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