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Physical Therapy in Sport 5 (2004) 2–12
Myofascial trigger points: the current evidence
Centre for Sports Medicine Research and Education, University of Melbourne, 300 Berkeley Street, Parkville, Vic., Australia
Received 10 November 2003; revised 17 November 2003; accepted 18 November 2003
This paper provides an overview of the current state of knowledge regarding the history, pathophysiology, mechanisms of pain production,
and proposed methods of treatment of myofascial trigger points. Despite the increasing body of published literature on this subject, manyfundamental questions remain unanswered. This paper aims to give the therapist a greater understanding of the current knowledge ofmechanisms of muscle pain, treatments that have been shown to be effective, and the ways in which these treatments may produce theireffect. Most effective treatments have at their core a form of counter-stimulation or application of a second noxious stimulus. It remainsunclear if it is this counter-stimulation or more specific elements of muscle stimulation that are the active ingredients, but it is possible thateach contributes to effective outcomes.
q 2003 Elsevier Ltd. All rights reserved.
Keywords: Myofascial trigger points; Counter-stimulation; Evidence-based medicine
quite trivial when assessed. It is not clear whether thepsychological disturbance seen in these patients is a part of
Although myofascial trigger points are a widely
the pathology or merely reactive to the chronic pain state.
recognised phenomenon in clinical practice, there remains
Importantly, psychological disturbance, from whatever
much to be elucidated with regards to their pathophysiol-
cause, will impact on a patient’s interpretation of pain
ogy, mechanisms of pain referral, and treatment of choice.
From the outset, it must be noted that much of the early
literature on trigger points, myofascial pain, and fibromyal-
As trigger points can also occur in the absence of pain
gia was based on anecdotal reports and the clinical
syndromes, this paper aims to address the current state of
experience of those using this form of treatment. Most
knowledge with respect to trigger points as an isolated
popular beliefs are based on theories generated on this basis,
phenomenon, rather than addressing treatment approaches
and it is only in recent times that a more scientific approach
to defining and treating the phenomenon of myofascial
Trigger points can be seen in the setting of occupational
trigger points has developed. Despite this increasing
or athletic injury due to muscle imbalances, postural
interest, much of the fundamental understanding remains
deficiencies, or secondary to another underlying pathologi-
based in the theories of the early clinicians and still requires
cal process. Examples of the latter include trigger points in
quadratus lumborum in association with an irritated lumbar
Trigger points are most often discussed in the setting of
disc, or gluteal trigger points in the presence of hip joint
myofascial pain syndromes, in which widespread or
pathology. Desk workers may present with headaches that
regional muscular pain is associated with hyperalgesia,
are reproducible with pressure over trapezius trigger points
psychological disturbance, and significant restriction of
due to the prolonged muscle contraction in inappropriate
postures, or the development of thoracic spine stiffness. It is
these syndromes recall an inciting factor for their pain,
important to assess for and treat any precipitating or
however, some may not. Inciting factors may often seem
perpetuating factors in the presence of trigger points inorder to maximise the chance of a long-term response to any
* Tel.: þ61-3-8344-4118; fax: þ 61-3-8344-4188.
E-mail address: email@example.com (L.K. Huguenin).
1466-853X/$ - see front matter q 2003 Elsevier Ltd. All rights reserved.
L.K. Huguenin / Physical Therapy in Sport 5 (2004) 2–12
Early writings on trigger points and their treatment were
In summary, the diagnosis of trigger points relies on
sporadic and lacked uniformity of diagnostic criteria. The
finding a local tender spot within a taut muscle band,
reproduction of recognisable symptoms, and a local twitch
response to snapping palpation or needle insertion.
reference for those involved in treating this condition. The
There are, however, several caveats to bear in mind when
theories of pathogenesis contained within this volume have
establishing examination findings, not the least of which is
subsequently been challenged, but never conclusively
the lack of a gold standard for assessment of trigger points.
disproved and the definition of trigger points presented is
This lack of standardised assessment makes validity studies
still the most widely used in clinical practice.
near impossible, although reliability trials have beenperformed. examined patients withchronic myofascial pain or fibromyalgia, and the most
common finding in their subjects was local tenderness andtaut muscle bands. Reliability of examination for taut bands,
The classical and most commonly used description of
muscle twitch, and active trigger points, however, was
Travell and Simons define trigger points as
In a blinded trial of physiotherapists experienced in
the presence of exquisite tenderness at a nodule in a
treating lower back pain ), the reliability of
palpable taut band (of muscle). Trigger points are able to
assessment for the presence of three trigger points described
produce referred pain, either spontaneously or on digital
by Travell and Simons was poor and it was noted that issues
compression. The clinical definition came to be that trigger
as simple as patient positioning, palpation technique, and
points are localised areas of deep tenderness within a taut
the amount of force applied significantly influenced results.
band of muscle. They exhibit a local twitch response
Of interest, reliability was not improved when the sample
(muscle fasciculation) or jump sign (whole body move-
was reanalysed for only those therapists reporting the use of
ment) in response to digital pressure or dry needling. In their
trigger point examination in their routine practice.
common trigger point locations and their referral zones.
inter and intra-rater reliability, using two highly trained
These locations have been noted to have significant
examiners for assessment of the presence and number of
similarities to acupuncture points used in traditional
trigger points in asymptomatic patients, was poor. In a study
of four clinicians together resulted in improved reliability of
Two main types of trigger points are described. Active
identification of trigger points. In a study by
trigger points are those that may be responsible for the
, it was reported that localisation of trigger points was
presenting pain complaint. They may also be associated
unreliable in untrained examiners, and only marginally
with less readily definable symptoms such as weakness,
more reliable in trained examiners. Further,
parasthesia, or temperature changes, and they may have
found that taut band and local twitch responses could
associated referred pain. Latent trigger points present with
not be reliably assessed, and examination for referred pain
muscle shortening, and pain occurs only on the application
had low reliability when extensive training had been
of external pressure. These trigger points may become
undertaken, but was not at all reliable without this. Another
activated by a variety of stimuli, including poor posture,
study has shown moderate reliability for the presence of
local tenderness and production of recognised pain, but poorreliability for twitch responses and the production ofreferred pain (
On palpation of a muscle, a trigger point is recognised as
a local tender spot within a taut muscle band. If a triggerpoint is active, the patient will recognise the symptoms
Currently, there is no gold standard pathological test for
produced when pressure is applied to it. Latent trigger points
the identification of trigger points. Therefore, much of the
will be painful on palpation, but the sensations will not be
research into the pathophysiology of trigger points is
recognisable. A local twitch response has been described in
directed towards indirectly verifying the common theories
response to ‘snapping palpation’ of the taut band, and to the
for their formation. Histological studies have been incon-
clusive, with either non-specific changes of fibrosis and
palpation is described as similar to plucking a guitar string.
absence of inflammatory cells, or negative findings (
The fingers are placed over the trigger point and then
Imaging of trigger points has not been shown to
quickly snapped back over the muscle at right angles to the
L.K. Huguenin / Physical Therapy in Sport 5 (2004) 2–12
One study that used biopsy indicated that there may be
phosphates were reduced and low energy phosphates
altered levels of high energy phosphates in painful muscles
increased at trigger point sites in patients when compared
to non-tender muscle points in both patients and controls
this has led to some promising pilot trials on the use of 31P
NMR which can assess the levels of different forms of
metabolic derangement at trigger point sites. However,
phosphate within the muscle. 31P NMR is a form of nuclear
lactate and pyruvate are the products of anaerobic muscle
magnetic resonance spectroscopy that can quantify relative
metabolism, and their levels were not increased. Therefore,
amounts of different phosphate compounds in tissues, as
although a pure ischaemic cause is unlikely, there is some
each compound is at a different energy state. Phosphate
evidence to suggest a metabolic abnormality at trigger point
compounds (e.g. ATP, phosphocreatine) in muscle are
sources of energy, and quantification could assist inassessing the metabolic status of the muscle. Unfortunately,
to date, there is no clear indication of the pathologicalchanges to be expected in myofascial pain.
The energy crisis theory could well co-exist with the
motor end plate hypothesis. The motor nerve synapses witha muscle cell at the motor endplate. Needle EMG studies
have found that each trigger point contains minute loci thatproduce characteristic electrical activity (
The aetiology of trigger points is not clear, but the two
most widely accepted theories (energy crisis theory and
motor endplate hypothesis), when combined, provide a
The endplate noise seen on EMG is thought to
plausible explanation. There is a third, yet to be experimen-
represent an increased rate of release of acetylcholine (ACh)
tally verified theory, which suggests the primary site of
from the nerve terminal. A small amount of activity at the
pathology to be the spinal nerve, with secondary muscle
motor endplate is not enough to cause muscle contraction,
changes occurring (). The more widely accepted
but can result in action potentials being propagated a small
theory is centred on the muscle cell and motor endplate
distance along the muscle cell membrane. This small
amount of propagation may be enough to cause activationof a few contractile elements and be responsible for some
The energy crisis theory is the earliest explanation of
5.3. Radiculopathic model for muscular pain
trigger point formation ). This theory postulates that increased
Not all researchers agree with the theories of Travell and
demand on a muscle (increased neural input), macrotrauma,
Simons. Most opposing theorists postulate a neurological
or recurrent microtrauma leads to increased calcium release
cause as the primary stimulus and trigger points as a
from the sarcolemma and prolonged shortening of the
sarcomeres. Prolonged shortening compromises the circula-
tion, with the subsequently reduced oxygen supply leaving
muscular pain and states that ‘myofascial pain describes
the cells unable to produce enough ATP to initiate the active
neuropathic pain that presents predominantly in the
process of relaxation. Ischaemic by-products of metabolism
musculoskeletal system’ (p. 121). The radiculopathic
accumulate (), being in part responsible for
model is based on all denervated structures exhibiting
some of the pain produced, by sensitisation and direct
super sensitivity. From clinical observations,
stimulation of sensory nerves. Unfortunately, there are no
states that neuropathic nerves are most commonly found at
studies to date that can confirm such muscle injury as the
the rami of segmental nerves, and therefore represent a
radiculopathy. If neural injury or compression and partial
The concept of altered muscle metabolism underlying
denervation are the site of origin of this pathology, he
the changes at trigger point sites was investigated by
believes that it helps to explain the lack of pathology seen in
Bengtsson (1986). Muscle energy stores can be measured by
muscle and the sensory, motor, and autonomic changes seen
the levels of various phosphate containing compounds.
Adenosine triphosphate, phosphocreatine, and adenosine
diphosphate are compounds capable of donating their
relates to intervertebral disc degeneration with nerve root
phosphate moiety and releasing energy for muscle activity.
compression or angulation due to reduced intervertebral
Adenosine monophosphate and free creatine are the
space and resultant paraspinal muscle spasm. This is
remaining compounds after this process and are, therefore,
described as a form of neuropathy. This neuropathy then
low energy molecules. In a biopsy study of patients with
sensitises structures in the distribution of the nerve root,
fibromyalgia, it was found that the levels of high-energy
causes distal muscle spasm, and contributes to other
L.K. Huguenin / Physical Therapy in Sport 5 (2004) 2–12
degenerative changes in tendons and ligaments within its
noise with extra ACh released in response to the needle
distribution that are then perpetuated by the ongoing muscle
shortening. Therefore, this theory is not only used to explain
trigger point formation, but also conditions such as
abnormal activity in normal subjects or in non-tender
muscle points 1 cm from the trigger points, there remains
Based on his theories, proposes that long
controversy about the significance of this ‘characteristic’
lasting pain relief requires needle treatment to the shortened
SEA. In rabbit muscle, this pattern of activity has been
paraspinal muscles in order to reduce nerve root com-
identified at trigger point sites, but not control sites, even
pression, as well as to trigger points more local to the site of
when the control sites were also located close to motor
humans is a little more confusing. In an unblinded study on
behind traditional trigger point teaching is circular and
ten human subjects, endplate noise occurred in all muscles
excludes the possibility of a non-muscular origin of the
tested at clinically determined trigger points (
pathology. They suggest that the characteristics of the pain
). Such endplate noise, however, also occurred in
from trigger points are not distinguishable from neural pain,
endplate zones outside of trigger points in four muscles.
and that a primary neurological cause is a much more likely
Taut bands outside of the endplate zone did not exhibit
explanation for the local and referred sensations of
endplate activity. The authors concluded that these
myofascial pain. To date, no neurophysiological studies
potentials are characteristic of, but not restricted to, trigger
have confirmed or denied these claims. Routine nerve
conduction testing has not identified any abnormalities, but
EMG has been found to exhibit SEA in both patients with
may be lacking the sensitivity to do so.
long-term myofascial symptoms and asymptomatic patientswith identified trigger points. In the study by , the onset of recorded EMG activity
corresponded well to the subjects’ report of the onset ofpain with needle advancement.
A pattern of EMG activity said to be characteristic of
SEA in trigger spots in rabbit muscle has been shown to
trigger points was first described in human subjects by
reduce after dry needling treatment when compared to a
occurred more reliably if local twitch responses were
observed in response to needle insertion. This finding
termed spontaneous electrical activity (SEA), and has
suggests that any effect of dry needling may be due to a
subsequently also been confirmed in rabbit studies (
more complex mechanism than muscle trauma alone.
SEA is seen as low amplitude backgroundnoise (50 mV), with superimposed high amplitude spikeactivity (100 – 700 mV), in a resting muscle. Initially, this
pattern of activity was postulated to represent stimulation ofintrafusal muscle spindle fibres, which are innervated by the
As early as 1938, the production of characteristic patterns
of local and referred muscle pain was described in response
Other researchers have since claimed that it is more likely to
to injection of hypertonic saline (Muscle
pain is likely to be transmitted by Group III (A delta, thin
). The motor end plate theory states that the back-
myelinated) and Group IV (c, non myelinated) afferent
ground noise (motor endplate noise) represents excessive
release of packets of ACh by the motor nerve terminal next
to the muscle cell. ACh is a neurotransmitter, which causes
mini depolarisations of the post-synaptic muscle cell
membrane (). A muscle contraction requires
a large amount of ACh release to initiate adequate
ever, serotonin has been shown to increase muscle pain in
depolarisation of the muscle membrane for propagation of
healthy volunteers, but not subjects with myofascial pain
an impulse. The spontaneous activity of normal motor
endplates shows more discrete, random, and non-overlap-
antagonist has not been shown to influence muscle pain
ping electrical activity (known as mini endplate potentials),
rather than the haphazard discharge that has been attributed
be important in the increase in pain threshold after electrical
to trigger points. Within this theory, the origin of the spikes
seen in trigger point EMG is unclear. One suggestion is that
pain has been positively correlated with muscle levels of
they may represent propagated single muscle fibre action
potentials occurring as a result of summation of background
Although substance P and calcitonin gene related peptide
L.K. Huguenin / Physical Therapy in Sport 5 (2004) 2–12
(CGRP) are important transmitters in the nerve endings in
muscle, and also at the spinal cord, they are not directly
that the phenomenon of referred muscle pain must have a
central basis. It is thought that in a resting state, each dorsal
horn neurone has a receptive field in the body from which it
Muscle pain from the injection of capsaicin (a substance
used for experimental pain production) has been shown to
have applied stimuli to known receptive fields of
be of lower intensity, but more likely to produce referral,
specific dorsal horn neurons in rats and found that new
either to skin or deeper structures when compared to
receptive fields have opened for these neurons. That is, the
intradermal injection of the same quantity and concentration
neurons now perceive noxious input as coming from more
than one source and a pain referral is experienced.
muscle is more likely to be referred, and although the exact
showed that this referral can cross to different spinal
mechanism of this remains to be investigated, it is likely to
cord levels in association with increased spinal cord levels
relate to central (spinal) mechanisms. Mechanoreceptors in
of substance P and CGRP. It is, therefore, theorised that the
muscle have a lowered stimulation threshold in the presence
increased release of substance P and CGRP in the dorsal
of excitatory compounds such as bradykinin
horn in response to a noxious stimulus diffuses around
several levels of the spinal cord and increases the sensitivityof those areas to noxious input. The levels of these twotransmitters have been found to be independent, and it is not
known if their source is local neurons or release from highercentres (). What was previously an
Although, as previously stated, there is no evidence of
innocuous stimulus may now be perceived as pain, and pain
inflammation or increased levels of nociceptive transmitters
may be perceived at a seemingly unrelated anatomical site.
in the region of trigger points, the most popular theories
This may also apply to the newly opened receptive field,
proposed to date assume that injury and mediator release is
such that a pressure or tightness sensation in the muscle is
the precipitant of trigger point related muscle pain, with
these sensitised nociceptors then having increased responses
Muscle spasm, as seen in many conditions of muscle pain
to normal mechanical stimuli. Theories implicating a
may relate to a connection between dorsal horn neurons in
primary neurogenic cause do not share this weakness,
the spinal cord and gamma afferent neurons. Gamma
although lack any confirmatory data. Further clarification of
afferent neurons supply muscle spindles and are responsible
for reflex muscle shortening, such as that seen with tendon
Once a painful stimulus is established, by whatever
reflexes. Inhibition of dorsal horn neurons indirectly inhibits
means, dorsal horn neurons may be sensitised and new
receptive fields opened due to the flux of substance P andother transmitters at the spinal cord in response to the initialpain This neural plasticity may help to
10. Clinical precipitants for trigger point formation
explain referred muscle pain and possibly be responsible forthe misinterpretation of signals previously recognised as
Trigger points are thought to form in response to
innocuous. Neural plasticity may be important in the
increased or altered muscle demands. Muscle overload, as
often seen in the pre-season conditioning phase of sport
training, is one such example. Other mechanisms ofincreased or altered muscle demands include prolongedmuscle contraction, such as in workplace postural errors,
proximal nerve compression and resultant muscle spasm,and post-trauma (). Latent trigger points
The traditional theory used to explain the phenomenon of
are thought to become activated in response to the same
referred pain is the convergence projection theory. This
conditions that cause trigger point formation, that is, muscle
states that each dorsal horn neuron has connections from
overload, prolonged muscle contraction, or nerve
more than one body part. Noxious stimuli are only expected
to arise in one of those body parts. When a noxious stimulus
Trigger points can also be influenced by descending
is received from another area, it is misinterpreted as coming
factors such as stress or constitutional illnesses. The
sympathetic ‘flight or fight’ response to stress is related to
increases in the amount of circulating catecholamines. It has
A modification of convergence projection theory postu-
been shown that the EMG activity in trigger points can be
lates that not all convergent connections are active all the
reduced by the use of sympathetic antagonists
time, but previously dormant spinal cord connections are
and that it increases at times of stress (
unmasked in response to a painful stimulus (
L.K. Huguenin / Physical Therapy in Sport 5 (2004) 2–12
Trigger points should, therefore, be considered when
assessing for the sources of pain in many different clinicalscenarios. For example, sedentary workers presenting with
head or neck pain may exhibit thoracic spine tightness or
Stretching after the application of a vapocoolant spray
signs of early degenerative change in their cervical spine
is reported by Travell and Simons (1983) to be the ‘single
and may have a history of poor posture at work. They may
most effective treatment’ for trigger point pain. An
also have some elements of their pain reproduced with
attempt was made to clarify this, using pain scales and
palpation of trigger points in the trapezius, long neck
pressure threshold as outcome measures for response to
extensors, or sternocleidomastoid muscle. Similarly, a
spray and stretch techniques in patients with chronic neck
lumbar disc injury is often responsible for significant pain,
but elements of this pain may be reproduced with pressure
study used contralateral sides as controls in symptomatic
on trigger points in the paraspinal, quadratus lumborum, or
patients and was not blinded, it did show a significant
gluteal muscles. Osteitis pubis may be accompanied by
reduction in both reported pain and pain pressure
trigger points in the adductor muscles or the gluteals.
threshold after the intervention. There was no correlation
Importantly, trigger points can form in either of these
between the improvements in these two parameters. It was
regions purely in response to an increase in load, without
postulated that the coolant spray acted by a counter-
irritation mechanism. From these results, it is impossible
Of interest, is that clinical syndromes seen may not
to say if spray or stretch in isolation might have the same
reflect the locality of the trigger points, but rather, their
referral zones. Examples include posterior thigh pain
reproduced from gluteal trigger points or achilles tendon
program of ischaemic pressure and stretching to a program
pain reproduced from calf trigger points. When assigning
of stretching alone in subjects with trigger points in the
causality for pain to trigger points, it is essential to assess
trapezius region. Ischaemic pressure combined with stretch-
carefully for the amount of contribution to the overall
ing resulted in a greater improvement in pain scores and
syndrome. To illustrate this, consider the following; the
pain pressure threshold. The pressure was applied prior to
commonest source of pain in the Achilles region is still
the stretching and, therefore, could well have been acting in
pathology at or around the Achilles tendon, but when this
a counter-stimulatory fashion. Importantly, this research
diagnosis is not clear cut on clinical assessment, trigger
shows a benefit of massage techniques above the effect of
points at a proximal location may enter into the therapist’s
consideration. Likewise, when the pain complaint is out ofproportion to the evident local pathology, or when treatmentof a local area fails to completely relieve symptoms, if
11.1.2. Transcutaneous electrical nerve stimulation
trigger points are a possible contributing factor, they should
Transcutaneous electrical nerve stimulation (TENS) is
be considered and carefully assessed. It is important not to
often postulated for use in chronic pain and can be used at
assign significance to trigger points if they do not produce
different frequencies and intensities to attempt to achieve
reproduction of a recognisable pain. Non-specific pain does
not identify a contributing trigger point according to the
100 Hz, 2 Hz and control TENS on subjects with trigger
point related chronic pain in the thoracic, neck, or head
is one of the essential criteria for diagnosis of an active
region. Low frequency and control TENS had no effect on
pain, whereas the high frequency resulted in significantpain relief. None of the modalities resulted in any changein pain pressure threshold.
postulated the results to be due to modulation of centralpain sensitivity. also found a reduction
Trigger point therapy is essentially divided into invasive
in pain with the use of 60 Hz TENS when compared to
and non-invasive techniques. Non-invasive techniques are
placebo, but interestingly also found a significantly greater
those that have been traditionally employed by physical and
improvement in pain threshold in the active group. A third
manual therapists. In recent years, there has been marked
arm of their trial used electrical muscle stimulation or
increase in the use of invasive therapies, in particular, dry
interferential. Although this group did not report the same
needling to manage trigger points. Anecdotally, all therapies
benefits on pain, they did exhibit a marked improvement in
have their supporters. Scientifically, however, very few of
range of cervical lateral flexion. Again, a central
them stand up to scrutiny. Of those that do produce a result,
mechanism of pain relief was postulated, but it was also
a clear mechanism for this improvement has not been found,
suggested that both modalities be tried together to
but all share the feature of application of a noxious stimulus.
maximise effects on range of motion and pain. There is
This section will describe the evidence for a variety of non-
no data to date on the expected duration of any
invasive and invasive methods of managing trigger points.
L.K. Huguenin / Physical Therapy in Sport 5 (2004) 2–12
letters to journals, however, and it wasn’t until much later
A search of the literature only identified one well-
that the therapies were more formally investigated. Most of
designed trail on the use of ultrasound for the treatment of
the substances listed are irritants to muscle and are not
trigger points in patients with neck and shoulder myofascial
considered in modern practice, however, local anaesthetics
pain. Therapeutic ultrasound was used in a three-armed trial
are still widely used. Interestingly, very early in the
ultrasound with home exercise and massage, sham ultra-
insertion of a needle somewhere in the region of the pain
sound with home exercise and massage or a non-interven-
without introducing analgesic solutions has been reported to
tion control group. Both intervention groups showed
give frequent lasting relief. This is the basis on which
significant improvements in the number and sensitivity of
investigation of dry needling began, and, to date, there is no
trigger points, but the ultrasound had no additional
evidence to convincingly refute his statement.
advantage. Despite the use of massage and stretching inthis trial, there was no reduction in pain scores or analgesic
use in the subjects of any group. This contradicts the
Local anaesthetic is certainly the substance most
findings of the other studies on stretching discussed above,
investigated for injection into trigger points. Many different
agents have been used, and most of them have equivalentresults to the injection of normal saline
Although some studies indicated potential benefits for
finding is that the pain relief, when seen, well outlasts the
expected half-life of the injected solution, suggesting
mechanisms of pain relief above the pure pharmacological
one of the anaesthetic. It must be noted, that in these studies
it is extremely difficult to have a true placebo, particularly if
double blinded trial on 18 patients with upper limb active
Steinbrocker’s early comments are taken into account.
trigger points and found a significant reduction in pain
Overall, local anaesthetic injection is most likely to
threshold immediately, and a larger reduction at 15 min
improve subjective outcome measures (e.g. pain scores)
after therapy in the active laser group.
used pulsed infrared laser in neck pain and found an
improvement that was higher in the active group, but only at
motion and pressure threshold have been reported
day 24 after 12 treatments and after 3 months of follow up.
This may well be explained by central modulation of
pain as the dominant factor in relief. This is supported by the
conjunction with routine physiotherapy in a double blinded
fact that in all of the above research reports pain relief far
fashion. They found a significant increase in skin resistance
outlasts the half-life of the local anaesthetics used, making it
over trigger point sites with laser therapy that was
unlikely to be a purely local phenomenon.
postulated to accompany the resolution of the pathology,
Local anaesthetic use can result in reversible myotoxi-
however, there is no data to date to corroborate this
city, seen as ischaemia and necrosis of muscle fibres in the
found no difference between five treatments of helium –
These changes are much worse in the presence of
neon laser and placebo on pain at any time point in a double
vasoconstrictors (adrenaline). Perhaps this is simply the
optimum form of counter-irritation, where a true inflamma-
laser on neck and shoulder pain in a double blind trial, and
tory response produces mediators sufficient to reset the
found that subjective reports of improvement were higher in
spinal transmission of pain, and hence, result in prolonged
the placebo group. There is, therefore, no reproducible
evidence to date of the benefit of using laser therapy in the
Injection of the skin over the trigger point with sterile
water has been postulated as an appropriate treatment ifcounter-stimulation is the active mechanism (
Although there was evidence for prolonged painrelief in long standing neck pain patients in the study of
Literature exists from the first half of last century
detailing the use of injection therapies for the treatment of
number of injections at multiple points over three
muscle pain, described as ‘fibrositis’. Most of these
separate treatments. Sterile water injection (more painful)
involved the injection of local anaesthetic formulations,
resulted in greater improvements than saline injection
but hypotonic glucose, urea, and quinine were also proposed
(less painful). Subcutaneous injection is a very painful
procedure that is generally not well tolerated by patients,
and a large number of injections over multiple treatments
muscle pain with injection were case reports, case series or
are likely to influence patient compliance, despite
L.K. Huguenin / Physical Therapy in Sport 5 (2004) 2–12
the existence of some evidence to say that it can reduce
In a double blind randomised controlled trial, dry
needling versus a non-penetrating placebo needling of the
Of interest to those treating mainly acute or athletic pain
gluteal muscles for trigger point related referred hamstring
is that, injection therapy has been shown to have a more
pain in athletes found no change in the chosen range of
rapid onset of pain relief in those with isolated regional pain
motion measures, but an equivalent improvement in activity
than in those with multiple regions involved and longer
related pain scores in both groups (Huguenin et al.,
A recent trial evaluated the use of acupuncture at distal
points, local dry needling, and sham laser acupuncture on
Botulinum toxin injection has been proposed for use in
trigger point therapy, based on the assumption that there is
Although none of the groups exhibited a large reduction
excessive ACh release from motor nerve terminals.
in pain, it is interesting to note that the acupuncture group
Botulinum toxin is produced by the bacteria Clostridium
improved by 30%, whereas the other two groups did not. In
botulinum and acts by blocking the release of ACh at the
the dry needling protocol, the needle was moved within
neuromuscular junction. Whilst one early pilot trial
trigger points until a twitch response was seen. Twitch
suggested a potential benefit over saline at 2 – 3 weeks
responses are painful and do correlate with post-treatment
soreness, and this may therefore have clouded the results
research. In a double blind design of patients with unilateral
seen. The most important point to be taken from this trial is
neck pain, injection of saline or 50 or 100 units of botulinum
the lack of response when a non-noxious placebo (sham
toxin produced equivalent results. There was no dry
needling or placebo groups. All three treatments resulted
The major drawback to the use of dry needling over local
in similarly improved pain scores and pain pressure
anaesthetic injection is the higher incidence of post-
treatment soreness (This would appear to be
unexplained finding is that subsequent treatment of the
maximal in the 24 h after therapy and is usually manageable
non-responders from all groups (saline, 50 and 100 units
with heat packs and stretching, but may be intolerable to
Botox) with 100 units of Botox resulted in a significantly
some patients, and therefore care with patient selection is
better response in those who received 100 units of Botox as
Dry needling involves multiple advances of an
acupuncture-type needle into the muscle in the regionof a trigger point, aiming to reproduce the patient’s
Given that dry needling appears to be as effective as local
symptoms, visualise local twitch responses, and achieve
anaesthetic, but has no convincing benefit over placebo
relief of muscle tension and pain. Unfortunately, there
treatment, the mechanism of action of all of these therapies
are few well-designed published studies of this technique.
remains to be clarified. The placebo treatments used have
In an early study, dry needling was found to be
varied, but all have still involved the application of a
equivalent to local anaesthetic, corticosteroid, and coolant
penetrative or non-penetrative but nonetheless noxious
spray in the treatment of lower back pain (
stimulus to the skin. Central opioid release is thought to
produce a global reduction in pain perception by gating
investigated subjects with tension headache and found
spinal cord pain impulse transmission. This is known as
that muscle dry needling resulted in equivalent improve-
diffuse noxious inhibitory control. Reversal of local
ments in pain and neck range of motion compared to
anaesthetic-induced analgesia has been observed with the
placebo (subcutaneous) dry needling. The methods of
range of motion measurement in this study, however,
This implicates the endogenous opioid system, which acts to
produce hypoalgesia at a spinal cord level, to at least a
In another study, a four armed blinded trial in dental
partial extent in the reduction of pain seen with this therapy.
patients found no improvement in pain pressure threshold,
This is the system implicated in the production of a runners’
but equivalent improvements in pain intensity and unplea-
santness, regardless of group allocation (
important in production of the placebo effect (
). Groups randomly received placebo needling, local
anaesthetic plus placebo needling, dry needling plus placebo
Beyond these suppositions, there is little hard evidence to
local anaesthetic, or placebo dry needling plus placebo local
date on the mechanisms of action of any of the therapies
anaesthetic over two sessions. Interestingly, the placebo dry
discussed. It is a notoriously hard area to research due to the
needle used did penetrate to the subcutaneous, but not the
interactions of so many systems on both a regional and
whole-body level. Stress and the sympathetic nervous
L.K. Huguenin / Physical Therapy in Sport 5 (2004) 2–12
system have been shown to increase pain perception, but the
effect of these treatments on this system has not beenconclusively evaluated.
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more effective than placebo. The application of a noxious
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Low Variability of the POLG (CAG)n Repeat in North Eurasian Populations BORIS A. MALYARCHUK,1 MARTA PAPUGA,2 TOMASZ GRZYBOWSKI,2 IGOR B. ROGOZIN,3 MARCIN WOZNIAK,2 MIROSLAVA V. DERENKO,1 SERGE YU. RYCHKOV,4JAKUB CZARNY,2 ILIA A. ZAKHAROV,4 AND DANUTA MIS´CICKA-S´LIWKA2We investigated the frequency of different repeat-length allelesof the trinucleotide CAG microsatellite repeat in the co
By ALAN ABELSON The markets -- even gold -- respond to the Russian invasion of Georgia with a resounding ho-hum. The core cabal. WHAT A SHAME! IT WOULD HAVE BEEN A DREAM TICKET : Edwards and Spitzer. They'd have been a cinch in 2012, if Obama doesn't make it this year, to walk away with the votes of the all- important hot-hormones group, 18-to-29-year-old males. (You know, the co