Surgical Treatment of a Lesion Associated With NORSE
New-onset refractory status epilepticus (NORSE) has high morbidity and mortality. The authors describe the successful surgical treatment of a 56-year-old man presenting with NORSE. Magnetic resonance imaging showed a left temporal lobe lesion suspicious for a low-grade tumor, while PET imaging with the alpha[C]methyl-L-tryptophan (AMT) radiotracer showed increased cortical uptake extending beyond this lesion and partly overlapping with epileptogenic cortex mapped by chronic intracranial electroencephalographic monitoring. Resection of the epileptic focus resulted in long-term seizure freedom, and the nonresected portion of the PET-documented abnormality normalized. Histopathology showed reactive gliosis and inflammatory markers in the AMT-PET–positive cortex. Molecular imaging of neuroinflammation can be instrumental in the management of NORSE by guiding placement of intracranial electrodes or assessing the extent and severity of inflammation for antiinflammatory interventions.
In adults with new-onset focal seizure(s), cranial CT or MRI often reveals an epileptogenic lesion. In such cases, the lesion is often suspicious for an underlying neoplasm, although nonneoplastic conditions can also mimic brain tumors. In some adults, seizures occur as NORSE. This disorder is often characterized by CSF pleocytosis and lack of an obvious underlying cause. In some cases, seizures are preceded by a febrile illness. Magnetic resonance imaging may show signal abnormalities, often multifocal, on T2-weighted and FLAIR sequences. Treatment is difficult, and morbidity and mortality are high. The etiology of this condition is unclear; an underlying inflammatory process, such as viral encephalitis or an autoimmune condition, is frequently assumed but rarely can be proven. It is also often uncertain whether the observed MRI abnormalities represent the causes or consequences of severe seizures. Here we present the clinical history, neuroimaging, electrophysiological, and histopathological findings, and long-term posttreatment follow-up of an adult treated for NORSE associated with an inflammatory brain lesion. We demonstrate how the use of AMT-PET imaging facilitated the diagnosis and assisted with successful treatment after detecting tissue with seizure-associated inflammation. AMT-PET is an imaging modality that can effectively detect epileptic foci and lesions such as tumors due to AMT accumulation resulting from increased tryptophan transport and metabolism via the inflammatory and immunosuppressive kynurenine pathway.
Abstract and Introduction
Abstract
New-onset refractory status epilepticus (NORSE) has high morbidity and mortality. The authors describe the successful surgical treatment of a 56-year-old man presenting with NORSE. Magnetic resonance imaging showed a left temporal lobe lesion suspicious for a low-grade tumor, while PET imaging with the alpha[C]methyl-L-tryptophan (AMT) radiotracer showed increased cortical uptake extending beyond this lesion and partly overlapping with epileptogenic cortex mapped by chronic intracranial electroencephalographic monitoring. Resection of the epileptic focus resulted in long-term seizure freedom, and the nonresected portion of the PET-documented abnormality normalized. Histopathology showed reactive gliosis and inflammatory markers in the AMT-PET–positive cortex. Molecular imaging of neuroinflammation can be instrumental in the management of NORSE by guiding placement of intracranial electrodes or assessing the extent and severity of inflammation for antiinflammatory interventions.
Introduction
In adults with new-onset focal seizure(s), cranial CT or MRI often reveals an epileptogenic lesion. In such cases, the lesion is often suspicious for an underlying neoplasm, although nonneoplastic conditions can also mimic brain tumors. In some adults, seizures occur as NORSE. This disorder is often characterized by CSF pleocytosis and lack of an obvious underlying cause. In some cases, seizures are preceded by a febrile illness. Magnetic resonance imaging may show signal abnormalities, often multifocal, on T2-weighted and FLAIR sequences. Treatment is difficult, and morbidity and mortality are high. The etiology of this condition is unclear; an underlying inflammatory process, such as viral encephalitis or an autoimmune condition, is frequently assumed but rarely can be proven. It is also often uncertain whether the observed MRI abnormalities represent the causes or consequences of severe seizures. Here we present the clinical history, neuroimaging, electrophysiological, and histopathological findings, and long-term posttreatment follow-up of an adult treated for NORSE associated with an inflammatory brain lesion. We demonstrate how the use of AMT-PET imaging facilitated the diagnosis and assisted with successful treatment after detecting tissue with seizure-associated inflammation. AMT-PET is an imaging modality that can effectively detect epileptic foci and lesions such as tumors due to AMT accumulation resulting from increased tryptophan transport and metabolism via the inflammatory and immunosuppressive kynurenine pathway.
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