Limbic Encephalitis as a Presenting Complication for Small Cell Lung Cancer

Limbic encephalitis (LE) is a rare neurological paraneoplastic complication that occurs secondary to malignant tumors. It is commonly presented as refractory seizures that are resistant to most anti-epileptics. We are presenting a unique case of small cell lung cancer complicated with LE. The challenging part of our case is that the patient had a history of seizure disorder in the past, and she was treated initially as an anti-epileptic treatment failure. A 68-year-old patient with a history of epilepsy was admitted to the ICU with resistant status epilepticus (SE), and respiratory failure secondary to pneumonia. Further workup revealed that the patient has small cell lung carcinoma. An extensive workup done to investigate resistant seizures revealed that she had a rare type of paraneoplastic autoantibodies (Anti-Hu) in the cerebrospinal fluid, which supported the diagnosis of the paraneoplastic autoimmune LE. High dose steroids helped to decrease the seizures episodes, but the family decided to proceed with palliative measures only at the end. Diagnosing LE requires ruling out other common causes of SE. Treatment options include treating underlying cancer as well as means of immunosuppression or antibody removal by tacrolimus and cyclophosphamide and even intravenous immunoglobulin (IVIG) or plasma exchange. It is important to consider LE in the differential diagnosis when managing patients with resistant SE in the ICU, even if the brain imaging and cerebrospinal fluid (CSF) analysis were within normal limits.