068 Bradycardia as a rare neurocardiac prodrome to Leucine-rich glioma inactivated-1 antibody encephalitis

Introduction Leucine-rich glioma inactivated-1 antibody encephalitis has been associated with bradycardia as a neurocardiac prodrome.1 Concurrent occurrence of cardiac arrhythmia and faciobrachial dystonic seizures have not previously been reported. Case A 73-year-old male presented with a 6 week history of frequent episodes of an unpleasant sensation associated with sinus bradycardia requiring pacemaker implantation. Episodes continued despite pacemaker. He was diagnosed with a seizure disorder and commenced on levetiracetam without response. Subsequently, on video EEG, subtle facial grimace and upper limb tonicity were captured, in keeping with faciobrachial dystonic seizures without an EEG correlate. MRI Brain showed no radiological evidence of encephalitis. Serum limbic encephalitis panel confirmed LGI1 antibodies. Other autoimmune and paraneoplastic antibodies were negative. He was treated with a course of corticosteroids. Induction dose of intravenous immunoglobulin was prematurely terminated after one dose due to MRSA bacteraemia and tricuspid valve endocarditis, necessitating removal of the pacemaker with no recurrence of seizures or bradycardia at follow up without further treatment. Conclusion This case illustrates a rare presentation of LGI-1 antibody encephalitis with complete remission following incomplete induction course of intravenous immunoglobulin and corticosteroids. Neurocardiac prodrome as episodic bradycardia or asystole may precede the onset of encephalitis by approximately 2 months.1 2 There is a good response to immunotherapy, however relapse is common.3 This case illustrates that clinically atypical presentations of cardiac arrhythmia may warrant neurological review and raises a possibility that early initiation of immunosuppressive therapy may significantly alter the disease course of LGI-1 antibody encephalitis. References Naasan G, Irani SR, Bettcher BM, Geschwind MD, Gelfand JM. Episodic bradycardia as neurocardiac prodrome to voltage-gated potassium channel complex/leucine-rich, glioma inactivated 1 antibody encephalitis. JAMA Neurology 2014;71(10):1300–4. Nilsson AC, Blaabjerg M. More evidence of a neurocardiac prodrome in anti-LGI1 encephalitis. Journal of the Neurological Sciences 2015;357(1):310–1. van Sonderen A, Thijs RD, Coenders EC, Jiskoot LC, Sanchez E, de Bruijn MAAM, et al. Anti-LGI1 encephalitis. Clinical Syndrome and Long-Term Follow-up 2016;87(14):1449–56.