Myofascial  Pain Syndrome

Dr. Madhu S

Human body comprising 400 skeletalmuscles along with skeletal system is the largest organ system by weight. Pain or fatigue of this system is the leading cause of patients clinician consultation. [1,2]

Myofascial pain syndrome (MPS) is a type of musculoskeletal pain condition characterized by deep and aching local & / or referred pain, and also by the presence of trigger points. These trigger points are hyperirritable spot in muscle or facia and known to cause sensory, motor and autonomic symptoms on compression. [3]

The prevalence and incidence of MPS is not exactly known. Few epidemiological studies have investigated the prevalence of MPS. A study on patients attending clinic for chronic head and neck pain found 54.6% having MPS. Another study comprising of patients presenting to internal medicine with pain found prevalence of 29.6% and was the most common cause of pain [4]. Different studies have found that MPS is associated with other pain conditions such as migrane, tension headache, neck pain, shoulder pain, low back pain and pelvic pain [5,6].

The reason for development of trigger points is unclear. Taught bands are found to be precursors of trigger points. Injury to muscles because of trauma or repetitive strain on muscles are the most common factors initiating taught bands or trigger points. Trigger points are sometimes seen in asymptomatic individuals and when tender they are called as Latent tender points. Injury or repetitive strain leads to progressive increase in oxidative metabolism and metabolic distress at motor end plates, particularly type 1 fibres. Higher levels of neuropeptides such as substance P, CGRP , catecholamines, tumor necrosis factor alpha, Interleukin 1, interleukin 6 have been found in active trigger points. Increased miniature endplate potential and excessive acetylcholine release in trigger points have been found in some studies. Through this mechanism, peripheral sensitization could occur and lead to ‘wind up’ phenomenon and central sensitization leading to development of chronic pain. [7,8]

Myofascial pain is characterized by chronic dull aching pain and is associated with soft tissue and muscle tenderness. Patient may present with mild symptoms caused by latent trigger points with no pain but some functional disability or stiffness or may present with severe pain related to movement or position of the muscle and with active trigger point or may present with severe pain at rest.

Referral pain is seen based on the site of involvement, for example, patient with upper trapezius trigger point usually has referred pain at posterolateral aspect of neck and may also have temporal headache on the same side. MPS may also be associated with autonomic component involvement resulting in symptoms suggestive of visceral disease [6].  These symptoms include excessive lacrimation, sweating, redness and oedema at trigger point area.

The diagnostic criteria for trigger points are under debate, but there are three minimum clinical diagnostic criteria and six confirmatory criteria.

Clinical diagnostic criteria:

  1. Presence of a palpable taut band within a skeletal muscle
  2. Presence of a hypersensitive spot within the taut band
  3. Reproduction of a referred pain sensation with stimulation of the spot

Confirmatory criteria:

  1. Presence of a local twitch response with snapping palpation of the taut band
  2. Presence of a jump sign
  3. Patient recognition of the elicited pain
  4. Predicted referred pain patterns
  5. Muscle weakness or muscle tightness
  6. Pain with stretching or contraction of the affected muscle

Other conditions that may present similar to MPS are tension headache, migrane and cluster headache, low back syndromes, pelvic pain, intermittent claudication, bursitis, arthritis and tendinosis.  Another important condition considered in differential diagnosis is Fibromyalgia syndrome. Though MPS was described as early as 1843 [9], many consider it to be a subtype of Fibromyalgia syndrome. In 1999, Hans et al described the differentiating features of MPS and fibromyalgia syndrome. ‘Jump sign’ and associated referred pain on palpation of trigger point in MPS differentiates it from fibromyalgia syndrome [10]anaesthetics or steroids [9]ogy and hence an algoritom ave been fo.

Treatment of MPS primarily focus on identification and correction of underlying cause. The less understood complex pathophysiology of MPS posts challenge in treatment. Multimodal management is employed for treating myofascial trigger points. The pharmacologic treatment comprises of analgesics, muscle relaxants, anticonvulsants, antidepressants. NSAIDS and cox -2 inhibitors are used to decrease pain, however more studies are required to define their role. Benzodiazepines, tizanidine and tropisetron have demonstrated some evidence in the treatment of MPS [11].

Non pharmacologic intervention such as massage, pressure release and other intervention have shown to be effective in immediate pain relief. Injection into trigger points is an effective treatment probably by disruption and termination of the dysfunctional activity of motor end plates. Trigger point injection include dry needling, short or long acting anaesthetics or steroids [7, 8, 9].

Newer modalities, such as botulinum toxin injection, ultrasound, Transcutaneous electric nerve stimulation (TENS), Electrical twitch obtaining intramuscular stimulation (ETOIMS) have shown promising results in randomized control study [11].

The appropriate diagnosis and management of MPS is an important part in rehabilitation of limb pain and regional axial syndromes. Further research is needed to understand pathophysiology, epidemiology and effectivenes of treatnment and hence develop an algorithmic approach in its management.

References

  1. Victoria Wapf, Andre Busato. Main health related problems patients attended their physicians for.BMC complementary and alternative medicine. 2007;7:41.
  2. Schneider M, Veron H, Ko G, Lawson G, et al. Chiropractic management of fibromyalgia syndrome, a systematic review of the literature.J Manipulative Physiol Ther. 2009;32:25–40.
  3. Simons DG. Diagnostic criteria of myofascial pain due to trigger points. J Musculoskelet Pain. 1999;7:111e120
  4. Skootsky S, Jaeger B, Oye RK. Prevalence of myofascial pain in general internal medicine practice. West J Med. 1989;151:157e160.
  5. Fernández de las Peñas C, Cuadrado ML, Arendt-Nielsen L, Simons DG, Pareja JA. Myofascial trigger points and sensitisation: an updated pain model for tension type headache. Cephalalgia 2007;27:383–93.
  6. Simons D, Travell J, Simons P. Travell & Simons’ myofascial pain & dysfunction: the trigger point manual. Baltimore: Williams & Wilkins; 1999.
  7. Tough EA, White AR, Cummings TM, Richards SH, Campbell JL. Acupuncture and dry needling in the management of myofascial trigger point pain: a systematic review and meta-analysis of randomised controlled trials. Eur J Pain 2009;13:3–10.
  1. Vernon H, Schneider M. Chiropractic management of myofascial trigger points and myofascial pain syndrome: a systematic review of the literature. J Manipulative Physiol Ther 2009;32:14–24.
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  3. Hans SC, Harrison P. Myofascial pain syndrome and trigger point management.Reg Anesth.1999;22:89–101.
  4. Desai MJ, Saini V, Saini S. Myofascial Pain Syndrome: A Treatment Review.Pain and Therapy. 2013;2(1):21-36