Autonomic nervous system dysfunction in workers exposed to lead, zinc, and copper in relation to peripheral nerve conduction: a study of R-R interval variability.

Quantitative assessment of the autonomic neurotoxicity due to lead was undertaken by measuring variability in the electrocardiographic R-R interval (CVRR) in 16 male workers exposed to lead, zinc, copper, and tin and in 16 unexposed control subjects. Two component coefficients of variation in the R-R interval, the C-CVRSA (respiratory sinus arrhythmia) and C-CVMWSA (Mayer wave related sinus arrhythmia), were examined; these indices are considered to reflect parasympathetic and sympathetic activities, respectively. Maximal motor and sensory conduction velocities (MCV and SCV) in the median nerve were also measured. In the 16 exposed workers, blood lead concentrations ranged from 16 to 60 (mean 34) micrograms/dl. The CVRR and C-CVRSA were found to be significantly reduced in the workers with elevated lead, zinc, and copper absorption as compared to unexposed control subjects; also, the MCV and SCV were significantly slowed. The C-CVMWSA was not significantly reduced, and was positively related to plasma zinc concentrations. No significant relationships were found between indicators of lead and copper absorption and these electrophysiological measurements. These data suggest that subclinical toxicity of lead occurs in the parasympathetic component of the autonomic nervous system as well as in the peripheral nerves. Zinc may antagonize the autonomic nervous dysfunction caused by lead.     

Subclinical cervico-spino-bulbar effects of lead: a study of short-latency somatosensory evoked potentials in workers exposed to lead, zinc, and copper

Subclinical central and peripheral nervous system dysfunction among lead-exposed workers was studied by measuring short-latency somatosensory evoked potentials (SSEP) and maximal motor and sensory nerve conduction velocities (MCV and SCV) following stimulation of the median nerve at the wrist. The examinations were conducted in 20 gun-metal foundry workers exposed to lead, zinc, copper, and tin, with blood lead (BPb) concentrations of 16 to 64 micrograms/dl (mean, 42 micrograms/dl). The interpeak latency of SSEP in the cervico-spino-bulbar region [N9(Erb)-N13 latency] was significantly prolonged, and the MCV and SCV in the forearm were significantly slowed. Multiple regression analysis revealed that the yield of urinary lead following challenge with calcium disodium ethylenediamine tetraacetate (CaEDTA) and packed red blood cell volume were the major factors associated with the prolongation of SSEP latency in the cervico-spino-bulbar region. Similarly, the interpeak latency in the upper central nervous system (N13-N20 latency) was inversely related to the zinc concentration in erythrocytes; latency up to the Erb's point [N9(Erb) latency], which reflects conduction time in a long pathway of the sensory median nerve, was inversely related to urinary zinc level; the MCV and SCV in the palm were positively related to erythrocyte zinc concentration and plasma copper concentration, respectively. These findings suggest that the subclinical neurophysiological effects of lead occur not only in peripheral nerves but also in the central nervous system. It appears that zinc antagonizes the central and peripheral neurologic dysfunction caused by lead; similarly, copper antagonizes the peripheral sensory nerve dysfunction.     

Autonomic and peripheral nervous system dysfunction in workers exposed to mixed organic solvents

Summary To assess possible solvent-induced dysfunction of the autonomic and peripheral nervous systems, 11 solvent-exposed workers and 11 age-matched unexposed controls were examined using the coefficient of variation in electrocardiographic R-R intervals (CV_RR) and the distribution of nerve conduction velocities (DCV). Two components of CV_RR, i.e., the C-CV_RSA and CCV_MWSA, were also examined, which are considered to reflect parasympathetic and sympathetic activities, respectively. The workers had been occupationally exposed to toluene and/or solvent mixtures such as thinners, for 35–360 months. In the solvent-exposed workers, the CV_RR and C-CV_RSA were significantly reduced compared with unexposed controls. Similarly, the faster velocities of the DCV and median nerve conduction velocities were significantly slowed. The reduction in the CV_RR was significantly correlated with duration of exposure in the solvent-exposed workers. These data, despite the small sample size and the variety of organic solvents, suggest that organic solvents may affect both the faster myelinated nerve fibers and autonomic nervous activity (principally, parasympathetic component).     

Effects of pesticides on the peripheral and central nervous system in tobacco farmers in Malaysia: studies on peripheral nerve conduction, brain-evoked potentials and computerized posturography

We examined the effects of pesticides on the central and peripheral nervous system in the setting of a tobacco farm at a developing country. Maximal motor and sensory nerve conduction velocities (MCV and SCV, respectively) in the median, sural and tibial nerves, postural sway, and brain-evoked potentials (auditory event-related and visual-evoked potentials) were measured in 80 male tobacco farmers and age- and sex-matched 40 controls in Kelantan, Malaysia. Median SCV (finger-wrist) in farmers using Delsen (mancozeb, dithiocarbamate fungicide), who showed significant decrease of serum cholinesterase activities, were significantly lower compared with the controls. Sural SCV in farmers using Fastac (alpha-cypermethrin, pyrethroid insecticide) and median MCV (elbow-wrist) in farmers using Tamex (butralin, dinitroaniline herbicide) were significantly slowed compared with their respective controls. In Delsen (mancozeb, dithiocarbamate) users, the power of postural sway of 0-1 Hz was significantly larger than that in the controls both in the anterior-posterior direction with eyes open and in the right-left direction with eyes closed. The former type of sway was also significantly increased in Tamaron (methamidophos, organophosphorus insecticide) users. In conclusion, nerve conduction velocities and postural sway seem to be sensitive indicators of the effects of pesticides on the central and peripheral nervous system.     

Peripheral somatic and autonomic nerve functions in patients with occupational vibration disease

In order to evaluate the functions of the peripheral somatic nerve and autonomic nerve in patients with occupational vibration disease objectively and quantitatively, four examinations were performed on twenty 44-63 yr old patients with occupational vibration disease and their total operating time ranged from 5,000 to 43,750 h. 1) Motor nerve conduction velocities (MCV) and sensory nerve conduction velocities (SCV) of the ulnar and median nerves were measured using conventional methods. 2) Electrogustatory thresholds under the controlled area of the chorda tympani nerve were measured by Tomita's method using an electrogustometer (610-M, M.E.C.). 3) Dopamine-beta-hydroxylase (DBH) activity in blood was assayed by the photometric assay of Nagatsu and Udenfriend. 4) Coefficient of variation of R-R interval in ECG (CVR-R) was measured after 15-min-resting in supine position by using a R-R interval analyzer (Autonomic R 100, M.E.C.). The results of these examinations were compared with those of special examinations for the diagnosis of vibration disease. In patients with occupational vibration disease, MCV and SCV of the ulnar and median nerve were lower in value than those in age-matched healthy controls. In particular, MCV of the ulnar nerve, MCV and SCV of the median nerve were significantly lower in the patients than in the controls. Nerve conduction velocities were significantly correlated with skin temperature and nailpress test, though diminished nerve conduction velocities observed in vibration disease patients were considered to be attributable to peripheral circulatory disturbance.(ABSTRACT TRUNCATED AT 250 WORDS)     

奥克托今对作业工人周围神经传导速度的影响

目的 探讨奥克托今（HMX）对作业工人周围神经传导速度的影响。方法 选取76名接触HMX的作业人员为接触组。并以38名不接触HMX和神经毒物质的健康人作为对照。按标准方法测定正中神经，尺神经，腓总神经运动传导速度和感觉传导速度及运动潜伏期，同时测定车间空气中HMX浓度。并对不同接触浓度和不同作业工龄进入地比较。结果 接触组腓总神经远端运动潜伏期明显延长，正中神经近端感觉传导速度明显减慢，高浓度接触组正中神经，尺神经远端感觉神经潜伏期较低浓度组明显延长。20年以上工龄组正中神经，尺神经，腓总神经运动传导速度和正中神经感觉传导速度明显减慢，接触组腓总神经运动传导速度异常检出率明显高于对照组。结论 HMX对下肢神经传导速度影响明显，并与接触。浓度和作业工龄长短关系密切，但HMX影响周围神经传导速度的机制还不清楚，是否与神经递质释放有关，有待进一步探讨。     

Peripheral nerve conduction velocities in chain-saw operators.

The motor, sensory and mixed nerve conduction velocities of median and posterior tibial nerves were measured in seventeen forest workers engaged in chain-saw operation for 2 to 16 yr (mean 12 yr). The conduction velocities were significantly diminished in the distal part of the upper limb. The sensory nerve conduction velocities (SCV) of the median nerve at the part of the palm were slow in 12 workers; longer residual latency, in 6; and the mixed nerve conduction velocities slowed at the part of the forearm, in 6. From the relationships of the nerve conduction velocities to white finger attacks and electromyograms, it was assumed that vibration directly affected the distal part of the sensory and motor nerve fibers in the upper limbs, and that the diminished SCV in the palm was one of the most sensitive indices of vibration effects.     

苯对接触工人外周神经传导速度的影响

[目的 ]探讨苯对周围神经系统的影响。 [方法 ]对苯接触观察对象 13人、苯中毒者 14人为接触组 ,另选无毒物接触史的工人 48人为对照组 ,应用神经肌电图检测方法进行运动和感觉神经传导速度测定。 [结果 ]接触组尺神经及下肢腓浅神经感觉传导速度显著慢于对照组 (P <0 .0 5 ) ,其余所检神经传导速度与对照组相比差异无显著性 (P >0 .0 5 )。接触组下肢腓浅神经感觉传导速度异常率显著高于对照组。正中神经远端潜伏期较对照组明显延长 (P <0 .0 5 )。[结论 ]苯对周围神经存在一定程度的影响 ,感觉神经传导速度对于诊断周围神经病的价值优于运动神经传导速度     

Autonomic and peripheral nervous system dysfunction in workers exposed to hand-arm vibration: a study of R-R interval variability and distribution of nerve conduction velocities

Summary To assess the effects of vibrating-tool operation on the autonomic and peripheral nervous system, we measured the variability in the electrocardiographic R-R interval (CV_RR) and the distribution of nerve conduction velocities (DCV) in 24 men who were vibrating-tool operators and in 17 healthy adult men (control group). Of the 24 tool operators, 13 had a history of vibration-induced white finger [VWF(+) group] and 11 had no such history [VWF(–) group]. Two components of CV_RR, i.e. C-CV_RSA and C-CV_MWSA, which have been considered to reflect parasympathetic and sympathetic activities, respectively, were also examined. Both the CV_RR and the C-CV_RSA in the VWF(+) group and the CV_RR in the VWF(–) group were found to be significantly depressed as compared with the control values; moreover, a significant difference in the C-CV_RSA was observed between the VWF(+) group and the VWF(–) group. The faster DCVs and the sensory median nerve conduction velocity were significantly slowed in the VWF (+) and VWF(–) groups. The C-CV_MWSA was significantly correlated with most of the DCV parameters and with the median nerve conduction velocities in all 24 vibrating-tool operators. These data suggest that operation of vibrating tools, which involves exposure to combined stressors of local vibration, heavy work, climate, and noise, affects both the faster myelinated nerve-fiber activity and the parasympathetic activity; the sympathetic activity at rest in workers exposed to hand-arm vibration may be related to depression of peripheral nerve conduction.     

20名手传振动作业工人的神经肌电图分析

目的探讨手传振动对作业工人周围神经的损害情况。方法对20名从事手传振动作业工人和30名无接触职业危害的健康成人进行神经肌电图检查分析。结果①MCV检测结果显示正中神经运动传导远端潜伏期延长（占85．0％）、MCV减慢（占35．0％）（P〈0．01）;②SCV捡测结果显示正中神经SCV减慢（占40．0％）、尺神经SCV减慢（占30．0％）（P〈0．01）;③肌电图检查结果表现为小力收缩时多相电位增多（占42．5％）及安静时出现纤颤电位（占15．0％）（P〈0．05或P〈0．01）。结论振动对作业工人周围神经损伤明显,神经肌电图检查最早表现为正中神经运动传导远端潜伏期延长,随着损伤加重,进一步出现神经传导速度减慢,运动和感觉同时受累。     

Auditory event-related potential (P300) in relation to peripheral nerve conduction in workers exposed to lead, zinc, and copper: effects of lead on cognitive function and central nervous system.

By measuring auditory event-related potential (P300 and N100) and peripheral nerve conduction velocities, the subclinical effects of lead, zinc, and copper on the central and peripheral nervous system were examined in 22 male gun metal foundry workers exposed to these metals. Their blood lead (BPb) concentrations ranged from 12 to 59 micrograms/dl (median 30). Control subjects were 14 healthy workers, employed at the same factory, who had never been occupationally exposed to these metals. In the gun metal foundry workers, the latencies of P300 and N100 were significantly prolonged; the latency of P300 was significantly correlated with BPb concentrations and other indicators of lead absorption. Similarly, the maximal motor and sensory conduction velocities in the radial and median nerves were significantly slowed, and were significantly correlated with indicators of lead absorption. The data suggest that lead exposure at low levels affects cognitive and central auditory nervous system function together with peripheral nerve conduction.     

Effects of lead,zinc and copper absorption on peripheral nerve conduction in metal workers

Summary To examine the antagonistic effects of lead, zinc and copper on the nervous system in man, we measured maximal motor and sensory conduction velocities (MCV and SCV, respectively) in the distal radial and median nerves in 20 gun metal founders with asymptomatically increased absorption of these metals [blood lead concentrations ranged from 16 to 64 g/dl (mean 42)]; and analyzed metal effects on nerve conduction by multiple regression analysis. The MCVs in the radial and median nerves and the SCV in the forearm segment of the median nerve were significantly slowed; indicators of lead absorption (urinary delta-aminolevulinic acid and coproporphyrin) were inversely correlated with the SCV in the radial nerve. The SCVs in the radial nerve and in the hand segment of the median nerve, which were not significantly slowed, were positively related to indicators of copper absorption (plasma or erythrocyte copper). The SCV in the radial nerve was also positively related to the indicator of zinc absorption (plasma zinc); similarly, the MCVs in the radial and median nerves were positively related to the indicators of zinc absorption (erythrocyte or urinary zinc). These findings suggest that copper and zinc antagonize the subclinical effects of lead on peripheral nerve conduction velocities; the conduction velocity in the distal radial nerve is sensitive not only to asymptomatic lead absorption but also to zinc and copper absorption.     

Reversible nerve lesions after accidental polychlorinated biphenyl exposure

Several capacitors containing polychlorinated biphenyls (PCB) exploded in a cardboard plant. During the accident, and in the clearing work, several workers were in probable contact with PCB and/or its degradation products. Nausea, intense perspiration, and headache were acute symptoms, which cleared quickly. The 15 men with the greatest exposure were studied neurophysiologically twice, namely, two and six months after the explosion. Motor conduction velocities (MCV) of the right median, ulnar, and peroneal nerves; sensory conduction velocity (SCV) of the right sural nerve; and distal SCVs of the right median and ulnar nerves were measured with skin electrodes. Thirty male workers with a similar age distribution served as referents. Two months after the explosion all SCVs and distal SCVs were slower in the exposed men, and still six months after the explosion the distal SCV of the ulnar nerve and the SCV of the sural nerve were slightly slower among the exposed. However, clear improvement occurred in the distal SCVs during the follow-up. As in many toxic distal axonopathies, the distal SCVs were reversibly impaired after an accidental exposure to PCB fumes. PCB seem to exhibit neurotoxic properties in humans.     

Effects of occupational use of vibrating tools in the autonomic, central and peripheral nervous system

Objectives:The objective of this study was to clarify the autonomic, central and peripheral nervous effects of vibrating-tool operation. Methods: The ECG R-R interval variability (CV_RR), including the C-CV_HF, C-CV_LF (two component CVs of the CV_RR reflecting parasympathetic and sympathetic activities, respectively) and the power spectral densities (PSD_HF and PSD_LF) after autoregressive analysis, short-latency somatosensory evoked potentials (SSEP), distribution of nerve conduction velocities (DCV), and median and radial nerve conduction velocities (NCVs) were measured in 17 vibrating-tool operators and the same number of age-matched control subjects. Some of the operators complained of white finger even in summer as soon as they arrived at the cold workplace. Design: The significance of the differences in neurophysiological data between the exposed and unexposed groups and the associations between these data in the former were investigated. Results: The CV_RR, C-CV_HF and PSD_HF were significantly lower in the vibrating-tool operators than in the matched controls. The N9–N13 interpeak latency of the SSEP, i.e., conduction time of the cervico-spinobulbar pathway, in the operators was significantly prolonged as compared with the controls; the faster velocities of the DCV and the NCVs were significantly slowed in the operators. The N9–N13 interpeak latency in the operators was significantly correlated with the C-CV_HF. Conclusion: Complex stressors of local vibration, cold, noise and heavy work, seem to affect the cervico-spinobulbar, parasympathetic and peripheral nerve functions. Also, parasympathetic hypofunction may imply a consequence in brainstem pathology induced by cold exposure in addition to vibration. Received: 2 July 1996 / Accepted: 17 January 1997     

Psychological performance in relation to central and peripheral nerve conduction in workers exposed to lead, zinc, and copper

Psychological performance was examined in relation to central and peripheral nerve conduction by means of the Wechsler Adult Intelligence Scale test, short-latency somatosensory-evoked potential (SSEP), and median nerve conduction velocity in 19 male gun-metal foundry workers exposed to lead, zinc, and copper. (Their blood lead concentrations--ie, 16-64 micrograms/dl with a mean of 42--and plasma zinc and copper concentrations were significantly higher than those of control subjects). In these workers, the score of picture completion (psychological performance) was significantly low; indicators of lead absorption, but no indicators of zinc and copper absorption, were significantly correlated with this score. The score of picture completion was significantly correlated with the N11-N13 latency of SSEP (conduction time in the spinobulbar region) in the workers; their N11-N13 latency, together with the N9 and N9-N11 latencies, was significantly prolonged and was significantly correlated with indicators of lead absorption. Furthermore, their maximal motor and sensory conduction velocities of the median nerve were significantly slowed. It is concluded that both psychological performance and central and peripheral nerve conduction may be impaired in lead-exposed workers with BPb's below approximately 60 micrograms/dl.     

Arsenic in drinking water and peripheral nerve conduction velocity among residents of a chronically arsenic-affected area in Inner Mongolia

BACKGROUND: It remains unclear whether chronic ingestion of arsenic in drinking water affects the peripheral nervous system. We examined the effects of arsenic exposure on nerve conduction velocity using electromyography. METHODS: A cross-sectional study was conducted of a population living in an arsenic-affected village in Hetao Plain, Inner Mongolia, China. A total of 134 (93.7%) of 143 inhabitants took part in the study, and 36 (76.6%) of 47 inhabitants in a low-arsenic exposed village were recruited as a control group. Of the participants, 109 inhabitants in the arsenic-affected village and 32 in the low-arsenic exposed village aged > or =18 years were used for the analyses. An expert physician performed skin examinations, and median nerve conduction velocity was examined by electromyography. Arsenic levels in tube-well water and urine were measured. A mean level of arsenic in tube-well water in the arsenic-affected village was 158.3 microg/L, while that in the low-arsenic exposed village was 5.3 microg/L. RESULTS: No significant differences in the means of the motor nerve conduction velocity (MCV) and sensory nerve conduction velocity (SCV) were observed in relation to arsenic levels in tube wells, urine, and the duration of tube-well use. Further, no differences in mean MCV or SCV were found between the subjects with and without arsenic dermatosis, with mean SCV of 52.8 m/s (SD 6.3) in those without and 54.6 m/s (5.2) in subjects with arsenic dermatosis (p=0.206). CONCLUSION: These findings suggest that chronic arsenic poisoning from drinking water is unlikely to affect nerve conduction velocity, at least within the range of arsenic in drinking water examined in the present study.     

砷作业工人神经电生理研究

本文对50名砷中毒、25名砷接触工人进行了肌电和神经传导速度的检查。对42名对照者仅作了神经传导速度的检查。发现慢性中毒组纤颤波的检出率为34%,砷接触组为8%。砷中毒组的正中神经,腓肠神经和尺神经SCV 显著减慢;尺神经MCV 延长;而砷接触组仅见尺神经MCV 减慢。以神经传导速度最低限((?)-2SD)进行分析,其减慢的检出率较高。长期接触砷可致周围神经源性损害,恢复较慢,感觉神经传导速度减慢似为多见。神经电生理的测定可作为砷中毒的一项诊断指标,可检出早期砷对周围神经的损害。     

75例2型糖尿病患者神经传导速度检测分析

目的:对2型糖尿病患者进行神经传导速度(NCV)检测,为糖尿病并发周围神经病变的早期诊断与治疗提供一项客观检测指标.方法:采用Viking IV肌电/诱发电系统仪对75例2型糖尿病患者的运动神经传导速度(MCV)和感觉神经传导速度(SCV)进行测定.结果:75例共测定周围神经300条,总异常率为54.3%,其中SCV的异常率(63.3%)高于MCV的异常率(45.3%),异常率比较有非常显著性差异(x2=9.79,P＜0.01).NCV异常率与年龄、上下肢无明显关系,而与病程长短有关.结论:NCV的改变是诊断糖尿病周围神经病变重要的早期客观指标,可作为糖尿病患者常规检查项目之一.     

Determination of the distribution of nerve conduction velocities in chain saw operators.

By measuring the distribution of conduction velocities (DCV) in sensory fibres of the median nerve, the effects of local vibration on all faster and slower large myelinated nerve fibres were examined in 10 male chain saw operators (three operators had frequent attacks of white finger; the attacks were only occasional in four and negative in three). All parameters of DCV, and conventional sensory nerve conduction velocity were significantly slowed in the chain saw operators. It is suggested that local vibration affects the faster and slower nerve fibres; parameters of the DCV are sensitive indicators of both the neurological and vascular effects.     

Determination of the distribution of nerve conduction velocities in chain saw operators

By measuring the distribution of conduction velocities (DCV) in sensory fibres of the median nerve, the effects of local vibration on all faster and slower large myelinated nerve fibres were examined in 10 male chain saw operators (three operators had frequent attacks of white finger; the attacks were only occasional in four and negative in three). All parameters of DCV, and conventional sensory nerve conduction velocity were significantly slowed in the chain saw operators. It is suggested that local vibration affects the faster and slower nerve fibres; parameters of the DCV are sensitive indicators of both the neurological and vascular effects.