Abstract
Objectives: To investigate clinical and electroencephalographic features of the seizures in different types of neuronal surface antibody (NSAb)-associated autoimmune encephalitis (AE).Methods: The clinical data of the seizures were analyzed in 18 patients with NSAb-associated AEs diagnosed in the First Affiliated Hospital of Dalian Medical University.Results: From May 2013 to April 2019, a total of 18 cases of NSAb-associated AE were diagnosed, including 9 cases of leucine-rich glioma-inactivated 1 protein (LGI1) antibody-associated encephalitis, 7 cases of anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis, and 2 cases of anti-γ-aminobutyric acid B receptor (GABABR) encephalitis. All nine cases (100%) with LGI1 AE had seizures manifesting in three types: faciobranchial dystonia seizure (FBDS) (44.4%), mesial temporal lobe epilepsy (MTLE)-like seizure (66.7%), and focal to bilateral tonic–clonic seizure (FBTCS) (77.8%). Six of nine (66.7%) showed abnormal signal on hippocampus or basal ganglia in brain MRI. Five of seven cases (71%) with anti-NMDAR encephalitis had seizures manifesting in three types: focal aware seizure (40%), focal-impaired awareness seizure (20%), generalized tonic–clonic seizure (GTCS) (100%), and status epilepticus (SE) (40%). Three of seven (42.8%) showed abnormalities in brain MRI. Both patients with anti-GABABR encephalitis had seizures manifesting in two types: GTCS and MTLE-like seizure, one with SE. One showed abnormal signal on left hippocampus in brain MRI. All patients (100%) with three types of AE had abnormalities in electroencephalogram (EEG), showing diffuse (4/18) or focal slow waves (14/18) in background, interictal (10/18), or ictal (6/18) epileptic discharges in the temporal or other regions; two patients with anti-NMDAR encephalitis showed delta activity or rhythm in frontotemporal region. All patients with seizures showed good response to immunotherapy except one with LGI1 AE.Conclusions: Most patients with NSAb-associated AE had seizures; seizure types varied between different types of AE. In LGI1 AE, the hippocampus and basal ganglia were two main targets; the corresponding seizure type was MTLE-like seizure and FBDS, respectively. Anti-NMDAR encephalitis had more generalized than focal seizures. Delta activity or rhythm in the frontotemporal region in EEG was helpful for diagnosis. Anti-GABABR encephalitis was characterized by refractory seizures as initial symptom, mainly GTCS or MTLE-like seizure. Most seizures in NSAb-associated AE showed good response to immunotherapy, and antiepileptic drugs should be considered as an add-on symptomatic treatment.
Highlights
Autoimmune encephalitis (AE) is a new category of encephalitis mediated by autoimmune mechanisms [1]
From May 2013 to April 2019, a total of 18 cases of NSAbassociated AEs were diagnosed in our hospital, including 9 cases of leucine-rich gliomainactivated 1 protein (LGI1) AE, 7 cases of anti-NMDAR encephalitis, and 2 cases of anti-GABABR encephalitis
The seizures manifested in three types: faciobranchial dystonia seizure (FBDS) in four patients (44.4%), mesial temporal lobe epilepsy (MTLE)-like seizure in six patients (66.7%), and focal to bilateral tonic–clonic seizures (FBTCS) in seven patients (77.8%)
Summary
Autoimmune encephalitis (AE) is a new category of encephalitis mediated by autoimmune mechanisms [1]. According to different antigens targeted by immune responses, autoimmune encephalitis can be divided into the following types: intraneuronal antibody-associated AE (paraneoplastic limbic encephalitis), neuronal surface antibody (NSAb)associated AE, intracellular synaptic protein antibody-associated encephalitis, which is between the two types mentioned above such as glutamate decarboxylase (GAD) antibody-associated encephalitis, and other autoimmune encephalitis without definite antigens such as acute disseminated encephalomyelitis (ADEM) [2, 3]. Compared with paraneoplastic limbic encephalitis, NSAb-associated encephalitis is a novel category of autoimmune encephalitis with antibodies targeting neuronal surface antigens (such as ion channels, receptors, proteins, etc.), mediating relatively reversible neuronal dysfunction mainly through humoral immune mechanism, and the effect of immunotherapy is good. The paraneoplastic limbic encephalitis, whose antibodies are against intraneuronal antigen, can lead to irreversible neuronal damage through T-cell-mediated immune response, and the effect of immunotherapy is poor [2, 3].
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