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Results for “Neural Conduction”

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At least 55 records · Page 3Linked to original sources
PubMed1979

Osmotic swelling effects on neural conduction.

Local anesthetics administered intrathecally seen more effective when in hypobaric solution than when in hyperbaric solution. To test whether an unrecognized osmotic effect might be playing a part in this, sheathed vagus nerves of rabbit were incubated in electrolyte-deficient or electrolyte-free media of various degrees of hypo-osmolarity. The nerves gained weight over a period of 15 min. They lost nearly half their sodium, but very little potassium, within 5 min. Electrolyte depletion by incubation in sucrose solutions depressed the amplitude of the C-fiber component of the compound action potential more rapidly in hypo-osmotic than in iso-osmotic solutions. In iso-osmotic sucrose, 50 per cent depression developed in 61 +/- 12 min (mean +/- SD, n = 5), but in 0.6 iso-osmotic sucrose, 50 per cent depression was reached in 17 +/- 3 min (n = 5). Lidocaine, 100 microM (approximately 0.003 g/100 ml) in iso-osmotic sucrose was without observed effect; lidocaine, 100 microM in 0.6 iso-osmotic sucrose produced 50 per cent depression in 7 +/- 2 min (n = 4). Thus, osmotic swelling plus electrolyte depletion, but not electrolyte depletion alone, markedly intensified inhibition of conduction by lidocaine. All effects were reversible by returning the nerves to isotonic physiologic incubation medium. The results suggest that intrathecal osmotic swelling of neural tissue may contribute to the conduction block in hypobaric spinal anesthesia.

Anesthesia, Spinal↗
PubMed1992

[Normal values of neural conduction velocity in a group of 101 subjects].

Motor and sensory nerve conduction velocities were analysed in a group of 101 normal Brazilians. The normal values were obtained considering the group age, the distal and proximal segments of each nerve, the differences in the right and left side for each nerve. A significant decline in the conduction was found for the elderly aged group.

Adolescent↗
PubMed1977

[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↗
PubMedDate not supplied

[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↗
PubMedDate not supplied

[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↗
PubMedDate not supplied

[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↗
PubMed1986

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↗