Abstracts

Rationale: Anti-GABA-B receptor encephalitis is a rare and potentially life-threatening autoimmune disorder characterized by severe neurological symptoms, most commonly seizures and cognitive dysfunction. It often presents a diagnostic challenge due to its nonspecific initial symptoms and the potential for association with malignancies, particularly small-cell lung cancer. (1)This case emphasizes the importance of recognizing anti-GABA-B receptor encephalitis as a differential diagnosis in patients presenting with new-onset refractory seizures and altered mental status. It also underscores a multimodal treatment strategy including a combination of anti-inflammatory and antiseizure medication. The patient's significant recovery highlights the effectiveness of this approach and provides a practical framework for managing similar cases.

(1) Lancaster E, Lai M, Peng X, et al. Antibodies to the GABAB receptor in limbic encephalitis with seizures: case series and characterization of the antigen. Lancet Neurol. 2010;9(1):67-76




Methods: A 51-year-old female with a history of new-onset generalized tonic-clonic seizures on levetiracetam presented with slurred speech and confusion. Given the patient's acute onset of altered mental status, she was placed on electroencephalogram (EEG) monitoring. The EEG revealed independent left and right temporal/frontotemporal interictal epileptiform discharges and bihemispheric electrographic seizures. Intermixed theta and delta activity indicated a mild to moderate bilateral disturbance of cerebral function, consistent with encephalopathy of nonspecific etiology. Seizures were controlled with multiple antiseizure medications, including levetiracetam, lacosamide, and valproic acid. An MRI of the brain with and without contrast showed no acute intracranial abnormalities. High-dose intravenous methylprednisolone, followed by a tapering regimen and plasmapheresis, was administered due to the suspected autoimmune etiology. CT scans of the head, chest, abdomen, and pelvis with and without contrast revealed no primary neoplasm. A whole-body PET CT scan was performed to evaluate for occult malignancy, which showed no FDG avid malignancy. Extensive workup during hospitalization revealed positive anti-GABA-B antibodies in the cerebrospinal fluid.


Results: Follow-up visits demonstrated significant cognitive recovery, as evidenced by improved Kokmen scores. Within seven months, the patient reported a return to her normal baseline, with no breakthrough seizures.


Conclusions: This case highlights the importance of early diagnosis and a multidisciplinary approach in managing anti-GABA-B receptor encephalitis with refractory seizures. The patient's significant recovery and sustained seizure-free status demonstrate the efficacy of combining immunotherapy and antiseizure medications. Regular follow-up are crucial, especially given the finding that the maximum interval from encephalitis diagnosis to the discovery of a tumor was 28 months in a cohort. (2)


(2)Sun T, Zhao D, Zhang G, et al. Late-Onset Anti-GABAB Receptor Encephalitis:Clinical Characteristics and Outcomes Differing From Early-Onset Patients. Neurol Neuroimmunol Neuroinflamm. 2023 May 25;10(4):e200131.


Funding: n/a