Peripheral nervous system involvement in chronic spinal cord injury

Introduction: Upper motor neuron disorders are believed to leave the peripheral nervous system (PNS) intact. In this study we examined whether there is evidence of PNS involvement in spinal cord injury (SCI). Methods: Twelve subjects with chronic low cervical or thoracic SCI were included prospectively. Needle electromyography was done in 10 different muscles in each subject bilaterally. Nerve conduction studies (NCS) were conducted in the fibular, tibial, and femoral motor and fibular and sural sensory nerves. Results: Half the subjects had widespread abnormal spontaneous activity (SA), and the amount of SA correlated inversely with reflex activity and nerve length. Fibular nerve entrapment across the knee was seen in 6 subjects, and sciatic nerve entrapment was seen in 1. Apart from entrapment neuropathies, NCS changes were found predominantly in motor nerves. Conclusion: The presence of widespread electrophysiologic changes outside entrapment sites indicates that SCI has a significant impact on the entire PNS, affecting the motor part predominantly. Muscle Nerve 52 : 1016–1022, 2015     

AAEM minimonograph #11: Needle examination in clinical electromyography

The physiologic and histologic principles underlying clinical electromyographic studies are briefly reviewed as an introduction to the normal and abnormal findings in human subjects. Technical aspects of recordings as well as the specific types of discharges and their significance are discussed.     

足下垂的原因分析及其肌电图鉴别诊断价值

目的回顾性分析引起足下垂的各种可能原因,并探讨肌电图对于足下垂的鉴别诊断价值。方法收集2011年9月至2015年6月因足下垂就诊于我科的患者155例,连续入组,符合足下垂肌力评定标准,分析常规神经传导和针肌电图检测的结果。结果电生理显示腓神经单神经病变70例(45.2%)、坐骨神经病变9例、多发性神经病19例、腰骶丛病变9例、腰_5/骶_1神经根病变42例、运动神经元病变(MND)6例。在腓神经单神经病变患者中,腓骨小头处卡压性病变占72.8%(51/70),其他因素占27.2%(P0.05);电生理显示跨腓骨小头传导阻滞占71.4%、速度减慢2.9%、轴索损害25.7%(P0.05)。在多发性神经病、腰骶丛/根病变患者中,足下垂均为伴随表现;1例运动神经元病患者以足下垂为首发症状。结论就诊神经科的足下垂患者,虽然近半数是腓神经单神经病变所致,但鉴别诊断时,需关注下运动神经元其他水平的病变,尤其是全身性疾病的可能,这对于治疗和预后评估很重要;神经电生理检测可以确定病变水平和分布,从而提示病因线索。     

Critical reappraisal of referrals to electromyography and nerve conduction studies.

A large number of examinees referred to electromyographic (EMG) laboratories do not have symptoms or signs suggestive of a peripheral nervous system disorder, and the aim of the present study was to check this. All examinees evaluated by the author in a "general" EMG laboratory in the first 4 months of 2002 were included. Data on examinees, referral physicians and diagnoses, clinical symptoms and signs, and electrodiagnostic findings were statistically evaluated. Three hundred examinees, 42% men, were included. A neurological diagnosis was provided in 55% of referrals. Electrodiagnostic abnormalities were found in 45% of examinees. Using multivariate statistics, a positive effect of neurological referral diagnosis, history of paraesthesias and of weakness and sensory loss on examination, and a negative effect of history of pain on pathological electrodiagnostic findings were found. Except 20 patients with carpal tunnel syndrome, no patient with normal clinical examination had abnormal electrodiagnostic findings. Our study confirmed the inappropriateness of referrals to electrodiagnostic examination to screen patients for peripheral nervous disorders. We propose electrodiagnostic examination mainly of patients with unequivocal clinical signs of a peripheral nervous system lesion and of patients with typical symptoms of the carpal tunnel syndrome.     

AAEM minimonograph #34: polyneuropathy: classification by nerve conduction studies and electromyography

Electrodiagnostic evaluation of patients with suspected polyneuropathy is useful for detecting and documenting peripheral abnormalities, identifying the predominant pathophysiology, and determining the prognosis for certain disorders. The electrodiagnostic classification of polyneuropathy is associated with morphologic correlates and is based upon determining involvement of sensory and motor fibers and distinguishing between predominantly axon loss and demyelinating lesions. Accurate electrodiagnostic classification leads to a more focused and expedient identification of the etiology of polyneuropathy in clinical situations.     

Iatrogenic complications and risks of nerve conduction studies and needle electromyography.

Electrodiagnostic procedures are routinely performed in patients with a variety of neuromuscular disorders. These studies are generally well tolerated and rarely thought to be associated with any significant side effects. However, needle electromyography is an invasive procedure and under certain situations has the potential to be associated with iatrogenic complications, including bleeding, infection, nerve injury, pneumothorax, and other local trauma. Similar complications are possible if needles are used for either stimulating or recording. In addition, like all other electrical devices and monitoring equipment connected to patients, electrodiagnostic testing carries the risk of stray leakage currents that under certain circumstances can result in electrical injury, especially in patients in the intensive care setting. Similarly, certain precautions are required during nerve conduction studies (NCS) in patients with pacemakers and other similar cardiac devices. In this review, we address the known and theoretical complications of NCS and needle electrode examination, and the possible methods to avoid such hazards.     

Motor and sensory conduction velocities and electromyographic findings in man before and after carbamazepine treatment

ABSTRACT- Electromyography and nerve conduction velocities were examined in 12 consecutive patients before and after 3 months treatment with carbamazepine. All parameters measured remained unchanged during treatment. Differences between the influence of carbamazepine and phenytoin on the peripheral nervous system are briefly discussed.     

Peripheral neuropathy in glycogen storage disease type III: Fact or myth?

Introduction: The aim of this study was to assess whether peripheral neuropathy is a feature of glycogen storage disease type IIIa (GSD IIIa) in adult patients. Methods: Medical records of a cohort of adult GSD IIIa patients who underwent electromyography (EMG) and nerve conduction studies (NCS) were reviewed, and the results were correlated with physical examination findings. Results: Sixteen patients underwent EMG and NCS; 4 complained of exercise intolerance, 1 of foot paresthesia, and 11 of muscle weakness (3 proximal, 8 distal). None of the patients had sensory deficits on clinical examination. All motor and sensory conduction velocities and sensory amplitudes were within reference ranges. EMG showed myopathic motor unit potentials in 15 of the 16 patients. Conclusions: Based on the clinical examination and the NCS and EMG results, we did not identify any peripheral nerve involvement in our adult patients diagnosed with GSD III. Muscle Nerve 53: 310–312, 2016     

Needle electromyography of the diaphragm.

A method is described for performing needle electromyography of the diaphragm which is safe and causes little discomfort. It provides valuable information concerning neuropathies and myopathies which may affect the diaphragm, and complements information derived from phrenic nerve conduction studies. Firing patterns of motor unit potentials during spontaneous respiration identify upper motor neurone disorders causing respiratory insufficiency.     

Cranial nerve conduction and needle electromyography in patients with acoustic neuromas: A model of compression neuropathy

Of 45 patients with acoustic neuromas (0.3–5.0 cm), 73% had facial nerve impairment on electrophysiologic testing, but only 16% had facial weakness. Cranial nerve conduction was the most sensitive measurement, especially prolongation of the ipsilateral R1 latency of the blink reflex compared with that of the contralateral reflex. The severity of nerve conduction abnormality was highly correlated with tumor size. Our results confirm and quantitate the sensitivity of nerve action potential latency in response to chronic nerve compression. © 1994 John Wiley & Sons, Inc.     

Peripheral nerve injuries: a retrospective survey of 456 cases

This 16-year retrospective study reports the data on 456 consecutive patients with 557 peripheral nerve injuries (PNIs) between 1989 and 2004. Most patients were men (74%) and the mean age was 32.4 years. In 83% of cases the PNIs were isolated; combined lesions most commonly involved the ulnar and median nerves. Upper-limb PNIs occurred in 73.5% of cases; the ulnar nerve was most often injured, either singly or in combination. Vehicle accidents affecting the brachial plexus or radial, sciatic, facial, and peroneal nerves were the most common cause of injury. Penetrating trauma commonly affected the ulnar and median nerves; falls and gunshot wounds frequently affected the ulnar, radial, and median nerves; and sports injuries, particularly soccer, affected mainly the peroneal and tibial nerves. More than half of the brachial plexus lesions after vehicular accidents were from motorcycle crashes.     

A comparison of magnetic and electrical stimulation of peripheral nerves

We compared magnetic stimulation using different coil designs (2 rounded coils and a butterfly-prototype coil) with electrical stimulation of the median and ulnar nerves in 5 normal subjects. Using magnetic stimulation we were able to record technically satisfactory maximal sensory and motor responses only with the butterfly coil. Submaximal electrical stimuli preferentially activated sensory rather than motor axons, but submaximal magnetic stimuli did not. The onset latency, amplitude, area and duration of responses elicited electrically or magnetically with the butterfly coil during routine sensory and motor nerve conduction studies were similar, and motor and sensory conduction velocities were comparable when studied over long segments of nerve. However, the motor conduction velocities with magnetic and electrical stimulation differed by as much as 18 m/sec in the across-elbow segment of ulnar nerve. Thus, recent developments in magnetic stimulator design have improved the focality of the stimulus, but the present butterfly coil design cannot replace electrical stimulation for the detection of focal changes in nerve conduction velocity at common entrapment sites, such as in the across-elbow segment of the ulnar nerve.     

Central and peripheral nervous system functions are independently disturbed in HIV-1 infected patients

We examined the peripheral nervous system (PNS) (nerve conduction velocity (NCV)) and the central nervous system (CNS) (basal ganglia-mediated psychomotor speed) in 93 males seropositive for human immunodeficiency virus type 1 (HIV-1) with no prior history of opportunistic brain disease, antiretroviral treatment or intravenous drug use. Patients with different degrees of slowing of peroneal and sural NCV showed no significant differences in psychomotor speed as assessed by tremor peak frequency, most rapid alternating movements, reaction times and contraction times. There was no significant correlation between psychomotor measures and NCV. Psychomotor slowing test findings were independent from peripheral nervous system damage indicating uncorrelated disturbances of CNS and PNS function in HIV-1 infection. Differences in HIV-1 viral quasispecies or host responses may determine the predominance of CNS or PNS injury. Received: 7 September 2001, Received in revised form: 9 November 2001, Accepted: 13 November 2001     

Comparing neuropathy in multiple myeloma and AL amyloidosis

Peripheral neuropathy (PN) is frequent in patients with monoclonal gammopathy due to plasma cell dyscrasia, but little is known about the comparative impact of nerve dysfunction in different disorders. We compared clinical and laboratory results between two diagnostic groups. We recruited 76 untreated multiple myeloma (MM) and 27 AL amyloidosis (ALA) patients for evaluation of symptoms, clinical findings and nerve conduction studies (NCS). We diagnosed significant PN using total neuropathy scores (TNS > 7) in 17.6% of MM and 48.1% of ALA patients and in 27.7% of MM and 35.7% of ALA patients using NCS findings. TNS score grades were significantly higher in the AL amyloidosis patients (Fisher's exact test: P = .02) but a NCS based PN diagnosis was not significantly different (Fisher's exact test: P = .13). A significantly higher TNS vibration (P = .04) and pin (P = .02) sensory sign and TNS reflex (P = .04) sign score was found in amyloidosis patients. Likewise, quantitative sensory thresholds for vibration was higher in amyloidosis patients (Welsh ANOVA: P = .01). NCS revealed signs of more frequent axonal tibial neuropathy with significantly lower motor response amplitudes (P = .02) and resulting higher TNS scores (P = .002), while sural nerve sensory response amplitudes were without significant difference (P = .86). We found more severe TNS grades of PN in AL amyloidosis patients compared with MM patients. We also found higher sensory symptoms scores and higher thresholds for vibration but similar sensory involvement using NCS. The NCS exclusively showed signs of an axonal neuropathy.     

神经活检在周围神经疾病诊断中的意义及与电生理检查相关性分析

目的探讨神经活检在周围神经病诊断中的意义,并分析病理检查与神经电生理检查结果的一致性。方法收集2009-2011年作者医院行腓肠神经活检的16例周围神经病患者的临床诊断、电生理诊断和病理诊断资料;分析电生理诊断、光镜诊断和电镜诊断在判断轴索损害或/合并髓鞘损害的一致性,并分析其结果不一致的可能原因。结果电生理检查结果示异常12例(12/16),其中表现为轴索损害为主5例(5/16),髓鞘损害为主7例(7/16);病理检查结果示15例(15/16)患者有不同程度的髓鞘或轴索损害;4例(4/16)患者经神经活检后原有的诊断得到了补充或修改;进一步分析神经病理对于周围神经损害的诊断与电生理诊断无统计学差异。结论 (1)神经活检能够发现一些间质改变和亚临床、亚电生理的神经损害,从而对疾病的认识和治疗提供帮助。(2)神经病理对于周围神经损害的诊断与电生理诊断相关性较好,但当电生理表现为轴索损害时其一致的趋势欠佳,可能与轴索损害的多样性有关。     

Needle electromyography practice patterns in patients taking novel oral anticoagulants: A survey‐based study

Introduction: This study sought to evaluate needle electromyography (EMG) practice patterns among electromyographers with patients taking novel oral anticoagulants (NOAC). Methods: A survey questionnaire was sent to members of the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) via email web link. Anonymous survey responses were collected through an online website. Results: Fifty‐eight AANEM members responded, 28 (48%) of whom worked at a teaching hospital and 30 (52%) of whom worked in a private setting. Fifty‐four (93%) responders perform needle EMG on patients taking NOACs. Twenty‐nine (50%) responders examine paraspinal muscles, and 20 (40%) responders examine facial muscles. Among 14 responders who perform single‐fiber EMG (SFEMG), 8 examine patients taking NOACs. Discussion: Although most of the electromyographers perform needle EMG on patients taking NOACs, they reported variable practice patterns in examination of the paraspinal and facial muscles and in performing SFEMG. A prospective risk–benefit study is required. Muscle Nerve 58 : 307–309, 2018     

Literature review of the usefulness of nerve conduction studies and electromyography for the evaluation of patients with carpal tunnel syndrome

The sensitivity and specificity of nerve conduction studies (NCS's) and electromyography (EMG) for the diagnosis of carpal tunnel syndrome CTS) were evaluated by a critical review of the literature. With a search of the medical literature in English through May 1991, 165 articles were identified and reviewed on the basis of six criteria of scientific methodology. The findings of 11 articles that met all six criteria and the results of 48 additional studies that met four or five criteria are presented. We concluded that median sensory and motor NCS's are valid and reproducible clinical laboratory studies that confirm a clinical diagnosis of CTS with a high degree of sensitivity and specificity. Clinical practice recommendations are made based on a comparison of the sensitivities of the several different median nerve conduction study (NCS) techniques.     

重症肌无力患者针电极肌电图肌源性受损表现的临床意义

目的分析重症肌无力(myasthenia gravis,MG)患者针电极肌电图(needle electrode electromyography,NEMG)检查结果的临床意义。方法回顾性分析2011-01-01—2013-12-31期间在解放军第309医院神经内科住院治疗的335例确诊MG患者的NEMG检查结果和临床资料,根据NEMG检查是否出现肌源性受损表现将患者分为两组,对比分析两组患者的临床特点。结果29例(8.7%)NEMG出现肌源性受损表现,异常NEMG均无自发电位,仅表现为运动单位电位(motor unit potential,MUP)波幅降低、时限缩短。NEMG检查有肌源性受损表现组临床绝对评分(20.8±7.3)高于无肌源性受损表现组(14.9±9.0,t=1.79,P0.05)。NEMG检查无肌源性受损表现者多以眼外肌无力为首发症状(85.62%),以肢体和球部肌肉起病者比例较低(14.38%);与无肌源性受损表现者相比,有肌源性受损表现者以眼外肌为首发症状者比例较低(55.17%),多以肢体和球部肌肉受累起病(44.83%),两组差异有统计学意义(χ2=9.79,P0.01)。两组间比较,性别、发病年龄、病程、Osserman分型及胸腺病理类型差异均无统计学意义(均P0.05)。结论 NEMG检测表现为肌源性受损者病情较无肌源性受损表现者重。电生理检查可在一定程度上提示MG病情的严重程度。