Anti-Alpha-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic Acid Receptor Encephalitis: A Review

Abstract

Anti-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) encephalitis, a rare subtype of autoimmune encephalitis, was first reported by Lai et al. The AMPAR antibodies target against extracellular epitopes of the GluA1 or GluA2 subunits of the receptor. AMPARs are expressed throughout the central nervous system, especially in the hippocampus and other limbic regions. Anti-AMPAR encephalitis was more common in middle-aged women and most patients had an acute or subacute onset. Limbic encephalitis, a classic syndrome of anti-AMPAR encephalitis, was clinically characterized by a subacute disturbance of short-term memory loss, confusion, abnormal behavior and seizure. Magnetic resonance imaging often showed T2/fluid-attenuated inversion-recovery hyperintensities in the bilateral medial temporal lobe. For suspected patients, paired serum and cerebrospinal fluid (CSF) testing with cell-based assay were recommended. CSF specimen was preferred given its higher sensitivity. Most patients with anti-AMPAR encephalitis were complicated with tumors, such as thymoma, small cell lung cancer, breast cancer, and ovarian cancer. First-line treatments included high-dose steroids, intravenous immunoglobulin and plasma exchange. Second-line treatments, including rituximab and cyclophosphamide, can be initiated in patients who were non-reactive to first-line treatment. Most patients with anti-AMPAR encephalitis showed a partial neurologic response to immunotherapy.

Autoimmune Encephalitis With Multiple Auto-Antibodies With Concomitant Human Herpesvirus-7 and Ovarian Teratoma: A Case Report

“…Serology and qPCR of HHV-7 in CSF and serum were not detected due to the limited amount of samples retained. The carrier frequency of HLA class II allele DRB1 * 16:02 was not detected in this paper either, which was reportedly associated with anti-NMDAR encephalitis (19).…”

“…Ovarian teratoma was found using cancer screening. Patients with co-existing anti-NMDAR antibody and neuronal surface antibody have a worse outcome than those with only anti-NMDAR antibody ( 19 ). Thus, early use of second-line immunotherapies is worth considering for these patients ( 18 ).…”

Thymoma‐associated autoimmune encephalitis: Analysis of factors determining prognosis

“…In this review, AMPAR was the most common antibody, mediating most of the rapid excitatory neurotransmission in the brain 24 and is often associated with tumors. 69 A review published last year 70 found that patients with thymoma accounted for the largest proportion of patients with tumor who were also positive for AMPAR antibodies, suggesting that patients presenting with these antibodies should be routinely screened for thymus CT. The second antibody in this article is the anti‐VGKC.…”

Paraneoplastic Neurologic Syndromes

“…Most patients with AMPA-associated encephalitis experience at least partial improvement with tumor-directed treatment and immunotherapy, but only 30% of patients have been reported to return to their prior baseline. 32 Ma1-Associated and Ma2-Associated Encephalitis Temporal lobe epilepsy with psychiatric changes is very common in anti-Ma antibody disorders, and seizures can be refractory. Testicular germ cell tumors are found in a high percentage of patients, and ultrasound can be more beneficial than standard CT in detecting occult tumors.…”