Nerve Conduction Velocity Measurements Research Articles

Development of the Improved Apparatus for the Nerve Conduction Velocity Measurement

Development of the Improved Apparatus for the Nerve Conduction Velocity Measurement

Matched filters in nerve conduction velocity estimation.

The evoked response signal-to-noise ratio in peripheral sensory nerves is of the order of one or less. To reduce noise induced errors in the nerve conduction velocity measurement, signal averaging is employed. The number of responses required depends upon the signal-to-noise ratio and the acceptable error. It is proposed to use maximum likelihood estimators to improve the signal-to-noise ratio and hence, reduce the number of responses required. The matched filter and generalized cross correlator are studied and noise performance equations obtained. It is shown that the matched filter offers a 6.8 dB improvement over the conventional 5 kHz band-limiting filter. It is further shown that the matched filter as a prefilter in the generalized cross correlator gives the optimum correlator configuration for the low signal-to-noise ratio case. These results are verified with experiments.

Measurement of the motor nerve conduction velocity: precise method of estimating maturity in newborn.

Summary. During the period from 1 October 1979 to 31 January 1981, 548 estimations of maturity were made on 523 infants at the Department of Medical Obstetrics of the Neukolln Hospital in Berlin, using the motor nerve conduction velocity (NCV) of the ulnar nerve combined with the Farr system. The mean value of the NCV increases from 13.0 m/s in the 33rd week of gestation to 30.4 m/s in the 44th week. Over the whole range the NCV showed a highly significant correlation (r=0.946, P<0.00001) with the gestational age of the infant, whereas the Farr system deviated strongly in a false positive direction up to the 38th week of gestation. The measurement of the NCV of the ulnar nerve is a simple and very precise postpartum estimation of the gestational age.

Nerve conduction velocity measurement of dorsal nerve of penis in normal and impotent males

Erection is dependent on peripheral and central neural influences. Both systems are open to electrophysiologic assessment in impotent males. Peripheral function can be assessed by measuring the conduction velocity in the dorsal nerve of the penis, and central pathways by measuring the cortical pudendal evoked response. These tests can be further supplemented by recording of nocturnal penile rigidity and by Doppler recording of penile blood flow to provide accurate causal delineation.

N-Hexane-induced changes in nerve conduction velocities and somatosensory evoked potentials.

Fifteen women from a shoe factory were examined clinically and their cerebral evoked responses to 256 electrical stimulations of the median nerve were averaged. Neurophysiological investigations included maximal motor (MCV) and distal sensory (dSCV) nerve conduction velocity measurement on ulnar, median, and peroneal nerves. A referent group was composed of 15 age-matched women without exposure to neurotoxic chemicals. MCVs and dSCVs of the exposed workers were significantly reduced vs referents, while P15 and N20 components of the somatosensory evoked potentials (SEP) showed an increased latency. A negative linear relationship was found between dSCV and P15 latency. However, two subjects with an abnormally low dSCV showed normal SEP latency, and two other subjects displayed abnormal SEP latency, while their dSCV was in the normal range. Therefore, SEP investigation may give additional information on nervous system function, even in subjects with peripheral neuropathy. The later SEP components were much flatter in the exposed than in the referent group, suggesting some neurotoxic effects of n-hexane on the central nervous system too.

Effect of experimental folate deficiency on lipid metabolism in liver and brain.

1. Rats were given a purified folate-deficient diet containing 5 g succinylsulphathiazole/kg for 4-5 months in two experiments. Control rats were supplemented with folic acid in the drinking-water. 2. Weight gain was much below normal in the folate-deprived rats after the first month. Very low folate levels were recorded in blood, liver and peripheral nerve (12-33% of control). In the central nervous system, including the cerebrospinal fluid, the folate depletion was less conspicuous (50-80% of control). Only marginal signs of anaemia were found and no signs of neurological dysfunction were detected, using nerve conduction velocity measurement and co-ordination tests. 3. Light and electron microscopy of the folate deficient liver revealed fatty infiltration, and enlargement of liver parenchymal cells, nuclei and nucleoli. There was often a considerable amount of bile ductular cells in the lobuli but no cirrhosis. The morphological changes resembled those observed in choline deficiency. 4. Phospholipid N-methylation in liver was depressed in folate-deficiency. This was probably due to a decreased availability of S-adenosylmethionine caused by the low concentrations of methylated folate in liver. Intraperitoneal administration of methionine did not normalize phospholipid methylation. 5. In folate deficiency the proportion of ethanolamine phosphoglyceride in liver was increased at the expense of choline phosphoglyceride, which is consistent with a decreased phospholipid methylation. Also an increase in liver triacylglycerol was noted, in accordance with the morphological observations. Brain lipid composition was unchanged. 6. After the injection of labelled ethanolamine, isotope accumulated in liver phosphoethanolamine in folate deficiency, probably due to an impairment of the CTP:ethanolaminephosphate cytidylyltransferase (EC 2.7.7.14) reaction. The mechanism of this impairment is discussed. 7. Although the low concentrations of folate was the main nutritional change in the deprived animals, changes with respect to vitamin B12 and maybe also choline cannot be excluded. We conclude that some of the changes in folate deficiency, i.e. fatty liver and decreased biosynthesis of liver phospholipids may be due to a precipitated deficiency of lipotropic agents, whereas other differences may be specific for deficiency of folate per se, such as changes in liver phospholipid fatty acids and some of the morphological aberrations.

Nerve Conduction Velocity Measurement Techniques

This paper investigates the applicability of cross-correlation and spectral analysis to the measurement of nerve conduction velocity. These techniques are introduced and compared with the standard clinical technique on the basis of measurement results and theoretical signal-to-noise ratios. The techniques give good agreement with the standard technique and offer some potential advantages. The extent of the advantage depends somewhat on the hardware complexity in the standard technique and on the relative costs of correlation hardware.

A family study of Charcot-Marie-Tooth disease.

Forty-seven cases of Charcot-Marie-Tooth peripheral neuropathy were seen in 18 families within a defined area, with a disease prevalence of 1 in 16 400. Maximum motor nerve conduction velocity (MNCV) measurement divided off two types of neuropathy (MNCV less than 30 ms-1 and greater than 40 ms-1), but did not distinguish clinically affected from normal in families whose probands had median nerve MNCV greater than 40 ms-1. In the neuronal type of neuropathy ((MNCV greater than 40 ms-1) two genotypes were seen, autosomal dominant (ADN) and autosomal recessive (ARN). Most cases with the demyelinating type (MNCV less than 30 ms-1) had an autosomal dominant genotype (ADD) but one family had possible X linked recessive inheritance (XRD). In one autosomal dominant family a father and son had different electrophysiological types of neuropathy. Peroneal muscle weakness was progressive with age in the ADD genotype and certain patterns of phenotypic features were associated with the major genotypes. Age of onset was not found to be reliable in distinguishing genotypes. Care is needed when counselling isolated male cases because of asymptomatic affected females in the autosomal dominant genotypes, and the possibility of ill defined X linked forms.

Conduction velocity in nerve fibres with axonal atrophy due to chronic β,β′-iminodiproprionitrile (IDPN)

Serial measurements of maximal motor nerve conduction velocity and muscle action potential amplitude were made on 2 groups of rats for up to 16 months. Group A received 0.05% IDPN in drinking water. Group B received a single injection of 1 g/kg i.p. In the chronically intoxicated animals conduction velocity progressively fell compared with control animals, from a reduction of 7% after 4 months to 22% after 13 months. There was no reduction in muscle action potential amplitude. Marked axonal atrophy was found in distal ventral roots. Many grossly dilated axons were present in proximal ventral roots. In the animals which received a single dose of IDPN no electrophysiological changes were found. A few dilated axons were present in proximal ventral roots. but changes were less severe than in Group A. No distal axonal atrophy was demonstrated.

Measurement of motor nerve conduction for precise maturity determination in low birth weight newborn infants

Between 1.10.1979 and 31.1.1981, maturity estimation tests were conducted on 379 eutrophic and 78 hypotrophic neonates at the Department of Obstetrics in Berlin Neukölln by means of motor nerve conduction velocity (NCV) combined with the FARR system. In both eutrophic and hypotrophic infants the median of the nerve conduction velocity rises almost in a straight line from 16.5 m/sec in the 34th week of gestation to 25.7 m/sec in the 41st week. The significance calculation of the nerve conduction velocity of both groups showed no variation (p less than 0,01). On the other hand the maturity estimation made with the FARR system deviated strongly in a false positive direction up to the 38th week of gestation. The measurement of the motor nerve conduction velocity of the ulnar nerve has proved to be a simple and very precise estimation of the postpartum gestational age which makes it possible to distinguish with certainty between premature eutrophic infants and hypotrophic infants of low birthweight.

An analysis of lateral predominance in adolescent idiopathic scoliosis with special reference to convexity of the curve.

An analysis of lateral predominance of 51 patients with adolescent idiopathic scoliosis is presented. Determination of handedness, the dominant foot, and the dominant eye was performed. Postural equilibrium was studied by stabilometry, and the vestibular function was evaluated with electronystagmography. Central and peripheral nervous function were evaluated as reflected by electroencephalography and nerve-conduction velocity measurements. Results were compared with those obtained for a control group and were evaluated with special reference to convexity and location of the curve. Significant differences were found between patients with right convex curves and those with left convex curves in the distribution of eye predominance and in labyrinthine sensitivity. The direction of convexity was correlated with the predominant labyrinth for both groups. An analysis of these findings indicates that they can be of pathogenetic importance.

ELECTROPHYSIOLOGIC ASSESSMENT OF PERIPHERAL NEUROPATHY in CHILDREN WITH CHRONIC RENAL FAILURE (CRF)

Peripheral nerve function is frequently altered in CRF although clinical manifestations in children are rare. For assessment of uremic neuropathy the measurement of motor nerve conduction velocity (MNCV) has widely been used. In an earlier study we failed to find a correlation between MNCV and severity of CRF. In the present study a more sensitive neurographic parameter has been applied: the relative refractory period as estimated by neuromuscular reaction to paired stimuli (NMRPS). This method was tested in 24 children with CRF on conservative treatment(CT), 11 pts immediately before and after a haemodialysis(HD) session and 13 pts after transplantation(TP). In CT a correlation was found between some parameters of NMRPS and serum creatinine(SCR). The changes of NMRPS correlated even better with those of SCR during a HD session. After TP a significant improvement of MNCV was observed whereas NMRPS was unchanged. These data suggest that 1) NMRPS is a sensitive parameter of uremic neuropathy which might be used to control adequacy of therapy, 2) short term improvement of neuroaxonal function occurs by HD, 3) long-term improvement of myelin sheeth function is induced after TP.

Detection of uremic neuropathy by reflex response latency

Dialysis time necessary for treatment of terminal renal failure is very different in different patients. Adequacy of therapy cannot be controlled by laboratory measures but only by clinical means. Uremic peripheral neuropathy is regarded as the most reliable indicator of insufficient dialysis treatment. Serial measurements of peripheral nerve function therefore make individual adjustment of dialysis schedule possible. In some cases motor nerve conduction velocity is not sensitive enough for this purpose, as conduction velocity in afferent nerve fibers is disturbed at an earlier stage of uremic intoxication. Measurement of sensory nerve conduction velocity is time consuming and afferent fibers can also be examined in proprioceptive reflexes. The suitability of H-reflex response latency (RRL) for detection of slight uremic neuropathy was analysed. The wide range of RRL in healthy subjects can be explained by the different length of neural pathway in different subjects. A strong correlation between RRL and body height was found in healthy subjects. Relating RRL to the body height gives a highly sensitive measure of peripheral nerve function. Asymptomatic uremic neuropathy was detected very much earlier by RRL than by motor nerve conduction velocity. The method proved to be well suited for routine monitoring of uremic neuropathy in patients on dialysis.

Peripheral electrophysiological parameters in mice treated with misonidazole

The clinical use of the radiosensitizer misonidazole may be limited by the incidence of peripheral neuropathy reported following total doses in excess of 18 g. A recent report noted a decrease in nerve conduction velocity following a single i.p. injection of 1 mg/g misonidazole in mice. The present study was unable to confirm such changes when nerve conduction velocity measurements were made in situ or in isolated sural, tibial or median nerves of mice. Other electrophysiological parameters such as threshold, strength-duration curves, refractory time or the ability to carry high-frequency stimulation also showed no change. However, it was noted that a single administration of the radio-sensitizer produced a marked decrease in body temperature which persisted for at least 2 h after the elimination of the drug from the blood serum. The physiological response of reduction of body temperature may protect the mouse against the effect of the toxic chemical species involved in the induction of neurotoxicity.

Peripheral neuropathy in arsenic smelter workers

We conducted a double-blind controlled study of individuals exposed to arsenic trioxide in a copper-smelting factory. Subjects fell into three categories of peripheral neuropathy: none, subclinical, and clinical. The subclinical group had no symptoms or signs of numbness or reduced reflexes, but did have reduced nerve conduction velocity and amplitude measurements. Clinical neuropathy groups had signs and symptoms of neuropathy and electrophysiologic abnormalities. The clinical and subclinical groups correlated with increased content of arsenic in urine, hair and nails. The incidence of subclinical and clinical neuropathy was greater in arsenic workers than in unexposed controls.

Late Adult-Onset Metachromatic Leukodystrophy

A diagnosis of adult-onset metachromatic leukodystrophy (MLD) was established in a living 63-year-old man with progressive dementia and peripheral neuropathy. Decreased nerve conduction velocities and elevated spinal fluid protein concentration led to more specific diagnostic studies required to confirm the diagnosis. This case expands the spectrum of adult-onset MLD to patients with dementia and polyneuropathy past the sixth decade of life. Measurement of nerve conduction velocities may help to uncover cases of adult-onset MLD and should be included in the evaluation of dementia.

Statistical variation of nerve conduction velocity: An analysis in normal subjects and uraemic patients

The maximal nerve conduction velocity (NCV) of 6 sensory nerves (N. radialis, suralis and peronaeus superficialis, bilaterally) was determined in 88 normals and 59 uraemic patients. When the effect upon nerve conduction velocity of age and temperature was removed through partial correlations, it became possible to verify the negative correlation between the height of the patient and NCV. This explained as much as 35% of the remaining variance in males. There were also other significant differences in the nerve functions between the sexes. A set of “statistical corrections” (grouping of NCV's according to the subject's sex, computing of the average NCV's of an individual, and height-, age- and temperature normalization of single or mean NCV values) substantially decreased the variability of NCV. At the same time, the sensitivity of NCV measurement in the early diagnosis of nerve dysfunction caused by uraemia was increased. It is suggested that the results of NCV measurements should not only be reported as rough, absolute data, but also as normative values, taking into account the known physiological determinants.

Postnatal development of laryngeal reflexes in the dog.

An investigation of laryngeal reflex maturation was undertaken in the dog to identify its period of most rapid postnatal differentiation. The canine model was selected because of its laryngeal reflex similarity to that of the human being. Observations in the dog indicate maximum differentiation to occur 1 to 1 1/2 months postnatally, based on measurements of recurrent laryngeal nerve myelination and conduction velocity. Latency and threshold analyses of evoked laryngeal responses additionally confirm this viewpoint. The importance of these observations rests in an understanding of developmental upper respiratory tract mechanisms that may be chronologically related to causes of fatal ventilatory events producing unexplained infant death. Such a correlation, requiring further confirmation, is based on the assumption that a critical period of most rapid development allows a transient susceptibility to noxious influences that can cause a disruption in organ function and even death of that organism itself.

Indirect estimation of spinal cord conduction velocity in man

A method is described for deriving an indirect estimate of the velocity of impulse propagation in the spinal cord of intact man. The estimate is computed from measurements of motor and sensory nerve conduction velocity in the limbs, F-wave latencies, and the latencies of somatosensory evoked potentials. The mean estimated spinal cord conduction velocity in normal subjects was found to be 55.1 m/sec, with a standard deviation of 9.9. This method appears to have potential application in the electrophysiological evaluation of patients with myelopathic disorders.

Changes in Peripheral Nerve Function with Long-Term Hemofiltration Treatment

The changes in the peripheral nerve function of three patients with chronic renal failure who were treated over a period of 1-1/2 to 2 years by hemofiltration have been analyzed in the form of a longitudinal study by quantitative measurements of vibratory perception threshold and nerve conduction velocity. Changes in vibratory perception threshold were measured in six patients both before and after treatment. Despite increased values of creatinine and BUN, an improvement in the peripheral nerve function of all patients undergoing hemofiltration could be observed, although vibratory perception and nerve conduction velocity did not return to normal. All of the vibratory perception threshold measurements made directly after hemofiltration showed an improved vibratory perception in comparison to the original values. A comparison of the measurement methods showed a good correlation and clearly indicated the advantage of vibratory perception threshold measurements as a means for the routine diagnosis of nephrogenic polyneuropathy.