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Myofascial Pain An Overview
Trigger Points And Acupuncture Points:
Trigger Points: Diagnosis and Management
Superficial dry needling and active stretching in the treatment of myofascial pain--a randomised controlled trial.
Acupuncture and dry-needling for low back pain and CMP.
Pain sensitivity in pericranial and extracranial regions.
Use of botulinum toxin in the treatment of chronic myofascial pain.
Contributing factors to chronic myofascial pain: a case-control study.
Effects of low-power laser exposure on masseter muscle pain and microcirculation.
A preliminary comparison of the efficacy and tolerability of botulinum toxin serotypes A and B in the treatment of myofascial pain syndrome:
The management of oromandibular motor disorders and facial spasms with injections of botulinum toxin.
The efficacy of dry needling and procaine in the treatment of myofascial pain in the jaw muscles.
Counseling and PT as Treatment for Myofascial Pain of the Masticatory System
Trigger points: diagnosis and management.
Position Paper on Trigger Point Injections
Myofascial Pain in Athletes

Myofascial Pain An Overview

Eng-Ching Yap,1MBChB (Bristol), MRCPI, FAMS1 Department of Rehabilitation Medicine, Tan Tock Seng Hospital, Singapore Address for Correspondence: Dr Yap Eng Ching, Tan Tock Seng Hospital Rehabilitation Centre, 17 Ang Mo Kio Ave 9, Singapore 569766.Email: eng_ching_yap@ttsh.com.sg

Introduction

    The skeletal muscle is the single largest organ in our human body. It accounts for nearly 50% of our body weight. Any of these muscles may develop pain and dysfunction. Musculoskeletal pain is a major cause of morbidity.1 Its prevalence increases with age. A growing number of individuals in our ageing population have musculoskeletal pain that affects their daily activities and function. It has a significant impact on their quality of life. This is creating a growing financial burden on our healthcare system.
    In traditional medical training, management of musculoskeletal pain has focused much attention on the bones, joints and nerves.2 Muscles in general, and myofascial pain in particular, have received less attention as a major source of pain and dysfunction. Myofascial pain, which is treatable, is often under-diagnosed and under-treated. A large number of patients can be left suffering in pain for years.
    This review will focus on myofascial pain which is a major cause of musculoskeletal pain in modern society, and its management.

What is Myofascial Pain (MFP)?

The traditional and narrow definition of myofascial pain is that it is pain that arises from trigger points (TRPs) in a muscle.3 TRPs are small and sensitive areas in a muscle that spontaneously or upon compression cause pain to a distant region, known as the referred pain zone. Tender spots (TSs), in contrast to TRPs, only cause pain locally. Taut bands (TBs) are groups of muscle fibres that are hard and painful on palpation. TB is an objective and consistent palpatory finding in muscles with myofascial pain. Within TB, the most painful and sensitive areas are the TRP and TS. Nowadays, in broader terms, myofascial pain includes muscle pain from TB with TRP and/or TS. The muscles are in spasm, with increased tension and decreased flexibility. It usually presents with regional muscle pain distributed in 1 or 2 quadrants of the body.

Fibromyalgia, on the other hand, is a separate category of a muscle pain condition.4 The muscle pain is diffuse, with tender points as defined by the American College of Rheumatology. The muscle pain is widespread, distributed symmetrically above and below the waist. However, there is no TB in the muscles. Although MFP and fibromyalgia are separate entities, these 2 conditions may occur concomitantly. MFP may develop in fibromyalgia patients. TB with TRP/TS may develop in the muscles with diffuse pain. The common denominator of both conditions is negative laboratory findings and no systemic inflammation.

Epidemiology

MFP is a major cause of musculoskeletal pain. There is a high prevalence of MFP in patients with regional musculoskeletal pain. It is one of the most frequent causes of back pain and neck pain.5 In a study of 164 patients referred to a pain clinic with chronic head and neck pain of at least 6 months duration, 55% were found to have a primary diagnosis of MFP.6 In a general medical clinic study, the primary complaint of 30% of patients was due to MFP.7 The prevalence of MFP pain in pain management centres is higher. In a comprehensive pain centre study on 283 consecutive patients, 2 physicians independently reported MFP as the primary diagnosis in 85% of cases.8 One physician who examined 96 patients in another pain centre study found MFP to be the primary cause of pain in 74% of cases, and 93% of cases had at least part of their complaint caused by precipitating and Perpetuating Factors.

Trauma

Macrotrauma – Contusions, sprains and strains may give rise to MFP acutely.
Microtrauma – The onset is more subtle. Chronic repetitive overloading or overuse of muscles may lead to fatigue and gradual onset of MFP.
Mechanical
Internal factors – Poor posture, scoliosis
External factors – Poor ergonomics, when the working environment of an individual is poorly molded to his or her physique
Degeneration Ageing, structural degeneration of bones and joints, with gradual loss of myofascial flexibility, may lead to MFP
Nerve Root Compression Irritation of the nerve root may lead to sensitisation of the spinal segment and MFP in the innervated muscles
Emotional Psychological Stress Anxiety, increased sympathetic output and sleep deprivation may lead to increased muscle tension, fatigue and decreased MFP threshold.
Endocrine and Metabolic Deficiencies
Thyroid and oestrogen insufficiencies are known to cause MFP.
Nutritional Deficiencies Vitamins and minerals insufficiencies may perpetuate MFP.
Chronic Infection Chronic virus or parasite infections may perpetuate MFP.
Chronic Muscle Imbalance Chronic muscle imbalance is prevalent in our modern society. In the human body, skeletal muscles can be broadlydivided into 2 groups.
Dynamic muscles, such as rhomboids and gluteus medius, are muscles that are activated when one is in dynamic motion. These muscles are relatively inhibited when one is in a static posture.
Postural muscles, such as scalenes and quadratus lumborum, are muscles that are activated when one is in a static posture. These muscles are relatively inhibited when one is in dynamic motion. With a sedentary lifestyle, as one spends more time in static postures than in motion, dynamic muscles will become progressively inhibited and lax while postural muscles will become progressively tight and inflexible. An imbalance between the dynamic and postural muscles will gradually develop. The muscle imbalance may lead to MFP.
Pathophysiology

Precipitating factors of MFP may cause the facilitated release of acetylcholine at motor end plates, sustained muscle fibre contractions and local ischaemia with release of vascular and neuroactive substances, and muscle pain. More acetylcholine may then be released, thus perpetuating the muscle pain and spasm. Electrodiagnostic studies have shown increased electromyographic activities at TRPs and TSs. Local muscle fibrosis may occur after a prolonged period of time.

Spinal Segmental Sensitisation (SSS) If MFP is left untreated, it may become an irritative focus and send persistent pain impulses via a sensory neuron into the spinal cord. The spinal loop that is constantly bombarded with noxious stimuli and irritated may develop the facilitated release of nociceptive neurotransmitters with lowered threshold for synaptic activation, amplification and perpetuation of pain – a state called spinal segmental sensitisation. This condition may affect sensory, motor and sclerotomal components of the hyperactive and hyperexcitable spinal segment with the following physical manifestations:
Dermatomal sensitisation: Due to increased sympatheticoutput, the skin and subcutaneous tissues become indurated with trophoedema. The skinfold thickness is increased and the affected area is exquisitely tender.
Myotomal sensitisation: Muscles innervated by the spinal segment that is sensitised develop hypertonicity and spasms with TRP/TS.
Sclerotomal sensitisation: Bursitis, enthesitis, epicondylitis and tendonitis may occur in the affected distribution innervated by the spinal segment that isupregulated.

Cycle of Degeneration
Muscles and joints in the human body are closely interlinked. Motion at one joint is related to motions at adjacent joints, from distally to proximally, from the lower limbs and lower trunk to the upper limbs and upper trunk. When MFP persists for some time without treatment, adjacent structures may also evolve their own TRP/TS, called satellite TRP/TS. MFP may impede normal joint motion, cause joint dysfunction and lead to joint degeneration. The pathology may spread through a ripple effect from one motion segment to adjacent motion segments and then to other parts of the musculoskeletal system.

Clinical Presentations
MFP is a great imitator.24,25 It frequently presents as regional musculoskeletal pain. In the upper limb, it may present as shoulder pain in patients with impingement or capsulitis. In the lower limb, it may present as hip or knee pain in patients with osteoarthritis. Neck or back pain of myofascial origin may mimic radiculopathy with pain radiating down upper or lower limb. The pain may be referred from TRP/TS over the dermatome of a sensitised spinal segment innervating the TB. It may also result from neurological entrapment.
The brachial plexus may be compressed as it passes through tight scalenus muscles in the upper trunk. The sciatic nerve may be compressed as it passes through tight piriformis muscle in the lower trunk. History and Examination
During history taking and physical examination, one should look for precipitating and perpetuating factors of the MFP. One should also look for yellow flags or indicators of psychosocial factors associated with chronic pain syndrome. Red flags or indicators of serious concomitant musculoskeletal pathologies, such as fractures, neurologicaldeficits, malignancy and infection, should be excluded.
During inspection, asymmetry of posture and restriction of active and passive range of motions should be noted.Abnormal movement pattern as a result of myofascial pain and tightness should also be noted.
Palpation is the basic method of diagnosis. In order to feel and locate the TB accurately, it is important to adequately relax muscles that are in pain and spasm. This is essential for subsequent needling treatment to be effective. Relaxation can be achieved mechanically by passively approximating the origin of a muscle to its insertion. Relaxation can also be achieved by neuromuscular techniques, as elaborated in the exercise section below. Optimal muscle relaxation should be attained before effective palpation using the following methods:

Flat palpation: With finger bellies for an initial survey of muscle tone for any spasm or superficial tenderness.
Finger tip palpation: Across muscle fibres for the TB and TRP/TS in small superficial muscles.
Pincer palpation: Between the thumb and fingers for accessible muscles, such as sternocleidomastoid, upper trapezius, pectoralis major, latissimus dorsi and hip adductors.
Overlying hand palpation: One hand applies pressure while the underlying hand palpates for the deep muscles, such as glutei muscles and piriformis. After TRPs/TSs in the TBs are located, an algometer (force gauge meter) can be applied manually over it to measure the minimum pressure that induces pain.23
Associated dermatomal sensitisation and trophoedema can be detected clinically by pinching and rolling the skin between thumb and finger, either along the trunk longitudinally or across the limb circumferentially. The skin innervated by the sensitised spinal segment will be thickened and tender. Due to increased sympathetic activity

Cycle of degeneration. and induration, skin electric resistance over the sensitised spinal segment is decreased.
The increased skin electric conductance can be objectively measured with an electric conductance meter by electrical current passed between a reference electrode held in one hand and an explorative electrode moved across the examined dermatome.

Imaging Studies
Imaging studies may provide useful anatomical information. However, MFP, TB, TRP and TS usually do not show up in these investigations. Abnormal imaging findings, degenerative changes, prolapsed discs and rotator cuff tears are also frequently found among asymptomatic individuals and not necessarily the cause of pain.

Therefore, it is important for the clinician who is treating the patient to correlate the medical history and physical examination with imaging results to determine the musculoskeletal pain generator.

Treatment

Treatment of MFP requires a multifaceted approach. In the short term, the aim is to abolish the TB, TRP and TS for pain relief. In the long term, flexibility has to be restored to the muscle, and any associated precipitating or perpetuating factors have to be removed, so as to reduce the recurrence rate.

Physical Modalities
Physical modalities are useful supplementary treatments for MFP.30,31 They may help to control muscle pain and spasm. However, they should not be used in isolation. Otherwise, they may provide only temporary relief with limited benefits. Heat therapy is one of the most commonly used physical modalities. It increases blood flow and tissue distensibility and decreases muscle spasm and pain.

Hot pads provide superficial heat with limited subcutaneous penetration.
Ultrasounds, on the other hand, provide deep heat with higher subcutaneous penetration. Contraindications of heat therapy include circulatory insufficiency, sensory or cognitive impairment, malignancy and inflammation.
Electrical therapy is another commonly used physical modality. It improves vascular circulation to eliminate inflammatory byproducts from the painful site. It also helps to relieve muscle spasm and oedema. However, it should not be used over carotid sinus or pregnant uterus and in patients with a cardiac pacemaker or defibrillator, malignancy or infection.
Medication is another useful supplementary treatment for MFP. Paracetamol or muscle relaxants may be prescribed for mild MFP. If these are ineffective, non-steroidal anti-inflammatory drugs (NSAID) or cyclo-oxygenase-2 (COX-2) selective inhibitors may be used, particularly if there is a local inflammatory component to the MFP.
Narcotic analgesics may sometimes be necessary for severe MFP. Adjuvant analgesics, such as antidepressants or anticonvulsants, may be added if there is a neuropathic component to the MFP. Somnolence, an attending effect of muscle relaxants, narcotic analgesics, antidepressants and anticonvulsants, may be useful at night for patients with emotional stress and sleep deprivation.

Needling and Infiltration
Two types of needles are commonly used: hypodermic and acupuncture needles. Hypodermic needles allow needling with infiltration of local anaesthetic during the procedure. The local anaesthetic helps to relieve postneedling soreness. Gauge 25 and 27 hypodermic needles are usually used. Acupuncture needles are stainless steel filiform needles with a diameter range of 0.25 to 0.35 mm. They are finer and less traumatic. However, they do not allow for the infiltration of local anaesthetic during the procedure. One of the aims of needling is to mechanically break up the TRP/TS and any associated fibrotic core. The needle is targeted at the point of maximum tenderness within the TB. When the needle penetrates the TRP/TS, the TB is disrupted. The muscle may manifest a local twitch response, and the TB with TRP/TS disappear.

The management of SSS requires careful examination of objective signs of dermatomal, myotomal and sclerotomal sensitisation, and determination of the spinal segment sensitised. Treatment is then targeted at the spinal segment, with careful choice of needling locations and targets, in order to alleviate the hyperactivity. Paraspinous block, described by Fischer, involves infiltration of local anaesthetic along the paraspinous space adjacent to spinous process of the vertebra, followed by needling of the interspinous ligament that is sensitised. Together with needling and disruption of TRP/TS in other sensitised muscles, the hypercontractile elements are disrupted and hyper-irritability in the spinal segment is desensitised neuromechanically. Biomechanical tension at adjacent structuresis also relieved and the recurrence of MFP is reduced after treatment.

Needling also inhibits nociception and provides pain relief by spinal cord pathway modulation, generalised neurohumoral stimulation and release of endorphin. Various other needling methods have been described. Baldry describes the superficial dry needling technique where dry needles are inserted into superficial tissues overlying TRP/TS and left in situ for 30 seconds to 3 minutes. Chu and Schwartz described the electrical twitch obtaining intramuscular stimulation, a needling technique with electrical stimulation.

Acupuncture is based on traditional Chinese medicine diagnoses of organ dysfunction and system imbalance. Needling at acupoints located along meridians and extrameridians treats blood stagnation and relieves pain. It helps to restore blood circulation and equilibrium in the human body.

Contraindications to needling include bleeding diatheses, anticoagulation, local or systemic infection and inability to rest the treated region after the procedure.

Exercise After needling the TRP/TS, it is essential to correct the muscle imbalance to achieve a good therapeutic result. It is important to try to restore normal length and flexibility to the muscles. However, one should be careful of achieving this by direct stretching exercises when a muscle is still in pain and spasm. Direct stretching may cause more pain and more spasm in the painful muscle. Instead, flexibility may be restored to the painful muscle through limbering exercises. The following neuromuscular relaxation techniques may be applied:

Muscle relaxation by exhalation.
Muscle relaxation by eye movement, inferiorly and in the direction in which relaxation is desired.
Muscle relaxation following isometric contraction, by autogenic inhibition.
Muscle relaxation following minimal activation of the antagonist muscle, by reciprocal inhibition.

It is also important that strengthening exercises should not be started too early. Before pain has fully subsided, the muscles are still tight and in spasm. Strengthening exercises, if started too early, may cause more pain, spasm and tightness. Strengthening exercises should only commence after the pain has been fully treated and resolved. It should then begin gradually with isometric exercises and progress to repetitive low resistance exercises to develop endurance, before high resistance exercises to develop strength, as well as stabilisation exercises.

Conclusion

MFP is a common and treatable cause of morbidity. If left undiagnosed and untreated, it may develop into chronic pain with overlying psychosocial and functional problems.  This may lead to further distress, anxiety and evendepression. The vicious cycle may give rise to further somatic preoccupation. This major source of musculoskeletal dysfunction requires more focused attention. Its early diagnosis and treatment may help to reduce overlying psychosocial complications and the attending financial burden of chronic pain syndrome.

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Trigger Points And Acupuncture Points:

Background Trigger point therapy to relieve myofascial pain is an accepted contemporary medical treatment. Acupuncture also may be a useful modality to treat myofascial pain.
Objective To explore the relationship between trigger and acupuncture points and their corresponding referred-pain patterns and acupuncture meridians.
Methods A total of 255 trigger points were compared with 747 acupuncture points. Anatomy software and atlases were used to find trigger and acupuncture points that are within 2 cm of each other and enter the same muscle, defined as corresponding points. The clinical pain indications of corresponding points were compared, as were the trigger points' referred-pain patterns and the acupuncture points' meridian distributions.
Results Of the 255 trigger points, 92% had anatomically corresponding acupuncture points. Of these acupuncture points, 79.5% had regional pain indications similar to their corresponding trigger points. Complete or near-complete agreement in the distributions of the myofascial referred-pain patterns and acupuncture meridians were found for 76% of corresponding points; at least some agreement was found for another 14%.
Conclusions The scientific basis of myofascial pain should help further elucidate acupuncture's therapeutic mechanisms in treating pain. This study's results may facilitate increased integration of acupuncture into contemporary clinical pain management.
To read full article http://www.medicalacupuncture.org/aama_marf/journal/vol17_3/article_3.html

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Trigger Points: Diagnosis and Management

DAVID J. ALVAREZ, D.O., and PAMELA G. ROCKWELL, D.O., University of Michigan Medical School, Ann Arbor, Michigan

Trigger points are discrete, focal, hyperirritable spots located in a taut band of skeletal muscle. They produce pain locally and in a referred pattern and often accompany chronic musculoskeletal disorders. Acute trauma or repetitive microtrauma may lead to the development of stress on muscle fibers and the formation of trigger points. Patients may have regional, persistent pain resulting in a decreased range of motion in the affected muscles. These include muscles used to maintain body posture, such as those in the neck, shoulders, and pelvic girdle. Trigger points may also manifest as tension headache, tinnitus, temporomandibular joint pain, decreased range of motion in the legs, and low back pain. Palpation of a hypersensitive bundle or nodule of muscle fiber of harder than normal consistency is the physical finding typically associated with a trigger point. Palpation of the trigger point will elicit pain directly over the affected area and/or cause radiation of pain toward a zone of reference and a local twitch response. Various modalities, such as the Spray and Stretch technique, ultrasonography, manipulative therapy and injection, are used to inactivate trigger points. Trigger-point injection has been shown to be one of the most effective treatment modalities to inactivate trigger points and provide prompt relief of symptoms. (Am Fam Physician 2002;65:653-60. Copyright© 2002 American Academy of Family Physicians.)

For a full version of this article, and an explanation of trigger point injections, and treatments, go HERE

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Superficial dry needling and active stretching in the treatment of myofascial pain--a randomised controlled trial.

Acupunct Med. 2003 Sep;21(3):80-6. Edwards J, Knowles N.
A pragmatic, single blind, randomised, controlled trial was conducted to test the hypothesis that superficial dry needling (SDN) together with active
stretching is more effective than stretching alone, or no treatment, in deactivating trigger points (TrPs) and reducing myofascial pain. Forty
patients with musculoskeletal pain, referred by GPs for physiotherapy, fulfilled inclusion/ exclusion criteria for active TrPs. Subjects were randomised into three groups: group 1(n = 14) received superficial dry needling (SDN) and active stretching exercises (G1); group 2 (n = 13) received stretching exercises alone (G2); and group 3 (n = 13) were no treatment controls (G3). During the three-week intervention period for G1 and G2, the number of treatments varied according to the severity of the condition and subject/clinician availability.
     Assessment was carried out pre-intervention (M1, post-intervention (M2), and at a three-week follow up (M3). Outcome measures were the Short Form McGill Pain Questionnaire (SFMPQ) and Pressure Pain Threshold (PPT) of the primary TrP, using a Fischer algometer. Ninety-one per cent of assessments were blind to grouping. At M2 there were no significant inter-group differences, but at M3, G1 demonstrated significantly improved SFMPQ versus G3 (p = 0 .043) and significantly improved PPT versus G2 (p = 0 .011). There were no differences between G2 and G3. The mean PPT and SFMPQ scores correlated significantly in G1 only, though no significant inter-group differences were demonstrated.
     Numbers of patients requiring further treatment following the trial were: 6 (G1); 12 (G2); 9 (G3). CONCLUSION: SDN followed by active stretching is more effective than stretching alone in deactivating TrPs (reducing their sensitivity to pressure), and more effective than no treatment in reducing subjective pain. Stretching without prior deactivation may increase TrP sensitivity.
Publication Types:   Clinical Trial  Randomized Controlled Trial

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Acupuncture and dry-needling for low back pain.

Cochrane Database Syst Rev. 2005 Jan 25;(1):CD001351. Furlan A, Tulder M, Cherkin D, Tsukayama H, Lao L, Koes B, Berman B.
Institute for Work & Health, 481 University Avenue, Suite 800, Toronto, ON, CANADA, M5G 2E9.

BACKGROUND: Although low-back pain is usually a self-limiting and benign disease that tends to improve spontaneously over time, a large variety
of therapeutic interventions are available for its treatment.
OBJECTIVES: To assess the effects of acupuncture for the treatment of non-specific low-back pain and dry-needling for myofascial pain syndrome
in the low-back region. SEARCH STRATEGY: We updated the searches from 1996 to February 2003 in CENTRAL, MEDLINE, and EMBASE.
We also searched the Chinese Cochrane Centre database of clinical trials and Japanese databases to February 2003. SELECTION
CRITERIA: Randomized trials of acupuncture (that involves needling) for adults with non-specific (sub)acute or chronic low-back pain,
or dry-needling for myofascial pain syndrome in the low-back region.
DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed methodological quality (using the
criteria recommended by the Cochrane Back Review Group) and extracted data. The trials were combined using meta-analyses methods or levels of
evidence when the data reported did not allow statistical pooling.
MAIN RESULTS: Thirty-five RCTs were included; 20 were published in English, seven in Japanese, five in Chinese and one each in Norwegian, Polish and
German. There were only three trials of acupuncture for acute low-back pain. They did not justify firm conclusions, because of small sample
sizes and low methodological quality of the studies. For chronic low-back pain there is evidence of pain relief and functional
improvement for acupuncture, compared to no treatment or sham therapy. These effects were only observed immediately after the end of the
sessions and at short-term follow-up. There is evidence that acupuncture, added to other conventional therapies, relieves pain and
improves function better than the conventional therapies alone. However, effects are only small. Dry-needling appears to be a useful adjunct to
other therapies for chronic low-back pain. No clear recommendations could be made about the most effective acupuncture technique.
AUTHORS' CONCLUSIONS: The data do not allow firm conclusions about the effectiveness of acupuncture for acute low-back pain. For chronic
low-back pain, acupuncture is more effective for pain relief and functional improvement than no treatment or sham treatment immediately
after treatment and in the short-term only. Acupuncture is not more effective than other conventional and "alternative" treatments. The data
suggest that acupuncture and dry-needling may be useful adjuncts to other therapies for chronic low-back pain. Because most of the studies
were of lower methodological quality, there certainly is a further need for higher quality trials in this area.

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Counseling and Physical Therapy as Treatment for Myofascial Pain of the Masticatory System

Antoon De Laat, LDS, GHO/Karel Stappaerts, PT, PhD/Sven Papy, PT Journal of Orofacial Pain Year 2003 Volume 17, Issue 1Pages: 42 - 49
Aims: To prospectively evaluate the effectiveness of a treatment regimen comprising counseling and physical therapy in patients with myofascial pain of the masticatory system, and to explore whether the duration of the physical therapy offered (4 vs 6 weeks) would influence the treatment result. Methods: Twenty-six patients were randomly distributed over 2 groups. All patients received reassuring information, advice regarding relaxation of the jaws, avoiding parafunctions, and limited use of the jaws. In addition, a physical therapy program (heat application, massage, ultrasound and muscle stretching) was initiated 2 weeks after the start of the study (group I, receiving 4 weeks of physical therapy) or immediately from the start of the study (group II, receiving 6 weeks of physical therapy). The following parameters were taken at baseline, 2, 4, and 6 weeks: visual analog scale (VAS) scores of present pain; lowest and highest pain over the past period; percentage of pain relief; jaw function assessment by the Mandibular Function Impairment Questionnaire (MFIQ); and pressure pain thresholds (PPTs) of the masseter, temporalis, and thumb muscles. Statistical analysis used a linear mixed model and corrected for multiple testing (Tukey test). Results: Pain and MFIQ scores decreased while PPTs increased in both groups. Only after 4 and 6 weeks, significant differences were present for the PPT of the masseter in group I (P < .02) and the temporalis in both groups (P < .01). Also, the VAS scores of present (P < .02), minimal (P < .01), and maximal (P < .0001) pain and the MFIQ score (P < .001) improved. After 6 weeks, a mean of 60% pain decrease was reported (P < .0001). There were no significant differences between the groups receiving 4 weeks vs 6 weeks of physical therapy. Conclusion: A conservative approach involving counseling and physical therapy resulted in significant improvement in parameters of pain and jaw function in patients with myofascial pain. A controlled study will be necessary to elucidate the specific effectiveness of physical therapy over counseling or no treatment.

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Pain sensitivity in pericranial and extracranial regions.

Ashina S, Jensen R, Bendtsen L. Cephalalgia. 2003 Jul;23(6):456-62.

Department of Neurology and Danish Headache Centre, Glostrup Hospital, University of Copenhagen, Glostrup, Copenhagen, Denmark. ashinas@dadlnet.dk

Chronic myofascial pain is very common in the general population. The pain is most frequently located in the shoulder and neck regions, and nociceptive input from these regions may play an important role for tension-type headache. The mechanisms leading to the frequent occurrence of muscle pain in the shoulder and neck regions are largely unknown. It is possible that the pain is caused by increased sensitivity of muscle nociceptors or by central sensitization induced by nociceptive input from muscle. The primary aim of the present study was to compare muscle pain sensitivity in the trapezius and anterior tibial muscles. The secondary aim was to investigate whether temporal summation, a clinical correlate of wind-up, is more pronounced in muscle than in skin and, if so, whether such a difference is more pronounced in the trapezius than in the anterior tibial region. Sixteen healthy subjects were included. Pressure-pain thresholds and electrical cutaneous and intramuscular pain thresholds were measured at standard anatomical points in the trapezius and anterior tibial regions. Temporal summation was assessed by repetitive electrical stimulation. Pressure-pain thresholds (P = 0.005) and intramuscular electrical pain thresholds (P = 0.006) were significantly lower in trapezius than in anterior tibial muscle. Temporal summation was present in skin and muscle of both regions (P < 0.001). The degree of temporal summation was significantly higher in muscle than in skin in the trapezius region (P = 0.02), but not in the anterior tibial region (P = 0.47). In conclusion, we found that muscle pain sensitivity was higher in the trapezius than in the anterior tibial muscle. We also demonstrated that temporal summation could be induced in both muscle and skin and, importantly, that temporal summation was significantly more pronounced in muscle than in skin in the trapezius but not in the anterior tibial region. These data may help to explain why chronic muscle pain most frequently is located in the shoulder and neck regions.

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Use of botulinum toxin in the treatment of chronic myofascial pain.

De Andres J, Cerda-Olmedo G, Valia JC, Monsalve V, Lopez-Alarcon, Minguez A. Clin J Pain. 2003 Jul-Aug;19(4):269-75.

Multidisciplinary Pain Management Center, Department of Anesthesia, Valencia University General Hospital, Spain. deandres_jos@gva.es

BACKGROUND: Myofascial pain syndrome (MPS) is defined as acute or chronic pain with sensory or motor autonomic symptoms, referred from active myofascial triggering points with associated dysfunction. Previous studies have suggested the usefulness of botulinum toxin A (BTX-A) in the treatment of MPS since it is capable of controlling muscular spasms, as well as other alternative mechanisms of action. OBJECTIVES: To analyze the efficacy of BTX-A treatment and its effect on daily life activities assessing pain reduction using a visual analogue scale (VAS); degree of improvement in physical impairment and disability scoring in the Oswestry low back pain questionnaire; and psychologic status using the Hospital Anxiety and Depression Scale (HAD), in patients suffering from MPS. METHOD: An open-label interventional prospective trial was conducted in 77 patients diagnosed of refractory MPS (defined as the presence of muscle spasm with pain on mobilization or stretching, plus the existence of trigger points with associated referred pain), resistant to both conservative management and to physical therapy. The BTX-A dosages for the different muscles were chosen according to a standardized protocol. Electromyographic guidance was used to localize the motor end plate prior to injection in superficial muscles; while fluoroscopic guidance was employed to evidence intramyofascial spread of the contrast solution within deep muscles. The assessment of treatment efficacy was based on a pain VAS applied before enrollment, at 15, 30, and 90 days and upon completion of the study; the Lattinen test to establish a relationship between pain intensity and its corresponding impact on daily living; and the HAD scale to assess psychologic stress, performed both before treatment and at the end of the study; and the Oswestry Questionnaire was used to evaluate patients' ability to carry out daily life activities according to their degree of physical impairment and disability scores. RESULTS: The global analysis revealed a positive correlation between the VAS score prior to treatment and the scoring at 15, 30, and 90 days. This correlation was maintained when analyzing independently for superficial or deep muscles. The correlation coefficients for HAD scores and the Lattinen test values showed a significant association between pre- and post-treatment findings. No adverse events were recorded for 83.1% of the cases. CONCLUSIONS: The results of this study are consistent with other studies showing the efficacy of BTX-A for treating pain in MPS. The evaluation of the psychologic dimension of this disorder and its associated disability can provide valuable information for the adequate management of these patients and for assessing treatment outcome. PMID: 12840622

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Contributing factors to chronic myofascial pain: a case-control study.

Velly AM, Gornitsky M, Philippe P. Pain. 2003 Aug;104(3):491-9.

Centre for Clinical Epidemiology and Community Studies, Sir Mortimer B. Davis Jewish General Hospital, Room A-132, 3755, chemin de la Cote-Sainte-Catherine, Montreal, Quebec, Canada H3T 1E2. avelly@epid.jgh.mcgill.ca

This case-control study was designed to investigate the contributing factors for chronic masticatory myofascial pain (MFP). Eighty-three patients with MFP, selected from the dental clinics of the Jewish General and Montreal General Hospitals, Montreal, Canada, and 100 concurrent controls selected only at the first clinic, participated in this study. The association with MFP was evaluated for bruxism, head-neck trauma, psychological factors (symptom check list 90 revised questionnaire, SCL-90R) and sociodemographic characteristics by using unconditional logistic regression. Clenching-grinding was associated with chronic MFP in multiple models including anxiety (OR=8.48; 95% CI: 2.85; 25.25) and depression (OR=8.13; 95% CI: 2.76; 23.97). This association also remained for MFP, excluding all other temporomandibular disorders (TMD). Clenching-only (OR=2.54; 95% CI: 1.10; 5.87) and trauma (OR=2.10; 95% CI: 1.0; 4.50) were found to be associated with the chronic MFP, when the level of anxiety was adjusted in the model. No significant change was noted when the effects of clenching-only (2.76; 95% CI: 1.20; 6.35) and trauma (OR=2.08; 95% CI: 1.03; 4.40) were adjusted for depression. Clenching-only and clenching-grinding remained related to MFP regardless of patients being informed about these habits. A higher score of anxiety (OR=5.12; 95% CI: 1.36; 19.41) and depression (OR=3.51; 95% CI: 1.07; 11.54) were associated with MFP, as well as other psychological symptoms. In addition, female gender had almost three times the risk of chronic MFP than males when the model was also adjusted for psychological symptoms. Grinding-only, age, household income and education were not related with chronic MFP. Tooth clenching, trauma and female gender may contribute to MFP even when other psychological symptoms are similar between subjects.

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Effects of low-power laser exposure on masseter muscle pain and microcirculation.

Tullberg M, Alstergren PJ, Ernberg MM. Pain. 2003 Sep;105(1-2):89-96.

Department of Clinical Oral Physiology, Institute of Odontology, Karolinska Institutet, Box 4064, SE-141 04 Huddinge, Sweden.

One possible cause of the reported positive treatment effect by low-power laser exposure in muscle pain conditions could be that it increases the local microcirculation. The aim of this study was therefore to investigate the immediate effects on masseter muscle blood flow by low-power laser exposure in patients with chronic orofacial pain of muscular origin in comparison to healthy individuals. Twelve patients with myofascial pain of orofacial muscles and 12 age and gender matched healthy individuals participated in the study. Before laser exposure the subjects were examined clinically and the patients scored their current pain intensity from the most tender masseter muscle. Intramuscular laser-Doppler flowmetry was performed unilaterally in the most tender point (patients) or in a standardized point (healthy subjects) of the masseter muscle. The muscle was first exposed with a Gallium-Aluminum-Arsenide laser (active laser) or placebo laser for 2 min in a randomized and double-blind manner. After another 8 min the muscle was treated with the other laser for 2 min and the LDF recording continued for 8 min. Finally, the patients again assessed the pain intensity. Data were analyzed blindly by one of the authors not participating in data collection. The pain intensity was not affected by laser exposure. The blood flow did not change significantly in the patients, but increased after active laser exposure and decreased after placebo exposure in the healthy individuals. The difference between active laser and placebo was significant. In conclusion, the results of this study do not support an effect of low-power laser exposure on masseter muscle microcirculation in patients with chronic orofacial pain of muscular origin.

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A preliminary comparison of the efficacy and tolerability of botulinum toxin serotypes A and B in the treatment of myofascial pain syndrome: a retrospective, open-label chart review. Clin Ther. 2003 Aug;25(8):2268-78.

Lang AM.

Emory University Hospital, Atlanta, Georgia, USA. orthorehab@earthlink.net

BACKGROUND: Myofascial pain syndrome (MPS) is characterized by acute or chronic regional muscle pain associated with single or multiple trigger points within taut bands of muscle. Botulinum toxins have clinical utility when sustained focal muscle relaxation is required and may be a useful addition to the treatment armamentarium for MPS. OBJECTIVE: The purpose of the present article was to compare the efficacy and tolerability of botulinum toxin serotypes A and B (BTX-A and BTX-B) in the treatment of MPS. METHODS: This was a retrospective, open-label, single-center chart review. Charts of all patients who received either BTX-A or BTX-B for MPS between January and November 2001 were included in the review. Patients rated the intensity of their pain on a visual analog scale (VAS) from 0 = no pain to 10 = worst pain imaginable before and after receiving BTX-A or BTX-B. RESULTS: The charts of 91 patients (74.7% female, 25.3% male; mean [SD] age, 47 [10.2] years) who received BTX-A (n = 56; mean dose, 256.9 U; range, 100-600 U) or BTX-B (n = 35; mean dose, 9000 U; range, 2500-20,000 U) were included in this retrospective review. Patients who received BTX-A had significantly greater mean reductions in VAS pain scores compared with those who received BTX-B (mean reduction, 2.7 vs 1.8, respectively; P < 0.001). Patients who received BTX-A also reported significantly longer durations of pain relief compared with those who received BTX-B (4.5 vs 2.7) months; P < 0.001). Eight of 56 patients (14.3%) in the group that received BTX-A reported mild adverse events that included flulike symptoms, injection-site pain, and weakness of the neck muscles. Seven of 35 patients (20.0%) in the group that received BTX-B reported adverse events that included mild flulike symptoms, dry eyes, severe visual disturbances, and severe dry mouth. CONCLUSION: Patients with MPS who received BTX-A reported significantly greater reductions in pain for longer durations compared with those who received BTX-B. No patients who received BTX-A experienced severe systemic adverse events, compared with 4 patients who received BTX-B. The results of this comparison are consistent with the US Food and Drug Administration-approved labeling indicating that BTX-A is not interchangeable with any other botulinum toxin in terms of biological activity.

PMID: 14512133

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The management of oromandibular motor disorders and facial spasms with injections of botulinum toxin. Phys Med Rehabil Clin N Am. 2003 Nov;14(4):727-48.

Clark GT.

Department of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, Los Angeles, CA 90024-1762, USA. glennc@dent.ucla.edu

Although much work is yet to be done in this area, nine general conclusions can be derived: 1. Local site-of-injection side effects from botulinum toxin injections are rare, assuming proper technique is used. 2. The two most common medication-related side effects from botulinum toxin orofacial injections are alterations in salivary consistency and inadvertent weakness of the swallowing, speech, and facial muscles. These complications are injection site-specific (eg, more common with lateral pterygoid injections and palatal and tongue muscle injections) and dose-dependent problems. These problems are bothersome but are not contraindications for the therapy if it is needed. 3. The data presented in this article are mostly case series-based and open trial-based information that is promising, but randomized, blinded, controlled trials are needed to establish the true efficacy of this method for the orofacial motor and pain disorders. 4. The novice should begin with injection of muscles he or she can inject with low risk of incorrect placement. The hard-to-find muscles should be avoided when starting out. The novice clinician should inject and dissect a few cadavers to improve injection technique. 5. The general latency for botulinum toxin type A is 1 week, its duration is 2 to 3 months, and it is recommended that injection be done no more than once every 12 weeks to avoid development of antibodies against the toxin. 6. Depending on the target muscle, injection dose is 10 to 50 U of Botox type A per site with a total dose of 200 U in the masticatory system. More than this can be used (400 U maximum) if other sites in the head and neck are included in the injection protocol. 7. Regarding injecting painful muscles that do not exhibit palpable muscle hardness or EMG-determined spasticity or observable involuntary movements but have chronic myofascial trigger points or the patient localizes them as the site of their chronic daily headache pain, botulinum toxin injections might be helpful used in this manner, but conclusive data for this controversial application of botulinum toxin are still missing. 8. Hemifacial spasm has the largest number of open-label, clinical trials, some of which have a 10-year follow-up. The conclusions reached by all of these reports is that treatment of hemifacial spasm with repeated injections of botulinum toxin has been highly successful and that the dose and relative effect of the injections are stable over time. 9. Although EMG-guided injection may be useful, EMG is neither practical nor needed in most situations for orofacial injections because most of the orofacial muscles are easily palpable muscles or have definitive bony landmarks to help with the localization process.

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The efficacy of dry needling and procaine in the treatment of myofascial pain in the jaw muscles.
J Orofac Pain 1997 Fall;11(4):307-14 McMillan AS, Nolan A, Kelly PJ

Department of Restorative Dentistry, University of Newcastle, Newcastle upon
Tyne, United Kingdom.

In patients with myofascial pain, painful trigger points are often treated using dry needling and local anesthetic injections. However, the therapeutic
effect of these treatments has been poorly quantified, and the mechanism underlying the effect is poorly understood. In a randomized, double-blind,
double-placebo clinical trial, a pressure algometer was used to measure pain-pressure thresholds in the masseter and temporalis muscles of 30
subjects aged 23 to 53 years with myofascial pain in the jaws, before and after a series of dry needling treatments, local anesthetic injections, and
simulated dry needling and local anesthetic treatments (treatment group A: Procaine + simulated dry needling; treatment group B: dry needling +
simulated local anesthetic; control group C: simulated local anesthetic + simulated dry needling). Subjects rated pain intensity and unpleasantness
using visual analogue scales, and the data were analyzed using analysis of variance.
    Pain pressure thresholds increased slightly after treatment, irrespective of the treatment modality. Pain intensity and unpleasantness
scores decreased significantly at the end of treatment in all groups. There were no statistically significant between-group differences in pain pressure
thresholds and visual analogue scale scores at the end of treatment. The findings suggest that the general improvement in pain symptoms was the
result of nonspecific, placebo-related factors rather than a true treatment effect. Thus, the therapeutic value of dry needling and Procaine in the
management of myofascial pain in the jaw muscles is questionable.

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Trigger points: diagnosis and management.

Am Fam Physician 2002 Feb 15;65(4):653-60
Alvarez DJ, Rockwell PG. Department of Family Medicine, University of Michigan Medical School,
Ann Arbor, USA. dalvarez@umich.edu

Trigger points are discrete, focal, hyperirritable spots located in a taut band of skeletal muscle. They produce pain locally and in a
referred pattern and often accompany chronic musculoskeletal disorders. Acute trauma or repetitive microtrauma may lead to the development of
stress on muscle fibers and the formation of trigger points. Patients may have regional, persistent pain resulting in a decreased range of
motion in the affected muscles. These include muscles used to maintain body posture, such as those in the neck, shoulders, and pelvic girdle.
   Trigger points may also manifest as tension headache, tinnitus, temporomandibular joint pain, decreased range of motion in the legs, and
low back pain. Palpation of a hypersensitive bundle or nodule of muscle fiber of harder than normal consistency is the physical finding
typically associated with a trigger point. Palpation of the trigger point will elicit pain directly over the affected area and/or cause
radiation of pain toward a zone of reference and a local twitch response.
   Various modalities, such as the Spray and Stretch technique,ultrasonography, manipulative therapy and injection, are used to
inactivate trigger points. Trigger-point injection has been shown to be one of the most effective treatment modalities to
inactivate trigger points and provide prompt relief of symptoms.

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