PAIN is an unpleasant sensory/emotional experience associated with actual or potential tissue damage or described in terms of such damage
It is described by duration, site, distribution, type
1. Acute pain – sudden onset, obvious cause, identifiable pathology, responds to analgesics, and treatment of the pathology, associated with the emotions of fear and apprehension.
2. Chronic pain – insidious onset, no evident cause or readily identifiable pathology, responds poorly to analgesics, patient depressed
Physiology of pain:
- Nociceptive stimuli (inflammation, infection, trauma, chemicals, thermal stimulus, biochemical stimulus)
- Acts on peripheral pain receptors (non myelinated nerve fibres).
- The impulse transmitted in form of a chemical transmitter substance across the synaptic cleft & an electric potential along the neuron.
- Pain is perceived centrally causing peripheral release of endorphins (endogenous morphines)
- From small interneurons that block the presynaptic release of the chemical pain transmitter (substance P) = tolerance
Gate control theory of pain:
- Spinal gates at dorsal horn – at each segment of spinal cord
- Heat, touch and pain impulse compete for the gate – therefore non painful stimulus blocks transmission of noxious stimulus
- Modulated by substantia gelatinosa (SG) in the dorsal horn
- Which then influences the first central transmission cells (T cells)
- SG – modulating gate – permits only one type of impulse to pass through
- Larger nerves eg. touch receptors carry impulse to brain quicker and get through gate, blocking nociceptors
- Therefore use massage and heat therapy to inhibit pain sensation
Causes of facial pain and headaches
1. Local causes:
- Dental or oral disease
- Referred pain
- Upper respiratory tract lesions
- Neck lesions
- Ocular lesions/ defective vision
- Trauma
2. Neurologic causes:
- Trigeminal neuralgia
- Glossopharyngeal neuralgia
- Herpetic neuralgia
- Intracranial disease
3. Psychogenic causes:
- Tension headaches
- Atypical facial pain
- Temporomandibular pain dysfunction syndrome
4. Vascular causes:
- Migraine
- Migranous neuralgia
- Temporal arteritis
5. Systemic causes:
- Severe hypertension
- Drugs (vinca alkaloids etc)
Diagnostic features of conditions presenting with orofacial pain
Common diseases in this list need to be ruled out before diagnosis of rare conditions
1. Acute osteomyelitis:
- Causative lesion – carious tooth/PDL disease, and bone swelling
- Moth eaten appearance only manifests when approx 30% of bone undergoes osteolysis
2. Acute pulpitis:
- Sensitivity to temperature extremes and sugary foods
- ↑ pain at night or when lying down.
- Vitalometry – indicates that the pulp is still vital
- Percussion sensitivity – indicates apical spread
3. Apical abscess:
- Non vital tooth with fistula, parulis or extra oral drainage tracts
- This may be acute (with febrile presentation) or chronic
4. Cracked tooth syndrome:
- Apico-occlusal crack which does not show up on x-ray
- Pain on mastication
- Lateral pressure on the inclines of the cusp causes pain
5. Cluster headaches:
- Seasonal headaches with acute episodes in the evenings + ipsilateral conjunctival
reddening and nasal discharge
6. Internal derangement of TMJ meniscus/ capsule adhesions
7. Myalgia of masticatory muscles:
- Pain and spasm of muscles of mastication – marked by a trigger point on one or more of these muscles (masseter, medial and lateral pterygoids, temporalis)
- Usually found in patients with a history of jaw clenching on anxiety
8. Otitis media:
- Unilateral hearing impairment and bulging, perforated, red or purulent tympanic membrane
9. PDL abscess:
- Expression of pus from the PDL pocket of a vital tooth
- Characterized by presence of calculus and alveolar bone damage
- If the tooth is non vital, it’s a perio-endo lesion
10. TMJ capsulitis/ synovitis/ arthritis:
- Pain over the joint
- Limited mouth opening or deviation on opening
- Crepitus on palpation of the TMJ – indicates bone erosions – secondary to arthritis
11. Neuralgia (Trigeminal, Glossopharyngeal or Postherpetic):
- Pain of neural origin, paroxysmal pain
- Distinct trigger zone on skin/ in mouth
- Middle aged or old patients, female patients
- Trigeminal neuralgia is called ‘Tic Doloureux’ when it is accompanied by spasms of the muscles of facial expression
Classical trigeminal neuralgia:
- Sudden unilateral, severe, brief, stabbing, recurrent pains in the distribution of trigeminal nerve branches
- Pain is paroxymal
- Provoked by light touch
- Confined to trigeminal distribution
- Unilateral
- Lasts from few seconds to 2 minutes
- Etiology: Intracranial compression of nerve by vasculature/foramina (osteopetrosis)
- Diagnosis: History, CT scan, MRI, LA during an attack attenuates the pain instantly
- Management: Carbamazepine, cryotherapy, vascular decompression
12. Atypical facial pain:
- No known organic cause (diagnosis of exclusion)
- Described by the patient in vague terms, treated as a symptom of depressive illness
- It is also called psychogenic pain
13. Myofascial pain dysfunction syndrome (MPDS)
The diagnostic protocol for acute facial pain
Is the contributing lesion clinically visible (intra- and extra-oral examination for caries, PDL
disease, swellings, erosions, joint sounds, radiographic changes)?
If YES:
− Is it accompanied by fever (a sign of acute disease)?
If YES:
− Pulp or PDL: Abscess or osteomyelitis
− Mucosal lesions: Viral vesiculo-ulceration
− Facial swelling: Cellulitis or space infection
− Salivary swelling: Mumps or obstructive sialadenitis
− TMJ or mid ear: Infectious capsulitis or otitis media
If NO:
1. Dull or episodic aches:
2. Constant ache:
- Teeth or jaws:
− Atypical facial pain
− Myalgia of muscles of mastication
- TMJ: Temporomandibular myalgia
3. Acute episodic ache:
- Short term (seconds): Trigeminal neuralgia
- Long term (minutes): Cluster headaches
NB: Manage pain and re-evaluate in 1 wk to eliminate an organic source eg cracked tooth
4. Chronic episodic ache:
- Teeth or jaws:
− Atypical facial pain
− Myalgia of muscles of mastication
− Cardiogenic (one of the signs of hypertension)
− Vasogenic (migraine)
- TMJ: Myalgia
Facial paralysis
UMN lesion: Lesion of the neural pathway above the anterior horn cell of spinal cord, or motor nuclei of the cranial nerves
LMN lesion: Affects nerve fibers traveling from anterior horn of spinal cord or cranial motor nuclei to the relevant muscles
1. Bell’s palsy: Picture
- LMN paralysis of the face – due to inflammation in the stylomastoid canal
- Reversible in 80% of cases
- Management: Corticosteroid therapy
2. Ramsay Hunt syndrome:
- Severe facial palsy – due to herpes zoster infection of the geniculate ganglion of the facial nerve
- In hereditary craniofacial malformation
3. Tardive dyskinesia: Picture
- Complication of longterm treatment with phenothiazines or butyrophenones
- Clinical: Involuntary facial movements
4. Horner’s syndrome: Picture
- A series of signs and symptoms – secondary to trauma to the cervical sympathetic trunk
- Clinical: Miosis (papillary constriction), ptosis (drooping eyelids), facial anhidrosis (loss of sweating) and occasionally enophthalmos
5. Adie’s pupil: Unilateral dilatation + very slow light reflex – due to syphilis. Picture
6. Argyll-Robertson pupil: Picture
- Failure of light reflex, but dilation for accommodation.
- Also seen in neurosyphillis + other conditions affecting the Edinger Westphal nucleus eg diabetes mellitus, sarcoidosis, encephalopathies, midbrain tumors, trauma and amyloidosis
DentMistry 