Journal of the peripheral nervous system : JPNS
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J. Peripher. Nerv. Syst. · Jan 1997
Effects of aging on nerve conduction block induced by bupivacaine and procaine in rats.
To test the hypothesis that the dose requirement for local anesthetics is changed in aged animals, the effects of two different local anesthetics on nerve conduction block were tested in young and old rats. Young (6 months) and old (27 months) male Fisher-344 rats were anesthetized with intraperitoneal pentobarbital and diazepam. Stimulating electrodes were placed in the sciatic notch and in the ankle and recording electrodes were placed distally in the ipsilateral foot to record evoked electrical activity of the interosseous muscles. ⋯ To test the effects of aging on conduction block, equipotent doses of bupivacaine (0.2%), an amide-linked local anesthetic, or procaine (0.6%), an ester-linked local anesthetic, were injected next to exposed sciatic nerves and evoked electrical activity was monitored following repeated stimulation at the sciatic notch. At 10 minutes after injection, bupivacaine produced significantly greater nerve block in old rats (100 +/- 0.0%) than young rats (29.8 +/- 41.6%) (P < 0.01); the difference for procaine (old 67.5 +/- 40.4% vs. young 30.4 +/- 35.3%) was not statistically significant. The lower dose requirement for bupivacaine, and the apparent differences compared to procaine, may have implications for the use of local anesthetics in an aging patient population.
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J. Peripher. Nerv. Syst. · Jan 1996
Clinical TrialPain relief by various kinds of interference stimulation applied to the peripheral skin in humans: pain-related brain potentials following CO2 laser stimulation.
Pain perception is changed by various kinds of interference stimulation applied to the peripheral skin in humans. We investigated pain-related somatosensory evoked brain potentials (pain SEPs) following CO2 laser stimulation applied to the hand or foot in normal subjects, to elucidate the underlying mechanisms. A pain visual analogue scale (VAS) was also scored to determine the degree of subjective feeling of painful sensation. ⋯ These findings could not be accounted for by simple changes in the subjects' attention. Pain relief was more prominent at the second pain ascending through C fibers than that of the first pain ascending through Adelta fibers. The responsible sites for this phenomenon are considered to be the dorsal horn of the spinal cord, the brainstem and some parts of the brain such as the second sensory cortex and the cingulate cortex.
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J. Peripher. Nerv. Syst. · Jan 1996
Expression of type I and III collagen and laminin beta1 after rat sciatic nerve crush injury.
Extracellular matrix changes are thought to be essential to the regeneration of peripheral nerves. The production of this matrix is believed to be regulated by interactions between axons and their supporting cells. In this study matrix production and cell proliferation were studied during rat sciatic nerve regeneration after a crush injury, and compared to that after rat sciatic nerve transection. ⋯ The proliferation of Schwann cells and the expression of collagen mRNAs are not, at least directly, related to the axonal regeneration. However, the long-lasting and strong expression of laminin beta1 mRNA after a nerve crush injury may be related to good axonal regeneration. The expression of type I collagen in the epineurium may lead to clinically well-recognized epineurial scarring and thus impede axonal regeneration.
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J. Peripher. Nerv. Syst. · Jan 1996
Regeneration of putative sensory and sympathetic cutaneous nerve endings in the rat foot after sciatic nerve injury.
The present study examines the occurrence of calcitonin gene-related peptide-, substance P- and tyrosine hydroxylase-like immunoreactive profiles in glabrous and hairy foot skin from normal and nerve-injured rats. After neurotomy/suture, glabrous skin samples contain few calcitonin gene-related peptide-, substance P- and tyrosine hydroxylase-like immunoreactive profies. The number of calcitonin gene-related peptide- and substance P-like immunoreacive profiles in the epidermis is significantly subnormal. ⋯ In both skin types, the contralateral occurrence of such profiles is subjectively normal. These results show that the occurrence of calcitonin gene-related peptide-, substance P-, and tyrosine hydroxylase-like immunoreactive profiles in glabrous and hairy foot skin is clearly subnormal after neurotomy and suture and less abnormal after nerve crush. After neurotomy and suture the contralateral side is also affected.