Degeneration patterns of postganglionic fibers following sympathectomy

Cardiovascular autonomic reflex function after bilateral cardiac sympathetic denervation for ventricular arrhythmias

BACKGROUND

Bilateral cardiac sympathetic denervation (BCSD) is an effective therapy for ventricular arrhythmias (VAs) in cardiomyopathies (CMPs). After BCSD, residual autonomic nervous system (ANS) function is unknown.

OBJECTIVE

The purpose of this study was to assess ANS responses in patients with CMP before and after BCSD as compared with demographically matched healthy controls.

METHODS

Patients with CMP undergoing BCSD and matched healthy controls were recruited. Noninvasive measures-finger cuff beat-to-beat blood pressure (BP), electrocardiography, palmar electrodermal activity (EDA), and finger pulse volume (FPV)-were obtained at rest and during autonomic stressors-posture change, handgrip, and mental stress. Maximal as well as specific responses to stressors were compared.

RESULTS

Eighteen patients with CMP (mean age 54 ± 14 years; 16 men, 89%; left ventricular ejection fraction 36% ± 14%) with refractory VAs and 8 matched healthy controls were studied; 9 patients with CMP underwent testing before and after (median 28 days) BCSD, with comparable ongoing medication. Before BCSD, patients with CMP (n = 13) had lower resting systolic BP and FPV than did healthy controls (P < .01). Maximal FPV and systolic BP reflex responses, expressed as percent change were similar, while diastolic BP, mean BP, and EDA responses were blunted. After BCSD, resting measurements were unchanged relative to presurgical baseline (n = 9). EDA responses to stressors were abolished, confirming BCSD, while maximal FPV and BP responses were preserved. Diastolic BP, mean BP, and FPV responses to orthostatic challenge pointed toward a better tolerance of active standing after BCSD as compared with before. Responses to other stressors remained unchanged.

CONCLUSION

Patients with CMP and refractory VAs on optimal medical therapy have detectable but blunted adrenergic responses, which are not disrupted by BCSD.

Manifestations of pain symptoms in reduced occlusion

This article presents the analysis of the relevant literature highlighting the mechanisms of the development of malocclusion and pain symptom at the reduced occlusal vertical dimension. In this case, the key complaint presented by patients is permanent steady pain described as dull, stabbing, or compressing by its character. Most often, the pain is localized within the paratoid-masticatory area as well as buccal, temporal and frontal areas, and irradiates to the upper and lower jaw or the teeth that often leads to performing unnecessary dental manipulations; to the region of the temporomandibular joint (TMJ); to the ear that sometimes is accompanied with fullness and tingling in the ears. In some cases this pain can irradiate to the hard palate and tongue. Many patients note the growing intensity of pain when chewing. Some patients experience episodic increase in pain when there are pain attacks described as compressing or stabing in the background of steady dull pain. The pain gets more intense even at the slightest movements of the head, lower jaw, or when speaking. The duration of the pain attack is approximately 20–30 minutes. A few minutes before the onset of the attack, all patients notice the emergence of somes forerunning symptoms, e.g. hyperlsalivation, paresthesia, toothache. The attacks can be provoked by conversation, overcooling, and emotional tension. It has been experimentally proven that a prolonged muscle contraction, which is often observed during emotional stress, can cause pain in the regions mentioned above. But whether will it arise or not and to what extent, it depends on the state of adaptive capacity of the body and dentofacial system. When the adaptive capacity of the body and the dentofacial system as its part are weakened, the local background for the occurrence of pain symptoms in the maxillofacial area may be: affective states (depression, anxiety), prolonged chewing load, and prolonged neck muscle tension during dental manipulations. Among the local factors that can cause pain, malocclusions rank the leading place. For example, a hyperbalancing contact is a sign of impaired muscle activity and coordination during the maximal closure of teeth in the lateral position of the mandible, and occlusal contacts on the balancing side affect the distribution of muscle activity during parafunctional closure, and this redistribution can impact on the temporomandibular joint (Andres K. H. et al.). Occlusion abnormalities may result from reduced occlusal vertical dimension, deformation of the dentitions caused by periodontal disease, partial loss of teeth, pathological tooth wearing, as well as due to improperly inserted fillings, unfit inlays, onlays, crowns. Reduced occlusal vertical dimension can also cause otalgia and some other otorhinolaryngological problems, pathogenesis of which is quite debatable and controversial in current literature. J. S. Costen considered hearing loss, tingling and other ear symptoms are associated with pressure produced by the head of the mandible joint onto the auditory tube. Reducing the vertical occlusal dimension results in increasing pressure of the head of the mandible joint onto the subtle bone arch of the articular fossa, which separates the cavity of the joint from the dura mater; this can trigger dull pain in the spine. It is important to remember that pain is a symptom that most often makes patients to search for a dental care. Pain is one of the first clinical manifestations of the body decompensation. Patients with TMJ dysfunction who experience the pain symptom is to a greater or lesser extent make up a group of patients who require a special integrated approach in their treatment.

Video-Assisted Thoracic Sympathectomy for Hyperhidrosis

By the 1980s, endoscopy was in use by some groups in sympathetic denervation of the upper limbs with vascular indications. Low morbidity, cosmetic results, reduction in the incidence of Horner syndrome, and the shortened time in hospital made video-assisted thoracic sympathectomy (VATS) better accepted by those undergoing treatment for hyperhidrosis. Over the last 25 years, this surgical procedure has become routine in the treatment of hyperhidrosis, leading to a significant increase in the number of papers on the subject in the literature.

Removal of half the sympathetic innervation does not reduce vasoconstrictor responses in rat tail artery

Following reinnervation of denervated rat tail arteries, nerve-evoked contractions are at least as large as those evoked in normally innervated arteries despite a much lower nerve terminal density. Here nerve-evoked contractions have been investigated after transection of half the sympathetic innervation of normal tail arteries. After 1 week, the noradrenergic plexus 50-70 mm along the tail was about half as dense as control. Excitatory junction potentials recorded in smooth muscle cells of arterial segments isolated in vitro were half their normal amplitude. Surprisingly, nerve-evoked contractions of isometrically mounted segments were not reduced in amplitude, as was also the case after only 3 days. After 1 week, enhancement of nerve-evoked contractions by blocking either neuronal re-uptake of noradrenaline with desmethylimipramine or prejunctional α2-adrenoceptors with idazoxan was similar to control, suggesting that these mechanisms are matched to the number of innervating axons. The relative contribution of postjunctional α2-adrenoceptors to contractions evoked by long trains of stimuli was enhanced but that of α1-adrenoceptors was unchanged. Transiently, sensitivity to the α1-adrenoceptor agonist phenylephrine was slightly increased. After 7 weeks, amplitudes of nerve-evoked contractions remained similar to control, and sensitivity to phenylephrine had recovered but that to the α2-adrenoceptor agonist clonidine was slightly raised. The normal amplitude of nerve-evoked contractions after partial denervation is only partly explained by the greater contribution of α2-adrenoceptors. While the post-receptor mechanisms activated by nerve-released transmitter may be modified to amplify the contractions after partial denervation, our findings suggest that these mechanisms are normally saturated, at least in this artery.

Moustache Reconstruction in Patients With Cleft Lip

Men with clefts often have limited or even missing moustache growth in scar areas or in the upper lip prolabium. However the histological testing showed the absence or at least the inactive form of androgenic receptor in hair follicle of cleft site, transplantation of autologous grafts harvested from hair was successful in all six cases either into scars or the prolabium. A more natural effect was achieved by using micrografts. The positive reaction of patients proved there is a need for detailed treatment in highly outgoing individuals.

Sympathetic-dependence in bradykinin-induced synovial plasma extravasation is dose-related

While previous studies have implicated a role for sympathetic postganglionic neuron-terminals in bradykinin-induced plasma extravasation, a recent report by Cambridge and Brain [Br. J. Pharmacol., 115 (1995) 641-647] has suggested that it is sympathetic-independent. However, the doses of bradykinin used in these two groups of studies were considerably different. Therefore, in the present study, we characterized the sympathetic-dependence of plasma extravasation at varying doses of bradykinin. By measuring the concentration of Evans blue dye extravasation into the joint perfusate following its intravenous injection, bradykinin-induced plasma extravasation in the knee joint cavity was determined spectrophotometrically. To examine the role of sympathetic postganglionic neuron terminals in mediating bradykinin-induced plasma extravasation, we used surgical ablation of the lumbar sympathetic chain. Intra-articular perfusion of BK dose-dependently increased synovial plasma extravasation. After surgical sympathectomy, the dose-response curve for bradykinin-induced plasma extravasation was significantly shifted to the right. We conclude that at concentrations observed in inflamed tissues (between 10(-8) and 10(-7) M), bradykinin-induced plasma extravasation is largely mediated by sympathetic postganglionic neuron terminals.

Influence of the sympathetic nervous system in the development of abnormal pain-related behaviours in a rat model of neuropathic pain

This study evaluated the effect of surgical sympathectomy on pain-related behaviours in a well established model of peripheral mononeuropathy produced by loose ligatures around the common sciatic nerve in the rat. Behavioural abnormalities include spontaneous abnormal position of the hindpaw after the nerve constriction, indicative of "spontaneous pain", and changes in responses to mechanical or thermal stimuli applied to this paw. These changes are usually maximal at week 2 after the surgery, stable until weeks 3-4, and disappear between weeks 8 and 12. To assess the role of the sympathetic nervous system in the development and persistence of these abnormalities, four groups of rats were behaviourally tested: (i) rats receiving a complete sham surgery, (ii) rats with a sciatic nerve constriction produced by loose ligatures around the common nerve trunk plus a sham sympathectomy, (iii) rats receiving a lumbar sympathectomy with a sham nerve ligature, and (iv) rats receiving a simultaneous surgical lumbar sympathectomy and a sciatic nerve constriction. The efficacy of the sympathectomy was assessed by the measure of the noradrenaline level in the sciatic nerve. Sympathectomy reduced selectively or even prevented the abnormal reaction to cold temperature and to heat (45 degrees C) in rats with a peripheral mononeuropathy. In contrast, the abnormal reaction to mechanical pressure was not influenced, and the behavioural abnormalities indicating spontaneous pain were still present. Sympathectomy alone resulted in a reduction of the vocalization threshold to pressure on both hindpaws, but also a short-lasting increased tolerance to cold immersion. This study confirms the selective role of the sympathetic nervous system in affecting the development and maintenance of some abnormal pain-related behaviours to thermal stimuli in rats with a moderate, but persistent, constriction of one sciatic nerve.

Fine sensory innervation of the knee joint capsule by group III and group IV nerve fibers in the cat

Afferent group III and IV nerve fibers of the knee joint markedly differ in their responsiveness to mechanical stimulation, which may be reflected in the structure and location of their terminals. Therefore, in sympathectomized cats, the fine afferent innervation of the knee joint capsule was studied via ultrastructural three-dimensional reconstructions over distances of up to 300 microns. Small peripheral nerves and "free" (noncorpuscular) sensory nerve endings were found in a superficial layer of the outer fibrous part of the capsule, in the patellar retinaculum, and in the outer and inner surface layers of the medial collateral and patellar ligaments. Group III nerve fibers showed a proximal myelinated portion inside the nerve, an intermediate portion that lacks a myelin sheath and is only surrounded by perineurium, and a distal portion outside of the perineurium that forms the sensory ending proper. Group IV fibers showed only two distinct portions, an intraperineurial (proximal) and an extraperineurial (distal) portion without any further morphological differences. Outside of the perineurium, a network formed by Schwann cells ("Schwann cell reticulum") provides a pathway for the distal portion of the sensory axons. No distinct subgroups of the sensory terminal fibers could be defined according to the configuration of the Schwann cells and the nerve fiber terminals. Sensory terminals were located adjacent to different structures such as venous and lymphatic vessels, fat cells, and collagenous fibers. Distinct parts of the same terminal nerve fiber were found in close contact to a vessel wall; others were surrounded by dense collagenous tissue. Close to sensory endings, mast cells and mast cell-like cells were frequently found, indicating a functional relationship.

Mitochondria in fine afferent nerve fibres of the knee joint in the cat: a quantitative electron-microscopical examination

The distribution of mitochondria, their content and concentration (expressed as the ratio of the mean volume of mitochondria and the surface of the sensory axon) were determined in group-III and -IV nerve fibres innervating the knee joint capsule in the cat. Mitochondria mainly accumulated in axonal swellings ("beads") and end bulbs of the terminal branches. Between single nerve fibres, marked differences in the content and the concentration of mitochondria were obtained in proximal portions (inside of the perineurium) and in distal portions (unmyelinated sensory endings). In group-III nerve fibres, the mitochondrial concentration ranged from 0.005 to 0.030 microns 3/microns 2 (proximal portion) and from 0.016 to 0.080 microns 3/microns 2 (distal portion). In unmyelinated group-IV nerve fibres, the values also showed a broad variation ranging from 0.001 to 0.011 microns 3/microns 2 (proximal portion) and from 0.003 to 0.019 microns 3/microns 2 (distal portion). The wide range of mitochondrial concentrations may reflect different energy consumption during receptive processes: nerve fibres with a low mechanical threshold and a high probability of excitatory events may be rich in mitochondria, whereas fibres with a high mechanical threshold and a low probability of excitatory events may be poor in mitochondria.

The nociceptor sensitization by bradykinin does not depend on sympathetic neurons

Nociceptive primary afferents develop an increased responsiveness in inflamed tissue. The aim of this neurophysiological investigation was to study the sensitivity changes of cutaneous nociceptors following application of the algesic inflammatory mediator bradykinin and to examine a possible contribution of the sympathetic nervous system. Single unit recordings were obtained in a skin-nerve in vitro preparation from unmyelinated nociceptive afferents supplying the hairy skin of intact or of chronically sympathectomized rats. In preparations from intact skin, mechano-heat-sensitive C-fibres responding to superfusion of the receptive fields with 10 microM bradykinin for 1 min were sensitized to heat stimulation 2 min later. On average, the threshold dropped by 5.0 degrees C, the maximal discharge frequency increased by 34% and the temperature eliciting this peak discharge dropped by 5.6 degrees C. This resulted in a leftward shift and an increased slope of the stimulus-response function indicating sensitization. In surgically sympathectomized animals, 52% of the nociceptive afferents were activated by bradykinin which is not different from normal controls. In sympathectomized animals neither the reduction of the mean threshold (4.6 degrees C) nor the increase of the peak discharge frequency (48%) differed significantly from intact controls. The change of the stimulation-response function following bradykinin application was virtually identical in intact and sympathectomized preparations. Moreover, bradykinin increased the heat discharge of individual fibres by a factor of 2.1 in intact and 1.9 in sympathectomized animals, respectively. In both preparations the increased responsiveness of the nociceptors was short-lived and had resolved 7 min after chemical stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural three-dimensional reconstruction of group III and group IV sensory nerve endings ("free nerve endings") in the knee joint capsule of the cat: evidence for multiple receptive sites

The noncorpuscular endings ("free nerve endings") of thinly myelinated group III and nonmyelinated group IV afferent nerve fibers have been examined in the knee joint capsule of sympathectomized cats by transmission electron microscopy and three-dimensional reconstruction of series of semi- and ultrathin sections. The sensory ending is the most distal part of a group III or IV nerve fiber that consists only of the sensory axon and associated Schwann cells but lacks a myelin sheath and is not surrounded by perineurium. The sensory axon divides into several branches and forms a terminal tree. The branches run either as single fibers or within small Remak bundles in parallel to sensory axons of other endings; they spread along vessel walls and also extend into dense connective tissue. Each sensory axon consists of a series of spindle-shaped thick segments ("beads") connected by waist-like thin segments. Thus all axons of sensory endings have a string-of-beads appearance, which resembles that of efferent sympathetic nerve fibers. The beads of the sensory axon and the end bulb at its tip show the same ultrastructural features which are characteristic of receptive sites: an accumulation of mitochondria and glycogen particles and various vesicles in the axoplasm and "bare" areas of axolemma that are not covered by Schwann cell processes. Group III and group IV sensory endings differ in the length of their branches (up to 200 microM in group III vs. more than 300 microM in group IV), number of beads per 100 microM axon length (about seven vs. nine or ten), mean diameter of axons (0.9-1.5 microM vs. 0.3-0.6 microM), and the presence of a neurofilament core consisting of bundles of parallel microfilaments only in group III. In conclusion, we propose that the sensory part of noncorpuscular "free nerve endings" is formed by the entire terminal tree of group III or group IV nerve fibers and that the beads in the course of the sensory axon represent multiple receptive sites.

Effects of pregnancy on the extrinsic innervation of the guinea pig uterus. A histochemical, immunohistochemical and ultrastructural study

The extrinsic innervation of the guinea pig uterus was studied by immunohistochemical, ultrastructural and enzyme histochemical methods. The extrinsic innervation was organized in two major ways. One consisted of nerve trunks and non-varicose nerve fibres running in the suspensory ligament, and the other of a plexus of varicose nerve fibres surrounding vessels, and non-vessel-related non-varicose nerve fibres in the mesouterus. The use of different neuronal and Schwann cell markers showed that the extrinsic innervation was predominantly adrenergic and contained only few peptidergic nerves. Acetylcholinesterase-positive (cholinergic) nerves were only found around the uterine artery. In late pregnancy, the extrinsic nerves of the mesouterus adjacent to foetus-containing uterine horns underwent pronounced degenerative changes comprising both Schwann cell and axonal structures. In comparison, no changes were found in extrinsic nerves of mesouteri adjacent to non-foetus-bearing uterine horns or in extrinsic nerves in the suspensory ligaments. Further, chemical sympathectomy produced axonal degeneration but no changes in the Schwann cells. In conclusion, the pregnancy-induced nerve degeneration is of a very special type different from that following chemical sympathectomy and represents a local phenomenon related to the conceptus. Hypothetically, this could be of importance for counteracting disturbances in placental blood flow.

Fiber size distribution of myelinated and unmyelinated axons in the medial and posterior articular nerves of the cat's knee joint

The distribution of fiber size in the posterior articular nerve (PAN) and medial articular nerve (MAN) of the cat's knee joint was studied by light and electron microscopy. The myelinated fibers of the PAN ranged from approximately 1 to 18 micron, with maxima at 3-4 micron and 8-9 micron. According to the classification of Boyd and Davey (1968), the PAN contained about 34% Group III fibers, 56% Group II fibers, and 10% Group I fibers. In contrast, the MAN showed a unimodal, skewed distribution, with a range from approximately 1 to 14 micron and a maximum at 3-4 micron. According to the Boyd and Davey classification, the PAN contained about 69% Group III fibers, 30% Group II fibers, and 1% Group I fibers. Unmyelinated fibers examined in the MAN showed a unimodal distribution, with a range of from 0.1 to 1.5 micron and a maximum at 0.4-0.5 micron. To differentiate between afferent and sympathetic fibers, a sympathectomy or ganglionectomy was performed on one side. The fiber size distribution indicated a considerable overlap in the diameter of the afferent and sympathetic unmyelinated fibers. Most sympathetic fibers had a diameter of between 0.8 and 0.9 micron, whereas afferent fibers showed a maximum at 0.3-0.4 micron. When data were combined for myelinated and unmyelinated fibers in the PAN, about 74% of the afferent fibers were found to belong to Groups III and IV; they are thought to terminate in noncorpuscular endings. The other 26% were found to belong to Groups I and II; they terminate in corpuscular receptors and muscle spindle primary and secondary endings.(ABSTRACT TRUNCATED AT 250 WORDS)

S-100-immunoreactive nerves in the guinea-pig uterus with reference to ultrastructural correlations: effects of chemical sympathectomy and pregnancy

In the guinea-pig uterus, by use of an indirect immunofluorescence method, S-100 immunoreactivity was found to be restricted to nerves that corresponded in number, distribution and type to adrenergic axons and pre-terminals. With advancing pregnancy S-100 immunoreactivity completely disappeared in uterine tissue adjacent to a fetus, in parallel with an ultrastructural degeneration of the adrenergic innervation. In the cervix and the uterine horn devoid of a fetus, however, the number and distribution of S-100-immunoreactive nerves was seemingly unchanged and no ultrastructural changes were found in adrenergic nerves. In contrast, chemical sympathectomy produced by 6-hydroxydopamine did not change S-100 immunoreactivity of uterine nerves. These findings suggest that there are differences in the denervation effected by chemical and by pregnancy-induced sympathectomy. The latter probably represents a special type of adrenergic denervation by inducing a degeneration of Schwann cells in addition to destruction of neuronal structures. This may explain the differences in the speed of regeneration of uterine adrenergic nerves following the two types of denervation.

Unmyelinated axons in a muscle nerve. Electron microscopic morphometry of the sternomastoid nerve in normal and sympathectomized rats

In continuation of earlier studies on the innervation of the sternomastoid muscle of the rat, a detailed morphometric analysis was performed on the unmyelinated axons of the nerve, in normal rats and after extensive cervical sympathectomy. In 4 normal rats an average of 314 myelinated and 319 unmyelinated axons were present. 42 days after surgery, the 3 animals showed Horner's syndrome and a highly significant 40% loss of unmyelinated axons. We therefore suggest that 40% of the C-fibers in this nerve are postganglionic sympathetic efferents and that the remaining 60% are type IV fibers, i.e., unmyelinated afferents. Our counts also indicate that part of the Remak bundles of the Schwann cells contain only sympathetic axons, whereas others contain mixed groups of sympathetic and afferent axons. Myelinated nerve fibers were not lost due to sympathectomy. Unexpectedly, the 3 animals analyzed 7-13 days after surgery showed Horner's syndrome but only a 16% loss of unmyelinated axons, which was not even statistically significant. Morphological signs of degeneration and sprouting did not provide any clue, but a possible explanation would be that a transitory sprouting of the remaining afferent C-fibers or Schwann cells occurred.

Sensory innervation of the Achilles tendon by group III and IV afferent fibers

In sympathectomized cats the innervation of the Achilles tendon by fine afferent nerve fibers was studied with semithin and ultrathin sections. Several different types of sensory endings of group III and group IV nerve fibers were identified. Of the five different types of endings in the group III range (T III endings), two are located within vessel walls. One of them ends in the circumference of the venous vessels (T III/VV). Its lanceolate terminals have characteristic receptor areas at their edges. The second type ends in the adventitia of lymphatic vessels (T III/LV). Its receptive areas are scattered along their terminal course. Two further group III endings ramify within the connective tissue compartments of the vessel-nerve-fascicles of the peritenonium externum and internum. One type is tightly surrounded by collagen fibrils (T III/PTic); the other terminates between the collagen fiber bundles (T III/PTgc). The latter arrangement recalls the ultrastructural relation between nerve terminals and collagen tissue in Golgi tendon organs. The fifth type innervates the endoneural connective tissue of small nerve fiber bundles (T III/EN). At least some of them come into close contact with bundles of collagen fibers which penetrate the perineural sheath to terminate within the endoneurium. The endings of group IV afferents (T IV endings) show a striking topographic relationship to the blood and lymphatic vessels of all connective tissue compartments of the Achilles tendon. They form penicillate endings which may contain granulated vesicles. In any event, they can easily be discriminated from the T III endings in the vessel walls. In close neighborhood to Remak bundles, a cell has been regularly found which fulfilled all ultrastructural criteria for mast cells. But this cell is not a mast cell proper because it is surrounded by a basal lamina (pseudo mast cell).