癌性Lambert—Eaton肌无力综合征四例临床及电生 …

目的 研究癌性Ｌａｍｂｅｒｔ－Ｅａｔｏｎ肌无力综合征（ＬＥＭＳ）临床及电生理特征。方法 回顾性地评价了４例病理证实的癌性ＬＥＭＳ（例１，２为小细胞性肺癌，例３为肾上腺癌，例４为乳腺癌）的临床和电生理资料。结果 面神经，腋神经及尺神经重复电刺激示，诱发电位起始波幅减小（０．４～０．７ｍＶ）；５Ｈｚ以下低频刺激后波幅递减１６％～５４％（对照：小于１５％）但在１０Ｈｚ以上高频刺激后波幅递增１２０％～６５     

重症肌无力伴Lambert-Eaton肌无力综合征8例分析

目的探讨重症肌无力(MG)合并Lambert—Eaton肌无力综合征(LEMS)的临床特点。方法回顾性分析8例MG合并LEMS患者的发病形式、首发症状、1临床表现和实验室及辅助检查。结果8例患者均慢性或亚急性起病，首发症状表现为双下肢无力4例(50％)。四肢无力4例(50％)，经过症状有球麻痹1例，睑下垂1例，面肌受累及呼吸困难各1例；8例患者伴癌6例(75％)，其中5例(62.5％)为肺癌；所有患者新斯的明试验( )，重复神经电刺激均示低频(2Hz、3Hz、5Hz)衰减(17％～40％)，高频(20Hz、30Hz)递增(200％～881％)。结论对以双下肢无力首发的MG，均应考虑到LEMS或合并LEMS的可能，常规行重复神经电刺激，确诊为LEMS后，应常规行胸部CT和／或腹部B超检查以早期发现肿瘤。     

脂质沉积性肌病合并周围神经病的临床和神经电生理研究

目的研究脂质沉积性肌病合并周围神经损害和不伴周围神经损害的临床及神经电生理特点。方法对19例病理证实的脂质沉积性肌病中7例合并周围神经损害（第一组）和12例不伴周围神经损害的患者（第二组）进行了常规肌电图、正中神经和胜后神经感觉传导速度及运动末端潜伏期测定。结果发现临床上两组不同卢、是前者病程较后者长（P＜0．01）；肌电图提示运动单位动作电位（MUAPS）时限第一组较第二组宽，去除多相波后更明显（P＜0．01），部分合并神经源性损害；神经传导速度测定结果提示，第一组可见感觉和运动神经传导速度减慢及感觉神经动作电位波幅降低。结论对临床上有典型的肌病症状、电生理为肌源性损害合并神经源性损害或单纯神经源性损害应考虑脂质沉积性肌病的可能，肌肉和周围神经活检是非常必要的。     

青壮年糖尿病周围神经病186例临床与神经电生理分析

目的：探讨青壮年糖尿病周围神经病（DPN）的临床与电生理变化。方法：分析186例青壮年DPN患者的临床特点，比较青壮年DPN组与对照组的神经传导速度（NCV）、远端潜伏期和远端波幅3个参数。结果：①临床特征以肢体麻木（52％）最多见、其次为自发痛（32％）；②青壮年DPN组NCV和远端波幅值低于对照组，远端潜伏期比对照组延长，两组3个参数比较差异均有统计学意义（P〈0．05）．③周围神经损害程度（轻、中和重度）明显高于对照组（P〈0．05）。结论：①青壮年DPN患者临床特点以肢体麻木与自发疼痛多见；②检测NCV、远端潜伏期和远端波幅，有助发现早期临床病变；⑨为周围神经损害程度（轻、中和重度）的诊断与治疗提供依据。     

POEMS综合征电生理特点分析

目的阐明POEMS综合征的电生理特点。方法回顾性分析22例POEMS患者的电生理资料。结果下肢神经的复合肌肉动作电位（CMAP）波幅的降低比上肢更为显著（P〈0．05），运动神经传导速度减慢在下肢更显著（P〈0．05），CMAP及感觉神经动作电位未引出者更常出现在下肢（P〈0．05），79．5％运动神经的远端潜伏期延长，远端潜伏期指数较正常显著增高（P〈0．05），下肢肌的异常肌电表现更易出现（P〈0．05）。结论POEMS综合征周围神经损害更常出现在下肢，且更严重；神经传导速度减慢主要发生于周围神经中间部分而非远端。     

75例正己烷中毒性周围神经病临床分析

目的 探讨正己烷中毒性周围神经病的临床特征、诊断及防治。方法 对密切接触正己烷的96名皮鞋厂工人中75人存在周围神经损害症状患者的临床资料进行分析。结果 75例均表现肢端麻木、无力，末梢型感觉障碍，17例四肢肌萎缩，2例出现球麻痹症状。神经电生理检查示神经传导速度减慢，波幅下降，部分有失神经改变。常规治疗组有效率18．78％，皮质激素治疗组25％，神经生长因子组60％，75例患者均明显好转，70例恢复正常工作。结论 正己烷中毒可引起周围神经轴索变性、脱髓鞘，出现周围神经受损症状。皮质激素治疗无效，神经生长因子优于普通神经营养药物。患者大多预后良好，症状、体症先天神经电生理恢复。     

Lambert-Eaton肌无力综合征6例临床与电生理特点分析

目的探讨Lambert-Eaton肌无力综合征(LEMS)的临床及电生理特点。方法分析2002-2011年作者医院诊断的6例LEMS患者的临床资料及神经电生理检查结果。结果 6例患者起病年龄34～65岁(中位数53岁),病程0.5～35个月(中位数4个月)。4例患者最初诊断为重症肌无力。5例患者伴恶性肿瘤。6例患者均以肢体近端无力起病。5例患者腱反射减低或消失。3例患者伴口干、眼干等自主神经症状。5例患者行新斯的明试验,其中4例阳性。6例患者均行神经电生理检查,共9次。5例行针极肌电图检查共6次,其中结果显示肌源性改变3次,神经源性改变2次,正常1次。5例行7次神经传导速度检查,全部提示复合肌肉动作电位明显减低。6例共行9次重复神经电刺激(RNS)检查,全部提示高频刺激波幅递增。结论掌握LEMS的临床及电生理特征有助于及时正确诊断。     

Lambert-Eaton肌无力综合征与癌

目的　 Lambert-Eaton肌无力综合征 (LEMS)临床少见。此报告旨在增进人们对这一综合征的认识。方法　对 2 3例 LEMS患者的临床资料做回顾性分析。结果　全组 2 3例 ,伴癌者 1 9例 (83 % ) ,其中小细胞肺癌(SCLC) 1 5例。首发症状以双下肢无力最常见 (5 2 % )。随访期间有颅神经受累 (61 % )、上肢无力 (70 % )、下肢无力 (1 0 0 % )、自主神经症状 (3 0 % )、腱反射减低 (87% )。高频 (2 0～ 5 0 Hz)重复神经电刺激波幅递增 1 0 0 %～71 8% ,平均增 2 82 %。有 1 5例 (79% )肌无力症状早于肺部症状平均 4.5个月。抗肿瘤治疗 1 2例 ,有 8例 LEMS症状显著改善或消失。结论　 LEMS与癌有显著相关倾向 ,尤其与 SCLC更明显。对 40岁以上男性 LEMS患者应积极寻找潜在的恶性肿瘤     

肌萎缩侧索硬化患者的重复电刺激研究

目的：研究肌萎缩侧索硬化（ALS）患者重复电刺激时复合肌肉动作电位波幅衰减的特点和影响因素。方法：对49例确诊为ALS的患者进行正中神经3Hz重复电刺激检查，同时记录患者的起病区域、病程和复合肌肉动作电位的波幅并分析其与低频衰减的相关性。在16块出现波幅衰减的肌肉进行强直收缩试验并观察其对波幅和衰减的影响。结果：49例ALS患者中，有15例出现明确衰减（衰减≥10％），13例呈界限性衰减（5％-9％）。上肢起病的患者较延髓和下肢起病组更容易出现明确衰减（P〉0．01）。波幅与衰减程度呈负相关（r=0．474），但病程与衰减不相关。在进行强直收缩试验的16块肌肉中，4块有活动后易化，6块呈强直后易化，5块出现强直后衰竭。结论：神经肌肉传递障碍在ALS中并不少见，低频衰减的程度与轴索损害的严重性相关；上肢起病的患者更容易出现拇短展肌的低频衰减；突触前机制可能与衰减的发生有关。     

系统性红斑狼疮合并周围神经病的临床特点和肌电图改变

分析２２例临床有或疑有神经系统损害的系统性红斑狼疮（ＳＬＥ）患者，其中仅３例被临床诊断为ＳＬＥ合并周围神经病，然神经电生理检查证实１３例为周围神经损害。主要临床特点为对称性和非对称性四肢远端麻木、疼痛，深浅感觉障碍，肌力减退，肌萎缩等。神经电生理检查显示神经传导速度减慢，波幅降低，异常自发电位（纤颤电位和正锐波），运动单元多相电位增加。电生理检查与病理改变相符：ＳＬＥ合并周围神经病既有轴索损害，又有脱髓鞘改变。提示神经电生理检查可以为ＳＬＥ患者提供早期或亚临床周围神经损害的依据。     

Small cell lung cancer with Lambert-Eaton myasthenic syndrome

Four of 69 cases of small cell lung cancer (SCLC) showed evidence of Lambert-Eaton myasthenic Syndrome (LEMS) were studied neurologically and neurophysiologically in four years. The LEMS appearance were preceded that of SCLC in 3 cases for two years at most. Repeated stimulation of ulnar nerve examination showed diminished amplitude of initial response (0.2-0.9 mv); Amplitude of the response at 3 c/s stimulation for 3 sec was diminished 20-63%. (control 3% decreases-13% increases) but that at 20 c/s stimulation for 10 sec increased 200-800% increases. (control: 20% decreases-56% increases). These findings were important for diagnosis of LEMS. The abnormalities of neurotransmission seems to be due to inadequate release of acetyl choline from nerve terminals at abnormal active zone of Ca++ channels.     

Electrophysiologic data on myasthenic syndromes of the Lambert-Eaton type. A series of 23 cases]

The electrophysiological data of 23 adult patients with Lambert-Eaton myasthenic syndrome (LEMS) have been reviewed. Lung carcinoma was disclosed in 17. In six cases with an EMG follow-up ranging between one and 17 years no carcinoma was detected. The results of repetitive nerve stimulation test (RNS) were not statistically different between the 2 groups. Low CMAP ulnar amplitude was present in all patients (mean: 1.7 mV). Decremental response at low rate of stimulation (3 Hz) was present in 17/20 (means: 30%). An abnormal incremental response at high rate of stimulation was present in all cases (mean: 826%). The authors emphasize the interest of a 50 Hz stimulation for 4 s. Increase of the 'F-wave' amplitude was noticed in some cases. Electrophysiological changes suggestive of an associated mild neuropathy were noticed in eight patients but H-reflex was present in 3/3 cases. SFEMG abnormalities were found in 6/6 cases. In one case, stimulated SFEMG showed more blockings and an increased jitter with low rate of stimulation. In one case the electrical pattern of RNS could be misinterpreted as myasthenia gravis in one tested muscle only. The author's results suggest that CMAP amplitude and RNS test could be used to appreciate the short-term improvement of LEMS with treatment and in some cases for the long-term follow-up.     

Diverse electrophysiological spectrum of the Lambert-Eaton myasthenic syndrome

Among 13 patients with the Lambert-Eaton myathenic syndrome (LEMS), three different patterns on the repetitive nerve stimulation test were observed at the time of initial testing. Type 1 pattern, seen in one patient, had low normal CMAP amplitude, decremental response at the low rate of stimulation (LRS), and relatively normal response at the high rate of stimulation (HRS). Type 2, seen in nine patients, had the classical triad: low CMAP amplitude, decremental response at LRS, and incremental response at HRS. Type 3, seen in three patients, showed low CMAP amplitude, decremental response at LRS, and initial decremental response at HRS. We believe that these three patterns represent different degrees of blocking in LEMS, from the mildest in type 1 to the most severe in type 3. Since types 1 and 3 can be misinterpreted as myasthenia gravis patterns, they must be recognized in LEMS and an incremental response documented by prolonged stimulation at HRS.     

Repetitive nerve stimulation studies in the Lambert–Eaton myasthenic syndrome

We compared changes in amplitude and area of surface recorded compound motor action potentials (CMAPs) during 20-Hz repetitive nerve stimulation and after maximum voluntary contraction in patients with the Lambert–Eaton myasthenic syndrome (LEMS), myasthenia gravis (MG), and normal controls. There was greater potentiation of CMAP amplitude after voluntary contraction than during 20-Hz stimulation in 10 of 14 LEMS patients; CMAP area increased more after exercise than during 20-Hz stimulation in all LEMS patients. Although abnormal potentiation of CMAP area and amplitude was seen in equal numbers of LEMS patients, more LEMS patients demonstrated a greater than 100% potentiation of CMAP area than of CMAP amplitude. We conclude that maximum voluntary contraction is preferable to brief 20-Hz RNS to demonstrate potentiation in LEMS because it is at least as sensitive and is less painful. Measurement of CMAP area in LEMS patients is not better than measuring the change in CMAP amplitude in demonstrating abnormal potentiation. Testing of a single hand muscle for potentiation in LEMS does not demonstrate abnormal potentiation in all LEMS patients. © 1994 John Wiley & Sons, Inc.     

Effects of a nitric oxide synthase inhibitor on non-cholinergic junction potentials in the circular muscle of the guinea pig ileum.

Intracellular microelectrodes were used to record junction potentials from the circular muscle cells of the guinea pig ileum in vitro at 37 degrees C in a modified Krebs solution containing nifedipine (1-2 microM) and hyoscine (1 microM). Transmural nerve stimulation, using volleys of three pulses at 50 Hz, produced a complex response consisting of an inhibitory junction potential (IJP) followed by a prolonged depolarization. Following the addition of the nitric oxide synthase inhibitor NG-nitro-L-arginine (NOLA, 100 microM) the amplitude of the IJP (recorded 10 mm aboral to the stimulating electrodes) was increased by approx. 10% (n = 4). The further addition of apamin (250 nM) abolished the IJP revealing a non-cholinergic excitatory junction potential (EJP). In other experiments (n = 8), preparations were treated with apamin then subjected to substance P desensitization (500 nM, > 20 min). Transmural nerve stimulation now produced a triphasic response (recorded 1 mm aboral to the stimulating electrodes) consisting of: (a) an initial hyperpolarization (approx. 5 mV) lasting about 1 s; followed by (b) a depolarization reaching a peak (approx. 7 mV less negative than the RMP) approx. 2 s after nerve stimulation; and finally (c) a small (approx. 3 mV) hyperpolarization. The addition of NOLA reduced all three phases by 80-90% (n = 8). The subsequent addition of L-arginine (5 mM) partially reversed these effects (n = 3). Conditioning hyperpolarization up to 20 mV increased the amplitude of the NOLA-sensitive IJP and EJP. Further conditioning hyperpolarization reduced the amplitude of the IJP and enhanced the amplitude of the EJP. Large conditioning hyperpolarizations (> 60 mV) reduced the amplitude of both the IJP and EJP. An estimation of the membrane conductance changes occurring during the initial hyperpolarization and depolarization suggest that it was either unchanged or increased. During large conditioning hyperpolarizations in the absence of nerve stimulation, the membrane potential was unstable and began to show spontaneous oscillations (up to 30 mV, every 4-5 s) resembling slow waves. These experiments indicate that NO, or a related compound, appears to mediate the nerve induced apamin-resistant IJP and substance P- and hyoscine-resistant EJP in the circular muscle of the guinea pig ileum.     

Ten-second exercise is superior to 30-second exercise for post-exercise facilitation in diagnosing Lambert-Eaton myasthenic syndrome

An incremental response after brief exercise or high-rate stimulation on the repetitive nerve stimulation (RNS) test is a critical diagnostic criterion for Lambert-Eaton myasthenic syndrome (LEMS). This prospective study was performed to determine what duration of exercise shows the highest diagnostic sensitivity for LEMS. The compound muscle action potential amplitude in the abductor digiti quinti muscle was obtained at rest and after 5 s, 10 s, 15 s, 20 s, 25 s, and 30 s of exercise. Incremental responses were compared for the different exercise durations in 24 studies performed in nine LEMS patients. The increment was highest with 5-s and 10-s exercises (244%-243%) and lowest with 30-s exercise (84%). A gradual decrease in the increment was noted from 5- to 30-s exercise. A significant difference in the increment was noted between 5- to 10-s and 20-s to 30-s exercise. There was significantly higher diagnostic sensitivity with the 10-s exercise compared with 30-s exercise at 100% increment and 60% increment levels. Higher increment and diagnostic sensitivity were achieved with 10-s exercise than with 30-s exercise. Thus, 10-s exercise should be the standard protocol for the RNS test for LEMS.     

Lambert-Eaton myasthenic syndrome

Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disease of the neuromuscular junction, and approximately 60% of patients with LEMS have a tumor, mostly small cell lung cancer (SCLC), as a paraneoplastic neurological syndrome. The clinical data of Japanese patients in the present study are as follows: the ratio of men to women is 3: 1 (mean age, 62 years; age range, 17-80 years). Of the patients with LEMS, 61% have SCLC, whereas the others do not have cancer. Clinical symptoms are usually characterized by proximal muscle weakness and dysautonomia. In less than 10% of the patients, there are signs of cerebellar dysfunctions (paraneoplastic cerebellar degeneration with LEMS; PCD-LEMS), and these are usually associated with SCLC. The diagnosis can be confirmed by detecting a specific antibody in a radioimmunoprecipitation assay and finding reduced amplitude of compound muscle action potential that increases by over 100% after maximum voluntary activation or 50Hz of nerve stimulation. The pathomechanism of LEMS is characterized by impaired transmission across the neuromuscular junction because of autoantibodies directed against the presynaptic P/Q-type voltage-gated calcium channels (P/Q-VGCCs). Histopathologic evaluation of the cerebellum in patients with PCD-LEMS showed a reduced number of P/Q-type VGCCs in the molecular layer. Therefore, it was hypothesized that P/Q-VGCC antibodies may induce cerebellar dysfunction after entering the CNS in patients with PCD-LEMS. Specific tumor therapy in patients with LEMS as well as cancer often improves the neurologic deficit. Tumor removal is the primary treatment for LEMS. If the result of the primary screening is negative, screening should be repeated after 3-6 months and thereafter every 6 months for up to 2 years. Most patients benefit from 3, 4-diaminopyridine administered with pyridostigmine. In those with severe weakness, intravenous gamma globulin (IVIg) or plasmapheresis confers short-term benefits. Prednisone when administered alone or in combination with immunosuppressive drugs can achieve long-term control of the disorder.     

Electrophysiological assessment of central and peripheral motor routes to the lingual muscles.

Compound muscle action potentials (CMAPs) of the lingual muscles were recorded by especially devised bipolar surface electrodes placed on the tongue. Distinct responses were evoked in the tongue muscles by peripheral electrical stimulation of the hypoglossal nerve medial to the angle of the jaw and by transcranial magnetic stimulation of the motor cortex. With cortical stimulation during voluntary activation of the tongue muscles it proved easy to obtain responses with the characteristics of centrally evoked responses allowing reliable measurements of latencies and amplitudes. By contrast, responses from magnetic stimulation of the intracranial segment of the hypoglossal nerve were more difficult to obtain and the reproducibility was often not satisfactory. In a group of 20 healthy subjects the average distal motor latency of both sides from peripheral stimulation was 2.4 ms and the corresponding amplitude was 9.3 mV on the left and 8.6 mV on the right side (range 5.1-16.0 mV). Cortical stimulation gave responses with an average onset latency of 8.6 ms and 8.8 ms and an average amplitude of 1.8 mV and 2.6 mV on the left and right sides of the tongue respectively (range 0.7-5.6 mV). From this mean conduction times of 6.2 ms on the left and 6.4 ms on the right side (SD 1.0 ms) between cortex and mandibular angle and relative amplitudes from cortical stimulation as compared with the peripheral CMAP of 29% on the left and 21% on the right side (range 7%-66%) were calculated. In 16 patients it was possible to differentiate between a central (supranuclear) and a peripheral (intranuclear) site for the lesions of the motors routes to the lingual muscles and to show subclinical lesions in some cases. With a recording arrangement allowing selective unilateral recording of muscle activity from both sides of the tongue the assumed bihemispheric motor representation of the lingual muscles was confirmed.     

Post-exercise exhaustion in Lambert–Eaton myasthenic syndrome

ObjectivesTo study post-exercise exhaustion by decrement (PEE-D) systematically in 24 repetitive nerve stimulation (RNS) tests in 14 patients with Lambert–Eaton myasthenic syndrome (LEMS).MethodsIn the abductor digiti quinti muscle, the compound muscle action potential (CMAP) amplitude and 3 Hz responses for 2 s were obtained with the supramaximal stimulation at rest, immediately after (PE0), 30 s after (PE30s), and at 1, 2, 3, and 4 m after 10-s exercise.ResultsThere was a 377% increment in the CMAP amplitude at PE0 and a mild increment (+26%) at PE30s. A transient but significant improvement (−22%) in the decremental response was observed at PE0, and a gradual worsening of decrement in subsequent tests, with the worst decrement noted (−50%) at PE2m.ConclusionPEE-D was found 2 m after exercise in LEMS.SignificancePEE-D may be physiologically closest to the reversible myasthenic fatigue after exercise observed in LEMS patients.