Delayed postretinal neural conduction in glaucoma patients: correlations between electrophysiological and computerized static perimetry parameters.
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Analysis of Variance↗
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[Hoffmann's reflex evoked on the soleus muscle and motor neural conduction velocity of the tibial nerve].
H reflex on the soleus muscle and motor tibial nerve conduction velocity are used to study peripheral nervous system maturation in 68 healthy children, from birth to 4 years of age. Proximal an distal conduction velocities develop in a parallel and approximately exponential way but proximal conduction velocities remain always faster. The latencies slightly decrease during the first 18 months of life and then increase very slowly.
Age Factors↗
[Sensory polyneuropathy and neural conduction block as an initial manifestation of polyarteritis nodosa].
Polyarteritis nodosa (PAN) is a systemic necrotising vasculitis which affects middle calibre arteries and which has a tendency to form aneurysms. It may appear as one of a great variety of clinical forms depending on the vascular territory afflicted. Almost any organ may be involved although the lung is usually unaffected. Neurological manifestations are very frequent in this disease (global incidence being around 80%), especially at the peripheral nervous system level. Multiple mononeuritis is the most usual manifestation classically associated with this type of vasculitis, but it may also appear as distal sensorimotor polyneuropathy, this being its most infrequent form of presentation. The presence of nerve conduction blocks has also been recently described, usually associated with demyelinating processes. However peripheral nerve affectation in vasculitis has its origins in small ischaemic infarcts in the sensorimotor conduction fibres. It may well be that segmentary demyelination and axonal degeneration reflect different levels of ischaemic damage.
Cerebral Angiography↗
[Changes in the neural conduction in spinal muscular atrophy of the Kennedy type].
Sensory conduction velocity of median and sural nerves was examined in 6 patients with spinal muscular atrophy (SMA) of Kennedy type. In all patients, except the youngest one, slight slowing of sensory conduction velocity and marked decrease of potential amplitude was observed. These changes might suggest that the Kennedy type of SMA differs from another types of SMA and, may be, does not fit into "pure" motoneuron disease.
Adult↗
[Neural conduction in workers after long-term exposure to mercury vapors].
36 workers exposed to mercury vapour intoxication were examined to estimate the abnormalities in peripheral nervous system. 18 workers showed on physical examination features of polyneuropathy and in this group 15 workers had on emg examination sensory polyneuropathy. Statistical analysis was performed to show correlations between polyneuropathy on emg and age, time of exposure to mercury vapour and urinary mercury level. No such correlations were demonstrated.
Adult↗
[Method of dissecting peripheral nerve sheaths with an ultrasonic microscalpel that does not disturb neural conduction].
A new method for dissection of the nerve sheaths by an ultrasonic microscalpel was tested in in-vivo experiments with the cat saphenus nerve. The compound nerve action potential consisting of A beta, A delta and C waves did not change after successive one-cm long dissections of the major nerve sheaths, epineurium and perineurium, demonstrating innocuous character of the method. Not deep plunging of the ultrasonic scalpel into the nerve, hemocoagulation when dissecting as well as drastically reduced mechanical efforts are the principal advantages of new method.
Animals↗
[Body building--effect on neural conduction velocity of the median nerve in the carpal tunnel].
The examination of 30 body builders showed that prolonged practice of this sport may lead to exercise-induced carpal tunnel syndrome (CTS). Three of these body builders demonstrated typical symptoms of CTS. It was shown that, especially when training had lasted for more than 6 years, the distal motor latency (DML) of the median nerve increased significantly. A clear correlation between the estimated total duration of training and the DML was found.
Adult↗
[Peripheral and central neural conduction in the rat].
The orthodromic sensory nerve conduction velocity was measured on the tail nerve of 35 male and 14 female Wistar rats. The spinal somatosensory evoked potential also was determined for the excitation of the tail and lower limb over the 5th and 1st lumbar vertebrae. The cervical response and cortical somatosensory evoked potential were determined for the stimuli of the hind and fore paw. Normal values are compared with the latencies evaluated by upper limb stimulus. Differences between both sexes are discussed.
Animals↗
[A study of peripheral neural conduction, motor and sensory, in diabetic patients treated with hyperbaric oxygenation].
INTRODUCTION: There are some occlusive disorders in the vasa nervorum and metabolic changes disminishing oxygen liberation by erytrocites at the capillary blood vessels, and these disturbances lead to endoneural microhypoxia. Hyperbaric oxygen reverts hypoxia in the diabetic neuropathy. OBJECTIVE: We studied motor and sensitive peripheric neuroconduction in nine diabetic patients, with distal symmetrical polyneuropathy, during normoglycemia. Four of them were insulin dependent and five were non insulin dependent. PATIENTS AND METHODS: The electrophysiological studies were done before treatment with hyperbaric oxygen, in a week, three and six months later. The abnormal electrophysiological parameters detected in diabetics were terminal latencies (enlarged), velocities of conduction (slowed) and distal amplitudes of compound action potentials (reduced). RESULTS: Neither distal latencies nor distal amplitudes and conduction velocities in peroneal nerve showed significative changes in the statistical analysis. We observed slower conduction velocities in the motor fibers of the median nerve in the examination performed six months after treatment. There was an increase of distal latency and retardation of the velocity of conduction six months later after treatment in the sensitive fibers of median nerve, whereas the amplitudes of sensitive action potentials decreased progressively. These changes suggest large diameter peripheral fibers didn't receive benefit with hyperbaric oxygen treatment. CONCLUSIONS: In all patients disappeared all symptoms of dysesthesias, paresthesias, distal pains and cramps in the legs and arms, suggesting functional changes in small unmyelinated fibers which we can't test with conventional techniques to prove it.
Adult↗
Manic-depression neural conduction speeds and action potential event dyscorrelation.
In manic-depressive disorder, the monotonic, humor/receptor, excess/deficit, i.e. gain, theories have prevailed for many years, even though there is increasing evidence of a timing abnormality that may or may not be related to gain. In addition, the manic-depressive course is clearly multimodal and unpredictable except in revealing but rare cases, yet the system is real, and thus presumably deterministic, clearly suggesting a dynamic instability. A wide range of disciplines was reviewed by the author. Those data that were significantly different by standard tests were considered. However, averaged values were always questioned. During this review, higher water compartmentalization differentials were found in manic-depressive patients. Also indicated, event-related potential components differed in latency correlations, suggesting action potential firing event dyscorrelation. In conclusion, the manic-depressive action potential firing events may be dyscorrelated in a space-time reference frame.
Action Potentials↗
Paradoxical preservation of neural conduction by lidocaine.
The interaction of glucose lack and local anesthetic on impulse conduction was investigated in rabbit vagus nerve. Glucose lack depressed the compound action potential 50 per cent in 47 +/- 7 min (+/- SD, n = 5) and extinguished it in 69 +/- 7 min. Lidocaine hydrochloride, 0.1 mmol/1 (0.0027 g/dl), delayed the onset of inexcitability caused by glucose lack: 50 per cent depression required 85 +/- 9 min, extinction required 131 +/- 20 min (P less than 0.001). The delay decreased with lower and higher lidocaine concentrations. Lidocaine also significantly decreased the potassium loss and sodium gain occasioned by 2.5 h of glucose deprivation. Thus, delayed extinction of excitability by local anesthetic in very low concentration may be due to decrease in permeability of the axonal plasma membrane not only to sodium but also to potassium ions.
Action Potentials↗
[Circadian, infradian and seasonal changes in neural conduction velocity with reference to the effects of temperature. II: Infradian and seasonal changes].
Using the longitudinal study it was shown that a number of sensory neurographic parameters changed systematically throughout the 4-day investigation. In particular the sensory NCV of the n. medianus of the hand increased significantly. Possible causes i.e. the activation of the metabolism are discussed. Should this assumption prove to be true repetitive stimulation of a nerve could have a therapeutic effect. The seasonal influences are displayed using the results of a cross-sectional study. Six out of 21 neurographic parameters showed significant seasonal variations. In the NCVs of the n. medianus and the n. ulnaris maxima were present in summer and autumn while the NCVs of the lower extremities had minima. In winter and spring differences between the NCVs of the lower and upper arm and leg were lowest. These differences may be caused by seasonal changes of the metabolism which modifies the coefficient of the temperature of the neurographic parameters.
Circadian Rhythm↗
Disturbances of neural conduction in isolated frog nerves following exposure to strong electric fields.
Frog sciatic nerves were isolated and the middle portion of each exposed to condenser discharges (field strength up to 1000 V/cm; time constants 0.2-8.0 ms) through the bathing fluid. The ability of the nerve to propagate action potentials (AP) was examined by stimulating the proximal end and recording the AP from the distal end of the exposed section. The fraction of the nerve fibers remaining propagative was estimated from the amplitude (or the area) of the compound AP. Strong discharges brought about a total block of propagation lasting for up to 30 minutes, followed by slow, but almost complete, restitution. The restitution was exponential against time and depended on the field strength and duration of the discharge. Discharges equal in energy but different in their voltage--condenser combinations had markedly different actions, with stronger effects being found at higher voltages and vice versa. Hence, the described effects are unlikely to be caused by dissipation of thermal energy only. Other mechanisms (ionic imbalance, dielectric breakdown, punch through) are discussed.
Action Potentials↗
Multifocal neural conduction impairment in forestry workers exposed and not exposed to vibration.
OBJECTIVE: The aim of the study was to assess peripheral neural involvement induced by exposure to hand-arm vibration. METHODS: Twenty lumberjacks, working regularly with chain-saws and exposed to hand-arm vibration (group E) and 20 forestry workers performing heavy manual work and not exposed to vibration (group NE) were matched with a control group of 20 healthy non-manual workers (group C). The subjects of groups E and NE, all symptomatic, and of group C underwent extensive bilateral neurophysiological examination consisting of: sensory conduction (velocity and amplitude) of radial, median and ulnar nerves in digit-wrist segments; sensory conduction (velocity) of median nerve in wrist-elbow segment; mixed conduction (velocity and amplitude) of median and ulnar nerves in palm-wrist segments; motor conduction velocity, including distal motor latencies, and amplitude of median (elbow-wrist) and ulnar (elbow-wrist and across the elbow) nerves. RESULTS: Electrophysiological abnormalities were found in 85% of group E's limbs, versus 62.5% of group NE's limbs. The most frequent pathological pattern in group E was a 'multifocal' impairment (multiple sites of several nerve segments), with a prevalent involvement of sensory rather than motor fibres in the hand, seldom extending to the forearm. Multivariate analysis showed that the neurographic parameters which better characterized workers exposed to hand-arm vibration had a pattern different from that usually found in idiopathic carpal tunnel syndrome (CTS). CONCLUSION: These results suggest that vibration-induced neural involvement can be considered neither pure digital neuropathy, nor definite CTS, as previously described.
Action Potentials↗
Sensory neural conduction of median nerve from digits and palm stimulation in carpal tunnel syndrome.
The median sensory nerve conduction between ring finger and wrist is a suitable parameter for early detection of carpal tunnel syndrome (CTS), although shorter segments of median nerve have also been proposed for the same goal. In order to assess the relative diagnostic value of the sensory nerve conduction velocity (SNCV) of the third palmar branch versus the SNCV of the second palmar branch, generally performed until now, we studied 62 patients with typical signs and symptoms of CTS. The following parameters were evaluated by surface recording: orthodromic SNCVs in digit-wrist segments for median (index = M2, third = M3 and ring = M4 fingers), ulnar (fourth = U4 finger) and radial (thumb = R1) nerves; SNCVs in palm-wrist segments by surface bipolar stimulation at each metacarpo-phalangeal interspace (second = P2 and third = P3 for the median nerve and fourth = P4 for the ulnar nerve); and distal motor latencies of the median and ulnar nerves. No responses at the wrist were recorded in 22.6% of patients after digital stimulation of M4, whereas the SNCV of P3, the palmar nerve branch arising from digital nerves of the medial side of M3 and the lateral side of M4, was measurable in 93.5% of patients. As significantly expressed (P < 0.001) by the increased ratio of the mean values of P2 and P3 in CTS patients, the SNCV of P3 decreased more frequently and to a greater extent than the SNCV of P2.
Action Potentials↗
[Circadian, infradian and seasonal changes in neural conduction velocity with reference to effects of temperature; I.: Circadian rhythm].
Using results of two collectives (one cross-section study covering 212 individuals and a longitudinal study of 10 individuals over a period of 4 days with 4 examinations/individual/day) circadian, infradian and seasonal influences on the changes observed are considered. The skin temperatures displayed significant circadian variations subsequent to electrical stimulation in 4 of 5 topographic regions from which the measurements were performed. Before stimulation in only one of five regions significant circadian changes were observed. Thus stimulation caused an increase in amplitude but no changes in phase. Pre- and post-stimulation rhythms were in phase. There was found a two-peaked circadian rhythm with maxima at late noon and at midnight. Probably there were systematic differences in skin temperature in the upper extremities compared to the lower ones. The latter showed a minimum in the early morning hours. The circadian effects are presented almost completely free of temperature influences for the sensory NCV of the n. medianus on the hand. As opposed to the simultaneously acquired 2-peaked circadian rhythm of the skin temperature an almost continuous decrease in the NCV can be observed from the early morning until midnight. After midnight there was an abrupt increase of the NCV by about 5%. The significant influences of the time-of-day on the NCV of the upper- and lower-arm could not be attained independent of temperature influences. It was nonetheless apparent that the motor and sensory NCV of the lower arm increased throughout the day in contrast to the NCV of the hand. Possibly, local' influences interfered thereby with the autonomic rhythm of the nerve.
Adolescent↗
[6th report on the standardization of terminology of the lower urinary tract function. Neurophysiological study methods, electromyography, studies of neural conduction, reflex latency, evoked potentials and sensory testing. Committee of Standardization of the International Continence Society, New York, May 1985].
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Electromyography↗
[Chemical substances involved in the neural conduction of peripheral nerves].
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Acetylcholine↗