1. Interventional Procedures for Trigeminal Neuralgia
Dr. Edmond Chung
Pain Team
QEH

2. Contents Methods Theory Indications Limitations Contraindications
Anatomy
Set up
Equipments

3. Contents (cont’d) Technique Side Effects & Complications Efficacy
What if the pain recurs ?
Peripheral nerve blocks

4. Methods Chemical – Glycerol
Radiofrequency thermocoagulation of Trigeminal Ganglion
Maxillary & Mandibular nerve blocks
Peripheral nerve blocks of the branches of Trigeminal nerve – supraorbital, infraorbital, mental nerve blocks

7. Indications
Trigeminal Neuralgia refractory to non-invasive means of Rx – V1, V2 or V3 dermatomes

9. Contraindications
Space-occupying lesions or microvascular compression in brain, esp brainstem (Check CT or MRI first!)
Coagulopathy
Infection
Uncooperative patient
Patient refusal

10. Anatomy Middle cranial fossa Dorsal & cranial to foramen ovale
Medial to the gasserian ganglion is the carotid artery & cavernous sinus
V1 (ophthalmic part) – most medial & greatest distance to the foramen ovale
V2 (maxillary part) – central
V3 (mandibular part) – most lateral & superficial

18. Limitations Pts who want to avoid numbness of face as result of RF
Pain in V1 dermatome

19. Equipments RF generator RF cannulae RF probes RF ground electrode
X-ray Image Intensifier (C-arm)

22. Set Up

25. Technique - landmark

39. Technique Pt on horizontal recumbent position
Head fixed on a radiolucent head rest by adhesive bandage
Under MAC (using TCI / TIVA technique)
Fluoroscopic guidance
Essential to obtain an optimal picture of foramen ovale
C-arm 45 deg caudal / cranial & deg sideways

40. Technique (cont’d)
22G 10cm RF needle with a 2mm free tip inserted along the direction of radiation beam (tunnel-vision technique)
N.B. beware piercing of oral mucosa
Needle advanced towards foramen ovale
Once needle enters the foramen, a clear “give” perceived
Check with lateral view on the depth of penetration – intersection of clivus & os petrosum

41. Technique (cont’d) Sensory Stimulation
Freq : 100 Hz
Voltage : V
The aim : to elicit paresthesia or pain in the division of trigeminal nerve, which you wish to lesion
Motor Stimulation
Freq : 2 Hz
Voltage : less than 1V
If you see contractions of masseter muscle, advance the needle deeper into the foramen ovale.

42. Technique (cont’d)
Lesion mode (additional bolus of IV propofol first) :
Lesion at 60 deg C for 60 sec
Allow to wake up after 1st lesion  retest with pin prick or sensory stimulation
Adjust position of needle or advance further accordingly
Re-institute GA
Repeat lesioning in 5 deg C increments for 60 sec each
At each stage, allow pt to wake up & retest with pin prick or sensory stimulation
Check corneal reflex

43. Results
Long term (years) success rates vary from 80 – 90%

44. Complications Corneal anesthesia / hyperesthesia – 13.7%
Dysesthesia in the treated area 5-7%
Masseter weakness 1-2%

45. Morbidity & Mortality Low morbidity
Can be performed on an out-patient basis
Mortality has not been reported

46. What if the pain recurs ? For repeated RF
To review with CT or MRI brain at intervals to exclude SOL
Refer to Neurosurgery for consideration of Gamma Knife or Radiosurgery

47. Maxillary or Mandibular Nerve Blocks

52. Peripheral Nerve blocks
Supraorbital nerve block
Infraorbital nerve block
Mental nerve block

56. Thank You