013; 70(2):229-234.
9. Paterson RW, Zandi MS, Armstrong R, et al. Clinical relevance of positive voltage-gated potassium channel (VGKC)-complex antibodies: experience from a tertiary referral centre. J Neurol Neurosurg Psychiatry 2013 Jun 11 (epub ahead of print)
10. Irani SR, Alexander S, Waters P, et al. Antibodies to Kv1 potassium channel-complex proteins leucine-rich, glioma inactivated 1 protein and contactin-associated protein-2 in limbic encephalitis, Morvan’s syndrome and acquired neuromyotonia. Brain 2010; 133(9):2734-2748.
11. Irani SR, Vincent A. Autoimmune encephalitis -- new awareness, challenging questions. Discov Med 2011; 11(60):449-458.
12. Alcantara M, Bennani O, Verdure P, et al. Voltage-gated potassium channel antibody paraneoplastic limbic encephalitis associated with acute myeloid leukemia. Case Rep Oncol 2013; 6(2):289-292.
13. Sadalage G, Karim A, Jacob S. Autoimmune encephalitis screen-a review of rapid diagnostic screening in 600 patients over 5 years. J Neurol Neurosurg Psychiatry 2013; 84(11):e2.
14. Butler CR, Miller TD, Kaur MS, et al. Persistent anterograde amnesia following limbic encephalitis associated with antibodies to the voltage-gated potassium channel complex. J Neurol Neurosurg Psychiatry 2014 (epub ahead of print) doi:10.1136/jnnp-2013- 206724.
15. Mittal M, Hammond N, G Lynch S. Immunotherapy responsive autoimmune subacute encephalitis: a report of two cases. Case Rep Med 2010; 2010:837371.
16. Lai M, Huijbers MG, Lancaster E, et al. Investigation of LGI1 as the antigen in limbic encephalitis previously attributed to potassium channels: a case series. Lancet Neurol 2010; 9(8):776-785.
17. Vincent A, Buckley C, Schott JM, et al. Potassium channel antibody-associated encephalopathy: a potentially immuno therapyresponsive form of limbic encephalitis. Brain 2004; 127(Pt 3):701-712.