Clinical Characteristics of Cognitive Impairment and 1-Year Outcome in Patients With Anti-LGI1 Antibody Encephalitis

Abstract

Introduction: Anti-leucine-rich glioma-inactivated 1 antibody (anti-LGI1) encephalitis is one of the most common autoimmune encephalitis. Anti-LGI1 encephalitis presented with subacute or acute onset of cognitive impairment, psychiatric disturbances, faciobrachial dystonic seizures (FBDSs), convulsions, and hyponatremia. The common sequela of anti-LGI1 encephalitis is cognitive disorder, but there are few studies on the recovery of cognitive function after immunotherapy. This study aimed to explore clinical characteristics of cognitive impairment and 1-year outcome in patients with anti-LGI1 encephalitis. Methods: The clinical data and characteristics of cognitive impairment of 21 patients with anti-LGI1 encephalitis from 2016 to 2019 in Nanjing Brain Hospital were analyzed retrospectively. At the time of onset of hospitalization and 1 year after discharge, the cognitive functions in these patients were assessed using two cognitive screening scales-Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment-Basic (MoCA-B). Results: Among the 21 patients, 13 were male and 8 were female, aged 51.10 ± 14.69 (age range 20-72) years. Nineteen patients, comprising 90.48%, had recent memory deterioration. Routine electroencephalography (EEG) results of 13 cases were abnormal. EEG results were epileptic or slow-wave activity involving the temporal lobes. Eleven cases of brain MRI were abnormal, and the focus involved the hippocampus and mediotemporal lobe. The decrease of short-term memory [recall scores: 0.57 ± 0.81 (MMSE), 0.76 ± 1.34 (MoCA-B)] is the most obvious at the time of admission. After intravenous (IV) injection of methylprednisolone and/or immunoglobulin, the clinical symptoms of the patients improved obviously. Total MMSE and MoCA-B scores of patients were significant increased after 1 year (21.19 ± 3.54 vs. 26.10 ± 3.02, P < 0.001; and 19.00 ± 4.38 vs. 25.19 ± 4.25, P < 0.001, respectively). Recall scores and orientation scores of MoCA-B were significantly improved after 1 year (0.76 ± 1.34 vs. 3.24 ± 1.48, P < 0.001; and 3.10 ± 1.26 vs. 5.00 ± 1.22, P < 0.001, respectively). However, 3/21 (14.29%) patients still have obvious short-term memory impairment (recall scores ≤ 1). Conclusion: Cognitive impairment is one of the most common manifestations of anti-LGI1 encephalitis, with the main prominent being acute or subacute short-term memory loss. Although most patients with anti-LGI1 encephalitis respond well to immunotherapy, a small number of patients still have cognitive disorders, mainly recent memory impairment, after 1 year.

Keywords: anti-LGI1 encephalitis; cognitive outcomes; mini-mental state examination; montreal cognitive assessment-basic; short-term memory impairment.

Figure 1

Brain MRI (A) showed lesions in the left hippocampus. Brain Magnetic resonance spectrum (MRS) showed a bit increased slightly elevated Choline compound (Cho) and Cho/Cr peak, the moderately decreased the N-acetyl aspartic acid (NAA) and NAA/Creatine (Cr) peak (B) in the left hippocampus.

Figure 2

Brain MRI (A) showed abnormal signal in right temporal and insular lobe, thalamus. On T2WI (B) and T2Flair (C) sequences, the right temporal and insular lobe, right thalamus showed slightly higher abnormal signal, the local cortex was slightly swollen, and on the DWI sequences, slightly higher signal was seen. On T2Flair sequence (C), there was high abnormal signal in the right hippocampus and no obvious abnormal signal in the left hippocampus. Arterial spin labeling (ASL) sequence (D) showed significant hyperperfusion in the right temporal and insular lobe, thalamus.

Figure 3

Total scores of MMSE (A) and MoCA-B (B) of different patients. We separately list the different patient with total scores of MMSE and MoCA-B at the time of hospitalization and 1 year after discharge. (A) Show the distribution of the MMSE scores for the 21 cases. (B) Show the distribution of the MoCA-B scores for the 21 cases. No moderate to severe cognitive impairment (MMSE ≤ 20) was determined at 1 year (A). MMSE, Mini-Mental State Examination; MoCA-B, Montreal Cognitive Assessment-Basic.

Figure 4

Distribution of patients by short-term memory (recall) score. We separately list the distribution of patients with different recall scores of MMSE (A) and MoCA-B (B). The MMSE recall items of 12 (57.14%) patients at the time of onset were scored 0 points, while only 2 patient after 1 year were scored 0 points. Only 1 patient had a normal recall of 3 points during the onset, and 9 patients got 3 points in this item after 1 year. MMSE, Mini-Mental State Examination; MoCA-B, Montreal Cognitive Assessment-Basic; **P < 0.01.