Reduction In Electromyographic Activity Research Articles

Electromyographic and affective responses of episodic tension-type headache patients and headache-free controls during stressful task performance.

Thirty-four subjects meeting diagnostic criteria for episodic tension-type headache and 42 who rarely experienced headaches participated in two laboratory sessions in which cephalic electromyographic (EMG) activity, electrodermal activity, heart rate, and finger temperature were recorded. Subjects performed relaxation, choice reaction time, psychomotor tracking, voluntary muscle contraction, and cold pressor tasks. Headache subjects showed significantly greater EMG activity than controls during baseline and stressful task performance. During relaxation, both groups reduced EMG activity from baseline levels, and there was no significant difference in EMG level between the groups during relaxation. Headache subjects reported higher levels of subjective anxiety, depression, anger, and stress than controls. Headache subjects also reported higher levels of pain than controls, and headache subjects reported greater pain during stressful task performance relative to baseline and recovery periods.

Electromyographic reflexes evoked in human wrist flexors by tendon extension and by displacement of the wrist joint.

1. The electromyographic (EMG) reflexes evoked in the wrist flexor muscle, flexor carpi radialis (FCR), by percutaneous extension of its tendon and by forcible extension of the wrist joint have been studied. Reflexes were elicited during steadily maintained voluntary flexor contraction of 10% of each subject's maximum. 2. Tendon extension, using 'ramp and hold' displacements, evoked fairly prolonged (ca 50 ms) increases in EMG activity. These responses were usually subdivided into two main excitatory peaks of respectively short (SL, ca 20 ms) and long (LL, ca 45 ms) latency. This pattern contrasted with that observed following brief tendon taps when only a single, SL peak was elicited. 3. 'Stretch' reflexes evoked by 'ramp and hold' wrist extensions, as has been noted by numerous earlier investigators, were also protracted and comprised two main excitatory components. These responses resembled those produced by tendon extension both in their general form and in their behaviour upon altering the velocity of mechanical stimuli. Quantitatively, however, two main differences were evident. The reflexes evoked by wrist extension, including their SL and LL peaks, were generally somewhat larger. Additionally, when parameters of the two modes of stimulation were adjusted to elicit SL responses of equivalent amplitude, the LL responses elicited by tendon extension were regularly smaller and of shorter duration than those elicited by wrist extension. 4. Termination of the two forms of mechanical stimulation, by releasing tendon or wrist extension, each elicited a SL reduction in EMG activity. Such troughs were more pronounced and more consistently observed upon release of wrist extension. 5. Neither local anaesthesia of the skin overlying the flexor tendons at the wrist nor ischaemia of the hand and lower forearm produced any systematic modification of reflex response patterns. 6. It is concluded that intramuscular receptors (presumably muscle spindles) in FCR mediate both the SL and LL reflexes evoked in this muscle by extension of its tendon. Intramuscular receptors also seem certain to be very largely responsible for the EMG responses generated in this muscle by wrist extension.

Some relationships between adaptation and electromyographic activity at laryngeal and masseter sites in stutterers

Cumulative integrated electromyographic (EMG) activity was recorded from laryngeal and masseter sites from ten stutterers during a five trial oral adaptation sequence. Results showed more activity at the laryngeal site than the masseter site. While significant reductions in EMG activity were not found, patterns were shown to be related to the subjects' dysfluency patterns over trials. Results were interpreted as suggesting that reduced muscle activity and adaptation (when they occur) are artifacts of other behavioral modifications resulting from overt motor practice.

Cephalic vasomotor and electromyographic feedback in the treatment of combined muscle contraction and migraine headaches in a geriatric case.

SYNOPSISThe effects of cephalic vasomotor response (CVMR) feedback and electromyographic (EMG) feedback on control of CVMR, frontalis EMG and temporal artery vasospasms in muscle contraction and migraine headaches were investigated in a 67 year old woman. Systematic reductions in EMG activity were not achieved during EMG feedback. The frequency of temporal artery vasospams declined. No changes in amplitude of blood volume pulse (BVP) were observed during EMG feedback. A decrease in headache activity was associated with EMG feedback which may have been due to the reduction in temporal artery vasospasms. A treatment withdrawal condition was introduced after six EMG feedback sessions during which an increase in headache activity occurred. When CVMR feedback was introduced, the patient achieved significant BVP reductions. This control was related to the largest reduction in headache frequency and duration. Ratings representing subjective perception of the degree of disability because of headache also decreased during EMG feedback, CVMR feedback, and follow‐up. At follow‐up, there was a moderate increase in headache activity which was partially attributed to limited home practice.This case demonstrates the successful use of biofeedback therapy in the treatment of combined vascular and muscle contraction headaches in an elderly patient and suggests that age not be a criterion for eliminating patients from this treatment. In addition, this case further supports the use of cephalic vasomotor feedback as an alternative to temperature training in the treatment of migraine.