2. 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
3. History of Pain
• Acute/Chronic
• Dull, deep, aching
• Mimics radicular/visceral pain
• Often referred to head/ neck/
leg/ hip
4. Some predisposers
• History of remote injury
relevant
• Postural stress, muscle
imbalance, overuse
• Iron deficiency
• Hypothyroidism
• Low Vit D
• Low B12
• Parasitic infections
5. • 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???
8. Central sensitization
Central nervous system
modulates afferent
nociceptive activity
• SENSITIZATION to
peripheral noxious
stimuli in DORSAL
HORN NEURONS
Substance P enhances
activation
9. Central sensitization
Dorsal horn neuron
nociceptive impulses
rostrally
activation of
somatosensory cortex
interprets all input as
coming from receptive
field of that neuron
(expanded due to
sensitization)
11. 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
12. 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
13. 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
15. 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
17. • 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
18. Diagnostic inactivation
When there is doubt clinically
• Manually
• Laser
• Dry needling
• TrP injection
• An immediate unequivocal decrease in pain is good evidence
19. 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
20. Lab investigations
• Not very usefu for diagnosis
• Can identify predisposers
• Anemia
• Hypothyroidism
• Vit D
• Vit B12
• Parasitic infections
