Trigeminal Neuralgia

Question 1

What is trigeminal neuralgia?

Answer 1

Facial pain syndrome in the distribution of ≥1 divisions of CN V

It is characterised by some combination of:

• paroxysms of sharp, stabbing, intense pain lasting up to 2 minutes
• and/or a constant component of facial pain
• without associated neurological deficit.

The pain can be precipitated by trigger areas/factors.

Repeat attacks are common

Question 2

What is the cause of trigeminal neuralgia?

Answer 2

• Compression (of nerve root)
  
  • superior cerebellar artery >> / posterior fossa tumour
• Demyelinating disease e.g. MS
• Other brainstem lesions e.g. infarcts, amyloid, Ca

Question 3

What are the major classes of trigeminal neuralgia (Burchiel classification)?

Answer 3

• Idiopathic trigeminal neuralgia type I (TNI)
  
  • ‘classic trigeminal neuralgia’
• Idiopathic trigeminal neuralgia type II (TNII)
  
  • ‘atypical TN’
• Trigeminal neuropathic pain (secondary to injury)
• Symptomatic TN (e.g. MS or tumour)
• Post-herpetic TN
• Atypical facial pain

Question 4

How can you differentiate between classic TN & atypical TN?

Answer 4

classic:

• sharp, shooting, electric shock-like pain.
• Pain should be episodic >50% of the time.

atypical TN

• Aching, throbbing, burning pain
• >50% of the time
• with a constant background.

Question 5

What are some risk factors for trigeminal neuralgia?

Answer 5

• old age
• MS
• female (low association)
• HTN (low association)

Question 6

Summarise the epidemiology of trigeminal neuralgia

Answer 6

• incidence: 4-13 per 100,000
• slight female predominance at all ages,
• rates appear to increase with age

Question 7

What are the presenting symptoms of trigeminal neuralgia?

Answer 7

• facial pain
  
  • trigeminal distributions
  • quality,
  • duration,
  • consistency of pain
• prior oropharyngeal or facial trauma
• prior herpetic outbreak

Question 8

What are the signs of trigeminal neuralgia O/E?

Answer 8

• pain on trigeminal nerve dermatomes
• other sensory/motor changes?

Question 9

What are the primary investigations for ?trigeminal neuralgia

Answer 9

none - diagnosis is clinical

Question 10

What are some possible secondary investigations for trigeminal neuralgia?

Answer 10

• intra-oral xray - suspected trauma
• MRI - if O/E suggests other pathology
• Trigeminal reflex testing
  
  • blink reflex
  • masseter inhibitory reflex