MYOFASCIAL PAIN SYNDROME

Steffi Andrat

What is Myofascial pain syndrome?

• Often overlooked• Central feature – MYOFASCIAL

TRIGGER POINTS

so named because its stimulation is like pulling the trigger of a gun, producing effects at another place (target) called the reference zone

Myofascial pain syndrome is defined as pain of muscular origin that originates in a painful site in muscle

History of Pain• Acute/Chronic• Dull, deep, aching

• Mimics radicular/visceral pain• Often referred to head/ neck/

leg/ hip

Some predisposers• History of remote injury

relevant• Postural stress, muscle

imbalance, overuse• Iron deficiency• Hypothyroidism• Low Vit D• Low B12

• Parasitic infections

• Certain effects of sex hormones on pain mechanisms• Estradiol modulates NMDA receptor in

dorsal horn increasing nociceptive response • Estradiol modulates excitability of

primary sensory afferent nerves

Gender differences???

ETIOLOGYHow a trigger is formed

Mechanism for tenderness and referred pain

Muscle

Injury Overuse

Metabolic stress

Postural imbalance

Substance PBradykininSerotoninCytokines

HISTAMINEIntracellular Ca

Muscle fibre contraction

Ach release

SNS

Ischemia Hypoxia

Central sensitizationCentral nervous system modulates afferent nociceptive activity• SENSITIZATION to

peripheral noxious stimuli in DORSAL HORN NEURONS

Substance P enhances activation

Central sensitizationDorsal horn neuron nociceptive impulses rostrally activation of somatosensory cortex interprets all input as coming from receptive field of that neuron (expanded due to sensitization)

On Examination• Identify MTrP

• Can be active or latent

Taut Band

Central TrP

• Tight/hard muscle band• Palpated perpendicular to fibre

direction• Once identified, palpate (pincer

grasp) to find area of greatest hardness (it is most tender) = centre/heart of TrP

• Compression at least for 5-10 seconds -Induces RP/LTR

Normal Fibres

Contraction knots

The purpose of locating the area of greatest hardness in the taut band, which is

also the area of greatest tenderness, is that THIS IS THE AREA TO BE TREATED

• Contains numerous electrically active loci and numerous contraction knots

• Sarcomeres within contraction knot are markedly shorter and wider

Additional characteristics

Mechanical stimulation of taut band local contraction Local Twitch Response• Should be differentiated

from DTR (entire muscle contracts)

• LTR = brief, 25-250 ms, high amplitude polyphasic electrical discharge

• For LTR, intact spinal reflex arc is needed

• Unique to TrP

Additional characteristics

Referred pain

Limited ROM• Due to pain on lengthening affected muscle• Examination gives clue about which muscle

has TrP

Additional characteristics

Weakness• Often but not always present• Reversed when TrP is inactivated

Autonomic changes• Vascular dilatation and constriction

erythema/blanching/warmth/cool areas in distribution of nerve innervating involved muscle

DIAGNOSIS

• Located on taut muscle band• Exquisite Tenderness at a point on it• Reproduction of patients pain• Local twitch response• Referred pain• Produces weakness• Restricted ROM• Autonomic activity

Essential for diagnosis

Simmonds et al

Diagnostic inactivationWhen there is doubt clinically• Manually• Laser• Dry needling• TrP injection

• An immediate unequivocal decrease in pain is good evidence

Objective identification• MR elastography – differentiates tissues of varying densities• Ultrasound – localizes hypoechoic elliptical focal areas• EMG – Signature signal - persistant low amplitude, high frequency

discharge in the active TrP - spontaneous electrical activity

Lab investigations• Not very usefu for diagnosis• Can identify predisposers• Anemia• Hypothyroidism• Vit D• Vit B12• Parasitic infections

Differential diagnosis of REGIONAL PAIN

SYNDROMES

HEAD AND NECK• Headache• Dizziness• Neurological signs• ROM neck is painful

• Upper trapezius• Levator scapulae• Posterior cervical msc• SCM• Facial muscles like masseter

SHOULDER

• ACJ dysfunction• Rotator cuff signs• Impingement

• Trapezius• Supraspinatus• Levator scapulae• Infraspinatus• Rhomboids• Subscapularis• Teres Major Minor• Pectorals• Lats dorsi• Deltoid

CHEST PAIN• History and signs of

esophageal disease• Cardiac disease

(angina)

• Pectoralis Major• Abd obliques• Rectus femoris• Back muscles

LOW BACK• Spondyloarthropathis• Spondylolisthesis• PIVD• Spinal stenosis

• Psoas• Quadratus lumborum• Paraspinals• Abd obliques• Rectii

PELVIS/HIP

• Internal organ disease (painful bladder, IBS, endometriosis)

• Radicular pain from LS spine

• Abdominal msc• Psoas• Quadratus lumborum• Piriformis• Adductors• Hams (specially upper

Semitendinosis)

KNEE• Intrinsic joint disease• Radiculopathy

• Vastus medialis, lateralis• Hamstring, gastrocnemius

ANKLE/FOOT• Intrinsic joint disease• Radiculopathy

• Anterior and posterior leg muscles

• Gastroc-soleus• Tibialis anterior• Foot intrinsics

Treatment

• Education• Pharmacological management

• Non pharmacological• Avoid unnecessary tests• Recognize and address underlying

factors

Anxiety?Depression?

Stress?

• Importance of sleep, cardiovascular fitness, body mechanics

• NSAIDs• Muscle relaxants• BZDs• Antidepressants• Tramadol• Lidocaine patch

• Education• Pharmacological management

• Non pharmacological

• Exercise• Postural and ergonomic

modifications• Stress reduction• Acupuncture• Massage• Ultrasound• Needling• Botulinum toxin

• Education• Pharmacological management

• Non pharmacological

THANK YOU