Articles: peripheral-nerve-injuries.
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1. The effects of sympathetic stimulation and close arterial injection of norepinephrine were tested on cutaneous myelinated-fiber (A delta) mechanical nociceptors [high-threshold mechanoreceptors-(MyHTMs)] from normal and from partially transsected nerves. 2. Neither sympathetic stimulation nor close arterial injection of norepinephrine (200 ng) excited MyHTMs (18) recorded from the uninjured great auricular nerve of adult rabbits. 3. ⋯ Four MyHTMs recorded from the injured nerves were excited by sympathetic stimulation and/or norepinephrine injection but only one gave more than two impulses within 60 s to either form of stimulation. 5. The meagerness of the sympathetic and adrenergic excitation of MyHTMs after nerve injury contrasts with that observed under similar conditions for C-fiber polymodal nociceptors. Therefore, induction of adrenergic responsiveness in nociceptors after partial denervation in cutaneous MyHTMs appears to be less important for mechanisms related to pathogenic pain than alterations in certain C-fiber nociceptors.
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Rev Esp Anestesiol Reanim · Mar 1995
Case Reports[Postoperative lesions of the peripheral nerves. 8 years' analysis].
Damage to a plexus or peripheral nerve is a rare and avoidable complication of surgical anesthesia. We reviewed 2,750 case histories of patients who underwent surgery between 1985 and 1992, finding 6 cases of nerve lesions presenting postoperatively. ⋯ Our data are important given the difficulty of studying the incidence of such cases due to patient dispersion and the loss of records of possible occurrences. The mechanisms by which lesions are produced are sometimes difficult to pinpoint but all are generally preventable.
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Neuroscience letters · Feb 1995
Quantitative evaluation of calcitonin gene-related peptide and substance P levels in rat spinal cord following peripheral nerve injury.
Levels of calcitonin gene-related peptide immunoreactivity (CGRP-ir) and substance P immunoreactivity (SP-ir) in the lumbar dorsal spinal cord of rats with either sciatic nerve transection or chronic constriction injury (CCI) were measured using radioimmunoassay. Significant decreases in CGRP-ir and SP-ir occurred in the ipsilateral spinal cord at 10 and 31 days after nerve transection. ⋯ Transection of the sciatic nerve produced greater decreases in peptide levels than did the CCI. Changes in spinal levels of these peptides may be involved in the appearance of neuropathic signs associated with nerve injury.
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1. Peripheral nerve injury sometimes leads to the development of neuropathic pain. One of the symptoms of such neuropathic pain is mechanical allodynia, pain in response to normally innocuous mechanical stimuli. ⋯ The response characteristics of MRAs change to those of typical RAs after a systemic injection of phentolamine, an alpha-adrenergic receptor blocker. 5. We conclude that many RAs become abnormal under the influence of sympathetic efferents in neuropathic pain, so that their response patterns change to those of MRAs. We propose that this abnormality is responsible for signaling the mechanical allodynia that can be seen in neuropathic pain states such as causalgia.