DISINHIBITION IN THE GAMMA-MOTONEURON CIRCUITRY - A NEGLECTED MECHANISM FOR UNDERSTANDING MYOFASCIAL PAIN SYNDROMES

Dysregulation in the gamma motoneuron circuitry is proposed as one mec hanism to explain the development of trigger point activity in myofasc ial pain syndrome. Dysregulation in this context is defined operationa lly as significantly (and functionally) different levels of electrical activity detected in the same muscle on the left and right sides of t he body that is persistently present with movement of that muscle. Neu rophysiological concepts as they pertain to muscles and motor control principles are reviewed. Research is integrated that ties together mat erial from diverse fields of psychology and medicine. Dysregulation in the gamma motoneuron circuitry may lead to disinhibition of muscle th at causes it to remain hyperactive after contraction, generate excessi ve electrical activity during movement, and/or inappropriately coactiv ate with other muscles during movement. Any or all of these phenomena may occur with dysregulation. Such dysregulation may be corrected by l earning, Immediate clinical implications are discussed, including the addition of specifically targeted neuromuscular retraining procedures via surface electromyography, as well as some conceptual and research issues that require further clarification.