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Advanced Neurology The diagnosis and treatment of anti-LGI1 autoimmune encephalitis

C*07:06 HLA I alleles in patients with anti-LGI1 AE, study conducted by Thompson et al. , FBDS ceased in
[31]
suggesting that the pathogenesis of this disease may also be only 10% of anti-LGI1 AE patients who took AEDs alone;
related to HLA I genes . A French study that performed in contrast, the cessation of FBDS was observed 30 days
[24]
HLA genotyping in patients with anti-LGI1 AE has after immunotherapy in 51% of patients and even earlier
[27]
found that 88% of patients carried DRB1*07:01, with in cognitively normal patients. The current findings on the
noncarriers being more likely to be young women and less origin of FBDS and whether it should be regarded as an
likely to have psychiatric symptoms. It may be that estrogen epileptic seizure are controversial . Some scholars call
[40]
can alter the expression of HLA . However, the only study it a seizure-like episode . In a study, Liu et al. divided
[28]
[42]
[41]
in the Chinese Han population has shown no evidence of LGI1 AE patients into two groups, the FBDS group and
association between DRB1*07:01~DQB1*02:02 haplotypes the non-FBDS group. F-fluorodeoxyglucose position
18
and this disease . These inconsistent results may be emission tomography ( F-FDG-PET) results showed that
[21]
18
due to the fact that the study populations are of different basal ganglia (BG) hypermetabolism was detected in seven
races; thus, it is speculated that genetic factors may play patients (44%) in the FBDS group but in only one patient
an important role in the etiology of this disease. Future (7%) in the non-FBDS group. It has been hypothesized that
studies with larger samples and more races are needed to BG abnormalities may be involved in the etiology of FBDS
verify this hypothesis. and LGI1-associated FBDS is more likely a dyskinesia
In recent years, several literatures have reported that rather than an epileptic disease. However, in another study
[43]
anti-LGI1 AE may be a rare complication of coronavirus by Liu et al. , anti-LGI1 AE patients initially presented
disease (COVID-19) vaccination [29,30] , with a strict time with FBDS, followed by classic limbic epilepsy or ipsilateral
relationship between the onset and vaccination (about tonic-clonic seizures (TCS), and electroencephalogram
2 weeks from vaccination to disease onset). Molecular (EEG) recorded changes in cortical potentials. These
mimicry and immune cross reaction may be involved in specific, stereotyped clinical presentations and EEG
its pathogenesis. Asioli et al. have reported four patients changes reflected both cortical and subcortical network
who developed anti-LGI1 AE after receiving two different involvement rather than a single site. They therefore
messenger ribonucleic acid (mRNA) vaccines, with one speculated that FBDS is more likely to be a part of epileptic
patient vaccinated with a viral vector vaccine. However, motor events.
since there are too few reported cases of vaccination-
related anti-LGI1 AE, it is not possible to determine 3.2. Cognitive disorders
whether the cause of the disease is related to specific types The majority of patients have rapidly progressive memory
of COVID-19 vaccines. impairment, short-term memory loss, and impaired
orientation. Other clinical manifestations include language
3. Clinical manifestations ability deficits, impaired executive function, impaired
[44]
Most patients have an acute or subacute onset, with visuospatial ability, and calculation disturbance . Brain
the most prominent manifestation being FBDS. Other magnetic resonance imaging (MRI) examination shows
manifestations include cognitive disorders (mainly recent that the hippocampus, temporal lobe, and basal ganglia
memory loss), hyponatremia, hyperkinetic movements are the main lesion sites [37,45,46-49] . At present, it is believed
(HMs), psychiatric disorders, as well as mood and sleep that inflammation in the acute phase is associated with
disorders. atrophy in the recovery stage, which may be the cause
of persistent cognitive impairment in patients with anti-
3.1. Faciobrachial dystonic seizure (FBDS) LGI1 AE. Studies by Thompson et al. have shown
[31]
FBDS is highly specific, with a positive rate of that patients with both cognitive impairment and FBDS
approximately 20 – 40% [31,32] . It often occurs as the initial have more abnormal examination results than patients
symptom of anti-LGI1 AE [31,33] . FBDS is a frequent and with FBDS alone. Abnormal findings of brain MRI
transient involuntary movement like dystonia, which and electroencephalogram and hyponatremia were
often involves unilateral upper limbs, face, and even lower almost exclusively observed in patients with cognitive
extremities. Its attacks are usually short, lasting only few impairment. There is evidence that cognitive impairment
[31]
seconds, but the frequency of attacks may reach dozens of can be prevented by early termination of FBDS .
times a day . Traumatic falls may occur when it manifests 3.3. Hyponatremia
[1]
as FBDS of the lower limbs. The results of previous studies
have indicated that antiepileptic drugs (AEDs) alone are Hyponatremia is another prominent feature of anti-LGI1
ineffective for FBDS, but the use of immunotherapy can AE. As shown in the previous studies, 60% of patients
significantly reduce or even eliminate FBDS [32,34-39] . In a developed hyponatremia after early treatment of the

Volume 1 Issue 3 (2022) 3 https://doi.org/10.36922/an.v1i3.237