Myofascial pain syndrome is a chronic pain disorder. In this condition, pressure on sensitive points in your muscles (trigger points) causes pain in the muscle and sometimes in seemingly unrelated parts of your body. This is called referred pain. The most essential components of MPS were tender spots that recreate symptoms when palpated. MPS was also associated with muscle stiffness, decreased range of motion of the affected joints, worsening symptoms with stress, palpable taut band or tender nodule, and referred pain with palpation of the tender spot.
Myofascial pain syndrome is caused by a stimulus, such as muscle tightness, that sets off trigger points in your muscles. Factors that may increase your risk of muscle trigger points include Muscle injury. An acute muscle injury or continual muscle stress may lead to the development of trigger points. Myofascial pain syndrome involves mainly muscular pain; whereas, fibromyalgia includes more widespread body pain, along with other symptoms, such as headaches, bowel problems, fatigue, and mood changes.
Pathophysiology
- Pathophysiology is poorly understood
- The energy crisis of muscle fibers is one postulated theory
- Repetitive or pronged activity leads to an overload of myofibrils with subsequent hypoxia, ischemia
- Dysfunctional intracellular calcium pumps
- Inflammatory state
- Other proposed theories include:
- Neurogenic inflamation
- Sensitization and limbic dysfunction
- Trigger points (TP) can be more accurately defined as “hyperirritable palpable nodules in the skeletal muscle fibers”
- Also described as tender points in a taut band of muscles
- Defined as detectable superficial palpable tenderness in the muscle or located in areas of spasm
- The typical size is 2-10 mm
- Sensitivity of spot generally increases with increased tension/ pressure
- Patients may have active or latent trigger points
- Trigger points may oscillate between active and latent depending on internal or external stressors
- Perpetuating and aggravating factors may lead from an acute to a more chronic syndrome
- Other diseases can look like MPS making it a challenging diagnosis
- No diagnostic gold standard, imaging, or laboratory modality for MPS
Causes
- Traumatic events
- Muscular overloads such as overuse activities, abnormal posture
- Structural factors such as spondylosis, scoliosis, and osteoarthritis
- Psychological stress
- Systemic pathology includes hypothyroidism, vitamin D deficiency, and iron deficiency.
- Physical deconditioning
- Structural
- Spondylosis
- Scoliosis
- Osteoarthritis
- Systemic
- Hypothyroidism
- Hypovitaminosis D
- Iron Deficiency
Differential Diagnosis Neck Pain
- Fractures
- C1
- Jefferson Fracture
- C2
- Odontoid Fracture
- Hangman’s Fracture
- C3-C7
- Cervical Spinous Process Fracture
- Cervical Teardrop Fracture
- Cervical Compression Fracture
- Transverse Process Fracture
- C1
- Subluxations and Dislocations
- Atlanto Occipital Dissociation
- Cervical Facet Dislocation
- Atlantoaxial Instability
- Neuropathic
- Cervical Cord Neuropraxia
- Cervical Radiculopathy
- Cervical Myelopathy
- Muscle and Tendon
- Cervical Whiplash
- Myofascial Neck Pain
- Pediatric/ Congenital
- Klippel Feil Syndrome
- Cervical Congenital Anomalies
- Pseudosubluxation
- Other Etiologies
- Cervical Disc Disease
- Cervical Spine Stenosis
- Cervical Vascular Injuries
- Spear Tackler’s Spine
Differential Diagnosis Back Pain
- Fractures
- Compression Fracture
- Burst Fracture
- Chance Fracture
- Spinous Process Fracture
- Transverse Process Fracture
- Rib Fracture
- Sacral Stress Fracture
- Neurological
- Lumbar Radiculopathy
- Cauda Equina Syndrome
- Sciatica
- Musculoskeletal
- Mechanical Back Pain
- Scoliosis
- Kyphosis
- Herniated Disc
- Facet Joint Pain
- Sacroilliac Joint Pain
- Spinal Stenosis
- Spondylolysis
- Spondylolisthesis
- Hyperlordosis
- Baastrups Disease
- Autoimmune
- Ankylosing Spondylitis
- Infectious
- Spinal Epidural Abscess
- Osteomyelitis
- Pediatric
- Scheuermann’s Disease
Diagnosis
- General: Physical Exam Neck, Physical Exam Back
- History
- Patients often suffer from localized muscle pain and referred pain in patterns
- Infraspinatus pain can be referred to as the Deltoid area
- The onset of symptoms may be acute or more insidious
- Some patients may have precipitating illness or trauma, others have no clear cause
- Physical Exam
- Digital pressure on a tender spot elicits pain similar to their usual pain distribution and/or aggravates current pain
- May reproduce a local twitch response by repetitive stimulation of the trigger point
- Pain may be referred to other areas
- Range of motion can be restricted
- Special Tests
- Jump Sign: Palpation of tender nodule cause spontaneous exclamation or movement
- Primarily a clinical diagnosis
Radiographs
- Can be useful to exclude other etiology of the affected area(s)
Ultrasound
- Trigger points may be more hypoechoic compared to surrounding muscle (need citation)
- Useful to exclude other pathology
EMG/NCS
- Endplate noise
Treatment
Prognosis
- By definition, nonsurgical
- The primary goal should be to treat suspected underlying causal or contributing factors
- Acute patients tend to have a favorable prognosis
- In chronic cases, the average duration of symptoms is 63 months, with a range between 6 and 180[3]
Analgesics
- NSAIDS
- Oral formulations not studied in MPS however shown to help in MSK conditions
- Hsieh et al: Topical diclofenac patch helped with symptoms of myofascial pain of the trapezius
- Tropisetron
- Used for fibromyalgia, myofascial pain
- One study showed it was superior to local anesthetics when used for local trigger point injections
- Opiates are not generally indicated
- Lidocaine Patch
- Limited studies show some benefits
Muscle Relaxants
- Tizanidine
- Malanga et al: effective in treating spasticity, pain in up to 89% of patients and 79% of physicians
- Benzodiazepines
- One study showed a statistically significant decrease in pain
- Cyclobenzaprine has not been studied in MPS
Anticonvulsants
- Gabapentin not studied in MPS
- Pregabalin not studied in MPS
Antidepressants
- Tricyclic Antidepressants not studied in MPS
- Duloxetine not studied in MPS
- Sumatriptan
Other Pharmacotherapy
- Botox (Botulinum Toxin)
- One study demonstrated botox injections a statistically significant difference in pain intensity, duration, and reduction of trigger points
- Other studies have shown no benefit
Nonpharmacologic Therapies
- Dry Needling
- Hong et al showed benefits with or without lidocaine
- Trigger Point Injections
- systematic review article concluded the ‘‘nature of the injected substance makes no difference to the outcome and that wet needling is not therapeutically superior to dry needling’[12]
- Corticosteroid Injections are not currently recommended
- Manual Therapy
- Considered one of the more effective treatments for MPS
- The definition is broad and includes deep pressure massage, stretch therapy, superficial heat, myofascial release among others
- No high-quality studies evaluating manual therapy
- Therapeutic Ultrasound
- Most studies have found mixed results, although they are generally of poor quality
- Gam et al found no benefit for therapeutic ultrasound in any MSK disorder[13]
- Transcutaneous Electric Nerve Stimulation (TENS)
- Multiple studies appear to show some benefits among non-invasive modalities
- One study compared it to trigger points and showed no statistically significant difference[14]
- Magnetic Stimulation
- Physical Therapy
- Patients should be educated on stretching exercises
