Discrimination of muscle tension in chronic pain patients and healthy controls

Abstract

The purpose of this study was to assess the perception of muscle tension in chronic pain patients and healthy controls. Twenty chronic back pain patients, 20 patients who suffered from temporomandibular pain and dysfunction, and 20 healthy controls were instructed to produce eight different levels of muscle contraction in either the m. masseter or the m. erector spinae. Each level was produced three times; trials were presented in random order. Analyses of the accuracy and the sensitivity of discrimination of muscle tension levels revealed that the patients were less able to perceive muscle contraction levels correctly and that they underestimated their actual levels of muscle tension. Patients and controls did not differ in the extent to which they contracted muscles not involved in the task. Patients suffering from musculoskeletal disorders seem to display a genuine deficit in discrimination of muscle tension that is related to neither local physiological changes at the site of pain, lack of motivation, in-attention, nor fatigue.

Sensing the body in chronic pain: A review of psychophysical studies implicating altered body representation

“…Impaired perception and regulation of muscle tension has been implicated in chronic pain (Flor et al, 1992(Flor et al, , 1999, particularly in individuals experiencing chronic tension headaches (Appelbaum et al, 1984), as well as pain in the neck, shoulder (Fowler and Kraft, 1974) and jaw regions (Flor et al, 1992). Hence, interest in this area is fuelled by the notion that relief can be brought about by relaxing the muscle.…”

“…Indeed, studies have confirmed increased activity of the affected muscle using EMG (Lund et al, 1991;Jacobs et al, 2011), which can be resolved with biofeedback and training (Fowler and Kraft, 1974). When assessing tension and/or force awareness during both acute pain states (e.g., induced with hypertonic saline injections (Weerakkody et al, 2003a)) or chronic pain states (Flor et al, 1992(Flor et al, , 1999, there is a consistent underestimation of the force generated by the painful muscle. An underestimation of tension by the affected muscle is consistent with the kinaesthetic data, suggesting a blunted awareness of feedback from the painful muscle, and may be involved in the long-term stiffening of muscles in the affected body part (Hodges and Tucker, 2011).…”

Varieties of relaxation methods and their unique effects

“…After training, the tense individuals could produce immediate muscle relaxation at least as immediate and profound as that produced by the athletes. More recently Flor et al (1992) found patients with low back pain or temporomandibular disorders were less accurate than nonpain comparison subjects in controlling levels of voluntarily-produced muscle tension in, respectively, the erector spinae and masseter muscles.…”

Palpation of Muscle and Skin. Is this a Reliable and Valid Procedure in Assessment of Patients with Long-lasting Musculoskeletal Pain?

“…Such factors can be development of muscle tension, direct trauma to the muscle, inefficient use, repetitive microtrauma from habits that produce muscle tension, or factors that gradually weaken and predispose the muscle to the development of trigger points. Examples are nutritional disturbances, structural disharmony, lack of exercise, sleep disturbances, or the presence of other disorders, such as joint problems, or inability to relax, sometimes caused by pain, which again causes increased muscle tension and a vicious circle, causing reduced microcirculation (2)(3)(4)(5)(6). Psychological factors have often been associated with increased risk of developing and sustaining muscular tension and pain (7)(8)(9)(10)(11)(12).…”