Autoimmune encephalitis with anti-LGI1-antibody: A case report

Renagaraj. G

Physician Assistant, Department of Neurology, Kauvery Hospital, Cantonment, Trichy

Abstract

We report a case of autoimmune encephalitis in a 62-year-old female with hypothyroidism, presenting with faciobrachial dystonic seizures, cognitive decline, and behavioral abnormalities. Diagnosis was confirmed by MRI brain findings and positivity for LGI1 antibodies. The patient responded well to immunosuppressive therapy including steroids, plasmapheresis, and mycophenolate mofetil.

Introduction

Anti- leucine-rich-glioma-inactivated 1(LGI1) antibody autoimmune encephalitis is a rare type of encephalitis. It is the most common autoimmune limbic encephalitis and the second most common after Anti-NMDAR encephalitis. The most prominent clinical features are epilepsy and cognitive decline. It was first described in 2010. It presents with features of limbic encephalitis, including cognitive decline, behavioral changes, seizure, hyponatremia, and characteristic faciobrachial dystonic seizures (FBDS). It usually presents between 30-80 years of age and is more commonly seen in males in the sixth to seventh decade of life.

Case Presentation

This 62-year-old female is a known case of hypothyroidism on regular medication, presented with recurrent episodes of faciobrachial dystonic seizure, memory disturbance, behaviour at symptoms hallucination, reduced speech and mild cognitive decline of 20 days’ duration. Initially evaluated outside and bought here for further management. Clinical features suggestive of autoimmune encephalitis. On evaluation here MRI brain plain with contrast showed T2/flair hyper intensity in caudate nucleus, periventicular Cortex and bilateral frontal cortex near the midline with patchy areas of diffusion restriction and contrast enhancement suggestive of autoimmune encephalitis, age related cerebral atrophy. EEG was normal. CSF analysis done. The autoimmune panel was positive for the LGI1 antibody. She was treated with a pulse dose of methylprednisolone followed by tapering of an oral steroid.

Patient showed good response to methylprednisolone.Five cycles of plasmapheresis were also completed. PET CT scan, done to rule out paraneoplastic syndrome, showed no evidence of primary malignancy. Mycophenolate Mofetil was added as a second line immuno suppressant following Pl Ex. The patient showed gradual improvement in cognition, behavior and functional status during hospital stay. No new neurological deficits were noted at discharge in a stable condition.

Discussion

LGI1-antibody autoimmune encephalitis is often associated with faciobrachial dystonic seizures and can mimic other neuropsychiatric conditions. MRI findings and antibody testing are pivotal for diagnosis. Immunotherapy, including corticosteroids and plasmapheresis, is effective, with additional immunosuppressant’s used for sustained remission.

Conclusions

Among patients with rapid progression cognitive decline, frequent refractory clinical/subclinical seizures, cardiac arrhythmias, autonomic dysfunction, and refractory hyponatremia should hint toward Anti-LGI1 encephalitis. This allows for early immunotherapy, improves long-term outcomes, and prevents structural brain damage. The positive LGI1 antibody in the CSF but not the serum supports the recent evidence of higher LGI1 antibody sensitivity in the CSF than in the serum.

Nightingale Journals

Kauvery Hospital
Find Doctor
Book Appointment