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

Interventional Procedures for Trigeminal Neuralgia

Dr. Edmond ChungPain Team

QEH

Contents

• Methods• Theory• Indications• Limitations• Contraindications• Anatomy• Set up• Equipments

Contents (cont’d)

• Technique• Side Effects & Complications• Efficacy• What if the pain recurs ?• Peripheral nerve blocks

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

Indications

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

Contraindications

• Space-occupying lesions or microvascular compression in brain, esp brainstem (Check CT or MRI first!)

• Coagulopathy• Infection• Uncooperative patient• Patient refusal

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

Limitations

• Pts who want to avoid numbness of face as result of RF

• Pain in V1 dermatome

Equipments

• RF generator• RF cannulae• RF probes• RF ground electrode• X-ray Image Intensifier (C-arm)

Set Up

Technique - landmark

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 & 15-20 deg

sideways

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

Technique (cont’d)

• Sensory Stimulation – Freq : 100 Hz– Voltage : 0.1-0.5V

• 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.

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

Results

• Long term (years) success rates vary from 80 – 90%

Complications

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

Morbidity & Mortality

• Low morbidity• Can be performed on an out-patient basis• Mortality has not been reported

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

Maxillary or Mandibular Nerve Blocks

Peripheral Nerve blocks

• Supraorbital nerve block• Infraorbital nerve block• Mental nerve block

Thank You