Cultural, clinical and physiological aspects of pain: a review

Whiplash injuries of the temporomandibular joint in motor vehicle accidents: speculations and facts

Referring to the temporomandibular joint (TMJ) of the human mandibular locomotor system, it has been asserted that displacement of the TMJ disc and inflammation of TMJ tissues are the results of acute and indirect trauma to the TMJ; on occasion this is allegedly experienced in motor vehicle accidents and commonly known as a TMJ whiplash injury. It is postulated that the TMJ whiplash injury is released in the occupant or occupants of a target vehicle when its rear end is impacted by the front end of a bullet vehicle. On the basis of detailed analyses of TMJ trauma/pain histories and TMJ magnetic resonance images, presented as circumstantial evidence in favour of the postulated TMJ whiplash injury, and detailed analyses of the mathematical biophysics of the mandibular locomotor system as well as direct experimental evidence, it is concluded that the postulated TMJ whiplash injury does not exist as a single and independent disease entity caused by motor vehicle accidents. If TMJ disc displacement and inflammation are present, they are expressions of an insidious and progressive pre-existing (pre-accident) disease entity that is comprised of TMJ synovitis/osteoarthritis (phase of inflammation with presence of immune system cells), TMJ internal derangement (phase of disc displacement and deformation with presence of proteinases), and TMJ osteoarthrosis (phase of degeneration with absence of immune system cells). For the asserted TMJ whiplash manoeuvre and ensuing injury to occur as postulated, the laws of physics and biology would have to be suspended.

Physiology and pathophysiology of skeletal muscle contractions. Part II. Static activity

An overview is presented of the physiology and so-called pathophysiology of static muscle contractions in the intact living organism. Static muscle activity produces no external mechanophysical work, but is used for fixation. Contingent upon the levels of the generated forces, and the duration of the isometric contractions, static activities give rise to fatigue and pains. The discomforts are viewed as somatic responses that are normally within physiological limits. That is, upon cessation of isometric contractions there is usually rapid recovery from the discomforts, and they do not normally induce chronic lesions.

Non-ulcer upper dyspepsia. Aspects of pain

Subjects with upper abdominal pain without any demonstrable organic basis are often met with the attitude that the pain is "not real'. Twenty-five patients with long-standing upper abdominal pain but with normal findings on X-ray examination, gastroduodenoscopy, and relevant blood analyses were examined with pain-measuring techniques. Two fundamentally different techniques--pain estimate on a visual analogue scale and magnitude matching by submaximal effort tourniquet technique, respectively--gave correlating values for pain intensity (r = 0.70; P less than 0.001), indicating that these patients' asserted pain actually is "real'. Values for pain tolerance, measured with the submaximal effort tourniquet technique, were compared with pain tolerance in a group of healthy volunteers and were found to be three times lower (P less than 0.001) in the patient group. A methodological study of the submaximal effort tourniquet technique was performed on the healthy volunteers. The method was found to be suitable for use in pain studies, since the pain produced gradually increased as a linear function of time.

Temporomandibular joint disfunction syndrome and myofascial pain dysfunction syndrome: a critical review

Temporomandibular joint (TMJ) dysfunction syndrome and myofascial pain dysfunction (MPD) syndrome have been primarily viewed as dental problems and have only recently received close attention by psychologists. The literature reviewed in the present paper reveals that a substantial portion of the population is affected by these disorders. There is, however, a great deal of confusion that exists in relation to the aetiology and treatment of these syndromes. In an attempt to clarify the current understanding of these disorders, the present review first presents a discussion of the symptoms which comprise each of these syndromes and the proposed physiological mechanisms associated with each symptom. Next, the aetiological theories for each of these syndromes are reviewed and critically evaluated. Treatments which have been derived from the theoretical models are then discussed. Finally, methodological considerations involving classification, assessment and treatment issues are presented and future research needs are outlined.

Progressive jaw muscle fatigue of experimental tooth clenching in man

To determine the onset of subjective fatigue and the subjective endurance of fatigue and pains in the masseter muscle, ten adult male subjects exercised maximal voluntary tooth clenching. Concomitantly, the electrical activity in the masseter muscle was recorded by bipolar surface electrodes and integrated. Onset of subjective fatigue occurred on average 21 s after onset of muscle hyperactivity and the isometric endurance time of the masseter muscle, during which period severe muscle pains were present, was on average 82 s. The electrical muscle activity of the threshold and endurance tests showed a curvilinear configuration (y =a + b log x), and it is suggested that progressive physiological, or peripheral, muscle fatigue accompanied the psychological, or central, endurance of tooth clenching.

Jaw muscle fatigue and pains induced by experimental tooth clenching: a review

Maximal voluntary isometric contractions of the elevator jaw muscles, with the mandible in the position of maximal intercuspation of the natural teeth, can induce fatigue and weak as well as severe pains in the jaw muscles of children and adults. A subjective sensation of muscle fatigue appears after about 0.5 min of clenching, and it seems as if the psychological parameter of fatigue onset to a large, but unknown, extent is determined by the physiological parameter of the amount of isometric contractile activity, and perhaps also the original strength of the muscle; however, also individual psychological factors seem to play a role. Pains in the elevator jaw muscles appear after about 1 min of clenching. Although isometric contractions are necessary to cause onset of jaw muscle pains, it is conceivable that perception of the moment of onset of pains to a large, but unknown, extent depends on psychological factors, perhaps the intensity of pains; however, also physiological factors may play a role. The severe muscle pains and gradually increasing subjective exhaustion of the elevator jaw muscles can be endured for about 2 min of maximal voluntary tooth clenching. It is suggested that the psychological parameter of muscle endurance to a large, but unknown, extent depends on the physiological parameter of isometric contractile activity but also individual psychological factors seem to play a role.