Oral Dysaesthesia & facial pain Flashcards
Define dysaesthesia
descriptive term describing abnormal and/or unpleasant sensation (when touched) due to damage to peripheral nerves
Further description: dermatome affected and characteristics
Pathophysiology in general terms: due to abnormality in neuronal function - either peripherally (more common) or centrally
more specifically - pathophysiology varies according to the cause i.e. different mechanisms may elicit similar symptoms
What is atypical facial pain vs dysaesthesia?
dysaesthesia is a descriptive term that covers a range of patient symptoms, has a myriad of aetiologies therefore tx depends on the cause and outcome is also dependent on aetiology
whereas atypical facial pain is a clinical entity, aetiology is hypothetical at present, treatment is difficult and outcome speculative
Define neurogenic, neuropathic, neurological
neurogenic = arising from nerves
neuropathic = pathology associated with nerves
neurolgical = associated with nerves
Most frequent causes of iatrogenic neuropathies
- 3rd molar surgeroes
- IAN blocks
- implant placement/surgery
How to prevent IAN injury during 3rd molar surgery?
- Pre-operative assessment: IOPA, OPG, CBCT, CT (risk stratification)
- Operative technique
What may darkening of the root of lower 3rd molar indicate? What is a limitation? What might you do to further investigate?
superimposition of root and IAN canal. 2D image of a 3D entity
→ CBCT
Do pre-op CBCTs lower the incidence of post-op neurosensory disturbances?
No, doesnt change the fact that the exo will be required (for other reasons) but allows risk stratification
What happens when a nerve is damaged? What does degree of injury tell us and why is it helpful?
depends on:
- type of injury
- neural anatomy
- degree of injury (extent to which normal physiology and anatomy are disrupted) - can be indicative of the extent to which can return to normal AND guide management (primarily determination of conservative vs surgical)
In LA-associated Neurosensory disturbances (NSDs) which type of injection technique is most commonly associated?
IAN block (>90%)
Which % anaesthetic solution is most commonly associated with NSDs?
4% solutions
(articaine - should never use for IAN blocks)
How can patients have functional difficulties with IAN dysaesthesia (i.e. eating, drinking, speaking)
although IAN block stop sensory supply, it can cause functional difficulties due to altered sensation (possibly due to no proprioceptive feedback)
What sensory issues might a patient with IAN dysaesthesia experience? (6)
- paraesthesia/anaesthesia
- allodynia (extreme sensitivity/pain)
- pain
- burning
- tingling
- formication
What are some neurosensory testing methods used to assess dysaesthesia? (5)
- light touch
- sharp-blunt discrimination
- 2-point discrimination
- subjective function
- area affected
How may a nerve be damaged if no direct trauma occured on it?
- displacing the nerve can cause damage due to stretching (from inside out) - nerve stretches → axons and myelin sheath damaged → nerve integrity damaged
- surrounding edema compresses nerve (outside in)
Common non-iatrogenic causes of dysaesthesia?
- diabetes
- excess alcohol
- nutritional deficiencies
- drugs
- MS
- Others - patient who had SCC taken out and comes to you with a numb lip - they have distal spread of malignancy until proven otherwise
What are the different degrees of nerve injury according to the Sunderland/Seddon classifications
1st degree - neuropraxia (focal segmental de-myelination: nerve intact but signalling ability damaged - transient weakness/paraesthesia0
2nd-4th degree - axonotmesis (axon and myelin sheath damage but surrounding CT still intact)
5th degree - neurotmesis (axon and myelin sheath damaged, completely severed/cut)
Wallerian degen occurs D to site of injury in 2-5
(bracket stuff is kinda extra maybe idk if he said in lec)
Who do the majority of patients with neuropathies consult and why is it a problem?
dentists (our job -to exlude the dental causes)
2 types of responses to nerve injury?
Wallerian degeneration - if a nerve is split - axons in distal part undergo degeneration
Inside-out progession - ?
What is atypical facial pain? How may it occur?
persistent idiopathic facial pain
Occurs daily more than 2hrs a day over 3 months in absence of clinical neurological deficit (when it appears normal during a neurologic exam - examines sensation, range of movement, power)
Possibly relatively minor trauma or minor operation
2 broad types of facial pains?
“Headaches” - tension headaches, myofascial pain/headasches
Neuralgias/neuropathies - TN, post-herpetic neuralgia, atypical facial pain (AFP/PIFP), chronic pain syndromes (e.g. Complex regional pain syndrome)
Most frequent features of pt with AFP/PIFP?
- female 76% (but not related to menstrual cycle)
- 40s
- not hormonally related
- sleep undisturbed (usually w myo-fascial pain - will have pain that wakes them or when they wake)
What to do before diagnosing AFP or pain in general?
- know that it is very uncommon/rare
- first exclude dental causes, then consider other causes
- if links to other facial pain conditions (myofascial pain, headaches - what type?, referred pain, TN → these are better managed) (??)
