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Introduction:

Autoimmune encephalitis has a divergent presentation, typically presenting as limbic or brainstem encephalitis.  LGI1 encephalitis presents with subacute cognitive impairment, mental disorder, movement disorder – faciobrachial dystonic seizures. We present a case of LGI1 encephalitis in the setting of localized lung squamous cell carcinoma.

Case:

A 78-year-old woman with history of breast cancer status post resection and radiation and no prior neurological history was seen for evaluation. She had typical faciobrachial dystonic seizures, affecting the left more than right arm with associated facial dystonia and vocalizations. They occurred about twenty times daily. She had cognitive dysfunction, dysarthria, and hypophonia. Her neurologic examination showed mild bradykinesia on the left side. EEG of the episodes revealed no seizure activity. Given the semiology of the episodes, LGI1 encephalitis was strongly suspected. Initial paraneoplastic panel was positive for VGKC antibodies without LGI1 positive serologies. The patient was started on IVIG and Solumedrol for empiric treatment of immune-mediated encephalitis. Repeated titers for the LGI1 antibody complex were positive. She had partial improvement of her seizures despite IVIG, Levetiracetam, and Clonazepam.   Seven months following her presentation, she was found to have a lung mass. Surgical resection demonstrated Stage I Small Cell Carcinoma. Following the resection, she had complete resolution of seizure activity and cognitive function. She was able to come off IVIG and anti-convulsants.

Discussion:

LGI1 encephalitis is typically not associated with malignancy. There has been no reported case of association between squamous cell carcinoma of the lung and LGI1 encephalitis. This case suggests that surveillance for systemic malignancy should be more considered in cases of LGI1 autoimmunity.

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