Trigeminal Neuralgia

Question 1

What is trigeminal neuralgia?

Answer 1

A sudden, unilateral, severe, brief stabbing, recurrent pain in the distribution of one or more branches of the 5th CN

Question 2

What is the incidence of trigeminal neuralgia?

Answer 2

3-5/ 10,000
Women> men
Often are 50+

Question 3

What are 3 types of trigeminal neuralgia?

Answer 3

Idiopathic
Classical
Secondary

Question 4

What is the presentation of trigeminal neuralgia?

Answer 4

Unilateral
Sharp shooting pain
Paroxysms
Describe: knife, electric shock

Question 5

When in the day is it more common to see trigeminal neuralgia?

Answer 5

Day > night

Increased activity

Question 6

What is the pathophysiology of trigeminal neuralgia?

Answer 6

Local demyelination of trigeminal nerve

Nerve loses myelin allows jumping of electrical signals

Question 7

What structure is between pons (brain) and trigeminal ganglion?

Answer 7

Dorsal root

Question 8

What artery overlies the nerve and what significance is this?

Answer 8

Inferior cerebellum artery

Question 9

Causes of classical, secondary and idiopathic tN?

Answer 9

Classical - blood vessel
Secondary - underlying pathology
Idiopathic - unknown

Question 10

What are secondary causes of TN?

Answer 10

Multiple sclerosis
Tumour cerebellar-pontine angle
Peripheral neuropathy
Skull base deformity

Question 11

What would you see on MRI of pt w/ MS and TN?

Answer 11

White plaques of demyelination

Question 12

How many pt w/ MS get TN?

Answer 12

6%

Question 13

Example of peripheral neuropathy that can cause TN?

Answer 13

Charcot-Marie Tooth

Question 14

Example of skull base deformity that can cause TN?

Answer 14

Pagets

Question 15

What is management of TN?

Answer 15

Drugs - first choice (if don’t control then surgical)

Surgical

Question 16

Example of surgical options of tx of TN?

Answer 16

Microvascular decompression
Ganglion procedures
Stereotactic radiosrugery
Cryoanalgesia

Question 17

What types of medications can be used for TN?

Answer 17

Sodium channel blockers
Gabapentin/ pregabalin
Phenytoin
Valporate

Question 18

Example of Na channel blocker?

Answer 18

Carbamazepine
Oxcarbazepine
Lamotrigine

Question 19

What is tx of choice for TN?

Answer 19

Na channel blocker and anticonvulsant

Slow release preparation 2x day

Question 20

Can dentist prescribe carbamazepine?

Answer 20

Technically yes

Not easy drug to prescribe - complex drug as induced liver enzyme altering metabolism of other drugs

Question 21

What liver enzyme does carbamazepine induce?

Answer 21

P450

Metabolises other drugs esp warfarin, OCP, Ca channel blockers

Question 22

What dosage would carbamazepine be given in?

Answer 22

2x daily

Increase dose gradually

Question 23

Side effect of carbamazepine?

Answer 23

Rash
Ataxia
Sommonlence
Dyscrasia (Rare) - affect blood marrow formation and reduce WBC/ platelet

Question 24

When can microvascular decompression be used?

Answer 24

Pt w/ classic TN - can see artery pressing on nerve

Question 25

What is microvascular decompression?

Answer 25

Major neurosurgical procedure (1 week in hospital) to move blood vessel away from nerve

Question 26

Problems w/ microvascular decompression?

Answer 26

Significant risk - CSF leak, infection (meningitis), damage to nerves (CN defect), deafness, stroke risk

Question 27

Adv of microvascular decompression?

Answer 27

>80% complete pain relief - often life long

Question 28

What pt would be suitable for microvascular decompression?

Answer 28

Young fit pt | Wouldn't do on elderly

Question 29

What is involved in ganglion procedures?

Answer 29

GA | Inject into ganglion - damaged nerve fibres (C/A delta fibres = pain)

Question 30

Advantage of ganglion procedures?

Answer 30

Less invasive - better for elderly pt

Question 31

Disadvantage of ganglion procedures?

Answer 31

Sensory deficit - doesn't damage just small pain fibres Not permanent - 2-3yrs

Question 32

How is ganglion procedure undertaken?

Answer 32

Needle inserted through frogmen ovale into ganglion | Glycerol injection/ compression balloon/ thermocoagulation

Question 33

What is cryoanalgesia?

Answer 33

Freezing of peripheral nerve

Question 34

Problems w/ cryoanalgesia?

Answer 34

Recovery and recurrence of pain Fibrosis - only do 1-2x per pt Sensory deficit

Question 35

When can cryoanalgesia be useful?

Answer 35

If pt has trigger e.g on lower lip (can freeze mental nerve)

Question 36

What is stereotactic radiosrugery?

Answer 36

High dose of gamma radiation | One off tx

Question 37

How many grays does trigeminal nerve receive during stereotactic surgery?

Answer 37

80 grays

Question 38

In an audit what problems where associated w/ stereotactic radiosurgery?

Answer 38

Delay in pain relief Failure of tx - 20-30% pt get some paraesthesia Recurrence of pain