A miniaturized cuff electrode for electrical stimulation of peripheral nerves in the freely moving rat

A bipolar cuff electrode for electrical stimulation of small diameter peripheral nerves is described. The cuff is made of a highly flexible rubber-impression material, and the electrode assembly is suited for chronic implantation. Its manual construction is easy and reliable, utilizing only simple tools. The cuff completely envelopes nerves of varying diameter and requires a minimal amount of manipulations of the nerve, thereby reducing the chance of surgical trauma. The snug envelope prevents the nerve from drying, and minimizes shunting between the two leads by extracelfular fluids. Small outer dimensions were achieved: 1.4 × 1.1 × 2.3 mm (width × height × length) when used with nerves of 1 mm diameter, which minimizes pressure and damage to surrounding tissues. Morphometric analysis of nerves enclosed in cuffs for 28–30 h revealed a small decrease in the number of large-diameter fibers. Stimulation thresholds remained, however, constant throughout the experiments.     

Coupling between reaching movement direction and hand orientation for grasping

In a previous work, we demonstrated that orientation of the hand in the horizontal plane (azimuth) at the time of grasping depends on the direction of the reaching movement in the horizontal plane. Here we report three experiments to further investigate the generality of this coupling. Azimuth of the hand for grasping was studied while subjects were reaching for objects placed at various locations on a horizontal board. Hand movements were recorded with an electromagnetic sensor giving information about hand 3D position and orientation. As expected, hand azimuth for grasping was coupled with movement direction in the central part of the workspace (but reached a limit for rightmost reaching directions). The coupling did not depend on the direction of where the object had to be put after grasping. Various initial positions and azimuths of the hand were compared to the most comfortable initial hand posture. The coupling between hand azimuth and movement direction remained whatever the initial hand azimuth. This demonstrates that reaching movement direction is coupled with azimuth at the time of grasping and not with a rotational hand movement. The coupling between hand azimuth and movement direction subsisted when the initial upper trunk orientation was changed. Thus our results cannot be explained by an invariance of the coupling coded in hand-centered or shoulder-centered coordinates. They rather suggest that the movement is produced in a frame of reference associated with the environment.     

Intraneural fibroma of the median nerve at the wrist

Distal median neuropathy from carpal tunnel syndrome is the most well known lesion affecting the median nerve. Mass lesions may affect the nerve at the wrist. We present to our knowledge the first histologically confirmed case of an intraneural fibroma.     

Hand orientation for grasping and arm joint rotation patterns in healthy subjects and hemiparetic stroke patients

We previously demonstrated that the hand orientation for grasping (azimuth) is strongly coupled to arm movement direction in the horizontal plane. The question is whether this coupling is directly controlled or secondary to a regulation of the arm angular configuration. To this purpose, we quantified hand orientation and arm joint rotations during unconstrained reaching movements in healthy subjects and in patients with hemiparesis due to stroke since they use altered joint rotation patterns for reaching. Seven healthy subjects and eight patients with a right hemiparesis participated (four had a moderate and four had a mild disorder). Four electromagnetic sensors were used to measure hand orientation and to compute the wrist, elbow and shoulder joint angles. Hand azimuth at the time of grasping was correlated to arm movement direction in all the healthy and hemiparetic individuals. In healthy subjects, a regression analysis of the arm joint rotations suggested that the coupling between hand azimuth and movement direction was not due to a correlation with a particular degree of freedom. Patients used different hand orientations for grasping and different joint rotation patterns that varied according to their level of disability and the use of compensatory strategies. The findings observed in both healthy subjects and patients with stroke show that the coupling of hand azimuth for grasping to movement direction was controlled independently of the set of joint rotations used for reaching. This suggests that it is a basic synergy directly controlled by the motor system.     

拇指感觉神经传导速度诊断轻度腕管综合征的临床应用价值

目的:探讨拇指感觉神经传导速度(sensory nerve conduction velocity,SCV)诊断轻度腕管综合征的临床应用价值。方法:对18例(26只手)轻度腕管综合征的患者和15例(30只手)年龄性别相匹配的正常人,测定了腕部正中神经和桡神经的感觉神经传导速度,并进行对比研究。结果:中指正中神经SCV的异常率为50%,腕部正中神经/桡神经(刺激拇指)SCV差值的异常率为84.6%,明显大于用常规检查方法组(刺激中指),有8例12只手腕部正中神经感觉动作电位(刺激拇指)中出现双峰电位,而对照组则无。结论:在腕管综合征肌电图的诊断中,比较正中神经和桡神经SCV的差值是早期诊断腕管综合征的敏感指标之一。     

正中神经短潜伏期躯体感觉诱发电位头部分布研究及其临床意义

对46例健康成人,30例缺血性脑血管疾病、10例局灶性皮质病变病人进行4或5道记录,研究正中神经短潜伏期躯体感觉诱发电位(SEP)头部分布。顶 N20波、前额 P20波与中央前 P22波的时间-空间特征明显不同;在缺血性脑血管疾病中,中央前成分异常率(80%)明显比顶成分(30%)高,X~2=9.3,P<0.01;局灶性皮质病变,顶 N20-前额 P20与中央前 P22出现分离性异常现象。多道记录可以明确区分中央前 P22与前额 P20,顶 N20-前额 P20与中央前 P22有不同的神经起源,中央前 P22对缺血性脑血管疾病是一种敏感的诊断指标,同时记录这几个成分将提高 SEP 的诊断敏感性。     

Median Nerve Stimulation in a Patient with Complex Regional Pain Syndrome Type II

A 54-year-old man experienced injury to the second finger of his left hand due to damage from a paintball gun shot 8 years prior, and the metacarpo-phalangeal joint was amputated. He gradually developed mechanical allodynia and burning pain, and there were trophic changes of the thenar muscle and he reported coldness on his left hand and forearm. A neuroma was found on the left second common digital nerve and was removed, but his symptoms continued despite various conservative treatments including a morphine infusion pump on his left arm. We therefore attempted median nerve stimulation to treat the chronic pain. The procedure was performed in two stages. The first procedure involved exposure of the median nerve on the mid-humerus level and placing of the electrode. The trial stimulation lasted for 7 days and the patient''s symptoms improved. The second procedure involved implantation of a pulse generator on the left subclavian area. The mechanical allodynia and pain relief score, based on the visual analogue scale, decreased from 9 before surgery to 4 after surgery. The patient''s activity improved markedly, but trophic changes and vasomotor symptom recovered only moderately. In conclusion, median nerve stimulation can improve chronic pain from complex regional pain syndrome type II.     

腕管综合征患者正中神经区域外症状及其可能机制

腕管综合征(Carpal Tunnel Syndrome, CTS)是正中神经在腕部通过腕横韧带下方腕管处受压而出现的手部症状,是最常见的外周神经卡压神经疾病[1].一项欧洲流行病学调查显示,该病终生罹患风险为10%,在总体人群中患病率为2.7%[2].CTS的典型症状是手部正中神经分布区感觉异常、麻木、疼痛等,较大程度地影响患者的生活质量,在美国,其是工作日损失和员工赔偿金的主因之一[3].虽然CTS是正中神经损害导致的手部症状,但患者经常会有手部尺神经分布区不适以及其他正中神经区域外症状.为此,本文对CTS患者的临床表现特点,正中神经区域外症状特点,及其可能机制作一综述.     

重症肌无力患者体感诱发电位的研究

３０例ＭＧ患者作了正中神经Ｍ－ＳＥＰ额顶同步描记,有延髓以上ＣＮＳ功能异常１４例（４６．７％）,以一侧Ｐ２２波ＡＭＰ降低或消失最多见。８例治疗后复查,７例的异常恢复,１例临床好转但ＥＰ未变且对侧又异常。胸腺瘤术后３月始恢复。６例原ＥＰ正常者治疗后复查有１例一度又有异常。异常主要与症状及胸腺瘤有关。与ＥＥＧ结果比较一致,但阳性率明显为高。认为此项检查有助探讨ＭＧ的ＣＮＳ损害和指导治疗。     

环指感觉神经感觉传导速度在轻度腕管综合征诊断中的应用

目的 寻找诊断轻度腕管综合征(CTS)敏感的电生理检查方法。方法 临床症状、体征符合CTS,正中神经运动末端潜伏期正常的患者19例(29侧)和年龄性别相匹配的健康对照组23名(25侧),采用顺向性感觉神经传导速度(SCV)测定法分别测定环指(指4)正中神经和尺神经SCV,中指(指3)正中神经SCV。结果 环指尺神经SCV>45.2 m/s,正中神经SCV<44.1 m/s,和(或)尺神经SCV与正中神经SCV差值>8.1 m/s(x+σx),考虑符合CTS诊断。CTS组中指正中神经SCV测定异常率为66％,环指为76％,环指正中神经与尺神经SCV差值异常率为93％。环指刺激在8例(14侧)患者腕部正中神经处记录到双峰电位,但对照组均未见。结论 比较环指正中神经和尺神经SCV在鉴别轻度CTS方面是敏感的方法之一,在怀疑CTS时,该项检查可作为常规的电生理检查方法。     

Diagnostic specificity of sensory and motor nerve conduction variables in early detection of carpal tunnel syndrome

Summary In the carpal tunnel syndrome (CTS) sensory nerve conduction is more sensitive than motor conduction. However, 8%–25% of the sensory distal latencies in symptomatic hands may still be normal. A systematic study was made of the median, ulnar and radial orthodromic nerve conduction velocities (SNCV) stimulating each of the fingers separately. Four SNCVs from the median nerve, two SNCVs from the ulnar nerve and one from the radial nerve were obtained, and the ratio of the median to radial SNCV and the ratios of the median and ulnar SNCVs were estimated. The significance of these parameters in the diagnosis of the CTS was studied, and a rapid technique for the screening of nerve entrapment in the initial stages of the disease is proposed. Three hundred and seventy-five symptomatic hands were examined. Seventy-five hands showed normal distal latency, in which cases, however, the SNCV of the ring finger was always outside the normal range, while the SNCVs of the thumb, index and middle fingers were abnormal in 64%, 80% and 92% of cases respectively. The amplitudes of the sensory responses were the least sensitive of the parameters studied. Our results suggest that a study of the median nerve digital branch to the ring finger may be of value in providing an easily performed and rapid technique for screening an early median nerve entrapment at the wrist.     

A silver and gold technique for axons and axon-bundles in formalin-fixed central and peripheral nervous tissue

We have modified the reduced silver procedure of Liesegang and added a gold treatment. The technique has been successfully and routinely used to impregnate both peripheral and central nervous tissues of mice of different ages, and central nervous tissue of man. It was applied on conventionally (formalin) fixed and cryostat-cut material. In the periphery, nerves, individual axons, and sensory and motor endings stained a dark purple. In the brain, both bundles of axons and individual fine axonal branches were stained. When counterstained by a Nissl method, an excellent overall image of CNS structure is obtained.     

Median-ulnar nerve communications: electrophysiological demonstration of motor and sensory fibre cross-over

Summary In a 33-year-old female with carpal tunnel syndrome the presence of anomalous communications between median and ulnar nerves was electrophysiologically demonstrated in the forearm. Motor latencies from proximal and distal stimulation sites along the median nerve fibres to the abductor pollicis brevis were identical. Proximal latency increased after procaine infiltration of the ulnar nerve at the wrist. Normal latency to the abductor digiti minimi was obtained on stimulation of the median nerve at the elbow. Along the sensory fibres of the median nerve orthodromic conduction velocity was markedly slowed from digit III to the wrist and normal from the wrist to the elbow. On supramaximal stimulation of digit III a sensory response was also recorded from the ulnar nerve at the wrist. On stimulation of digit V a sensory potential was recorded from the median nerve at the elbow. This appears to be the first electrophysiological demonstration of an anomaly involving both the motor and sensory fibres of both the median and the ulnar nerves.

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Zusammenfassung Bei einer 33-jährigen Patientin mit einem Carpaltunnelsyndrom wurde das Vorhandensein einer abnormen Verbindung zwischen N. medianus und N. ulnaris am Vorderarm elektrophysiologisch nachgewiesen. Die motorische Latenzzeit vom Medianusstamm zum M. abductor pollicis brevis waren von proximalen und distalen Reizorten aus identisch. Die proximale Latenz nahm nach Procaine-Infiltration des Ulnarnerven am Handgelenk zu. Eine normale Latenz zum M. abductor digiti minimi wurde nach Stimulation des N. medianus am Ellbogen nachgewiesen.Die sensible orthodrome Leitgeschwindigkeit am Medianus war bei Reizung des Mittelfingers und Ableitung vom Handgelenk hochgradig verlangsamt, jedoch normal vom Handgelenk zum Ellbogen. Bei supramaximaler Reizung des Mittelfingers wurde auch vom Ulnarnerven am Handgelenk eine sensorische Antwort erzeugt. Bei Reizung des Kleinfingers wurde ein sensorisches Potential vom N. medianus am Ellenbogen abgeleitet.Unseres Wissens ist dies der erste Fall, in welchem elektrophysiologisch eine Anomalie sowohl der motorischen wie der sensiblen Fasern von Median- und Ulnarnerven nachgewiesen wurde.

     

刺激正中神经SEP中P_(22)波来源及其临床应用的再探讨

使用非头部参考电极在顶、额颅表同步描记正中神经体感诱发电位M-SEP,除N_(20)-P_(25)外,还可在额部记录到P_(22)-N_(30)波。分析了经CT、EEG或临床证实的额或/和顶叶病变者3组118人,并与年龄匹配的30名正常人对照;再分别麻醉中央后、前回前后经同样描记的10只家兔加以核对,对来源尚无定论的P_(22)波提出了多元性来源的见解,并根据其敏感性和恒定性,肯定了其临床应用价值,建议同步描记P_(22)波应作为M-SEP常规描记的一部分。     

60例腕管综合征患者的神经电生理检测与临床分析

目的 探讨腕管综合征(CTS)患者的神经电生理特征.方法 对临床症状、体征符合CTS的60例患者进行正中神经、尺神经的运动和感觉传导速度测定,及拇短展肌、小指展肌的肌电图检测.结果 60例患者中,双侧病变18例,单侧病变42例.60例CTS患者中78条正中神经感觉传导潜伏期均延长和感觉传导速度均减慢,60条正中神经感觉诱发波幅降低,74条正中神经运动远端潜伏期延长,4条正中神经运动远端潜伏期和诱发波幅正常.58块正中神经支配的拇短展肌呈神经源性损害.结论 神经电生理检查在CTS的诊断与鉴别诊断中有重要意义.     

Neurophysiological classification of carpal tunnel syndrome: assessment of 600 symptomatic hands

Following the AAEM electrodiagnostic guidelines, we developed a neurophysiological classification of carpal tunnel syndrome (CTS). Sixhundred hands with clinical CTS (mean age 51.4 yr., female/male ratio 5.5/1, right/left ratio 1.8/1) were prospectively evaluated and divided into six classes of severity only on the basis of median nerve electrodiagnostic findings: extreme CTS (EXT — absence of thenar motor responses), severe CTS (SEV — absence of sensory response and abnormal distal motor latency — DML), moderate CTS (MOD — abnormal digit-wrist conduction and abnormal DML), mild CTS (MILD — abnormal digit-wrist conduction and normal DML), minimal CTS (MIN — exclusive abnormal segmental and/or comparative study), and negative CTS (NEG — normal findings at all tests) Using this neurophysiological classification, the CTS groups appeared normally distributed (EXT 3% of cases, SEV 14%, MOD 36%, MILD 24%, MIN 21%, NEG 3%), and the age of patients and clinical findings appeared to be related to neurophysiological abnormalities. Significant differences in median neurophysiological parameters not included in the classification (such as palm-wrist sensory conduction velocity) were observed in the different CTS groups. The analysis of the groups showed that: 1) the majority of advanced cases (SEV and EXT) occurred in older patients (60–80 years), 2) most of the milder cases (MIN and MILD) occurred in young female patients. The aim of this study was to standardise the neurophysiological evaluation of CTS.This study was presented in part at the meeting Giornata Neurofisiologica Romana — Sindrome del tunnel carpale — Roma 27-Sept-96.     

A comparison of the excitability of motor axons innervating the APB and ADM muscles

Objective

Threshold tracking allows the non-invasive assessment of axonal excitability. This study aimed to determine whether axonal excitability of the motor axons of the median nerve (to APB) and ulnar nerve (to ADM) to the small muscles of the hands is sufficiently similar to be interchangeable; confirm the feasibility and reproducibility of ulnar studies and obtain control data for a young population for this site of stimulation.

Methods

Twenty normal subjects between the ages of 23–43 were studied using the TRONDF protocol of QTRACS, (©Prof Hugh Bostock, London). The median and ulnar nerves were stimulated at the wrist and the compound muscle action potentials were recorded from abductor pollicis brevis and abductor digiti minimi, respectively. Repeat studies were performed in four subjects to confirm reproducibility of the recordings.

Results

Stimulus intensity was greater and strength duration time constant was longer for the median nerve. Threshold electrotonus showed there was a greater change in threshold in the hyperpolarising direction for the median nerve compared with the ulnar nerve. There was however little difference in the recovery cycle and current threshold relationship.

Conclusions

Although recovery cycles and the current thresholds are similar for APB and ADM, there are definite differences in stimulus threshold, SDTC and threshold electrotonus which question the interchangeability of studies for these two sites.

Significance

This study demonstrates reproducibility of motor axonal excitability studies of the ulnar nerve at the wrist, provides young control data for this site of stimulation and suggests that although certain excitability indices are similar for the median nerve to APB and ulnar nerve to ADM there are definite differences making the interchangeability of the data questionable.     

Prolonged inhibition of rostral ventral lateral medullary premotor sympathetic neurons by electroacupuncture in cats

We have shown that electroacupuncture (EA) at the Neiguan-Jianshi (N-J) acupoints over the median nerve reduces myocardial ischemia by modulating the pressor response induced by application of bradykinin on the gallbladder. The present study was designed to investigate the neural substrate underlying the prolonged modulatory effect of EA on visceral afferent input into the rostral ventral lateral medulla (rVLM). Experiments were performed on ventilated anesthetized cats. Neuronal activity was recorded while either stimulating the splanchnic nerve or applying EA at the N-J acupoints. Thirty-three cells responsive to splanchnic nerve and median nerve stimulation were antidromically driven from the intermediolateral columns, T(2)-T(4), indicating their function as premotor sympathetic neurons. These neurons also received baroreceptor input demonstrating that they were cardiovascular sympathoexcitatory cells. Arterial pulse-triggered averaging and coherence analysis demonstrated a correlation between cardiac-related discharge activity with 2.8+/-0.3 Hz rhythms and arterial blood pressure. Stimulation (2 Hz, 1-4 mA, 0.5 ms) of the splanchnic nerve for 30 s evoked excitatory responses. These neuronal responses were reduced during and after 30-min stimulation of EA at the Neiguan-Jianshi acupoints. These splanchnic nerve-induced excitatory responses in neurons subjected to 30 min of EA were reduced by 68%. Iontophoresis of naloxone promptly reversed the EA-induced inhibitory effect by 52%. Neuronal activity in the rVLM induced by splanchnic nerve stimulation was reduced for 50 (or more) min after termination of EA in 7 of 12 rVLM neurons.Our results indicate that rVLM premotor sympathetic cardiovascular neurons receive convergent input from the gallbladder through the splanchnic nerve and N-J acupoints through the median nerves. Through an opioid mechanism, EA inhibits splanchnic nerve-induced excitatory responses of these rVLM neurons. Many of these neurons receiving convergent visceral and somatic input exhibit long-lasting inhibition by EA.     

Ultrasonography of palm to elbow segment of median nerve in different degrees of diabetic polyneuropathy

ObjectiveTo identify the relationship between the ultrasonographic cross-sectional area (CSA) of the median nerve and electrophysiologic findings in diabetic patients.MethodsSixty diabetic patients, 30 patients with carpal tunnel syndrome (CTS) and 30 healthy volunteers participated. The participants were divided into 4 groups: Control Group; Group I, diabetic patients without diabetic polyneuropathy (DPN); Group II, diabetic patients with DPN; and Group III, patients with CTS. Group II was subdivided into II-1 and II-2 according to DPN severity. The median nerve CSA was measured at 4 levels, and the wrist-to-forearm ratio (WFR) was calculated.ResultsThe median nerve CSAs were larger in Group II than in Group I and the Control Group. There were significant differences in the CSA between Group I and Group II-2 and between Group II-1 and II-2. There was no significant difference in the WFR among these groups. The CSAs at the wrist levels and WFR were significantly greater in Group III.ConclusionsThe median nerve CSA was greater in patients with DPN and was related to DPN severity. Diffuse increase in median nerve CSA without change in the WFR might be compatible with DPN. Ultrasonography could be applied for the diagnosis of DPN, especially in advanced cases.SignificanceUltrasonography might have value in the differential diagnosis of DPN and entrapment neuropathy.