ASIPP Practice Guidelines - Pain Physician

Manchikanti et al • ASIPP Practice Guidelines
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Even though there is a substantial amount of anecdotal
evidence, there is no controlled prevalence data on the
prevalence of myofascial pain. The authors exploring the
role of trigger points and myofascial pain and whiplash
injuries believe that the theory of trigger points lacks demonstrated
internal validity. Formal studies also have shown
that myofascial experts have difficulty in agreeing as to
the presence of a trigger point, which is the cardinal feature
of regional myofascial pain syndrome. In addition to
this, it has been shown that topographically, trigger points
of the neck overlay the cervical facet joints, and it has been
reported that pain patterns of cervical trigger points are
identical to those of referred pain from the facet joints.
The same theories can be extrapolated to the lumbar spine.
The literature describing effectiveness of trigger point injections
is enormous. There were seven controlled studies
(203-209) along with numerous observational studies.
Collee et al (205), in a double-blind, randomized evaluation
of local injection therapy of iliac crest pain syndrome
and low back pain, studied the effectiveness of a single
local injection of 5 mL of lignocaine, 0.5%, with 5 mL
isotonic saline in 41 patients. The results showed that in
the local anesthetic group, 52% of the patients improved
and in the saline group, only 30% improved. The data
demonstrated an effect of the local injection with lignocaine
that is somewhat larger than an injection with saline, which
also has some beneficial effect. The difference was not
consistent across all the settings (rheumatology practice
vs general practice).
Bourne (206) compared corticosteroid - lignocaine injections
with lignocaine alone in a trial of 57 patients suffering
from chronic back pain. The results showed that corticosteroid
- lignocaine mixture gave excellent results in 80%
of 30 patients treated with the mixture and in only 16% of
19 patients treated with lignocaine alone.
Hamerhoff et al (207) compared bupivacaine, etidocaine,
and saline for trigger point therapy in a randomized doubleblind
crossover study. They reported increased relief with
local anesthetic as compared with normal saline.
Fine et al (208) evaluated the effects of myofascial trigger
point injections, they reported pain relief in all subjects
with the injection of 0.25% bupivacaine injection along
with improvement in range of motion in those subjects who
initially demonstrated the limitation of movement. They
also showed that the relief achieved with trigger point injections
was reversed with naloxone but not placebo.
Jaeger and Shootsky (209) in a double-blind study evaluated
the effect of dry-needling, saline, procaine, and placebo.
They concluded that the use of saline or local anesthetic
appears to be more effective than dry-needling or
placebo.
In a controlled double-blind evaluation of the comparison
of mepivacaine injection versus saline injection for
myofascial pain. Frost et al (203) studied 28 patients with
acute, localized muscle pain by injecting four local injections
of mepivacaine, 0.5%, in 28 patients, and local injection
of an equal volume of normal saline in 25 patients.
The group receiving saline tended to have more relief of
pain, especially after the first injection. The results show
that pain relief is not due merely to the local anesthetic.
The study raises questions about the mechanism by which
local injections into muscle relieve pain, since there is the
possibility that a similar effect might also be achieved by
merely inserting a needle into the trigger point. Normal
saline is considered to be a more appropriate fluid for injection
therapy than local anesthetic since it is less likely
to produce side-effects. The positive aspects of this study
include its inclusion of neck, shoulder, lumbar, and gluteal
myofascial pain syndromes. The negative aspects include
that normal saline was more effective than local anesthetic
injection.
Garvey et al (204), in a prospective, randomized, doubleblind
evaluation of trigger point injection therapy for low
back pain, evaluated 63 individuals with low back strain.
Patients with nonradiating low back pain, with normal
neurological examination, without sciatic tension signs, and
with negative radiological evaluation and patients who
failed two months of conservative treatment were included.
Injection therapy was of four different types: lidocaine,
lidocaine combined with a steroid, acupuncture, and vapocoolant
spray with acupressure. The results showed that
noninjection therapy was effective in 63% of the patients
whereas injection therapy was effective in only 42% of the
patients. Thus, this study showed that trigger point therapy
seems to be useful in the treatment of low back strain, but
the injection substance apparently is not the critical factor,
since direct mechanical stimulus to the trigger point seems
to give symptomatic relief equal to that of treatment with
various types of injected medication.
In terms of the quality of evidence presented with trigger
point injection, the results were positive in five of the seven
controlled studies (205, 209). Based on the above, type
and strength of efficacy evidence is level III to level IV -
moderate to limited. Level III – moderate is defined as
Pain Physician Vol. 4, No. 1, 2001