Orofacial Pain

List and discuss the differential diagnoses of orofacial pain

When clinicians are faced with a case of orofacial pain, vigilance must be
given to what the patient is trying to communicate. Clinicians must have
sufficient knowledge of how to narrow down all the different diagnoses of
facial pain to reach a definite diagnosis, or at least a narrowed down
differential diagnosis.

Orofacial pain can come from five different categories:
- Dental
- Musculoskeletal
- Neurovascular
- Neuropathic
- Psychogenic

Dental facial pain relates to the dental hard tissues, the surrounding
periodontal ligament and the surrounding mucosa.

Musculoskeletal pain can be divided into three categories:
- Muscle problems, including myalgia, spasms and contractures
- Joint mechanics problems, including anterior disc displacement,
ankylosis, traumatic arthropathy, and temporo-mandibular joint disorder
(TMD)
- Arthritides, including rheumatoid arthritis and osteoarthritis.

Neurovascular pain can be divided into three caterogies:
- Migraines, with or without aura
- Tension-type headaches, with or without pericranial tenderness
- Trigeminal autonomic cephalgias, including cluster headache and
paroxysmal hemicranias.

Neuropathic pain can be divided into three categories
- Peripheral neuropathic pain, involving sensitisation of the peripheral
nerves (e.g. possibly involving neuritis or neuroma)
- Central neuropathic pain, in which the nerves of the CNS are
sensitised, such as in anaesthesia dolorosa and atypical odontalgia. It
is an important mechanism of persistent neuropathic pain
- Neuralgia, in which the nerve of interest is damaged via compression
of the nerve by surrounding vasculature, such as in trigeminal
neuralgia or glossopharyngeal neuralgia

Psychogenic pain can be understood under the biopsychosocial model, and
can include somatisation disorder and psychotic disorder.

It is imperative for the dental clinician to eliminate all possibilities of dental
facial pain before exploring the possibilities of musculoskeletal pain,
neurovascular pain, neuropathic pain and psychogenic pain. It is through a
systematic comprehensive intraoral and extraoral examination that this can be
achieved whilst minimising the possibility of missing important details.

An example of a format of a comprehensive oral examination includes:
- Pre-examination questionnaire
- Presenting complaint and symptoms
o In the context of orofacial pain, the patient will give you
important clues to your diagnosis, so this part is especially
important
- Medical history
o In the context of orofacial pain, to rule out any causes of
orofacial pain due to systemic diseases, to obtain a list of
medications for awareness of possible drug interactions,
allergies to be cautioned about, etc
- Dental history
- Social history
- Extraoral examination
o Including palpation of lymph nodes, palpation of muscles,
palpation of TMJ, testing TMJ function and analysis of overall
facial appearance
- Intraoral examination
o Including examination of soft tissues, examination of periodontal
tissues, hard tissue charting
- Investigations
o As required, for example OPGs, radiographs, CT scans, MRIs
- Diagnosis
o May include differential diagnosis
o Your diagnosis might need to be confirmed via further testing
- Treatment plan

It is important to keep in mind that as a dental health practitioner, you do not
have to fly solo – work with other members of the health practitioner team,
such as doctors, physiotherapists and surgeons, to help you reach a definite
answer and design an appropriate treatment plan that will address your
patient’s needs.

In the following part of this discussion, the following common possibilities of
orofacial pain will be discussed, including general information, aetiology,
presentations and management:
- Musculoskeletal pain: TMD
- Trigeminal neuralgia, primary and secondary
- Migraine
- Cluster headache
- Paroxysmal hemicranias
- Psychology of pain, including biological factors, behavioural factors,
and the biopsychosocial model, which branches into biobehavioural
assessment and biomedical assessment

TMD

Temporomandibular disorder is described as the dysfunction of muscles of
mastication and the temporomandibular joint.

It is said that the presence of TMD is influenced by a wide variety of factors,
but unfortunately the definite cause is poorly understood.

In order to properly diagnose TMD, the clinician should have an
understanding of the anatomy of the TMJ.

Examples of important anatomical details of the TMJ include:
- Condyles
- Articular disc made of avascular fibrous connective tissue
- Articular surface of temporal bone (glenoid/articular fossa)
- Capsule
- Temporomandibular, stylomandibular and sphenomandibular ligaments
- Superior and inferior joint cavities.
These collectively together allow for the hinge and slide movements of the
TMJ.

The TMJ is innervated by the auriculotemporal and masseteric branches of
the mandibular branch of the trigeminal nerve. The external carotid artery
gives the arterial blood supply.

Presentation of TMD includes:
- Uni/bilateral face pain
- Ear pain/tinnitus
o As the middle ear and the TMJ are intricately connected
- Tenderness of temporalis and masseter muscles
- Tenderness of TMJ
- Headaches (frontal, temporal, occipital)
- Eye pain (retro-orbital or peri-orbital)
- Pain on chewing or yawning
- Restricted mandibular movement
o Mouth opening <3cm
o Restricted lateral mandibular movements
- Crepitus

Some different modalities of management include:
- Conservative advice and counselling
- Self-help exercises
- Occlusal splint therapy
- Physiotherapy
- Relaxation
- Medication
- Arthrocentesis, which involved removal of synovial fluid from the TMJ
- Surgery, however this is a last resort

Trigeminal neuralgia

Trigeminal neuralgia presents as short-lasting (a few seconds to a few
minutes) unilateral facial pain that may be spontaneous or triggered by gentle
innocuous stimuli. The pain is often described as stabbing electric shocks.
These pain intervals are separated by pain-free intervals of varying duration.
These bursts of pain may occur hundred of times through the day, and
remissions can last months or years

The aetiology behind trigeminal neuralgia: persistent compression of enlarged
blood vessels upon of the trigeminal nerve injures the protective myelin
sheath or the A-beta neurons. These neurons then produce subthreshold
oscillations that generate ectopic discharges, which may cause transient
depolarisation in neighbouring c-fibres in the same ganglion.

Trigeminal neuralgia can be split into two categories:
- Primary/Classical, having no recognised pathological process
- Secondary, having previous pathological process present, such as
herpetic neuralgia

The neuropathic pain generated from TN can be very difficult to treat. The
anticonvulsant carbamazepine can be used, and nowadays remains the drug
of choice. In stubborn cases, gabapentin is also helpful in relieving pain.
Opiates such as morphine and oxycodone can also be prescribed, as there is
evidence of their effectiveness on neuropathic pain, especially when
combined with gabapentin. Surgical therapy is once again a last minute resort
and is only recommended if medicinal treatment is not effective. Some
procedures in which the patient can undergo includes microvascular
decompression, in which the nerves are relieved of the vessel’s pressure.
Other less conservative approaches include glycerol injection, sterostatic
radiosurgery and balloon compression in which the trigeminal nerve is
purposely damaged in order to stop the nerve pain signals.

Migraine

Migraine affects approximately 16% of the population and is more common in
females. Genetic factors may occur and usually develop in the first three
decades of life.

The migraine presents as unilateral severe, throbbing debilitating pain, with
phono- and photophobia. This may be accompanied with nasal stuffiness, as
well as nausea and vomiting. Post-dromally, the individual will be extremely
tiredness and will seek a dark room for sleeping.

Migraine may present with or without aura. Aura is a prodome which may
occurs hours or days before the onset of the migraine, and includes visual,
sensory, motor, language or behaviour disturbances.

The pathophysiology stems in the trigeminovascular system: the neural
innervation of the intracranial system is stimulated by neurotransmitters,
leading to a cascade of events that cause the pain. Triggers to migraines can
include foods, such as hot dogs, MSG and alcohol.

Management involves:
- Patient education: trigger avoidance
- Relaxation
- NSAIDs
- Preventative: Calcium channel blockers, serotonin antagonists
- Tricyclic antidepressants

Cluster headache

Cluster headache is a type of trigeminal autonomic cephalgia. It is less
common than migraines, affects more men than women, and has no
significant hereditary factor.

The patient experiences intense excruciating deep unilateral pain, often
accompanied with periorbital stabbing pain. The pain lasts between half an
hour to two hours, commonly occurring at the same time in the day (e.g.
2am).

Management includes:
- Patient education, avoiding triggers (e.g. maintaining sleep patterns to
avoid occurrence of headache)
- Compression of superficial temporal artery
- 100% oxygen
- Ergotimine

Paroxysmal hemicranias

Paroxysmal hemicranias are a type of trigeminal autonomic cephalgia. It is
more common in women. It involved frequent attacks, approximately 5 per
day, with shorter duration of about 15 minutes each.

Management involves indomethacin, 25 – 250mg/day.

- Psychology of pain, including biological factors, behavioural factors,
and the biopsychosocial model, which branches into biobehavioural
assessment and biomedical assessment

Psychology of pain

The psychology of pain involves a variety of biological and behavioural factors
which intertwine together in a complex manner:

Biological:
- Fitness level
- Autonomic balance
- Genetic factors
- Allostatic load
- Nutritional status

Behavioural:
- Principles of learning
- Relaxation
- Interpersonal process
- Cognitive regulation

The biopsychosocial model branches into two assessments in order to help
diagnose the cause of pain, and allow for the most effective management:

Biobehavioural which includes:
- Psychological interview
- Diagnostic questionnaire
- Relaxation training
- Cognitive restructuring

Biomedical which includes:
- Physical exam
- Investigations
- Medication
- Physical modalities