Behavioral Change, Seizures, and Temporal Lobe Lesion

Abstract

A 56-year-old man with a history of type 2 diabetes, hypertension, hyperlipidemia, sleep apnea, alcohol use disorder in remission, renal cell carcinoma, and mucinous adenocarcinoma of the lung sought care for evaluation of presumed limbic encephalitis. Six months before evaluation, he had development of anxiety, fatigue, and blurry vision. He was diagnosed with renal cell carcinoma, which was resected. Subsequently, worsening depression developed, which required self-admitted psychiatric hospitalization for suicidal ideation. After discharge he had subacute development of aphasia, inability to recognize family members, and delusions for which he was hospitalized. Brain magnetic resonance imaging demonstrated a large, partly expansile, T2/fluid-attenuated inversion recovery–hyperintense lesion involving the left hippocampus and parahippocampal gyrus, as well as temporal neocortex and white matter, which was interpreted as limbic encephalitis. Spinal fluid analysis showed 66 total nucleated cells/μ‎L with 93% lymphocytes, normal cytologic findings, protein concentration of 66 mg/dL, and 15 erythrocytes/μ‎L. The Kokmen short test of mental status indicated mainly an amnestic profile without delirium, with a total score of 31 of 38. Given the patient’s neuroimaging findings for limbic encephalitis and lack of clear encephalopathy, the initial focus was confirming or ruling out the diagnosis of limbic encephalitis. He underwent repeated cerebrospinal fluid analysis, which showed 3 total nucleated cells/μ‎L with a protein concentration of 67 mg/dL. Serum autoantibody testing showed a low-titer glutamic acid decarboxylase 65-kDa isoform antibody value of 0.17 nmol/L. Brain magnetic resonance imaging 3 months after his initial magnetic resonance imaging showed slight progression of the expansile, left temporal lobe, T2-hyperintense lesion, further involving the left parietal lobe white matter, temporal lobe neocortex, and splenium of the corpus callosum, without clear gadolinium enhancement. A diagnosis of anaplastic astrocytoma (World Health Organization grade III) was made. He was treated with temozolomide and radiotherapy, with radiographic improvement. However, he had development of medically refractory focal seizures with secondary generalization. Approximately 3 years after his initial diagnosis, the patient experienced functional decline, with brain magnetic resonance imaging demonstrating multiple new, bihemispheric, T2-hyperintense lesions concerning for multifocal glioma. Given his poor prognosis and functional status, the patient was transitioned to comfort care. The presentation of disease in this patient highlights the importance of neuroimaging interpretation in the context of clinical history. Although this case patient had some features that could suggest a paraneoplastic limbic encephalitis—including behavioral changes, seizure, systemic malignancy, and apparent clinical response to immunosuppression—several features were inconsistent with this diagnosis.