Clinical characteristics and prognosis of anti-alpha-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic acid receptor encephalitis

Abstract

Background Encephalitis associated with antibodies against alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) is an extremely rare type of antibody-mediated encephalitis. This research aims to investigate the clinical characteristics and prognosis of anti-AMPAR encephalitis. Methods This retrospective study enrolled nine patients with anti-AMPAR encephalitis. Demographic information, clinical manifestations, laboratory and radiological findings, treatment and response were collected and analyzed. These patients were followed up with an average period of 72 weeks to gather prognostic information. Results Nine patients (7 females and 2 males) were enrolled with a mean age at disease onset of 59 years old. Three clinical pictures, including limbic encephalitis (n = 7; 78%), pure amnesia (n = 1; 11%) and fulminant encephalitis (n = 1; 11%) were identified. New symptoms of dysphagia and deafness were identified in the clinical spectrum of anti-AMPAR encephalitis. All patients had positive blood AMPAR antibodies, and six of them (67%) had paired positive antibodies in cerebrospinal fluid (CSF). Brain magnetic resonance imaging (MRI) was abnormal in 75% of the patients with no specific patterns recognized. Six patients (67%) had tumors, including lung cancers and thymomas. After immunotherapy and oncotherapy, partial improvement of neurological symptoms was observed among all 6 patients with available records during their hospitalization. After a mean follow-up of 72 weeks, 3 patients had marked decrease of modified Rankin Scale (mRS) score, 1 patient had unchanged mRS score, 4 patients died and the other one was lost. Conclusions Anti-AMPAR encephalitis mainly presents as limbic encephalitis, and is paraneoplastic in 67% of cases. Thus, intensive screening for tumors is recommended for all anti-AMPAR patients. Although patients showed a good short-term therapeutic response, the overall prognosis was not satisfactory.

Anti-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor encephalitis developed after ovarian cancer cytoreduction surgery: a case report and literature review

“…AMPAR antibody titers in the serum or CSF were reported in 14 patients (Table 2 ). Notably, the CSF titer of several patients was negative; thus, acquiring paired serum and CSF samples of patients suspected of anti-AMPAR encephalitis is essential [ 16 , 17 ]. The AMPAR antibody would decrease after immunotherapy [ 3 , 18 – 20 ].…”

Paraneoplastic Neurological Syndromes of the Central Nervous System: Pathophysiology, Diagnosis, and Treatment

“…These patients tend to be older than those with non-paraneoplastic anti-GABA B R encephalitis, and may be more likely to present with a "classic limbic syndrome" rather than with OMS or other atypical symptoms. Anti-AMPAR encephalitis presents similarly, with most developing limbic encephalitis and some with clinical or radiological evidence of more widespread cerebral involvement [106]. Like anti-GABA B R encephalitis, the majority of cases are paraneoplastic, and most cases are associated with SCLC.…”

Autoimmune Encephalitis in a Patient with a Solitary Intracranial Plasmacytoma

“…Malignancies can cause several types of neurological syndromes, such as limbic encephalitis, encephalomyelitis, and rapidly progressive cerebellar syndrome (4). Small-cell lung cancer (SCLC) is most often associated with autoimmune encephalitis, but many other neoplasms such as breast cancer, thymoma, ovarian teratoma, and Hodgkin's lymphoma have been identified (1,(5)(6)(7)(8). Malignancy-induced autoimmune encephalitis is associated with onconeural autoantibodies against intracellular antigens (anti-Hu, anti-Ma1, anti-CV2) and cell membrane antigens [anti-N-methyl-Daspartate receptor (NMDAR), anti-α-amino-3-hydroxy-5methyl-4-isoxazole-propionic acid receptor (AMPAR), anti- Although hematological cancers such as lymphoma are known to cause paraneoplastic limbic encephalitis, plasma cell neoplasms co-occurring with autoimmune encephalitis have not been reported (9).…”