OBJECTIVE: Autoimmune encephalitis arising from autoantibodies against leucine-rich glioma-inactivated protein 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) are rare and with high clinical heterogeneity. They are easily misdiagnosed and missing diagnosed. This study aims to explore the clinical characteristics, auxiliary examinations, therapies and prognosis of anti-LGI1 and anti-CASPR2 encephalitis.
METHODS: Seventeen anti-LGI1 and 11 anti-CASPR2 encephalitis patients who were admitted to the Department of Neurology, Xiangya Hospital, Central South University between January 2018 and January 2021 were collected and retrospectively analyzed. Autoimmune encephalitis related antibodies and paraneoplastic antibodies were screened in all patients. The clinical manifestations, results of laboratory tests, imaging features, treatments and outcomes of 2 encephalitis groups were analyzed and compared.
RESULTS: In the anti-LGI1 encephalitis group, the age of 17 patients was 28-83 (53.18±19.08) years old, and the ratio of male to female was 9꞉8. There were 10 patients with cognitive impairment, 7 seizures, 4 faciobrachial dystonic seizures, and 1 psychiatric disturbance. Hyponatremia was observed in 7 patients. Eight patients had increased slow waves and 5 had epileptic discharge in electroencephalogram (EEG). Brain magnetic resonance (MRI) showed T2-weighted imaging (T2WI) and fluid attenuated inversion recovery (FLAIR) hyperintense signal in the temporal lobe, hippocampus and basal ganglia in 13 patients. In the anti-CASPR2 group, the age of 11 patients was 17-68 (47.18±16.20) years old, and the ratio of male to female was 5꞉6, with 7 limbic encephalitis, 1 Morvan syndrome, and 3 acquired neuromyotonia (NMT). Three patients had increased slow waves and 2 had epileptic discharge in EEG. Brain MRI showed T2WI and FLAIR hyperintense signal in the temporal lobe, hippocampus in 2 patients. Steroids, intravenous immunoglobin, and plasma exchange were administrated in 16 anti-LGI1 encephalitis and 8 anti-CASPR2 encephalitis patients with good therapeutic responses. Among them, 1 patient with anti-LGI1 encephalitis and 3 with anti-CASPR2 encephalitis were administrated with mycophenolate mofetil for immune maintenance therapy. No recurrences were observed in all patients with immunotherapy except for 2 patients who lost of follow-up. There were significant differences in cognitive impairment, hyponatremia, and brain MRI abnormalities between anti-LGI1 and anti-CASPR2 encephalitis patients (all P<0.05).
CONCLUSIONS: Limbic encephalitis is a common syndrome in both anti-LGI1 and anti-CASPR2 encephalitis patients. Anti-CASPR2 encephalitis has a wider clinical spectrum than anti-LGI1 encephalitis, presenting as NMT and Morvan syndrome, which has a closer relationship with tumors. Both of these 2 antibodies associated disorders are sensitive to immunotherapy and have a good prognosis.
目的: 抗富亮氨酸胶质瘤失活蛋白1(leucine-rich glioma-inactivated protein 1，LGI1)抗体、抗接触蛋白相关蛋白2(contactin-associated protein-like 2，CASPR2)抗体引起的自身免疫性脑炎较为罕见，临床异质性大，极易漏诊、误诊。本研究旨在总结抗LGI1抗体及抗CASPR2抗体脑炎患者的临床特征。方法: 收集2018年1月至2021年1月中南大学湘雅医院神经内科收治的抗LGI1抗体、抗CASPR2抗体脑炎患者共28例，所有患者进行自身免疫性脑炎相关抗体谱及副肿瘤抗原谱抗体筛查。回顾性分析28例患者的临床表现、辅助检查资料、治疗及随访情况，采用改良Rankin量表评估患者治疗前后的生活能力，并对这2种自身免疫性脑炎的临床特征进行比较和分析。结果: 28例中抗LGI1抗体脑炎17例，发病年龄28~83(53.18±19.08)岁，男女患者之比为9꞉8。临床表现为认知功能障碍的患者有10例，癫痫发作7例，面臂肌张力障碍发作4例，精神行为异常1例。实验室检查发现低钠血症7例；脑脊液检查异常4例，表现为白细胞数或蛋白质含量轻度上升各2例；脑电图异常13例，主要表现为慢波增多(8/13)及痫性放电(5/13)；颅脑磁共振成像(magnetic resonance imaging，MRI)异常13例，主要表现为颞叶、海马及基底节区T2加权成像(T2-weighted imaging，T2WI)及水抑制反转恢复序列(fluid attenuated inversion recovery，FLAIR)呈高信号。抗CASPR2抗体脑炎患者11例，发病年龄17~68(47.18±16.20)岁，男女患者之比为5꞉6。7例为边缘性脑炎，1例为莫旺综合征，3例为获得性神经性肌强直；临床表现为癫痫发作者4例，精神行为异常、认知障碍和意识障碍各1例；脑脊液异常3例，主要表现为白细胞数及蛋白质含量轻度升高；脑电图异常5例，主要表现为慢波增多(3/5)及痫性放电(2/5)；颅脑MRI异常2例，主要表现为颞叶、海马T2WI及FLAIR高信号。16例抗LGI1抗体脑炎及8例抗CASPR2抗体脑炎患者使用糖皮质激素、免疫球蛋白及血浆置换等一线免疫治疗，均反应良好，其中1例抗LGI1抗体脑炎及3例抗CASPR2抗体脑炎患者同时口服吗替麦考酚酯维持治疗；采用免疫治疗的患者除2例失访外，随访期内(6~36个月)均未见明显复发。2种抗体脑炎在认知障碍、低钠血症、颅脑MRI异常上差异均有统计学意义(均P<0.05)。结论: 抗LGI1抗体及抗CASPR2抗体脑炎均可表现为边缘性脑炎，抗LGI1抗体脑炎以认知障碍为主要表现，面臂肌张力障碍发作及低钠血症为特征性表现，易出现颅脑MRI异常；抗CASPR2抗体脑炎以癫痫发作为最常见临床表现，可累及周围神经系统而出现神经性肌强直、莫旺综合征且易合并肿瘤。2种抗体脑炎均对免疫治疗敏感，预后良好。.

BACKGROUND: Morvan syndrome (MoS) is a rare autoimmune syndrome associated with antibodies against two kinds of potassium channel proteins, contactin associated protein-like 2 (CASPR2) and leucine-rich glioma inactivated protein 1 (LGI1). MoS patients with only LGI1-antibody seropositivity have rarely been reported. Here, we describe a 64-year-old male MoS patient with only LGI1-antibody seropositivity.
METHODS: A 64-year-old male patient was referred to our hospital due to limb pain, widespread myokymia, insomnia, constipation, and hyperhidrosis for 1 month. The patient was diagnosed with MoS based on the clinical symptoms and positive LGI1-antibody in serum. He was treated with intravenous immunoglobulin (IVIG), intravenous methylprednisolone followed by oral prednisone, and other drugs for symptomatic relief. Several days later, myokymia and insomnia symptoms improved. After 60 days of follow-up, all the drugs had been stopped for 2 weeks, and the patient achieved complete remission without any medical side effects.
CONCLUSIONS: We report the clinical characteristics of a Chinese MoS patient with only LGI1-antibody seropositivity, and further support the view that non-neoplasm MoS patients respond well to immunotherapy.

To analyze the clinical characteristics and outcomes of patients diagnosed with acquired neuromyotonia and who were treated with tacrolimus.
A single center, retrospective study was performed on patients with acquired meuromyotonia whose treatment included tacrolimus. The clinical information, antibody tests, and electromyography results were reviewed. The Numeric Rating Scale for pain and modified Rankin scale were used to quantify outcomes.
This study included four patients who presented with fasciculation or myokymia in their limbs. Electromyography suggested peripheral nerve hyperexcitability. Autoantibodies including contactin-associated protein 2 (CASPR2), leucine-rich glioma inactivated protein 1 (LGl1) or IgLON5 antibody were detected in three patients, and another patient had Sjogren\'s syndrome. Initial treatment included membrane-stabilizing drugs and/or corticosteroids. Tacrolimus was administered at a dose of 3 mg once daily to all patients. All patients showed clinical improvement after the treatment. No recurrence was observed after gradual tapering or discontinuation of therapy during follow-up.
Tacrolimus may be a therapeutic option for acquired neuromyotonia. Further studies on tacrolimus in larger patient cohort should be performed.

Autosomal recessive axonal neuropathy with neuromyotonia (ARAN-NM) is a rare form of hereditary neuropathy. Mutations in HINT1 gene have been identified to be the cause of this disorder. We report two unrelated patients who presented gait impairment, progressive distal muscle weakness and atrophy, neuromyotonia and foot deformities. Electrophysiological studies showed axonal motor neuropathy and neuromyotonic discharges. Using Next-generation sequencing, we identified two homozygous mutations, NM_005340.6: c.112T > C; p.(Cys38Arg) and NM_005340.6: c.289G > A; p.(Val97Met) in HINT1 gene. Based on the clinical presentation and molecular genetic analyses, ARAN-NM was diagnosed in both patients and NM_005340.6: c.112T > C; p.(Cys38Arg) and NM_005340.6: c.289G > A; p.(Val97Met) in HINT1 gene were believe to be causative for the disorder.

Autosomal recessive axonal neuropathy with neuromyotonia (ARANNM) is a rare disease caused by mutations of histidine triad nucleotide binding protein 1 (HINT1) gene. ARANNM has been reported mainly in European countries but little reported so far in China. We describe novel mutations of HINT1 in three Chinese patients with ARANNM from unrelated families. Patient 1 was a 14-year-old girl who presented with progressive distal weakness of upper limbs at two years of age. After that, she reported weakness of both feet, and difficulty in muscle relaxation after making a fist. Patient 2 was an 18-year-old boy, who presented with progressive distal weakness of all limbs with foot drop at the age of ten with loss of ambulation at age 15. Patient 3 was a 26-year-old man who had been afflicted with weakness and atrophy of distal lower limbs since the age of 16 complaining about muscle stiffness of the lower limbs when standing and walking, and contraction of finger flexion muscles when releasing a forced grip. Electrodiagnostic testing revealed an axonal motor or sensorimotor neuropathy with or without myokymic discharges. Sural biopsy showed no pathological changes in patient 1 and mild axonal neuropathies with demyelination in patients 2 and 3. Genetic analysis revealed HINT1 with novel compound heterozygous c.112T > C (p.C38R) and c.171G > C (p.K57N) mutations in patient 1, homozygous c.112T > C (p.C38R) mutation in patient 2, as well as compound heterozygous c.112T > C (p.C38R) and c.98T > C (p.F33S) mutations in patient 3. Our study, for the first time, confirms ARANNM in the Chinese population. These genetic findings can help expand the genotypic spectrum of HINT1 mutations.

Primary Sjögren\'s syndrome (PSS) is a systemic autoimmune disorder characterized by chronic inflammation of exocrine glands such as the lachrymal and salivary glands, leading to xerophthalmia and xerostomia. Neurological manifestations are sometimes found in patients with PSS. A variety of neurological complications has been reported in patients with PSS, and both the central nervous system (CNS) and peripheral nervous system (PNS) can be involved in PSS. Several forms of neuropathy, including polyneuropathy, cranial neuropathy, and multiple mononeuropathy, are often seen in PSS patients. Herein, we report for the first time typical neuromyotonia (NMT) symptoms appearing in a patient with PSS. Neuromyotonia is a rare disorder caused by the hyperexcitability of peripheral nerves, causing spontaneous and continuous muscle contraction. We provide an overview of the literature relating to neurological involvement in PSS, and the etiology of acquired NMT. We also discuss the existence of contactin-associated protein-like 2 (Caspr2) antibodies in NMT patients.