Congenital myasthenic syndrome 22 due to PREPL gene mutation in 2 patients: case report and literature review / 中华实用儿科临床杂志

Clinical data of two patients with congenital myasthenia syndrome type 22 (CMS22) treated at the Children′s Hospital of Fudan University from February 2019 to November 2021 were retrospectively analyzed, and relevant literatures were reviewed.Both patients were female, aged 3 months 18 days and 3 months 26 days, respectively, with typical clinical features of CMS (postnatal onset, skeletal muscle weakness, feeding difficulties, and delayed motor development). Genetic testing revealed that one patient had a homozygous frameshift mutation of the PREPL gene from maternal uniparental disomy c. 1282_1285del(p.F428fs*18), and the other one had a compound heterozygous mutation, including the paternal homozygous frameshift mutation of the PREPL gene and maternal monoallelic nonsense mutation and splicing mutation c. [1501G>T; 2020+ 1G>T], p.[G501*; -]. Two patients were treated with Pyridostigmine bromide at the age of 6 months old and 4 months old, respectively, and the medication last for 15 months and 3 months (still under treatment), respectively.The treatment was effective.Through literature review, 7 English language articles were retrieved, involving 13 cases (2 cases in the presented study were included). The main clinical symptoms of CMS22 included neonatal onset with feeding difficulties and motor development delay, accompanied by cognitive impairment, growth hormone deficiency, and obesity.Genetic testing is favorable to the early diagnosis, early treatment, and symptom relief.

Congenital Myasthenic Syndrome / 罕见病研究

Congenital Myasthenic syndrome (CMS) is a group of partially treatable genetic disorders characterized by dysfunction of neuromuscular junction signaling.With the popularization of high-throughput sequencing and in-depth understanding of the disease in recent years, more than thirty pathogenic genes have been discovered and there is a correlation between genotype and clinical phenotype.Misdiagnosis and missed diagnosis are common in clinical practice. This paper summarized the molecular mechanisms, clinical features, electrophysiologic, pathological features and treatment of main subtypes of CMS to deepen the understanding of the disease.

Clinical, electrophysiological profile and prognosis in paraneoplastic syndrome with SRY-like high-mobility group superfamily of developmental transcription factors 1 antibody / 中华神经科杂志

Objective To summarize the clinical,electrophysiological profile and prognosis in paraneoplastic syndrome with SRY-like high-mobility group superfamily of developmental transcription factors (SOX) 1 antibody.Methods The clinical profile,laboratory examination,electrophysiology,tumor,treatment and prognosis of three patients of paraneoplastic syndrome with SOX1 antibody in Tangdu Hospital,Air Force Military Medical University from 2016 to 2018 were retrospectively analyzed.Results Proximal lower limbs weakness was the first symptom in all the three patients,weakness normally spreading proximally to distally,involving feet and hands,finally reaching the oculobulbar region,and dry mouth was the most common autonomic dysfunction.Compound muscle action potential (CMAP) amplitude was low in all the patients,and the CMAP amplitude became even lower at low stimulating frequencies.An increase in CMAP amplitude with high-frequency stimulation was found in two patients during the follow-up.Lambert-Eaton myasthenic syndrome (LEMS) and motor axonal peripheral neuropathy were considered.Acetylcholine receptors antibody was positive in one case and voltage-gated calcium channel antibody was positive in another case.Two cases were found complicated with small cell lung carcinoma,one case with small cell carcinoma of the esophagus.After treatment of intravenous immunoglobulin,chemotherapy and pyridostigmine,the prognosis of the patients was different.Conclusions SOX1 antibody as an antibody in paraneoplastic syndrome,is most common in small cell lung cancer with LEMS,sometimes with axonal peripheral neuropathy.LEMS needs to be considered when patients manifest proximal limb weakness and dry mouth,and screening for tumors is needed.

Prevalence of mutations responsible for glycogen storage disease type-II and congenital myasthenic syndrome in Brazilian Brahman cattle / Prevalência de mutações responsáveis pela estocagem de glicogênio tipo II e síndrome miastênica congênita em bovinos brasileiros da raça Brahman

Glycogen storage disease type II (GSD-II) and congenital myasthenic syndrome (CMS) are important autosomal recessive disorders in Brahman cattle. The objective of this study was to investigate the presence of mutations responsible for GSD II (E7, c.1057_1058delTA; and E13, c.1783C>T) and CMS (c.470del20) in purebred Brazilian Brahman cattle and in purebred Brahman bulls that were routinely used in breeding programs in Brazil. A total of 276 purebred Brahman cattle (167 females and 109 males, with ages ranging from 12-24 months) and 35 frozen semen samples taken from purebred Brahman bulls (22 bulls from the USA, 11 Brazilian bulls, one Argentine bull and one Australian bull) were used in this study. Genomic DNA was purified from hair root samples and from semen samples. Purified DNA was used in PCR genotyping to mutations c.1057_1058delTA (E7) and c.1783C>T (E13) in the GAA gene and c.470del20 in the CHRNE gene. The PCR products were purified and sequenced. The genotypic frequencies per polymorphism were estimated separately. Of the 276 Brahman cattle tested, 7.3% were identified as heterozygous for E7. All Brahman cattle studied were homozygous for the wild-type E13 allele. The E7 mutations was identified as heterozygous in 8.6% (3/35) of the commercial semen samples, whereas the E13 mutations was not identified. The c.470del20 mutation was identified as heterozygous in 0.73% of the hair root samples, but this mutation was not present in any semen sample assessed. No study had previously evaluated the prevalence of mutations responsible for GSD II or CMS in Brazilian Brahman cattle. In summary, the E7 and c.470del20 mutations are present in the Brazilian Brahman herd, and control measures should be adopted to prevent an increase in the incidence of GSD-II and CMS in Brahman cattle in Brazil.(AU)

A doença de armazenamento de glicogênio tipo II (DAG-II) e a síndrome miastênica congênita (SMC) são importantes doenças autossômicas recessivas no gado Brahman. O objetivo deste estudo foi investigar a presença das mutações responsáveis pela DAG-II (E7, c.1057_1058delTA; e E13, c.1783C>T) e pela SMC (c.470del20) em bovinos da raça Brahman e em touros Brahman que são rotineiramente utilizados em programas de reprodução no Brasil. Um total de 276 amostras de bulbo piloso de bovinos Brahman (167 fêmeas e 109 machos, com idade variando de 12 a 24 meses) e 35 amostras de sêmen congeladas de touros Brahman (22 touros americanos, 11 touros brasileiros, um touro argentino e um touro australiano) foram usados neste estudo. O DNA genômico foi purificado, das amostras de bulbo piloso e de sêmen, e utilizado na genotipagem por PCR das mutações c.1057_1058delTA (E7) e c.1783C>T (E13) no gene GAA e c.470del20 no gene CHRNE. Os produtos de PCR foram purificados e sequenciados. A frequência genotípica para cada polimorfismo foi estimada separadamente. Dos 276 Brahman testados, 7,3% foram identificados como heterozigotos para E7. Todos os Brahman foram homozigotos wild-type para o alelo E13. A mutação E7 foi identificada em homozigose em 8,6% (3/35) das amostras de sêmen comerciais, enquanto que a mutação E13 não foi identificada. A mutação c.470del20 foi identificada em heterozigose em 0,73% das amostras de bulbo piloso, mas esta mutação não estava presente nas amostras de sêmen avaliadas. Nenhum estudo prévio avaliou a prevalência das mutações responsáveis pela DAG-II ou SMC em bovinos Brahman brasileiro. Em suma, as mutações E7 e c.470del20 estão presentes no rebanho Brahman brasileiro, e medidas de controle devem ser adotadas para prevenir o aumento da incidência da DAG-II e SMC em bovinos da raça Brahman no Brasil.(AU)

Lambert-Eaton myasthenic syndrome: the 60th anniversary of Eaton and Lambert's pioneering article / Síndrome miastênica de Lambert-Eaton: o 60° aniversário do artigo pioneiro de Eaton e Lambert

ABSTRACT This historical review describes the contribution of Drs. Lee M. Eaton and Edward H. Lambert to the diagnosis of myasthenic syndrome on the 60th anniversary of their pioneering article (JAMA 1957) on the disease. There are important landmarks in their article on a disorder of the neuromuscular junction associated with thoracic neoplasm and the electrophysiological criteria for Lambert-Eaton myasthenic syndrome (LEMS). After 60 years, the main electrophysiological criteria described in Eaton and Lambert's pioneering article are still currently useful in the diagnosis of LEMS.

RESUMO Essa revisão histórica enfatiza a contribuição do Dr Lee M Eaton e do Dr Edward H. Lambert para o diagnóstico da síndrome miastênica no 60o aniversário do seu artigo pioneiro (JAMA 1957) para essa doença. Existem importantes marcos no artigo de Eaton e Lambert, como uma desordem da junção neuromuscular associada à neoplasia torácica e critério diagnóstico para síndrome miastênica de Lambert-Eaton (LEMS). Após 60 anos, os principais critérios diagnósticos descritos para LEMS no artigo pioneiro de Eaton e Lambert continuam úteis no diagnóstico da LEMS.

Guanosine diphosphate-mannose pyrophosphorylase-B gene mutations causing limb-girdle muscular dystrophy overlapping with congenital myasthenic syndrome / 中华神经科杂志

Objective To report four patients with secondary α-dystroglycanopathy caused by guanosine diphosphate-mannose pyrophosphorylase-B ( GMPPB ) gene mutations and review the literature aiming to analyze the clinical manifestations , muscle image , molecular pathology and genetic characteristics of the disease.Methods The medical history , physical examination , electromyography and other clinical data of four patients with secondary α-dystroglycanopathy from two families were collected and retrospectively reviewed from 2009 to 2017.Case 1 ( proband of pedigree 1) and case 2 ( proband of pedigree 2) were then further analyzed with muscle imaging , muscle pathology and targeted next generation gene sequencing (NGS).Results Four patients came from two families (three from the same pedigree), two males and two females, with an onset age of 17 -18 years.All four cases presented as limb-girdle muscular dystrophy (LGMD) overlapping with congenital myasthenic syndrome (CMS) characterized by evident proximal limb weakness in early adulthood and fluctuating muscle weakness .They all had delayed motor milestone and did not perform well in physical education since childhood . Serum creatine kinase was elevated markedly (1877-5275 U/L).Myogenic changes on electromyography and marked attenuation on three Hz repetitive nerve stimulation were observed in all patients .Muscle MRI showed prominent involvement of bilateral hamstrings in case 1 and case 2.Muscular dystrophic patterns were demonstrated on muscle biopsies . Targeted NGS revealed two compound heterozygous missense mutations in GMPPB for each case .Case 1 carried c.860G>T (p.R287L)/c851T>C (p.V284L).Case 2 and his two affected sisters (case 3 and case 4) carried c.1097A >G ( p.N366S)/c.589G >T ( p.V197F) .All of these mutations were novel variants and pedigree analysis suggested that the two mutations were from parents .Compared with normal controls, immunohistochemistry and Western blotting showed significantly decreased expression of α-dystroglycan in the muscle tissue from case 1 and case 2.The myasthenic symptoms of all four patients were improved to varying degrees after treatment with pyridostigmine bromide . Conclusions Mutations in GMPPB can lead to dysfunction both in muscle and in neuromuscular transmission causing overlapping between LGMD and CMS phenotypes . Cholinesterase inhibitors can partly improve the symptoms of myasthenia in such patients .

Limb Girdle Weakness Responding to Salbutamol: An Indian Family with DOK7 Mutation.

Background: Congenital Myasthenic Syndromes (CMS) are heterogeneous genetic diseases. Case characteristics: Two siblings presented with progressive limb girdle weakness without significant fluctuations or ocular muscle weakness. Repetitive nerve stimulation showed a decremental response and there was no response to pyridostigmine therapy. Outcome: A trial of salbutamol produced a remarkable, consistent improvement. Mutation in exon 5 of the DOK7 gene was found in both siblings. Message: Patients with congenital myasthenic syndrome with DOK 7 mutation benefit remarkably with salbutamol.

A Patient with Coexisting Myasthenia Gravis and Lambert-Eaton Myasthenic Syndrome

BACKGROUND: The coexistence of myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS) is very rare and remains controversial. CASE REPORT: A 48-year-old woman initially presented with noticeable right ptosis and intermittent diplopia. She then developed fluctuating proximal limb weakness and difficulty in swallowing. The serum titer of anti-acetylcholine-receptor antibody was elevated and the edrophonium (Tensilon) test was positive. However, repetitive nerve stimulation revealed abnormalities typical of LEMS. The patient exhibited a good response to treatment with anticholinesterase inhibitors and steroids, and long-term evaluation disclosed that she presented with the clinical, electrophysiological, and immunological characteristics of both diseases. CONCLUSIONS: The reported clinical and electrophysiological features suggest that this patient was a very rare case of combined MG and LEMS.

A Case of Lambert-Eaton Myasthenic Syndrome with Small-Cell Lung Cancer and Transient Increase in Anti-Acetylcholine-Receptor-Binding Antibody Titer

BACKGROUND: Lambert-Eaton myasthenic syndrome (LEMS) is a presynaptic neuromuscular junction disorder that is most frequently associated with small-cell lung cancer (SCLC). The titers of antibodies against voltage-gated calcium channels are frequently increased in LEMS, but only rarely is titer of anti-acetylcholine-receptor-binding antibodies (AChR-abs) increased. CASE REPORT: A 57-year-old male was admitted to our hospital due to dry mouth and eyes and progressive proximal limb weakness of 2 months duration. The results of a repetitive nerve stimulation test disclosed all criteria for the electrophysiological LEMS pattern, and the patient's AChR-abs titer was 0.587 nmol/L. At a follow-up performed 5 years after successful treatment of SCLC and LEMS, his AChR-abs titer had decreased to 0.001 nmol/L. CONCLUSIONS: We suggest that this was a case of transient pseudopositivity of AChR-abs in SCLC with LEMS.

Non-paraneoplastic Lambert-Eaton myasthenic syndrome: a brief review of 10 cases / Síndrome miastênica de Lambert-Eaton não paraneoplásica: uma breve revisão de dez casos

Lambert-Eaton myasthenic syndrome (LEMS) is an immune-mediated disorder of the presynaptic neuromuscular transmission, which more frequently occurs as the remote effect of a neoplasm, in the paraneoplastic form (P-LEMS), or in a non-paraneoplastic form (NP-LEMS); but few studies describe the clinical features of NP-LEMS. We analyzed the clinical manifestations, laboratory findings, electrophysiological studies, and treatment responses in ten Brazilian patients suffering from NP-LEMS. The mean age was 41.5 years. More often neurological findings were hyporeflexia or areflexia with a post-exercise improvement. Treatment response occurred with pyridostigmine, guanidine, prednisone, azathioprine, and cyclosporine; but not response was observed after intravenous immunoglobulin and plasma exchange. Age at onset, clinical manifestations, and electrophysiological abnormalities can help more in the diagnosis than serum antibodies; the symptomatic treatment with pyridostigmine was effective; and the immunosuppressive treatment with prednisone, azathioprine, or cyclosporine was more beneficial than plasma exchange or intravenous immunoglobulin treatment.

A síndrome miastênica de Lambert-Eaton (LEMS) é uma desordem imunomediada da transmissão neuromuscular pré-sinaptica, que mais frequentemente ocorre como efeito à distância de uma neoplasia, na forma paraneoplásica (P-LEMS), ou na forma não paraneoplásica (NP-LEMS); porém poucos estudos têm descrito as características da NP-LEMS. Nós analisamos as manifestações clínicas, laboratoriais, eletrofisiológicas, e resposta ao tratamento em dez pacientes brasileiros com NP-LEMS. A idade média foi de 41,5 anos. A manifestação neurológica mais freqüente foi hiporeflexia ou arreflexia com melhora após o exercício. A resposta ao tratamento ocorreu com piridostigmina, guanidina, prednisona, azatioprina, e ciclosporina; mas não com imunoglobulina intravenosa e plasmaférese. A idade de início, manifestações clínicas e eletrofisiológicas ajudaram mais no diagnóstico do que os anticorpos séricos; o tratamento sintomático com piridostigmina foi efetivo; e o tratamento imunossupressor com prednisona, azatioprina, ou ciclosporina beneficiou mais do que a plasmaférese ou a imunoglobulina intravenosa.

Lambert-Eaton myasthenic syndrome as a cause of persistent neuromuscular weakness after a mediastinoscopic biopsy: A case report / 대한마취과학회지

There are many causes of prolonged postoperative muscle weakness, including drugs, residual anesthetics, cerebrovascular events, electrolyte imbalance, hypothermia, and neuromuscular disease. Neuromuscular diseases are relatively rare, with the most common being myasthenia gravis and Lambert-Eaton myasthenic syndrome (LEMS). We report an unusual case in which a patient who was given a muscle relaxant during mediastinoscopy developed postoperative muscle weakness that was ultimately diagnosed as secondary to LEMS.

Clinical and electrophysiological characteristics of Lambert-Eaton myasthenic syndrome: a retrospective study in forty-five patients / 中华神经科杂志

Objective To analyze the symptoms and signs in forty-five Lambert-Eaton myasthenia syndrome (LEMS) patients retrospectively. Characteristics of electrophysiological examinations were investgated. Methods Forty-five LEMS patients were reviewed and information gathered regarding clinical complains neurological symptoms, and other concomitant diseases. The records showed that repetitive nerve stimulation (RNS) and nerve conduction velocity (NCV) were performed in all patients. Needle electromyography (EMG) and skin sympathetic response (SSR) were performed in some patients. Results (1) The mean age of neurological clinical onset age was (51.2 ±6. 8) years old. The two most common symptoms were slight weakness of lower extremities ( n = 35 ) and upper extremities (n= 5). Dysarthria was found in 3 patients and neck weakness in 2 patients. Tendon reflex decreased and disappeared in 38 patients. Autonomic nervous system manifestations were presented in 30 patients. (2) RNS increasing was observed in all patients from 156% to 636%. Low frequency RNS abnormalities were found in 29 patients.Sensory nerve conduction velocity abnormalities or sensory nerve conduction velocity combined motor nerve conduction velocity abnormalities were found in 19 patients ( 42% ). Of the 30 patients who underwent a needle EMG examination, 20 had myogenic or neurological damage. Thirteen abnormal findings were observed in 25 patients who underwent SSR examination. Conclusion The most common manifestations were weakness in lower extremities and autonomic nervous system dysfunction. Many abnormal electrophysiological results were found in LEMS patients, including NCV and EMG abnormalities. These findings indicated that clinical manifestations exceed the neuromuscular junction and perhaps included the peripheral nerve and muscle.

Lambert-Eaton Myasthenic Syndrome (LEMS) Presented With Ocular Symptoms

Lambert-Eaton myasthenic syndrome (LEMS) is characterized clinically by fluctuating muscular weakness; presentation with ocular symptoms is unusual. A 60-year-old man had developed diplopia and ptosis 2 years previously. The findings of a neurologic examination were normal except for bilateral ptosis and ophthalmoplegia. The amplitude of compound muscle action potentials recorded on the abductor digiti minimi increased (by more than 500%) during 50-Hz stimulation. This case demonstrates that LEMS should be included in the differential diagnosis of myasthenic symptom confined to the ocular muscles.

Surgical correction of strabismus in Lambert-Eaton myasthenic syndrome: case reports / Correção cirúrgica do estrabismo na síndrome de Lambert-Eaton: relato de dois casos

Lambert-Eaton myasthenic syndrome is a rare and acquired autoimmune disorder. We describe two female patients with medial rectus paresis as the only ocular manifestation. After a unilateral medial rectus recession and lateral rectus resection procedure, both patients recovered normal adduction. To our knowledge, this is the first report of surgery for extraocular muscle paresis in Lambert-Eaton myasthenic syndrome.

A síndrome de Lambert-Eaton é um distúrbio autoimune raro e adquirido. Apresentamos duas pacientes com paresia do reto medial como única manifestação ocular. Após retrocesso do reto lateral e ressecção do reto medial, unilateral, ambas as pacientes apresentaram normalização da adução. Até onde sabemos, este é o primeiro relato de cirurgia para paresia do reto medial na síndrome de Lambert-Eaton.

Adenocarcinoma pulmonar, dermatomiosite e síndrome miastênica de Lambert-Eaton: uma rara associação / Lung adenocarcinoma, dermatomyositis, and Lambert-Eaton myasthenic syndrome: a rare combination

A incidência das neoplasias pulmonares vem aumentando no Brasil e no mundo, provavelmente como resultado do aumento do tabagismo. Com o maior número de casos, surgem as apresentações atípicas. Relatamos o caso de um paciente do sexo masculino, 66 anos, tabagista e hipertenso, que apresentava quadro de fraqueza muscular proximal progressiva e, em dois meses, evoluiu com disfagia para alimentos sólidos, disfonia e lesões cutâneas em forma de "V" no tórax. O radiograma de tórax mostrou um nódulo pulmonar espiculado no lobo superior direito. A análise bioquímica revelou aumento da creatinoquinase. Após exames complementares e biópsias, o paciente foi submetido à lobectomia superior direita. A histopatologia evidenciou um adenocarcinoma moderadamente diferenciado. A análise global do caso e a revisão de literatura permitem sugerir que o quadro clínico do paciente era resultante da sobreposição de duas síndromes paraneoplásicas, a saber, a dermatomiosite e a síndrome miastênica de Lambert-Eaton, secundárias a um adenocarcinoma pulmonar.

The incidence of lung neoplasms is increasing in Brazil and in the world, probably as a result of the increase in smoking. Due to the greater number of cases, atypical presentations appear. We report the case of a 66-year-old hypertensive male smoker who presented progressive proximal muscular weakness and, in two months, evolved to dysphagia, dysphonia, and V-shaped skin lesions on the chest. A chest X-ray showed a spiculated pulmonary nodule in the right upper lobe. The biochemical analysis revealed elevated creatine kinase levels. After complementary tests and biopsies, the patient underwent right upper lobectomy. Histopathology showed a moderately differentiated adenocarcinoma. The overall analysis of the case and a review of the literature allow us to suggest that the clinical profile of the patient was a result of an overlap of two paraneoplastic syndromes (dermatomyositis and Lambert-Eaton myasthenic syndrome) secondary to lung adenocarcinoma.

Electrophysiological Changes in Lambert-Eaton Myasthenic Syndrome With Intravenous Immunoglobulin Therapy

No abstract available.

A Case of Lambert-Eaton Myasthenic Syndrome with Positive VGCC Antibodies Diagnosed in Small Cell Lung Cancer / 결핵및호흡기질환

Lambert-Eaton myasthenic syndrome (LEMS), a rare autoimmune neurological syndrome, is caused by defects in the secretion of acetylcholine from the presynaptic membrane, and is associated with the destruction of voltage gated calcium channels (VGCC) in the neuromuscular junction. LEMS can be confirmed by repetitive nerve stimulation and by the clinical symptoms, which are characterized by proximal muscle weakness in the lower extremities, decreased deep tendon reflexes and autonomic dysfunctions. In about 60% of patients with this disorder, underlying cancer-small cell lung cancer may be detected. Clinical symptoms may precede the diagnosis of malignancy, with the early diagnosis and treatment of the underlying malignancy being possible through the diagnosis of LEMS. A case of LEMS, with positive VGCC antibodies, in a 48-year-old man, which improved after chemotherapy of the underlying small cell lung cancer, is reported.

A Case of Lambert-Eaton Myasthenic Syndrome Associated with Atypical Bronchopulmonary Carcinoid Tumor

The Lambert-Eaton myasthenic syndrome (LEMS) is typically recognized as a paraneoplastic syndrome associated with a small cell lung carcinoma (SCLC), whereas LEMS with other neuroendocrine lung tumors, including carcinoids or large cell lung carcinoma, are highly unusual. Here, we report a rare case of LEMS with atypical bronchopulmonary carcinoid tumor: A 65-yr-old man presented with progressive leg weakness and a diagnosis of LEMS was made by serial repetitive nerve stimulation test. Chest CT revealed a lung nodule with enlargement of paratracheal lymph nodes, and surgically resected lesion showed pathological features of atypical carcinoid tumor. We concluded that LEMS could be associated with rare pulmonary neuroendocrine tumor other than SCLC, which necessitates pathologic confirmation followed by aggressive treatment for optimal management in these rare cases.

Re-evaluation of Repetitive Nerve Stimulation Test in Myasthenia Gravis and Myasthenic Syndrome

BACKGROUND: The repetitive nerve stimulation (RNS) test is a useful tool in the evaluation of neuromuscular transmission disorders. In our laboratory, we frequently use Oh's method, which tests 5 kinds of muscles (flexor carpi ulnaris (FCU), abductor digiti quinti (ADQ), orbicularis oculi, nasalis and trapezius) with 3 kinds of low rate stimulation (LRS) and high rate stimulation (HRS). This method has the advantage of high sensitivity, but is time consuming and painful to patients. So, we tried to reestablish the stage of RNS to overcome this problem and to create a useful test. METHODS: We analyzed RNS data from 369 patients, retrospectively. The number of patients with myasthenia gravis (MG) was 357 and the number with myasthenic syndrome was 12. We compared the sensitivity of individual muscle as well as individual stimulation rate. And we analyzed the results of MG and myasthenic syndrome to verify the usefulness of HRS. RESULTS: The sensitivity of RNS (LRS) was 69.7% in MG (generalized symptom 86.4%, only ocular symptom 40.3%). The sensitivity was higher with 3 pps and 5 pps than with 2 pps, while the exclusion of 2 pps did not affect the sensitivity. We found only 3 cases (1.0%) with post-tetanic exhaustion (PTE) in MG patients with negative results on LRS. The distributions of resting CMAP and post-exercise CMAP were different between MG and myasthenic syndrome. In most cases of myasthenic syndrome, the resting CMAP of ADQ and FCU was below 4.0 mV and post-exercise CMAP of ADQ and FCU was above 50%. CONCLUSIONS: LRS may be done with only 3 and 5 pps, and HRS of the ulnar nerve was helpful only if there was a suspicion of myasthenic syndrome (resting CMAP50%, in ADQ & FCU) or a borderline decremental response in LRS.