Comparative Study Non-paraneoplastic Autoimmune Encephalitis Associated with Gabaa and Gabab Receptor Antibody: A Single Center Experience and Focused Literature Review
Abstract number :
3.494
Submission category :
4. Clinical Epilepsy / 4B. Clinical Diagnosis
Year :
2024
Submission ID :
1557
Source :
www.aesnet.org
Presentation date :
12/9/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Lingxuan Li, Medical Student – Touro University California
Ning Zhong, MD, PhD – Kaiser Permanente Sacramento Medical Center
Rationale: Autoimmune encephalitis (AE) comprises a group of disorders when the immune system mistakenly attacks the brain, leading to inflammation and neurological dysfunction. Among AEs, anti-gamma aminobutyric acid (GABA) receptor AE, which targets either GABA-A or GABA-B receptors, is relatively rare. Over the past decade, it has gained increasing attention due to its unique clinical features, diagnostic challenges, and distinct therapeutic responses, which differ from the more commonly seen NMDAR or LGI1 AE. Unlike NMDAR or LGI1 AE, GABA receptor AE associated with neoplasms often results in poor outcomes. Therefore, this study focuses on non-neoplastic GABA receptor AE cases, which have potentially reversible pathophysiology and offer a more favorable prognosis.
Methods: This comparative study retrospectively analyzed demographic data, clinical manifestations, laboratory results, brain magnetic resonance imaging (MRI), electroencephalograms (EEG), therapy responses, and treatment outcomes of patients with a confirmed diagnosis of GABA-A or GABA-B receptor AE at our center. A comprehensive literature review was also conducted, summarizing the available published data on reported non-neoplastic GABA-A and GABA-B receptor AE cases. A secondary analysis was performed to further elucidate the key differences between GABA-A and GABA-B receptor AE.
Results: Seizures were the most common initial clinical symptoms in both GABA-A and GABA-B receptor AE cases, with focal impaired awareness seizures and generalized tonic-clonic seizures observed in over 80% of cases. EEG findings were similar across both groups; focal epileptiform discharges, generalized distribution epileptiform features, focal or diffuse slowing were seen in over 60% cases. Some patients (~30%) developed status epilepticus, requiring ICU admission and escalation of anti-seizure medications. Other clinical presentations, such as behavioral/neuropsychiatric disturbances, movement disorders, and metabolic symptoms, showed no significant differences between the two groups. Brain MRI revealed notable distinctions: GABA-A receptor AE typically presented with multifocal cortical and subcortical hyperintensities affecting bilateral hemispheres, especially in the temporal and frontal lobes; whereas GABA-B receptor AE predominantly showed abnormalities in the mesial temporal lobes. Long-term outcomes differed, with 80% of GABA-B receptor AE patients experiencing cognitive impairments, particularly in short-term memory and executive functions, while most GABA-A receptor AE patients showed good recovery. However, the small number of cases of GABAa receptor AE limits definitive conclusions when comparing long-term cognitive outcomes.
Conclusions: Differentiating between GABA-A and GABA-B receptor AE based solely on clinical presentations remains challenging. Brain MRI may provide important clues for distinguishing between these two types of AE. GABA-B receptor AE appears to be associated with more significant long-term neurocognitive deficits which likely correlated with the unique abnormal imaging findings in the limbic system. Such observations underscore the need for early intervention to improve patient quality of life.
Funding: no funding
Clinical Epilepsy