Abstracts

Rationale: The connection between paraneoplastic autoantibodies and limbic encephalitis with seizures is well established since there are several autoantibodies known to be associated with these symptoms. However, there are only rare reported cases in the literature of voltage gated calcium channel antibodies (VGCCAbs), typically associated with Lambert-Eaton myasthenic syndrome, occurring in the setting of limbic encephalitis and epilepsy. We report such an individual, with compelling improvements occurring after an aggressive search and definitive treatment for an underlying malignancy. Methods: We describe a 63-year-old male with a history significant for smoking and a recent diagnosis of seizures, presenting with psychiatric and cognitive deterioration over the course of a year. His symptoms consisted of progressively worsening short-term memory, poor recall, severe anxiety, insomnia, depressive symptoms, and increasing frequency of seizures, culminating in an urgent admission for status epilepticus. A search for an autoimmune basis for his symptoms revealed positive VGCCAbs. Results: Video-EEG during episode of nonconvulsive status epilepticus revealed frequent independent left and right temporal seizures manifested by an aura of anxiety, staring, behavioral arrest, and decreased responsiveness. Interictal sharp wave discharges were seen independently over the temporal regions. Neuroimaging showed microvascular changes but no evidence for vasculitis, and basic CSF analysis was unrevealing. ANA was elevated (1:320) with elevated double-stranded DNA titers. Paraneoplastic panel was positive for voltage gated calcium channel antibodies (P/Q and N type). Neuromuscular evaluation, previously conducted for evaluation of known cervical stenosis, did not demonstrate abnormalities on EMG or with repetitive stimulation. The presence of VGCCAbs along with patient's smoking history prompted further neoplastic evaluation including CT of the chest, abdomen, and pelvis and a full body PET scan. Work-up revealed enlarged mediastinal lymph nodes and a hypermetabolic right lower paratrachial lymph node measuring 2.3x2.1cm. Histopathology confirmed the diagnosis of metastatic small cell lung cancer. The patient was treated with steroids, IVIG, resection of his tumor, and chemotherapy with improvement in his both his seizure frequency, cognitive, and psychological symptoms. Conclusions: VGCCAbs associated with subacute limbic encephalitis and seizures is a rarely described occurrence. It is important to consider this diagnosis in patients presenting with these symptoms as it may facilitate early diagnosis and treatment of an underlying malignancy. Early treatment may also yield better neurologic outcomes.