Neuralgia

Question 1

Trigeminal neuralgia symptoms

Answer 1

Sudden
Severe
recurrent episodes
Sharp shooting pain or electric shock pain
At the distribution of one or more branches of trigeminal nerve innervation unilaterally
Triggered by touch/wind/etc
Relieves well with Tegretol

Question 2

Atypical trigeminal neuralgia

Answer 2

Constant aching component in addition to the sudden episode of sharp shooting pain or electric shock pain. Which may have variations in triggering factor
And responds less with Tegretol

Question 3

Triggering factor of TN

Answer 3

Touch
Mastication
Involutnary movement (Tic douloureux)
Wind

Question 4

Diagnosis

Answer 4

Patients description of pain that is very classical
Reinforced by MRI brain - TRO other brain diseases (vasc malformation, Multiple sclerosis, brain tumors)
May see vessel (superior cerebellar artery) pressing on trigeminal nerve at brainstem

No blood investigation is diagnostic but useful blood baseline prior to starting Tegretol - CBC, LFT, RP (pancytopenia/deranged liver function/ increased urea)

Question 5

Conservative or medical mx of TN

Answer 5

Tegretol
Pregabalin (lyrica)
Gabapentin
Phenytoin (Dilantin)

Question 6

Dosing of Tegretol

Answer 6

Start with 100mg bd
Up by 100mg bd daily
Max dose daily 1200mg

Example:
Day 1. 100mg bd
Day 2. 200mg bd
Day 3. 300mg bd
Day 4. 400mg bd
Day 5. 500mg bd
Day 6. 600mg bd (max dose already)
Maintain dose once achieve the effective dose
After 3 months, attempt to taper down the dose to its most minimum effective level.
Eventually to discontinue the meds

Question 7

Side effects of Tegretol

Answer 7

Dizziness
Drowsiness
Nausea and vomiting
Pancytopenia dt bone marrow depression
Deranged liver function

Question 8

Surgical tx

Answer 8

1. Peripheranl nerve block and ablation
2. Microvascular decompression - success rate >90% for first typical type; but 50% in the second atypical type
3. Gamma knife radiofrequency surgery

Question 9

Indications of microvascular deconpression

Answer 9

Young patient fit for surgery
Typical type of TN pain.
MRI evidence of vascular compression

Question 10

Indications of percutaneous rhizotomy and Gamma knife radiofrequency

Answer 10

Elderly patients
Poor medical conditions
Multiple sclerosis (bilateral TN)
Failed MVD
Limited life expectancy