
THE MYOFASCIAL COMPONENT OF FACIAL PAIN
by Andrew J Gallagher BAppSci(Physio) MAPAMSCM,
Director, Victorian School of Massage, Victoria, Australia
bstract:
The presentation of head and neck pain is a complex area of clinical
practice. It can involve symptoms arising from a great number of sites
relating to conditions of the musculoskeletal, dental and upper
respiratory systems.
The term craniomandibular dysfunction (CMD)
is being used to describe the complex condition involving abnormal jaw
mechanics, associated with facial pain incorporating dysfunction of the
masticatory muscles and the temporomandibular joint(9).
As the
pain of this disturbance is orofacial, it is more often seen more by
dentists than massage practitioners or physiotherapists. However,
evaluation of the voluminous literature on the subject reveals a strong
myofascial component to the syndrome, involving not only the
masticatory muscles, but also those of the cervical region as well. The
purpose of this article is to examine the role muscles of the cervical
and orofacial regions have in this syndrome, the pain patterns of their
associated trigger points, as well as to look briefly at the
interrelationship between the two muscle groups and how changes in head
posture may affect this relationship.
Introduction
Head,
neck and face pain are commonly encountered in the daily practice of
therapeutic massage, physiotherapy and indeed medical practice. Muscles
as a primary source of pain have long been recognised by massage
therapists and sections of the physiotherapy and medical professions.
Some of the leading workers in the field of musculoskeletal medicine,
such as Vladamir Janda, Janet Travell and David Simon, have constantly
brought to our attention through their clinical research the role of
muscles and their associated soft tissue investments (fascia) in the
aetiology of many clinical syndromes(3).
These syndromes are
often poorly managed and sometimes totally misdiagnosed because of the
failure of clinicians to recognise and appreciate the significance of
muscular dysfunction in the presentation of their patient's signs and
symptoms.
Muscles are sensitive structures with a capability to
act both as a source of afferent as well as being the target of
afferent impulses.
Muscles respond to stimuli, they move,
support and protect. In co-ordination with the nervous system, they
provide smooth regulated movements which, through sensory feedback to
higher centres, is constantly monitored to allow for continual
adjustment.
In this article, I would like to review the function
of the cervical and masticatory muscles and their development of head
and facial pain. Further, once establishing this role, I will review
the aetiology of craniomandibular dysfunction, examining the role
muscles have in the development and perpetuation of the clinical signs
and symptoms of CMD.
Cervical muscles - a review
The
cervical musculature is a well known source of head and neck pain and
in particular trigger point activity of these muscles quite often
presents as head and facial pain, sometimes in association, but not
always, with symptoms of the cervical region itself. In particular,
trigger points of this region have been well documented(6), as a source
of referred pain to the head and face.
Clinically this is often
described as tension headache, post whiplash syndrome or sometimes even
incorrectly attributed to psychogenic causes.
The muscles of the cervical region that refer pain to the head and face region include:
Upper trapezius
This
muscle refers pain in an arc up the side of the neck across the
occipital temporal and frontal regions to settle behind the eye. There
may also be some referral over the angle of the jaw. The upper fibres
can develop trigger points in response to trauma (whiplash), poor
posture, as well as over activity due to compensation in shoulder
pathology, particularly where the normal synergistic function of the
rotator cuff and deltoid are interfered with, resulting in chronic
shortening of the upper fibres.
The muscle is also prone to the
effects of stress and tension and is often the cause of common tension
headaches(5). Trigger points in this muscle may not greatly limit
cervical movement, however, palpation of the upper fibres in a routine
cervical examination will readily identify tension, with the referred
pain of an active trigger point readily provoked by stretch or firm
palpation.
Sternocleidomastoid muscle
This particular
muscle has been dubbed by Travell & Simon in their book Myofascial
Pain and Dysfunction as amazingly complex. This seems an apt
description when one considers the muscle's complex function, referred
pain pattern and involvement in non pain symptoms such as postural
dizziness and imbalance. It also can be the cause of satellite trigger
points developing in the masseter and temporalis muscles, which
obviously can result in Impairment of craniomandibular function; this
fact in itself illustrating the effect that cervical musculature
dysfunction can have on the genesis of the controversial
craniomandibular dysfunction or TMJ syndrome.
The muscle acts to
flex the head, while unilaterally it laterally deviates to the same
side whilst rotating to the opposite. It also acts to check
hyperextension of the neck as well as resisting forced unprotected
movement of the head, as seen in whiplash. The muscle also works with
the trapezius to stabilise the head, allowing the mandible to move
during talking and mastication.
The muscle functions as an
accessory respiratory muscle, hence its tight, overdeveloped appearance
often noted in the asthmatic or patient suffering emphysema.
The muscle refers two distinct pain patterns from active trigger points depending on which head of the muscle is involved.
The
more superficial sternal head gives rise to occipital and vertex pain,
as well as supraorbital, temporal and maxillary pain. The deeper
clavicular fibres give rise to ear and frontal pain (the frontal pain
can be bilateral) as well as retroauricular pain.
Autonomic
concomitants of trigger point activity in this particular muscle can
include tear discharge and reddening of the conjuctiva, disturbance of
vestibular function and space perception as well as postural dizziness.
These are similar symptoms resulting from experiments cited by
Baldry(2), that involved anaesthetising the first to third cervical
nerve roots in monkeys. It is not surprising to learn that the sensory
supply of this muscle is the C2 C3 nerves.
The altered sensory
information arising from the muscle with trigger points is part of the
vital proprioceptive information being relayed to higher centres; thus
it is not surprising that functions: such as that of the vestibular
apparatus which rely on this information are subsequently disturbed.
Active trigger points in the clavicular division have been observed to
affect hearing with an immediate improvement once the trigger point has
been deactivated.
Patients have also described tinnitus, but
this is usually associated with satellite trigger points in the deep
head of the masseter muscle rather than the sternocleidomastoid itself.
Splenii muscles
The
splenius capitis muscle which arises from the spinous processes of the
lower cervical and upper thoracic spine when containing active trigger
points can give rise to vertex pain, whilst the splenius cervicis
muscle arising from the spinous processes of T3 to T6 and inserting
into the upper three cervical transverse processes, refers pain to the
temporal area and behind the eye. These muscles are usually involved in
cervical syndromes associated with poor posture, injury or work
involving awkward neck positions. They are often seen with levator
scapulae dysfunction and contribute to the stiff neck syndrome as they
can limit rotation movements of the head.
As well as referring
pain to the head and face muscles, they can also contribute by trigger
point activity and tightness to the increased head forward position
which can influence mandibular positioning and accordingly masticatory
dysfunction.
Posterior cervical muscles (Semispinales Capitis, Semispinales cervicis)
The
semispinales muscles refer pain to the head, the cervicis causing
occipital pain, often seen as part of the tension headache syndrome
alongside trapezius. The cervicus is often part of the tension headache
syndrome, giving rise to a band of pain that when bilaterally involved
causes a tight hatband sensation around the head. The focus of pain is
often felt over the anterior aspect of the temporal fossa.
This
muscle can also cause entrapment of the greater occipital nerve leading
to occipital neuralgia due to taut band formation within the muscle.
Symptoms of this can include pain. numbness, tingling and burning over
the scalp and occipital region. A recent study by Akemi Takawo(1)
examining the significance of radiological changes in the cervical
spine and prevalence of occipital neuralgia, concluded that on the
basis of comparison of the cervical radiographs of symptomatic and non
symptomatic patients, there was no real evidence to indicate that
compression nerve roots at the neural foramen was a significant cause
of occipital neuralgia. In fact. they suggested (although not
specifically investigating it) that more attention needs to be paid to
the role of muscles, fascia and other soft tissues in the patho genesis
of occipital neuralgia.
The clinical finding of occipital neuralgia associated with semispinales trigger points, would clearly support this contention.
Suboccipital muscles
These
muscles which include the rectus capitis posterior major and minor, as
well as superior capitis oblique, and inferior capitis oblique, are
deep muscles which lie deep to the posterior cervical muscles, directly
inferior to the occiput. These muscles control the movements of the
upper two cervical joints: the alanto-occipital joint at which
flexion/extension and lateral tilting of the head occurs and the alanto
axial-joint which provides head rotation.
These muscles produce
pain patterns similar to that of the semispinales muscle and according
to Janda are prone to tightness as part of the cross layered syndrome
associated with chronic postural dysfunction which may have its origin
in pelvic asymmetries short leg syndrome, or a tight psoas muscle.
Haygure
et al (1992, see section on head posture in this article) have clearly
demonstrated the relationship between head posture and masticatory
muscle balance.
Their research has also shown the adverse effect
of head forward posture, which involves upper cervical extension,
(which can be caused by trigger points in, or tightness of the
sub-occipital musculature) on the position of the mandible leading to
masticatory muscle imbalance. which is one of the main features of the
craniomandibular Syndrome.
Hence, although the cervical muscles
warrant inclusion in this discussion on the basis of their pain
referral patterns, they more importantly are a potential source of
orofacial pain because of their postural role which influences the
position of the TMJ and subsequent masticatory muscle function.
Muscles of mastication
The
Masseter muscle has a deep and superficial component The fibres arise
from the zygomatic arch and maxilla, attaching to the outer surface of
the ramus and angle of the mandible. The superficial fibres elevate,
while the deep fibres retrude the mandible. Patients complain of pain
referred to the maxilla, upper and lower dentures, TMJ joint, ear and
mandibular regions.
The muscles act to close the jaw clenching into centric occlusion. The deeper fibres help to retrude the mandible.
The masseter and temporalis muscles function together, with the temporalis more involved in mandibular balance and posture(8).
The
patient complains of pain which is similar in nature to that which
arises from the temporomandibular joint. Opening of the mouth is
restricted; this restriction is more likely to be caused by trigger
points in the superficial rather than the deep fibres of the masseter
muscle.
Travel & Simon in Volume 1 of the Trigger Point
Manual cite causes of unilateral tinnitus which they put down to
referred motor activity of the Stapedius muscle of the tympanic
membrane. Spasm of this muscle they say could cause oscillation of the
middle ear ossicles.
This symptom has also been observed by the
same authors in cases of intracapsular TMJ disease, probably explained
by the facial connection of the TMJ to the middle ear.
In cases of bilateral tinnitus, other causes would need to be excluded.
Overstress
of this muscle can be brought about by various activities - bruxism or
forcible contraction of the muscle (cracking nuts or ice - Travell
& Simon) or by occlusal disharmony. This muscle is also one to
respond to increased states of emotional or psychological stress,
resulting in long periods of contraction and development of the
pain-tension-ischaemia cycle.
An increase in contractile
activity at rest, as seen in occlusal disharmony is likely to be a
significant cause of trigger point activity. (see Travell & Simon
p.224-225 for details)
Other causes include overstretching of
the muscle as in a prolonged dental procedure, direct trauma or
satellite trigger points caused by sternocleidomastoid trigger point
activity(8).
Temporalis
The temporalis muscle is a
fan-shaped muscle arising from the temporal bone and fascia of the
temporal fossa and inserting into the condylar process of the mandible.
The muscle acts to close the jaw, retrude the mandible and unilaterally
it deviates the mandible to the same side.
Trigger points in the
muscle can refer pain to the temporal region and upper denture. The
patient can complain of hypersensitivity of the upper teeth, with
headache (temporal) but rarely is mandibular function affected.
However, the patient may be aware of premature tooth contact.
Patients
primarily complain of pain and are aware of restricted mouth opening
(this is usually more restricted if the masseter muscle is involved).
Activation
of trigger points can come about through bruxism, occlusal imbalance or
due to direct trauma. (One patient I treated developed temporal trigger
point as the result of being hit in the temporal region by a following
ski lift.) Travell and Simon also cite auto accidents or forced
mandibular compression due to constant cervical tractions as being
among other traumatic causes of trigger point activity in the muscle
(folate deficiency can also cause restlessness of the masticatory
muscles).
Excessive gum chewing and mouth breathing have also
been cited by Travell & Simon as causing trigger points in the
muscle. Referred pain from the trapezius muscle may also result in
satellite trigger points in temporalis.
Lateral pterygoid
This
muscle lies deep to and behind the coronoid process and zygomatic arch.
It has a superior and inferior division. The upper branch attaches in
front of the sphenoid bone and behind the capsule of the TMJ.
The lower head arises from the lateral pterygoid plate and inserts behind to the neck of the mandible.
Pain from trigger points in this muscle is felt over the cheek and TMJ joint.
The muscle opens and protrudes the jaw bilaterally and laterally deviates it unilaterally (to the opposite side).
The superior division exerts traction on the disc at the level of condylar head on jaw closure.
Overactivity
or trigger point shortening of the superior division fibres therefore
displaces the disc forward and impedes its return to its normal,
position on the closure of the jaws.
The inferior division pulls
the condylar head forward and down so that condyle can translate over
the posterior surface of the eminence - a movement essential for full
opening.
Myofascial trigger points in this muscle can cause or be the result of premature teeth contact.
Those
patients diagnosed as suffering myofascial pain dysfunction display
symptoms similar to those described by Travell & Simon (p263) as
being due to active trigger points in the lateral pterygoid muscle
(pain in the TMJ muscular tenderness and malocclusion).
Because
the pain referred from this muscle and other masticatory muscles
includes the TMJ and teeth, it is not surprising that much treatment
has been 'misdirected to the joint and teeth with frustrating results'
Travell & Simon p263).
Medial pterygoid
This muscle arises from the angle of the jaw (inside surface and above to the lateral pterygoid plate).
It
acts to elevate the mandible and laterally deviate it to the opposite
side. Pain from active trigger points is felt inside the mouth (tongue,
pharynx and hard palate) as well as over the TMJ, mandible and in the
region of the lateral pterygoid muscle.
Ear stuffiness may also
be present. The muscle works with masseter and temporalis to close the
jaw. Bilaterally it assists the lateral pterygoid in protrusion, whilst
unilaterally it assists in deviation to the opposite side, alongside
the lateral pterygoid.
Patients describe pain from opening the mouth, chewing or clenching the teeth. Pain is also often experienced on swallowing.
Trigger
points can develop secondary to lateral pterygoid dysfunction or
occlusal disharmony in response to trigger points in the contralateral
muscle.
Digastric muscle
Arises from the symphysis of the mandible with the posterior belly inserting to the mastoid notch.
The posterior belly refers pain to the upper part of the sternocleidomastoid muscle, the throat and under the chin.
The anterior belly (less commonly) refers pain to the four lower incisor teeth and the alveolar ridge between them,
With
a fixed hyoid bone, this muscle assists in depressing, that is, opening
the mouth. Bilaterally the digastric muscles act to retrude the
mandible.
With the mandible bred, the muscle lifts the hyoid bone.
Although
not as important as the lateral pterygoid in mouth opening, its action
is necessary to fully open the mouth. EMG studies would indicate that
the muscle is strongly recruited in coughing and swallowing actions.
Apart
from pain, the patient will describe difficulty swallowing. The
sternocleidomastoid muscle (upper portions) is tender to touch as a
result of trigger point activity in the digastric, but palpation
reveals the absence of but bands In the sternocleidomastoid itself.
This
muscle usually develops trigger points in association with other
muscles of mastication as part of the craniomandibular syndrome.
Head posture
The
preceding review of the myogenic causes of head pain clearly
illustrates the potential of the cervical masticatory muscles to cause
the pain associated with CMD.
Further to this. the
interrelationship between these two groups of muscles is also of
considerable importance when trying to fully understand the symptoms of
CMD.
A recent study demonstrates the postural changes of the
craniovertebral region alongside morphological changes of cervical
region, were significantly different between their study group
(patients suffering symptoms of craniomandibular dysfunction) and the
healthy control group, whilst morphological changes of the dentition
(over bite or incisor inclination) were not significantly different
between the two groups.
Further. straightening (improved
posture) of the cervical spine was observed after stomatagnathic
treatment was carried out. Logically, this 'straightening' is
associated with relief of symptoms related to muscular imbalance in the
stomatagnathic system These postural changes were maintained at a six
month follow up.
In addition, the authors also suggest that the
reverse relationship can also exist, that is head posture can influence
stomatagnathic function. To support this, they quote the sliding
cranium theory(7).
The theory can explain how head posture may
perpetuate, if not initiate, craniomandibular dysfunction. The theory
proposes that as the cranium bends backwards, the occiput is translated
anteriorly causing a simultaneous shift of the whole maxillary
dentition in relation to the mandible whish must be forced anteriorly
to obtain occlusal support. This will probably affect the muscular
balance in its sup porting mechanism, particularly the lateral
pterygoid muscle.
As Huggare et al pointed out in their study,
head forward position (hyperextension of the upper cervical spine) is
often seen in patients who present with orofacial pain. In this
author's experience, correcting this upper cervical hyperextension can
often give relief of pain, which on initial examination appears to be
coming from the masticatory muscles alone. Further ignoring this
postural fault and treating the masticatory muscles alone in my
experience leads to recurrence of masticatory muscle pain, even when
initial treatment appears to have successfully normalised the muscle
length, and, as a result, function.
Craniomandibular syndrome
The
dental profession has long recognised the muscular component of
craniomandibular pain syndromes. Often described as TMJ pain
dysfunction syndrome, there has been a steadily growing volume of
literature since the dentist Colsen first described the syndrome in
1934, as involving painful hypomobility of the TMJ with associated
spasm And tenderness of the masticatory muscles. He also described many
associated symptoms including headache, deafness, tinnitus, a sensation
of fullness of the ear, vertigo and throat pain.
There are three
major views on the aetiology of craniomandibular syndrome, an extensive
discussion of these appears in Travell & Simon Vol 1, l71-173, and
in practice all three views to an extent overlap and certain patients'
presentation may lend greater support to one view or another.
However,
it is not surprising that many authors feel that components of each
theory co-exist and contribute to the development of the syndrome.
The three theories proposed are:
Muscular
This
theory strongly argued by Travell & Simon looks at the problem from
the perspective of muscle imbalance, focusing naturally enough on the
masticatory musculature, Examination of pain patterns from active
trigger points (see previous section on masticatory muscles) certainly
supports this theory, as these correspond with the symptoms experienced
by patients. In addition, some of the more bizarre symptoms of CMD such
as tinnitus, dizziness, hearing impairment, can also be explained on
the basis of impaired muscle function, in particular trigger points and
muscle shortening.
It is important to appreciate that muscle
changes do not necessarily involve increased EMG activity and should
not be referred to as spasm.
The results of tight muscles lead
to altered TMJ mechanics, including hypomobility, and as elsewhere in
the body, can also lead to increased wear on joints and eventual
degenerative changes.
Malocclusion can result from tightened
muscles, as the normal synergist agonist relationships are disturbed,
leading to a loss of smooth co-ordinated movement.
A specific
example of the effect of muscle activity of TMJ function can be seen in
the lateral pterygoid which, because of its attachment to the disc of
the TMJ joint when tight, can displace the disc forward, thus impeding
its return to a normal position on closure of the jaw.
Psychological theory
This
theory proposes that most of the symptoms are due to stress, tension or
emotional upset, leading to increased muscular activity as seen in
bruxism, especially at night. Nocturnal bruxism has long been regarded
as a symptom of stress.
Even the Bible, when referring to
extreme states of distress, refers to 'a great wailing and gnashing of
teeth.' Psychological tests on patients have often revealed stress
related behaviour, anxiety and poor coping skills in these patients.
It
is thought that eventually bruxism and clenching lead to changes in the
dentition and muscles, when then lead to TMJ disorders, muscular
imbalance and eventual malocclusion.
Malocclusion theory
This
theory is supported by the fact that when treated by use of splints to
prevent premature contact, patients receive considerable relief of
symptoms. Permanent relief can then be obtained by revising the
occlusion. Even within this school of thought, there are some divisions
of opinions, with some authors believing the occlusal disharmony causes
the muscular dysfunction, while others are more concerned about TMJ
mechanics being the end result.
The cause of premature contact
can be due to trigger points in the masticatory muscles and in fact
Schartz, cited in Travell & Simon, recommends relief of all
muscular tightness before splinting.
It has been argued that
after an initiating activity such as prolonged dental work, stress or
trauma, the malocclusion that results could perpetuate trigger point
activity, which is responsible for most of the pain experienced by the
patient. Further, the disturbed muscle function and proprioception
caused by, trigger points has been shown to cause malocclusion and
alter TMJ biomechanics.
As stated at the outset, this is a
complex and much written about subject. However, in all three theories
presented, muscular dysfunction plays a role, with interplay between
psychological and dental factors, leading to the entity described in
the literature as craniomandibular syndrome.
Whether muscular dysfunction causes, perpetuates or is a result of malocclusion depends on which authors one reads.
However,
all agree that somewhere along the line they become involved. The
relationship between malocclusion and muscular dysfunction could well
be the ultimate chicken or the egg situation.
Conclusion
Regardless
of which theory one subscribes to in relation to the origin of
craniomandibular dysfunction, muscles are of considerable importance
when looking at clinical symptoms.
Many of the described
features of the syndrome can be explained on the basis of muscular
dysfunction of the masticatory muscles alone.
Further not only
are the muscles of the cervical region capable of referring pain to the
head and face but also because of their role in controlling head
posture they can directly influence mandibular positioning leading to
bio-mechanical changes which place more stress on the muscles of
mastication contributing to the symptoms of CMD.
It is therefore critical that both cervical and masticatory muscles are examined for shortening and TP activity.
Failure
to do so may well result in perpetuating factors continuing to maintain
established CMD even if these factors were not responsible for the
condition in the first place.
References
1 Akemi Takawo,
Shinicki Migao, Jun Feramato "Clinical analysis of occipital
neuralgia'. Abstract from the proceedings of the 5th International
Headache Conference 1991.
2 Baldrv, PE, (1989) 'Acupuncture, trigger point and musculoskeletal pain', Churchill Livingstone, London.
3 Gallagher, A (1989) Course notes: Introduction to trigger Point Therapy. Victorian School of Massage, Melbourne.
4
Huggare, A 'Head Posture and Cervicovertibral and Craniofacial
Morphology in Patients with Craniomandibular dysfunction', The Journal
of Craniomandibular Practice Volio No. 3.
5 Janda, AV (1988)
'Muscles and cerviogenic pain syndromes'. In Grant R (ed) Physical
Therapy of the Cervical and Thoracic Spine 1988, New York, Church
Livingstone ch9.
6 Lewis, J. 'Muscle imbalance its effect of
posture and function a review of the Janda Approach', Australian
Massage Therapy Journal Vol 5, No. 1.
7 Makotskv (1989) 'The
effect of head posture on muscle contact position: The sliding cranium
theory'. Journal of Crandiomandibular Practice 7: 286-292.
8 Travell S, Simon D, (1983) 'Myofascial Pain and Dysfunction: the trigger point manual', Williams and Wilkins Baltimore.
9 Uppgaard, R 'Conservative and successful treatment of temporomandibular dysfunction in a private rural practice'.