LGI1 limbic encephalitis in a nonagenarian: successful treatment and implications for age-inclusive medicine

<h3>Background</h3> LGI1 limbic encephalitis is an autoimmune encephalopathy characterised by distinctive facio-brachial dystonic seizures and cognitive change. Previously reported age range at presentation is 31 to 84 years. We present a case in a 90 year old who underwent prompt treatment with plasma exchange (PLEX) and steroids with an excellent outcome. <h3>Case Presentation</h3> A 90 year old male presented with subacute confusion, reduced mobility and facio-brachial dystonic seizures. A lumbar puncture was not possible due to spinal osteophytes. Routine blood screen was normal, MRI brain scan was normal for his age, electroencephalogram showed an excess of slow activity but no periodic or epileptiform features. Screening radiology for a paraneoplastic cause was unrevealing. A clinical diagnosis of LGI1 encephalitis was made and he was treated with high dose steroids and PLEX. His symptoms rapidly improved and he returned home. Serum anti-LGI 1 antibodies were subsequently found to be positive. At the age of 91yr, facio-brachial dystonic seizures recurred with a further excellent response to PLEX. Steroids were weaned and he remains living an independent life, relapse free, at the age of 93. <h3>Conclusion</h3> The successful outcome highlights the importance of adopting a non-ageist approach, recognizing treatable neurological conditions in elderly individuals.