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Biomedical subjects

Ronald Melzack

Publications and source records attributed to Ronald Melzack.

At least 37 records · Page 2Linked to original sources
PubMed1989

Pain of first-trimester abortion: a study of psychosocial and medical predictors.

Pain during first-trimester abortion by suction-curettage under local anesthesia alone was measured with the McGill Pain Questionnaire (MPQ), and verbal and visual analogue scales in 109 women. The average intensity of abortion pain ranked among moderately intense pain recorded with the MPQ. However, the pain scores had a wide range and appeared influenced by several demographic, psychosocial and medical variables. A correlation/stratified multiple regression design was used to examine the sources of individual variability in pain reports. The results indicated that over a third of the variance in pain reports could be predicted by a set of variables which included the patient's age, self-reports of pre-operative depression, anxiety, fear, low pain tolerance, social and moral concerns, and gynecological characteristics such as uterus retroversion, menstrual pain and gestational age. Pain scores were significantly higher for women who reported moderate to severe levels of pre-abortion depression and for younger patients (13-17 years); other psychosocial and gynecological features made small additional contributions to the prediction of pain scores. The implications of the results are discussed in relation to pain management strategies and underscore the special needs of each woman facing an abortion.

Abortion, Induced↗
PubMed1989

An association between phantom limb sensations and stump skin conductance during transcutaneous electrical nerve stimulation (TENS) applied to the contralateral leg: a case study.

This report describes a placebo-controlled study of transcutaneous electrical nerve stimulation (TENS) applied to the contralateral lower leg and outer ears of an amputee with non-painful phantom sensations. The subject received TENS or placebo stimulation on separate sessions in which baseline periods of no stimulation alternated with periods of TENS (or placebo). Throughout the two sessions, continuous measures of stump skin conductance, surface skin temperature and phantom intensity were obtained. The results showed that TENS applied to the contralateral leg was significantly more effective than a placebo in decreasing the intensity of phantom sensations, whereas stimulation of the outer ears led to a non-significant increase. The pattern of electrodermal activity on the TENS session was consistently linear during baseline periods, indicating a progressive increase in sympathetic sudomotor activity. In contrast, during periods of electrical stimulation the pattern of electrodermal activity was consistently curvilinear indicating an initial decrease followed by an increase in sudomotor responses. Changes in stump skin conductance correlated significantly with changes in phantom sensations both in TENS and placebo sessions suggesting a relationship between sympathetic activity at the stump and paresthesias referred to the phantom. Two hypotheses are presented to account for these findings.

Adult↗
PubMed1989

Analgesia produced by normal doses of opioid antagonists alone and in combination with morphine.

In a recent study [30] it was reported that naloxone, at doses normally employed for opioid antagonism, produced a dose-dependent analgesia in BALB/c mice in the formalin test. We report here that another opioid antagonists, naltrexone, also produces analgesia under these conditions. Female BALB/c mice were injected subcutaneously with naltrexone (0.01-1.0 mg/kg) or saline alone and tested for analgesia using the formalin test. Naltrexone produced a statistically significant dose-dependent analgesia, with an ED50 of 0.05 mg/kg and almost total analgesia at doses of 0.1 mg/kg or greater. To determine the relationship between naloxone analgesia and better documented forms of opioid analgesia, BALB/c mice were injected with naloxone or saline following the administration of a pre-determined ED50 for morphine and tested for analgesia using the tail-flick and formalin tests. Naloxone antagonized morphine analgesia in the tail-flick test at both doses used (0.3 and 10 mg/kg). In the formalin test, however, naloxone attenuated morphine analgesia at the lower doses (0.1 and 0.3 mg/kg) and potentiated morphine analgesia at the highest dose (10 mg/kg). The implications of this finding are discussed.

Analgesia↗
PubMed1987

Acute and chronic pain in hemophilia.

The present study compared acute vs. chronic pain in hemophiliac subjects who suffer both types of pain. Characteristics of the acute pain produced by a hemorrhage into a joint and the chronic arthritic pain that results from repeated bleeding episodes were assessed with the McGill Pain Questionnaire and a visual analogue pain intensity scale. The results showed a high degree of similarity in the sensory, affective and evaluative properties of the two types of pain. The main difference between the acute and chronic pains was one of overall intensity, with the acute pain generally being described as more intense. A comparison of the arthritic pain in hemophilia with the pain of other arthritic disorders revealed no major differences. Sources of inter-individual variability were also explored and the results showed that the pain scores in hemophiliac subjects were largely unrelated to demographic and pain history variables. However, significant differences were observed in the way French- and English-speaking subjects described and rated their pain. Irrespective of the origin of their pain, French-speaking subjects characteristically rated their pain as more intense and more affectively laden than the English group. These results demonstrate that ethnocultural factors associated with language affiliation may contribute to inter-individual variation in pain perception.

Acute Disease↗
PubMed1987

Pain on a surgical ward: a survey of the duration and intensity of pain and the effectiveness of medication.

The effectiveness of analgesic medication for post-surgical pain was surveyed in a surgical ward of a large general hospital. Since earlier studies have shown that pain generally decreases rapidly and is negligible by the fourth day after surgery, the patients in the survey were assigned to 2 groups: those given analgesics during the first 4 days after surgery, and those given analgesics for pain after the fourth day. The results show that the patients with pain that persists beyond day 4 comprise a substantial proportion of the patients in a surgery ward (31%), are older, tend to use more words to describe their pain, and are helped less by their prescribed analgesic medications. This group is prescribed lower doses of analgesics and receives them more frequently; however, this prescription strategy appears to be ineffective since 26% of these patients report increased pain after medication compared to only 2% in the group that received analgesics during the first 4 days.

Analgesics↗
PubMed1987

Referred sensations in chronic pain patients.

This clinical note describes an unusual phenomenon of referred sensation reported in a sample of 98 chronic pain patients during electrical stimulation. Thirty-nine percent reported a variety of sensations referred to different parts of the body. Of these, 74% reported the sensations referred to the painful region. Among the sensations were paresthesias, pain, temperature changes, and pressure or constriction. The patients who had referred sensations had lower ratings of depression and had undergone more surgical operations than those who did not report referred sensations. Three case reports of patients with phantom limb pain are presented to illustrate the vividness with which these sensations are experienced. These data suggest that deafferentation due to disease, injury or other lesions of the CNS lead to a hypersensitivity and an increased likelihood of referred pain of long duration.

Amputation Stumps↗
PubMed1987

The short-form McGill Pain Questionnaire.

A short form of the McGill Pain Questionnaire (SF-MPQ) has been developed. The main component of the SF-MPQ consists of 15 descriptors (11 sensory; 4 affective) which are rated on an intensity scale as 0 = none, 1 = mild, 2 = moderate or 3 = severe. Three pain scores are derived from the sum of the intensity rank values of the words chosen for sensory, affective and total descriptors. The SF-MPQ also includes the Present Pain Intensity (PPI) index of the standard MPQ and a visual analogue scale (VAS). The SF-MPQ scores obtained from patients in post-surgical and obstetrical wards and physiotherapy and dental departments were compared to the scores obtained with the standard MPQ. The correlations were consistently high and significant. The SF-MPQ was also shown to be sufficiently sensitive to demonstrate differences due to treatment at statistical levels comparable to those obtained with the standard form. The SF-MPQ shows promise as a useful tool in situations in which the standard MPQ takes too long to administer, yet qualitative information is desired and the PPI and VAS are inadequate.

Humans↗
PubMed1986

Influence of psychological factors on postoperative pain, mood and analgesic requirements.

Previous research has indicated that postoperative pain, mood and analgesic requirements are influenced by diverse demographic and psychological variables. The data, however, are inconsistent and the extent of these influences has not been explored using multivariate statistical methods. In the present investigation patients scheduled for elective gallbladder surgery were examined for levels of pain, mood and analgesic needs, and the data were analyzed by using stratified stepwise multiple regression analysis. The results indicate that approximately half of the variability in the postoperative outcome measures could be predicted by a set of variables which include the patient's anxiety, extroversion, depression, educational level, previous chronic pain syndromes, and bias toward using medication. The implications of these results are discussed in relation to pain management strategies for surgical populations.

Adult↗
PubMed1986

Trigeminal neuralgia and atypical facial pain: use of the McGill Pain Questionnaire for discrimination and diagnosis.

Although trigeminal neuralgia and atypical facial pain can usually be distinguished on the basis of several well-established criteria, differential diagnosis is difficult in a small number of patients. The purpose of this study was to determine whether the McGill Pain Questionnaire (MPQ) is capable of discriminating between the two syndromes and might therefore serve as a diagnostic aid. The MPQ was administered to 74 patients in Pittsburgh and the data were analyzed statistically in Montreal. In an analysis of the data of 53 patients, 91% of the patients were correctly classified on the basis of 7 descriptors. To determine whether the key descriptors were able to predict the diagnosis of a second group, the discriminant function derived from the first analysis was applied to a new group of 21 patients. A correct prediction was made for 90% of the patients. The results indicate that, in difficult cases, the MPQ may be a useful tool to aid in differential diagnosis.

Diagnosis, Differential↗
PubMed1986

Deafferentation and chronic pain in animals: an evaluation of evidence suggesting autotomy is related to pain.

This paper examines evidence which suggests that the self-mutilation of deafferented limbs exhibited by laboratory animals is a response to pain or dysesthesia and is therefore an adequate model of chronic pain. Evidence from studies using physiological, pharmacological and behavioral methods provides strong support that autotomy reflects chronic pain. New evidence presented in this paper demonstrates that specific treatments can be used to manipulate the extent of autotomy, causing increases or decreases, as well as restricting it to specific parts of a denervated foot. This evidence argues that autotomy scores are an appropriate measure of the degree of pain or dysesthesia which results from the deafferentation of a limb.

Afferent Pathways↗
PubMed1985

The role of compensation in chronic pain: analysis using a new method of scoring the McGill Pain Questionnaire.

Patients who receive worker's compensation or are awaiting litigation after an accident have long been regarded as neurotics or malingerers who are exaggerating their pain for financial gain. However, there is a growing body of evidence that patients who receive worker's compensation are no different from patients who do not. In particular, a recent study found no differences between compensation and non-compensation patients based on pain scores obtained with the McGill Pain Questionnaire (MPQ). Since the MPQ is usually scored by using rank values rather than more complex scale values, the negative finding might be attributable to the loss of information by using rank values. Consequently, a simple technique was developed to convert rank values to weighted-rank values which are equivalent to scale values. A study of 145 patients suffering low-back and musculoskeletal pain revealed that compensation and non-compensation patients had virtually identical pain scores and pain descriptor patterns. They were also similar on the MMPI pain triad (depression, hysteria, hypochondriasis) and on several other personal that were examined. The only differences were significantly lower affective or evaluative MPQ scores and fewer visits to health professionals by compensation patients compared to non-compensation patients. These results suggest that the financial security provided by compensation decreases anxiety, which is reflected in the lower affective or evaluative ratings but not the sensory or total MPQ scores. Compensation patients, contrary to traditional opinion, appear not to differ from people who do not receive compensation. Accidents which produce injury and pain should be considered as potentially psychologically traumatic as well as conducive to the development of subtle physiological changes such as trigger points. Patients on compensation or awaiting litigation deserve the same concern and compassion as all other patients who suffer chronic pain.

Adult↗
PubMed1984

Effects of peripheral antisympathetic treatments in the tail-flick, formalin and autotomy tests.

The effects of peripheral adrenergic depleting agents on the threshold for non-damaging heat pain (tail-flick test), inflammatory pain associated with tissue injury (formalin test), and chronic pain or dysaesthesia associated with nerve lesions (autotomy test) were examined. Tail-flick latencies were increased by agents which deplete peripheral adrenergic transmitters--6-hydroxydopamine (6-OHDA) and guanethidine--as well as by an agent which prevents the synthesis of noradrenaline--FLA63. A combination of guanethidine and FLA63 also increased latencies, but no more than either treatment alone. Formalin pain scores were reduced by FLA63+ guanethidine and 6-OHDA, but not by guanethidine or FLA63 alone. The percentage of rats that exhibited autotomy was reduced minimally by 6-OHDA and guanethidine treatments which started the day of surgery, maximally by guanethidine treatments which started 4 days before surgery, and not at all by guanethidine treatments which started 4 days after surgery. The results obtained in the formalin and autotomy tests are interpreted in terms of the possible roles of adrenergic transmitters in stimulating and sensitizing damaged afferents immediately after injury. The tail-flick results, however, suggest that adrenergic transmitters also act in lowering thresholds of normal peripheral receptor-fibre units. The relevance of the findings to the development of chronic pain are discussed.

Animals↗
PubMed1982

Acute pain in an emergency clinic: latency of onset and descriptor patterns related to different injuries.

Features of acute pain were examined in patients at an emergency clinic. Patients who had severe, life-threatening injuries or who were agitated, drunk, or 'in shock' were excluded from the study. Of 138 patients who were alert, rational and coherent, 51 (37%) stated that they did not feel pain at the time of injury. The majority of these patients reported onset of pain within an hour of injury, although the delays were as long as 9 h or more in some patients. The predominant emotions of the patients were embarrassment at appearing careless or worry about loss of wages. None expressed any pleasure or indicated any prospect of gain as a result of the injury. The occurrence of delays in pain onset was related to the nature of the injury. Of 46 patients whose injuries were limited to skin (lacerations, cuts, abrasions, burns), 53% had a pain-free period. Of 86 patients with deep-tissue injuries (fractures, sprains, bruises, amputation of a finger, stabs and crushes), only 28% had a pain-free period. The McGill Pain Questionnaire was administered to patients who felt pain immediately after injury or after a delay, and revealed a normal distribution of sensory scores but very low affective scores compared to patients with chronic pain. The results indicate that the relationship between injury and pain is highly variable and complex.

Acute Disease↗
PubMed1977

Trigger points and acupuncture points for pain: correlations and implications.

Trigger points associated with myofascial and visceral pains often lie within the areas of referred pain but many are located at a distance from them. Furthermore, brief, intense stimulation of trigger points frequently produces prolonged relief of pain. These properties of trigger points--their widespread distribution and the pain relief produced by stimulating them--resemble those of acupuncture points for the relief of pain. The purpose of this study was to determine the correlation between trigger points and acupuncture points for pain on the basis of two criteria: spatial distribution and the associated pain pattern. A remarkably high degree (71%) of correspondence was found. This close correlation suggests that trigger points and acupuncture points for pain, though discovered independently and labeled differently, represent the same phenomenon and can be explained in terms of the same underlying neural mechanisms. The mechanisms that play a role in the genesis of trigger points and possible underlying neural processes are discussed.

Acupuncture Therapy↗