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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We sought to determine the effects of a cut injury on the thermal responsiveness of C-fiber nociceptors sensitive to heat and mechanical stimuli (CMHs). Teased fiber techniques were used to record from single CMHs that innervated the hairy skin of the monkey arm. Responses to heat stimuli ranging from 41 to 49 degrees C were compared before and after injury. In 11 CMHs, the injury was applied 4 mm peripheral to the edge of the receptive field. The response to the heat sequence was not significantly altered by this adjacent injury. In 16 CMHs, a cut was applied directly to the receptive field. This direct injury led to a significant increase in response to the sequence of heat stimuli (i.e., sensitization). It is concluded that spreading sensitization of C-fiber nociceptors to a cut injury does not occur in monkey.
Pain 1988 Mar
PMID:Responses to heat of C-fiber nociceptors in monkey are altered by injury in the receptive field but not by adjacent injury. 336 67

We identified eight patients with skeletal complications associated with hairy cell leukemia (HCL). The median time from diagnosis of HCL to the diagnosis of skeletal complications was 20 months (range, 0 to 93). All patients complained of pain and all but one lesion were located in the axial skeleton, primarily the proximal femur. Lytic lesions were seen on radiographic examination in all but one patient, and one patient additionally had multiple osteoporotic vertebral compression fractures. Radionuclide technetium bone scan was abnormal in all patients examined. Although the peripheral blood counts were variable (only two patients had a leukemic phase of the disease), all patients examined had a hypercellular bone marrow biopsy with hairy cells comprising at least 90% of the hematopoietic elements. The skeletal abnormalities responded well to local radiation therapy. Seven patients were begun on systemic therapy with interferon alpha-2b after the diagnosis of the skeletal lesion. Four of five evaluable patients had a partial hematological response and a substantial improvement in the degree of hairy cell infiltration of the bone marrow. None of these patients has had a recurrence of skeletal complications at a median follow-up time of 29 months. One patient failed to respond hematologically and developed additional bone lesions after 1 year of treatment. Another patient developed a new skeletal lesion 3 months after the cessation of interferon therapy at which time the bone marrow was essentially packed with hairy cells. This retrospective study indicates that bone involvement is a rare complication of HCL and is associated with a high tumor burden in the bone marrow. In addition to local radiation therapy, systemic treatment with interferon should be considered.
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PMID:Skeletal complications in hairy cell leukemia: diagnosis and therapy. 341 40

Splenectomy was performed on 47 patients with massive splenomegaly (spleen weight greater than 1.5 kg). With one exception, all patients had a haematological malignancy. The indications for splenectomy were for the diagnosis of unknown cause (n = 5), for the relief of pain (n = 8), as the initial treatment of hairy cell or prolymphocytic leukaemia (n = 8), and for the correction of a haematological cytopenia (n = 26). Splenectomy was completely successful in relieving pain and in establishing a diagnosis, and provided effective palliation in patients with hairy cell and prolymphocytic leukaemia. An immediate correction of a haematological cytopenia was achieved in 24 patients, and the correction was maintained for over 1 year in 11 patients. There were no postoperative deaths and morbidity was acceptably low. We conclude that patients with massive splenomegaly can derive considerable benefit from splenectomy and that massive splenomegaly should not be regarded as a contra-indication to splenectomy.
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PMID:Splenectomy for massive splenomegaly. 359 18

Brief radiant heat pulses, generated by a CO2 laser, were used to activate slowly conducting afferents in the hairy skin in man. In order to isolate C-fibre responses a preferential A-fibre block was applied by pressure to the radial nerve at the wrist. Stimulus estimation and evoked cerebral potentials (EP), as well as reaction times, motor and sudomotor activity were recorded in response to each stimulus. With intact nerve, the single supra-threshold stimulus induced a double pain sensation: A first sharp and stinging component (mean reaction time 480 ms) was followed by a second burning component lasting for seconds (mean reaction time 1350 ms). Under A-fibre block only one sensation remained with characteristics and latencies of second pain. The heat pulse evoked potential consisted of a late vertex negativity at 240 ms (N240) followed by a prominent late positive peak at 370 ms (P370). Later activity was not reliably present. Under A-fibre block this late EP was replaced by an ultralate EP beyond 1000 ms, which in the conventional average looked like a slow halfwave of 800 ms duration. This potential was distinct from eye movements, skin potentials or muscle artefacts. With cross-correlation methods waveforms similar to the N240/P370 were detected in the latency range from 900 to 1500 ms during A-fibre block, indicating a much greater latency jitter of the ultralate EP. Latency corrected averaging with a modified Woody filter yielded a grand mean ultralate EP (N1050/P1250), the shape of which was surprisingly similar to the late EP (N240/P370). The similarity of these components indicates that both EPs may be secondary responses to afferent input into neural centers, onto which myelinated and unmyelinated fibres converge. Such convergence may also explain through the known mechanisms of short term habituation and selective attention, why ultralate EPs are not reliably present without peripheral nerve block.
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PMID:Human cerebral potentials evoked by CO2 laser stimuli causing pain. 362 75

Previous studies of experimental neuromas have indicated that some axons terminating in the neuroma exhibit both spontaneous and mechanosensitive discharges. Since these spontaneous discharges appear to occur in potentially nociceptive axons (A delta and C fibers), it has been speculated that this activity may relate to pain that occurs after peripheral nerve injury. Recent results from our laboratory have revealed several possible sources of error in prior electrophysiological studies of neuromas. Most notably, gallamine, a muscle-paralyzing agent that has been used in the majority of previous studies of experimental neuromas, has profound potassium-channel-blocking properties that may increase spontaneous activity in damaged axons. The present study was conducted to re-evaluate the incidence of spontaneous activity in experimental neuromas, and the fiber types involved in these discharges. A group of 44 male Sprague-Dawley rats underwent unilateral saphenous axotomy 1-8 weeks prior to acute neurophysiological recording experiments, and 6 additional rats underwent acute control recording procedures only. Recording was performed in all animals using a modification of the microfilament recording technique to determine the conduction velocities (CVs) and origins of spontaneously discharging axons. A thorough search for spontaneous discharges was made in each nerve both before and after the administration of gallamine. Spontaneous activity was rare in acutely severed saphenous nerve and was not significantly affected by gallamine administration. In rats with 1- to 4-week-old experimental saphenous neuromas, spontaneous activity was rare but was increased by a factor of 12.75 after gallamine treatment. Gallamine administration produced significantly more of both A alpha beta and A delta activity, compared to control recordings. No spontaneous C-fiber activity was found originating in neuromas either before or after gallamine. C-fiber spontaneous discharges in the apparently isolated saphenous nerve segment had receptive fields in fascia, superficial vasculature, and hairy skin of the medial hindlimb. Our conclusions are as follows: (1) Neuromas exhibit only rare spontaneous discharges unless exposed to potassium-channel-blocking agents; (2) all C-fiber activity recorded in saphenous nerve with a distal neuroma is derived from vascular, fascial, and other receptive fields rather than from the neuroma; (3) these data are consistent with known clinical phenomena in that neuromas are not usually spontaneously painful.
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PMID:Has the amount of spontaneous electrical activity in experimental neuromas been overestimated? 368 47

Excision biopsy of the spleen was performed in 32 patients, using a recently invented instrument, which consists of a spring-trigger system for firing the two parts of a Tru-Cut needle. The biopsies were carried out under the guidance of an ultrasonic scanner. This technique yields sufficient material of high quality for a proper evaluation both of individual cells and the internal structure of the spleen. Eight patients had parenchymal abnormalities found by ultrasonic scanning: five had multiple abnormalities whereas three had a single abnormal area. Seven of these eight patients had a pathological spleen biopsy, consisting of Hodgkin's disease (four patients), "high-grade" malignant non-Hodgkin's lymphoma (two patients) or tuberculosis (one patient). In the other 24 patients with a normal ultrasonic picture of the splenic parenchyma five biopsies were pathological (3 cases of hairy-cell leukaemia, 1 of Gaucher's disease and 1 of Hodgkin's disease). Side-effects were: slight to moderate pain (16/32 patients) and bleeding requiring transfusion (4/32 patients). In one of these patients splenectomy was performed because of the bleeding. Two of the patients with bleeding complications suffered from hairy-cell leukaemia. It is concluded from this study that excision biopsy of the spleen is a diagnostic method which in some patients can replace splenectomy. The method seems to be valuable especially in patients with parenchymal abnormalities shown by ultrasonic scanning.
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PMID:Excision biopsy of the spleen by ultrasonic guidance. 391 62

Thermal thresholds (cool, warm, heat, heat pain) were determined in four skin regions (cheek, glabrous skin of the hand, hairy forearm, leg) of eight healthy human subjects. The thermostimulator was composed of Peltier elements and three rates of continuous stimulation were used: 1.4, 2.4, and 3.9 degrees C/s. Warm, heat, and heat pain thresholds increased with increasing rate of temperature change, and the increase was of equal magnitude with these three thresholds. However, the effect of increasing stimulus rate on cool thresholds was nonsignificant. Similar results were obtained in all skin regions studied. It is suggested that liminal warm, heat, and heat pain sensations are mediated by afferent fibers with conduction velocities of the same range (C-fibers) whereas liminal cool sensations are signaled by faster conducting afferent fibers.
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PMID:Influence of the rate of temperature change on thermal thresholds in man. 397 47

Lesions of limb nerves in man may be associated with a variety of painful disorders with trophic changes described by the generic term 'reflex sympathetic dystrophy'. Our hypothesis is that pain and trophic changes are produced by an abnormal discharge pattern in postganglionic neurons supplying the limb (see refs. 3,24). In relation to this hypothesis, reflex patterns in postganglionic vasoconstrictor neurons supplying the skin (CVC) and the skeletal muscle (MVC) of the cat hindlimb were investigated at various times after a peripheral nerve lesion had been produced. These reflex patterns were compared with those in animals without nerve lesions (control preparations). The following lesions were made: cutting and ligating the superficial peroneal nerve (skin nerve) with subsequent neuroma formation, suturing the central stump of the superficial peroneal nerve to the peripheral stumps of muscle branches of the deep peroneal nerve, suturing the central stumps of muscle branches of the deep peroneal nerve to the peripheral stump of the superficial peroneal nerve, cutting and resuturing the superficial peroneal nerve, deafferentation of the whole hindlimb. The responses of vasoconstrictor neurons to stimulation of arterial chemoreceptors, arterial baroreceptors (cardiac rhythmicity of postganglionic activity) and cutaneous nociceptors were tested. In the animals with nerve lesions, the following groups of postganglionic vasoconstrictor neurons were analyzed: neurons projecting to the lesioned nerve, neurons projecting to hairy skin through an intact skin nerve (sural nerve) and neurons projecting to skeletal muscle through intact muscle nerves. In control preparations without nerve lesions, MVC neurons were excited by stimulation of arterial chemoreceptors and cutaneous nociceptors and inhibited by stimulation of arterial baroreceptors. Most CVC neurons were inhibited by stimulation of chemoreceptors and nociceptors and weakly inhibited by stimulation of baroreceptors. In animals with nerve lesions a and b, many CVC neurons in the lesioned nerves, as well as in the non-lesioned cutaneous nerve nearby, behaved in the same manner as MVC neurons. With respect to the control, this difference proved to be statistically significant. In preparations with lesions a, b and c, MVC neurons did not change their reflex patterns. After nerve lesions d and e, no major changes of reflex patterns were observed in CVC and MVC neurons. The inhibitory influence of arterial baroreceptors on CVC activity decreased in deafferented preparations (lesion e).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Reflex patterns in postganglionic vasoconstrictor neurons following chronic nerve lesions. 406 81

1. The functional characteristics of cutaneous receptors in the squirrel monkey were determined by recording discharges of single myelinated afferent fibres in peripheral nerves with micro-electrodes or from fine filaments prepared by dissection. One hundred and sixty-nine fibres of the posterior femoral cutaneous nerve and 209 of the superficial radial nerve with conduction velocities between 4 and 88 m/sec were classified according to the nature of the most effective stimulus, discharge characteristics, adaptation rate and organization of the receptive field.2. Twenty per cent of the fibres innervating either hairy or glabrous skin required strong mechanical stimuli for activation; thresholds ranged from moderate to overtly damaging pressures. This class showed little or no sensitivity to thermal changes including noxious heat. Their receptive fields consisted of numerous, mechanically-excitable points or spots. All such fibres gave higher impulse frequencies to noxious than to innocuous mechanical stimuli and a large fraction were considered to be nociceptors because they responded only to noxious deformation. The conduction velocities of nociceptors were distributed between 5 and 28 m/sec.3. All but a few of the other fibres encountered responded vigorously to innocuous stimuli and were readily identified as corresponding to one of the receptor types known to exist in either the primate or the cat. These sensitive receptors were systematically tested by intense cutaneous stimuli; their response to injurious stimuli always could be mimicked by innocuous ones.4. Therefore, in the primate a particular class of slowly-conducting myelinated fibres is partially responsible for signalling mechanically-induced cutaneous damage. The probable relation between such afferent fibres and certain kinds of cutaneous pain is explored.
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PMID:Myelinated afferent fibres innervating the primate skin and their response to noxious stimuli. 496 83

1. The characteristics of receptors from the hairy skin of the hind limb of cat were studied by recording from single primary afferent fibres with fine micropipettes. The distinctive features of 513 fibres conducting under 51 m/sec are described.2. Seventy-four fibres conducting between 6 and 37 m/sec were classified as nociceptors because they responded only to damaging mechanical stimulation of the skin. These fibres responded maximally to pinching the skin with a serrated forceps or to cutting the skin. Noxious heat, noxious cold, acid applied to the receptive field and bradykinin injected into skin cuts did not evoke discharges from such receptors. Typically their receptive fields were 2-5 cm long by 1-2.5 cm wide and consisted of responsive spots (under 1 mm diameter) separated by unresponsive areas. There was a tendency for the most slowly conducting fibres so classified to be the least sensitive.3. Other afferent fibres had receptive fields similar to the nociceptors; however, they were excited by substantial but not noxious mechanical deformation. Their conduction velocities overlapped those of the nociceptors and extended upwards to 51 m/sec; the most rapidly conducting fibres tended to be the most sensitive to mechanical stimuli. These insensitive mechanoreceptors or moderate pressure receptors adapted more slowly than the nociceptors.4. The majority of fine myelinated axons originated from hair receptors and had conduction velocities concentrated between 14 and 22 m/sec.5. The possible relation of these observations to pain and reactions typical of pain is considered.
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PMID:Myelinated afferent fibres responding specifically to noxious stimulation of the skin. 605 86


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