Skip to main content

Advertisement

SpringerLink
Log in

The neurophysiology of myofascial pain syndrome

  • Published:
Current Pain and Headache Reports Aims and scope Submit manuscript

Abstract

This article discusses the neurophysiology of myofascial pain syndrome. The local twitch response is a characteristic finding of this condition; it is activated by snapping palpation, pressure, or needle insertion at the trigger point. It is manifested by a burst of activity in the muscle band that contains the activated trigger point. No activity is seen at other muscles bands. Data from experiments with the rabbit indicate that this is a spinal reflex, as it is abolished by transection of the motor nerve innervating the trigger point and infusion of lidocaine. Transection of the spinal cord above the level of the trigger point fails to permanently alter the trigger point response.

Needle examination recordings from trigger points show low-voltage spontaneous activity and activity resembling end-plate spikes. This activity is reduced with infusion of phentolamine and local intramuscular infusions of phenoxybenzamine. There are four hypotheses to explain the findings seen at the trigger point. The first is that trigger points are found at the muscle spindle. While this theory may explain the effects of a-adrenergic antagonists at the trigger point, it does not fully explain the electromyographic (EMG) findings recorded at the trigger point. The second theory is that trigger points represent hyperactive end-plate regions, as the EMG activity recorded at trigger points resembles that described at the end-plate region. Other theories that either deny the existence of myofascial pain syndrome or believe it represents a focal dystonia are also discussed.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References and Recommended Reading

  1. Elliott FA: Tender muscles in sciatica. Lancet 1944, 1:47–49.

    Article  Google Scholar 

  2. Kraft G, Johnson E, LaBan M: The fibrositis syndrome. Arch Phys Med Rehabil 1968, 49:155–162.

    PubMed  CAS  Google Scholar 

  3. Cobb CR, deVries HA, Urban RT, et al.: Electrical activity in muscle pain. Am J Phys Med 1975, 54:80–87.

    PubMed  CAS  Google Scholar 

  4. Awad E: Interstitial myofibrositis: hypothesis of the mechanism. Arch Phys Med Rehabil 1973, 54:449–453.

    PubMed  CAS  Google Scholar 

  5. Durette MR, Rodriquez AA, Agre JC, Silverman JL: Needle electromyographic evaluation of patients with myofascial or fibromyalgic pain. Am J Phys Med Rehabil 1991, 70:154–156.

    Article  PubMed  CAS  Google Scholar 

  6. Simons DG, Travell J, Simons LS: Travell and Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual, edn 2. Philadelphia: Lippincott Williams & Wilkins; 1999. This is the second edition of the classic Travell and Simons trigger point manual. It has been completely revised to include most of the recent neurophysiologic data. Simons describes his views on the origin of trigger points, including his energy crisis hypothesis.

    Google Scholar 

  7. Wolfe F, Simons DG, Fricton J, et al.: The fibromyalgia and myofascial pain syndromes: a preliminary study of tender points and trigger points in persons with fibromyalgia, myofascial pain syndrome and no disease. J Rheumatol 1992, 19:944–951.

    PubMed  CAS  Google Scholar 

  8. Gerwin RD, Shannon S, Hong CZ, et al.: Interrater reliability in myofascial trigger point examination. Pain 1997, 69:65–73.

    Article  PubMed  CAS  Google Scholar 

  9. Simons DG: Examining for myofascial trigger points. Arch Phys Med Rehabil 1993, 74:676–677.

    Article  PubMed  CAS  Google Scholar 

  10. Simons DG: Clinical and etiological update of myofascial pain from trigger points. J Musculoskeletal Pain 1996, 4:93–121.

    Article  Google Scholar 

  11. Bohr TW: Problems with myofascial pain syndrome and fibromyalgia syndrome. Neurology 1996, 46:593–597.

    PubMed  CAS  Google Scholar 

  12. Bohr TW: Fibromyalgia syndrome and myofascial pain syndrome. Do they exist? Neurol Clin 1995, 13:365–384.

    PubMed  CAS  Google Scholar 

  13. Simons DG: Electrogenic nature of palpable bands and “jump sign” associated with myofascial trigger points. Adv Pain Res 1976, 1:913–918.

    Google Scholar 

  14. Dexter JR, Simons DG: Local twitch response in human muscles evoked by palpation and needle penetration of trigger point. Arch Phys Med Rehabil 1981, 62:521–522.

    Google Scholar 

  15. Fricton JR, Auvinen MD, Dykstra D, Schiffman E: Myofascial pain syndrome: electromyographic changes associated with local twitch response. Arch Phys Med Rehabil 1985, 66:314–317.

    PubMed  CAS  Google Scholar 

  16. Hong CZ, Simons DG: Pathophysiologic and electrophysiologic mechanisms of myofascial trigger points. Arch Phys Med Rehabil 1998, 79:863–872.

    Article  PubMed  CAS  Google Scholar 

  17. Hong CZ, Torigoe Y: Electrophysiologic characteristics of localized twitch responses in responsive bands of rabbit skeletal muscle fibers. J Musculoskeletal Pain 1994, 2:17–43.

    Article  Google Scholar 

  18. Simons DG, Hong CZ, Simons DG: Prevalence of spontaneous electrical activity at trigger spots and at control sites in rabbit skeletal muscle. J Musculoskeletal Pain 1995, 3:35–48.

    Article  Google Scholar 

  19. Hong CZ, Torigoe Y, Yu J: The localized twitch responses in responsive bands of rabbit skeletal muscle fibers are related to the reflexes at spinal cord level. J Musculoskeletal Pain 1995, 3:15–33.

    Article  Google Scholar 

  20. Stuart DG, Hamm TM, Vanden Noven S: Partitioning of monosynaptic Ia EPSP connections with motoneurons according to neuromuscular topography: generality and functional implications. Prog Neurobiol 1988, 30:437–447.

    Article  PubMed  CAS  Google Scholar 

  21. Vanden Noven S, Hamm TM, Stuart DG: Partitioning of monosynaptic Ia excitatory postsynaptic potentials in the motor nucleus of the cat lateral gastrocnemius muscle. J Neurophysiol 1986, 55:569–586.

    Google Scholar 

  22. Hubbard DR, Berkoff GM: Myofascial trigger points show spontaneous needle EMG activity. Spine 1993, 18:1803–1807.

    Article  PubMed  CAS  Google Scholar 

  23. Hubbard DR: Chronic and recurrent muscle pain: pathophysiology and treatment, and review of pharmacologic studies. J Musculoskeletal Pain 1996, 4:123–143.

    Article  Google Scholar 

  24. Buchthal F, Rosenfalck P: Spontaneous electrical activity of human muscle. Electroencephalogr Clin Neurophysiol 1966, 20:321–336.

    Article  PubMed  CAS  Google Scholar 

  25. Wiederholt WC: “End-plate noise” in electromyography. Neurology 1970, 20:214–224.

    PubMed  CAS  Google Scholar 

  26. Chu J: Does EMG (dry needling) reduce myofascial pain symptoms due to cervical nerve root irritation? Electromyogr Clin Neurophysiol 1997, 37:259–272.

    PubMed  CAS  Google Scholar 

  27. Hong CZ: Lidocaine injection versus dry needling to myofascial trigger point. The importance of the local twitch response. Am J Phys Med Rehabil 1994, 73:256–263.

    Article  PubMed  CAS  Google Scholar 

  28. McNulty WH, Gevirtz RN, Hubbard DR, Berkoff GM: Needle electromyographic evaluation of trigger point response to a psychological stressor. Psychophysiology 1994, 31:313–316.

    Article  PubMed  CAS  Google Scholar 

  29. Bengtsson A, Bengtsson M: Regional sympathetic blockade in primary fibromyalgia. Pain 1988, 33:161–167.

    Article  PubMed  CAS  Google Scholar 

  30. Chen JT, Chen SM, Kuan TS, et al.: Phentolamine effect on the spontaneous electrical activity of active loci in a myofascial trigger spot of rabbit skeletal muscle. Arch Phys Med Rehabil 1998, 79:790–794. The action of phentolamine, an a-adrenergic antagonist, is studied in the rabbit trigger point model.

    Article  PubMed  CAS  Google Scholar 

  31. Banks RW: A histological study of the motor innervation of the cat’s muscle spindle. J Anat 1981, 133:571–591.

    PubMed  CAS  Google Scholar 

  32. Barker D, Banks RW: The muscle spindle. In Myology. Edited by Engle A, Banker B. New York: McGraw Hill; 1986:309–341.

    Google Scholar 

  33. Santini M, Ibata Y: The fine structure of thin unmyelinated axons within muscle spindles. Brain Res 1971, 33:289–302.

    Article  PubMed  CAS  Google Scholar 

  34. Grassi C, Passatore M: Spontaneous sympathetic command to skeletal muscles: functional implications. Funct Neurol 1990, 5:227–232.

    PubMed  CAS  Google Scholar 

  35. Passatore M, Grassi C, Filippi GM: Sympathetically-induced development of tension in jaw muscles: the possible contraction of intrafusal muscle fibres. Pflugers Arch 1985, 405:297–304.

    Article  PubMed  CAS  Google Scholar 

  36. Grassi C, Deriu F, Passatore M: Effect of sympathetic nervous system activation on the tonic vibration reflex in rabbit jaw closing muscles. J Physiol 1993, 469:601–613.

    PubMed  CAS  Google Scholar 

  37. Mense S: Nociception from skeletal muscle in relation to clinical muscle pain. Pain 1993, 54:241–289.

    Article  PubMed  CAS  Google Scholar 

  38. Hong CZ, Chen JT, Chen SM, et al.: Histological findings of responsive loci in a myofascial trigger spot of rabbit skeletal muscle from where localized twitch responses could be elicited. Arch Phys Med Rehabil 1996, 77:962.

    Google Scholar 

  39. Kuan TS, Lin TS, Chen JT, et al.: No increased neuromuscular jitter at rabbit skeletal muscle trigger spot spontaneous electrical activity sites. J Musculoskeletal Pain 2000, 8:69–82.

    Article  Google Scholar 

  40. Brown WF, Varkey GP: The origin of spontaneous electrical activity at the end-plate zone. Ann Neurol 1981, 10:557–560.

    Article  PubMed  CAS  Google Scholar 

  41. Partanen JV, Nousiainen U: End-plate spikes in electromyography are fusimotor unit potentials. Neurology 1983, 33:1039–1043.

    PubMed  CAS  Google Scholar 

  42. Partanen J: End plate spikes in the human electromyogram. Revision of the fusimotor theory. J Physiol Paris 1999, 93:155–166. A nontraditional theory on the etiology of end-plate spikes is presented. Although virtually no other muscle physiologist accepts this view, it deserves further consideration and study as it might explain some of the findings seen at trigger points.

    Article  PubMed  CAS  Google Scholar 

  43. Donaldson CC, Nelson DV, Schulz R: Disinhibition in the gamma motoneuron circuitry: a neglected mechanism for understanding myofascial pain syndromes? Appl Psychophysiol Biofeedback 1998, 23:43–57.

    Article  PubMed  CAS  Google Scholar 

  44. Jones RV, Lambert EH, Sayre GP: Source of a type of “insertion activity” in electromyography with evaluation of a histologic method of localization. Arch Phys Med Rehabil 1955, 36:301–310.

    PubMed  Google Scholar 

  45. Acquadro MA, Borodic GE: Treatment of myofascial pain with botulinum A toxin. Anesthesiology 1994, 80:705–706.

    Article  PubMed  CAS  Google Scholar 

  46. Cheshire WP, Abashian SW, Mann JD: Botulinum toxin in the treatment of myofascial pain syndrome. Pain 1994, 59:65–69.

    Article  PubMed  CAS  Google Scholar 

  47. Wheeler AH, Goolkasian P, Gretz SS: A randomized, double-blind, prospective pilot study of botulinum toxin injection for refractory, unilateral, cervicothoracic, paraspinal, myofascial pain syndrome. Spine 1998, 23:1662–1666.

    Article  PubMed  CAS  Google Scholar 

  48. McBroom P, Walsh NE, Dumitru D: Electromyography in primary fibromyalgia syndrome. Clin J Pain 1988, 6:117–119.

    Article  Google Scholar 

  49. Svebak S, Anjia R, Karstad SI: Task-induced electromyographic activation in fibromyalgia subjects and controls. Scand J Rheumatol 1993, 22:124–130.

    PubMed  CAS  Google Scholar 

  50. Zidar J, Backman E, Bengtsson A, Henriksson KG: Quantitative EMG and muscle tension in painful muscles in fibromyalgia. Pain 1990, 40:249–254.

    Article  PubMed  CAS  Google Scholar 

  51. Meadows JC: Observation on muscle pain in man with particular reference to pain during needle electromyography. J Neurol Neurosurg Psychiatry 1970, 33:519–523.

    Article  PubMed  CAS  Google Scholar 

  52. Melzack R: Myofascial trigger points: relation to acupuncture and mechanisms of pain. Arch Phys Med Rehabil 1981, 62:114–117.

    PubMed  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Department of Neurology, Medical College of Georgia, 1120 15th Street, 30912, Augusta, GA, USA

    Michael H. Rivner MD

Authors
  1. Michael H. Rivner MD
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Rivner, M.H. The neurophysiology of myofascial pain syndrome. Current Science Inc 5, 432–440 (2001). https://doi.org/10.1007/s11916-001-0054-6

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11916-001-0054-6

Keywords

Search

Navigation