Effect of Manganese on the Conduction Velocity of Peripheral Nerves in Exposed Workers
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Objective: To study the effect of the manganese exposure on the conduction velocity of peripheral nerves.Methods: Eighty-one subjects with manganese exposure as a case group and 82 normal workers as a control group.The conduction velocity of peripheral nerves was examined by electromyography.(Results:) The results showed that there was a significant difference in the peripheral conduction velocity in which the movement conduction velocity was much slower,the F wave shortest latency and the distal latency was longer in the case group(P0.05).Conclusion: Manganese was harmful to not only the central nerve system but also the peripheral nerve system.The peripheral nerves conduction velocity can be used as a reference parameter for diagnosis of the chronic manganese intoxication.Keywords:
Peripheral Nervous System
F wave
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Background and Aim: Motor nerve conduction studies help to understand the functional status of the peripheral and central nerves. Some of the studies in industrial workers have correlated the incidence of carpal tunnel syndrome with obesity and studied the function of the median nerve alone. Therefore, this study was aimed at assessing nerve conduction of major peripheral nerves in the obese individual without any comorbid condition or systemic complication. Methods: Upon meeting the inclusion and exclusion criteria, 52 age‑matched subjects were included in the study. They were divided into two groups (25 in control and 27 in study group; obese) based on their body mass index. Motor nerve conduction parameters (standardized distal motor latency in ms, amplitude of compound muscle action potential in mV and motor nerve conduction velocity in m/s) were recorded and the difference in these parameters between the groups was assessed using independent t‑test. Results: All the parameters depicted decreased motor conduction velocity in peripheral nerves (median, ulnar, tibial and common peroneal) in obese individuals compared with the control group. There was a significant prolongation of latency in all nerves and decrease in amplitude except in the tibial nerve. There was also a significant decrease in conduction velocity of tibial nerve in obese subjects compared to controls. Conclusion: From the present study, we observe that in obesity, there are increase in motor nerve latencies, decrease in the amplitude of action potentials and conduction velocity, which indicate slow transmission in peripheral nerve fibers.
Motor nerve
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Nerve conduction velocity and the amplitude of nerve and muscle action potentials have been measured in the median and anterior tibial nerves of normal adult and infant baboons. The effect of altered temperature on velocity has also been investigated. Seven adult baboons were intoxicated with acrylamide. In animals given 10-15 mg/kg/day, the gradual development of a peripheral neuropathy was accompanied by a decline in the amplitude of both muscle and nerve action potentials. There was also a gradual fall in conduction velocity. In some cases maximal motor velocity in the median nerve fell by as much as 34%, and in the anterior tibial nerve by as much as 49%, the largest falls being seen in animals showing the greatest reductions in response amplitude. Histological studies, reported elsewhere, have shown that the main pathological change in our animals was a degeneration of the peripheral nerves, with little demyelination. Fibre diameter histograms indicated that large fibres were particularly severely affected, and it seems likely that the reduced maximal conduction velocities were due to this selective loss of large-diameter fibres.
Tibial nerve
Sensory nerve
Motor nerve
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Conduction velocity from spinal cord to axilla (estimated using the F wave) has been compared with conduction velocity from axilla to wrist (measured in the conventional manner) in the motor fibres of the ulnar nerve in 17 controls subjects and in 11 patients with the Guillain-Barré syndrome (GBS). In the patients with GBS the conduction velocity was, in general reduced to a similar extent in both the proximal and the distal portions of the motor fibres, suggesting that the disease process is usually diffuse. In two patients, however, the conduction velocity in the proximal segment was disproportionally reduced and in one of these the conduction velocity in the distal segment was normal. It is concluded that the estimation of conduction velocity in the proximal segments of motor nerves may be of value in the assessment of patients with GBS.
F wave
Axilla
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Objective To observe the characteristics of electroneurography in type 2 diabetic patients with peripheral neuropathy. Methods The motor conduction velocity (MCV) of median, ulnar, tibial and peroneal nerves and the sensory conduction velocity (SCV) of median, ulnar and sural nerves were measured in 157 patients with type 2 diabetes mellitus. Results There were statistically significant differences in three parameters (latency, amplitude and nerve conduction velocity) between type 2 diabetic patients and normal subjects (P0.05). The frequency of abnormality rate in three parameters: (distance) latency(distance) amplitudenerve conduction velocity. The abnormality rates of three parameters of sensory nerves were higher than those of motor nerves; those of lower extremities were higher than those of the upper ones and those of the sural nerve were the highest. Conclusion The measurement of nerve conduction velocity may be helpful in the early diagnosis of peripheral neuropathy in diabetic patients.
Electroneuronography
Abnormality
Sural nerve
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Sensory and motor nerve conduction velocities in median and ulnar nerves of both upper limbs were examined in 30 forest-workers, felling trees with the aid of the mechanical saws, and demonstrating symptoms and signs of vibratory disease. A distinct decrease of the conduction velocity of sensory fibres and reduction of the nerve action potential amplitude of the examined nerves were found in these patients in comparison with the control group. Mean motor conduction velocity and distal motor latency of both nerves were included in the norm. No relationship occurs between the length of the work, time and the degree of the disorder of the sensory nerve conduction. The degree of the lesion of sensory fibres depends more on an individual susceptibility than on the length of the work time of workers exposed to local vibration.
Sensory nerve
Motor nerve
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Subclinical infection
Lead (geology)
Motor nerve
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Objective:To observe the motor nerve conduction block (CB) in patients with diabetic peripheral neuropathy(DPN),and the relationship between CB and other electroneurophysiological indexes.Methods:The electroneurophysiological data of 346 patients with diabetes mellitus,including motor nerve conduction velocity(MCV),F-response,sensory nerve conduction velocity(SCV),were analyzed retrospectively,and the amplitude and wave area of the compound muscle action potential(CMAP) elicited by stimulating the proximal nerve were compared with those elicited by stimulating the distal nerve so as to determine whether the CB exist or not.Results:①The conduction block was observed in 57 patients out of 346 ones with diabetic peripheral neuropathy,at a rate of 16.5%,sixty-two nerves showed abnormality in 1345 nerves detected(4.6%).The abnormality rate was the highest in tibial nerve.②The abnormality rate of SCV,F-response and MCV was 52.9%,47.4% and 45.1% orderly.③67.9% of all nerves with conduction block were accompanied by the prolongation of F wave latency and/or the decrease of F wave conduction velocity, 32.1%of them showed an increase of F-chronodispersion.Conclusions:Motor nerve conduction block might be observed in some patients with diabetes mellitus.The detection rate of conduction block might be the highest in tibial nerve.The motor nerve conduction block might be mostly accompanied by the abnormality of the other indexes of MCV.
F wave
Abnormality
Motor nerve
Sensory nerve
Tibial nerve
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Objective The aim is to study the effect on the conduction velocity of the peripheral nerve and biological indexes in workers exposed to lead. Methods In 66 observed subjects and 40 persons as the control group, the conduction velocity of peripheral nerve was examined by electromyography and several biological indexes were tested. Results The sense conduction velocity (MCV,SCV) of the median nerve and ulnar nerve was much slower and the distal sense latency( SL) of sural nerve was longer in 10 years workers than in 10 years controls (P 0. 05). Biological indexes PbB ,ZPP,EFP, Hb and PbU were different between 10 years and 0 years groups. The abnormal rate of the conduction velocity of the peripheral nerves and biological indexes in 10 years group has no more significant difference than in 10 years group, but the relative risk is 4. 1 and 5.3 times higher, respectively. Conclusion Lead is harmful to the peripheral nerve system in workers exposed for a long term.
Sural nerve
Lead (geology)
Nerve conduction study
F wave
Peripheral Nervous System
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Alterations in peripheral nerve impulse conduction during cooling were investigated in 7 surgical patients. A significant association between maximum conduction velocity and mean nerve temperature was found for peroneal nerve. Conduction velocity fell from 49.6 m./second at 35.5° C to one-half (25.9 m./second) at 23.5° C. and to one-fourth (12.1 m./second) at 21.5° C Conduction velocity decreased linearly at a rate of 1.84 m./second/degree centigrade between 36° and 23° C. (P
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The peripheral nerve conduction velocity between the wrist and elbow of the right upper limb and the relationship between this parameter and biochemical parameters for workers occupationally exposed to lead were studied. The results showed that nerve conduction velocity could be altered by lead exposure. The nerve conduction velocity was decreased when the exposure level was 0.0652 mg/m3 (time-weighed average), and it slowed further in proportion to increasing exposure levels. There was a negative correlation between the nerve conduction velocity and the length of exposure. A decrease in the nerve conduction velocity was noted after less than three years of exposure to lead. There was a close relationship between the nerve conduction velocity and the level of lead in the blood; the nerve conduction velocity decreased proportionally with increasing blood lead levels. The blood lead level associated with a change in the nerve conduction velocity was less than 40 micrograms/100 ml (less than 1.9 mumol/l). No correlation between the nerve conduction velocity and the amount of metabolites of porphyrin was found. The measurement of nerve conduction velocity can be used as one of the sensitive criteria for the early detection of the toxic effects of lead.
Lead (geology)
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