Neurobiology of the myofascial trigger point

The clinical phenomenon of the MTrP is accessible to any clinician who takes the time to learn to palpate skeletal muscle gently and carefully, and who is willing to learn the functional anatomy necessary to understand the regional spread of MTrPs through functional muscle units (Travell and Simons, 1992). Yet despite the years of clinical study of MPS, the pathophysiology of the central feature, the trigger point, has remained elusive. Many investigators have contributed to the general understanding of the mechanisms of pain perception, but we owe a particular debt of gratitude to Dr Seigfried Mense of Heidelberg for his pursuit of the study of pain originating in muscle lesions. However, Dr Mense would be the first to caution us against the direct transference of the results obtained with an inflammatory lesion produced in the experimental animal to the pain of MTrPs in the clinic patient. Notwithstanding that, researchers in the field of pain have given us an understanding of the basis for the hyperalgesia, allodynia and the previously difficult-to-understand finding of referred pain zones that we see daily in our patients. Finally, the interesting initial observations of Hubbard and Berkoff (1993), suggesting that the muscle spindle may be associated with the trigger point, open yet another door in our understanding of the nature of MPS.