Myofascial pain involving the masticatory muscles: An experimental model

Thirty healthy volunteers were assigned to one of the following two conditions: (1) hyperactivate the lateral pterygoid muscles by vigorously thrusting their mandible forward for 5 min, or (2) a non-exercise control condition. Subjects who protruded their mandible reported significantly more pain than control subjects. This pain was located in the immediate preauricular area. This pain was similar in quality and location to many patients diagnosed as having the myofascial pain-dysfunction syndrome. Other signs or symptoms associated with the syndrome (e.g., tenderness upon palpation, limitation of jaw function) were not produced. This constitutes the first direct, experimental test indicating that the pain of the myofascial paindysfunction syndrome may be caused by hyperactivity of the lateral pterygoid muscles.     

The submaximal effort tourniquet test: its use in evaluating experimental and chronic pain.

The submaximal effort tourniquet test has been widely used to evaluate experimental and chronic pain; however, there has been great variation in the manner in which the test has been applied. The present study systemitically evaluates how different levels of exercise duration and effort affect subjects' report of pain. The data indicate the following: (1) the manner in which the exercise is performed has an important effect on subjects' rating of pain, and (2) under all conditions studied, the pain ratings do not increase as a linear function of time. Both findings warrant precautions when using the submaximal effort tourniquet test to study experimental and chronic pain.     

Myofascial pain of the temporomandibular joint: A review of the behavioral-relaxation therapies

This paper reviews the behavioral-relaxation treatments of myofascial pain-dysfunction syndrome. The evidence indicates that this pain (located around the oral cavity) is due to muscle hyperactivity, most commonly of the lateral pterygoids. Research concerning relaxation techniques (i.e. progressive muscle relaxation and electromyographic feedback) has indicated the following: (a) in analogue research, normal healthy controls can learn to relax their muscles of mastication profoundly even during stress, and (b) in case reports, relaxation treatments are helpful clinical interventions, especially for pain patients who are not depressed, and who have not had the pain for more than a few years. Well controlled research is the next, essential step.     

Acupuncture and chronic pain mechanisms: the moderating effects of affect, personality, and stress on response to treatment.

The present study, part of a larger project investigating neurophysiological and psychosocial factors affecting response to acupuncture for chronic pain, compares responders and non-responders to acupuncture on a series of variables assessing personality, affect and stress. Subjects were 40 patients with pain beneath the waist level longer than 6 months duration selected from the roles of the Multidisciplinary Pain Clinic. Responders, defined as 50% or more reduction in pain estimate for greater than two weeks, were found to be less depressed, less passive and overly conventional, have shorter duration of pain, endorse less frequent exposure to stressors, and have less serious non pain-related illnesses. The findings are viewed as linking the intractability of pain states with psychosocial factors which may interfere with response to somatic modes of therapy or which may interfere via alterations of tonic neurohumoral factors. The study also in seen as supporting the importance of considering psychological variables in evaluating patients for pain treatment strategies and suggests inclusion of such variables in investigating response to other modalities of treatment for chronic pain.     

Acupuncture and chronic pain mechanisms.

Forty patients with chronic pain below the waist level not amenable to conventional medical and/or surgical treatment were randomly assigned to one or two different methods of acupuncture, after studying the underlying pain mechanisms using a Multidisciplinary Pain Clinic approach and the differential spinal block (DSB). One group received acupuncture needling in the classical acupuncture points referred to as meridian loci needling (MLN) and the other group received tender area needling (TAN) with needles inserted in the dermatomal distribution of the painful areas. The responses between the two groups showed no significant difference. Results were then related to the predetermined somatopsychological basis of the individual's pain problems as classified by the DSB. A group of patinets in whom pain relief occurred upon subarachnoid injection of 0.25% procaine followed by sympathetic blockade or 0.5% procaine injection followed by hypalgesia without motor loss, also reported maximum subjective improvement in their pain level following acupuncture therapy performed at a later time. The other group of patients in whom pain persisted despite sensory and motor blockade (1% procaine) responded very poorly to acupuncture therapy. DSB was found to be complimentary to acupuncture therapy in that it facilitated patient selection for the therapy.     

High versus low intensity acupuncture analgesia for treatment of chronic pain: Effects on platelet serotonin

The 26 chronic pain patients were tested in a baseline plus cross-over design. Half of the subjects were first treated with high intensity acupuncture; then they were treated with low intensity acupuncture. For the other 13 subjects the treatment order was reversed. In the first treatment sequence subjects reported lower pain estimates and engaging in more activities of daily living during treatment with high intensity acupuncture — but not with low intensity acupuncture. In addition, under high intensity acupuncture (i.e. with low pain levels), subjects had higher levels of platelet serotonin; this last finding is consistent with recent research which implicates central serotonin in pain control. The results of the second treatment sequence were ambiguous.     

Intrathecal normal saline without preservative does not have a local anesthetic effect

The effects of intrathecally administered normal saline (preservative-free) were studied in patients undergoing differential spinal block anesthesia for evaluation of chronic pain below the waist. The injection of 5 ml saline did not significantly change the sensitivity to pinprick measured in the lower back and both lower extremities. Temperature measurement in both the lower extremities and psycho-galvanic skin reflex did not show evidence of sympathetic block; the psychogalvanic skin reflex was abandoned because of inconsistent results. These findings refute the earlier conclusion of Urban and McKain who found that normal saline acts as a weak local anesthetic when injected intrathecally. We recommend use of normal saline (preservative-free) in 5 ml doses as a placebo for differential spinal block anesthesia.     

Failure of a predictive scale in identifying patients who may benefit from a pain management program: follow-up data

A 7-item scale to identify patients who may benefit from a pain management program was prospectively studied. The patient group consisted of 217 patients. The duration of follow-up was 2-3 years. Although an item-by-item analysis revealed some differences between successes, partial successes, and failures, the overlap was such that the total score was not predictive of outcome. Although this finding precludes clinical use of the 7-item scale in its present form, future modifications are suggested that may improve its predictive ability.     

Signal detection and threshold measures to loud tones and radiant heat in chronic low back pain patients and cohort controls

Eleven chronic low back pain (CLBP) and 11 age- and sex-matched control subjects were tested during two separate sessions for the perception of radiant heat and uncomfortably loud tones. Following the determination of a subject's pain threshold (PT) for radiant heat, a standard signal detection methodology was used to present 26 trials each of 4 stimulus levels. The stimuli were rated on a 9-point scale ranging from ‘nothing’ to ‘very strong pain.’ A similar procedure was used for the tone stimuli with the 9-point scale ranging from ‘nothing’ to ‘very strongly uncomfortable.’ It was found that the CLBP group had both higher heat pain and tone discomfort thresholds than the control group. For radiant heat only, the CLBP group had poorer discrimination as determined by P(I). The results are discussed within the framework of the hypervigilance and adaptation theories of pain perception.     

Problems with the use of oxycodone compound in patients with chronic pain

In a pain management program (200 patients), a group of daily users of oxycodone compound (29 patients) and a subgroup who were taking a “high dose” of oxycodone compound (13 patients) were compared with a group of 171 non-users of oxycodone compound. A significantly lower treatment success rate was observed in the users (P = 0.04) and high-dose users (P = 0.03). A similar trend was seen in preliminary data available in a larger sample (514 patients). Continued study of these findings is necessary. Meanwhile, in patients with chronic pain, there should be cautious use of this compound.     

Type III hyperlipoproteinemia: a comparative study of current diagnostic techniques.

Research into the prevalence, genetic transmission and pathophysiology of Type III hyperlipoproteinemia has suffered from the lack of a practical specific diagnostic procedure. In this study, very low density lipoprotein (VLDL) compositional criteria were established in a population lacking the beta-migrating VLDL characteristic of this disorder. Diagnosis by these criteria was compared to diagnosis using current criteria for the Type III lipoprotein pattern. In addition two techniques for detecting Type III without preliminary VLDL isolation by ultracentrifugation were evaluated. Plasma triglyceride (TG) concentration dependent cutlines for the compositional criteria reduced false positives at low TG levels and false negatives at high TG levels. Furthermore, an agarose electrophoresis heparin-manganese precipitation technique was effective for screening for a possible Type III pattern in plasma whereas the combination agarose-polyacrylamide gel electrophoresis system was not effective.     

Representation of the thoracic outlet syndrome as a problem in chronic pain and psychiatric management

The diagnosis of thoracic outlet syndrome depends upon subjective complaints and sometimes rather limited physical findings. There is a tendency to favour other non-specific diagnoses, like ‘soft tissue damage’ or to suspect neurosis, particularly in patients who have had motor vehicle or other injuries for which they claim compensation. We report here 3 patients in whom the diagnosis of thoracic outlet syndrome was overlooked and who responded to surgical treatment with good or excellent results.     

Daily variation of lipids and hormones in sera of healthy subjects.

The physiological day-to-day variation of selected hormone and lipid concentration values in sera of healthy subjects was studied. We drew blood specimens from 14 healthy volunteers, aged 22 to 40 years, (8 male and 6 female) at 0800 h on six separate days over a ten day interval. On one occasion all the twelve specimens from each subject (6 days X 2 replicates) were assayed for the hormones: thyroxine and cortisol; and the lipips: cholesterol and triglyceride which were analyzed by enzymatic methods. The assays were performed on one occasion in order to eliminate the batch-to-batch analytical variation which would tend to blur the physiological day-to-day variation. Using an analysis of variance technique, the total variation was separated into the physiological intraindividual day-to-day variation, the biological inter-individual variation, and the within-batch analytical variation. The mean physiological day-to-day variations in terms of percent coefficient of variation were 7.5% for thyroxine, 26.6% for cortisol, 4.8% for cholesterol, , and 25.0% for triglycerides.     

Sympathetic blocks for reflex sympathetic dystrophy

Seventy-one patients with reflex sympathetic dystrophy of the lower extremities were studied during a 3-year period. Of the 27 patients managed by conservative means, 11 (41%) showed signs of improvement 3 years after the onset of syndrome. Of the 43 patients treated by sympathetic nerve blocks, 28 (65%) experienced progress at the 3-year evaluation. Data suggest that early treatment with repeated sympathetic nerve blocks appears to improve the long-term outcome.     

Where is the noise in sdt pain assessment?

Many applications of sensory decision theory (SDT) to pain research have used discrimination as a measure of pain or sensory sensitivity. This belief is based on the classical SDT assumption that discrimination and criterion represent separation of sensory and decision processes. This assumed separation stems from a model where all noise or variability is part of the sensory transduction mechanism. We present an alternative formulation that allows for decision variability as well as variability in sensory transduction. This formulation documented by computer simulation shows that decision variability and sensory variability are indistinguishable and that any measure of discriminability is degraded by both. Thus discriminability is influenced by both sensory and non-sensory factors. There is no way of knowing if a drug-induced change in discriminability represents an analgesic effect or a change of the observer's ability to make consistent judgments.     

A chronic emergency room visitor with chest pain: successful treatment by stress management training and biofeedback

The successful treatment of a patient with chest pain who at baseline visited the emergency room (ER) up to 20 times monthly is described. Treatment consisted of re-education, stress management training and biofeedback. The importance of conceptualizing multiple ER visitations as an interaction of physiological, psychological, social and iatrogenic factors is discussed, and suggestions are made for recognizing such behavior and effectively referring patients for appropriate treatment.