Authors :
Presenting Author: Jimena Gonzalez-Salido, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Luis A. Marin-Castañeda, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Jimena Colado-Martinez, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Juan C. Cotua-Urzuola, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Irving Fuentes-Calvo, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Fernando Vasquez-Lopez, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Betsy C. Vázquez-Cruz, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Mijaíl Adán Rivas-Cruz, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Eithel A. Valenzuela-Mendivil, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Salvador Martinez-Medina, MD – National Institute of Neurology and Neurosurgery
Santiago Philibert-Rosas, M.D – Neurology Department, University of Wisconsin Madison
Gerardo Mendez-Suarez, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Ivan Díaz-Meneses, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Jesús Ramírez-Bermúdez, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Nora E. Kerik-Rotenberg,, MD – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Verónica Rivas, MD – National Institute of Neurology and Neurosurgery
Mario A. Sebastián-Díaz, MD,PHD – South Central High Specialty Hospital PEMEX
Iris E. Martínez-Juárez, MD, MSc – National Institute of Neurology and Neurosurgery. Mexico City, Mexico
Rationale:
Anti‐N‐methyl‐D‐aspartate (NMDA) receptor encephalitis is a severe neurological autoimmune disorder. Its diagnosis has typically relied on clinical presentation, brain magnetic resonance imaging (MRI), electroencephalogram (EEG), cerebrospinal fluid (CSF), and anti-neuronal antibodies. We aimed to describe brain metabolic changes over time employing 18 FDG PET/CT in patients with seizures and epilepsy secondary to Anti-NMDA receptor encephalitis.Methods:
Medical records of patients aged 18 and older at a National Institute of Neurology and Neurosurgery (NINN) in Mexico from 2016 to 2023 diagnosed with anti-NMDA receptor encephalitis and epilepsy or seizures were reviewed. Quantitative variables were expressed as mean and standard deviation and analyzed using the Student's t-test or a non-parametric equivalent. Qualitative variables were expressed as frequencies and percentages and analyzed using Pearson's Chi-square or Fisher's exact tests.Results:
We included 19 patients in the analysis, all of whom underwent two 18 FDG-PET/CT scans. Of these, 11 (57.9%) patients were female, with a mean age of 27.4 ± 10.77 years (range: 20-32 years). Abnormal movements were observed in 10 (52.6%) patients. The most common type of epilepsy was focal motor seizures with loss of awareness, and 89.5% had less than one seizure per month. The mean follow-up interval between the two PET scans was 20.53 months (range: 5-48 months). In the first 18 FDG-PET/CT, abnormal metabolism was present in all 19 (100%) patients. Hypometabolism was observed in 18 (94.7 %) patients, predominantly in the occipital lobe, while hypermetabolism was observed in 13 patients (68.4%), mainly in basal nuclei and frontal lobe. At follow-up 18 FDG-PET/CT, hypometabolism persisted in 8 (42.1%) patients, mainly in the parietal and occipital lobes, and hypermetabolism was observed in 7 (36.8%) patients, predominantly in the frontal lobe. We observed significant hypometabolism in the insula compared to the first PET scan (p=0.01) and hypermetabolism in the thalamus (p=0.05) (Table 1). Abnormalities were also identified in complementary studies: CSF in 16 patients (84.2%), MRI scans in 4 (21.1%) patients, and EEG recordings in 17 (89.5%) patients. Almost all patients (94.7%) had taken antiseizure medication (ASM) in the past year. Of these, ten patients (52.6%) were on two or more ASMs; this decreased to 2 patients (10.5%) at follow-up. All metabolic patterns gradually improved over time, and 18 (94.7%) patients achieved seizure freedom.Conclusions:
These findings reveal that 18 FDG-PET/CT is a remarkable diagnostic and monitoring tool for patients with seizures or epilepsy secondary to anti-NMDA receptor encephalitis, as it helps identify distinct metabolic patterns in the brain. Hypometabolism at baseline is the most common finding, associated with the resolution of cerebral metabolic changes and improvement in seizure freedom.
Funding:
The authors reported that there is no funding associated with the abstract.