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Gasserian Ganglion RF Neurotomy procedure for Trigeminal Neuralgia
Gasserian ganglion radiofrequency ablation is a long-term solution for the management of pain due to trigeminal neuralgia. The procedure is usually done under local anaesthesia.
When Gasserian Ganglion Radiofrequency Ablation is performed?
Gasserian Ganglion Radiofrequency Ablation/Neurotomy is a procedure regularly used in patients with trigeminal neuralgia. The procedure involves complex needle manoeuvring to perform selective radiofrequency heat treatment of the affected divisions.
Trigeminal neuralgia is a chronic pain condition that affects the trigeminal nerve, which is responsible for sensation in the face. The pain is often described as sharp, stabbing, or electric shock-like, and can be triggered by everyday activities such as eating, talking, or brushing teeth.
The procedure is typically recommended when conservative treatments such as medications or injections have failed to provide relief 3. It is also used in patients who are unable to tolerate the side effects of medications or who have comorbidities that make them unsuitable for other treatments. The procedure involves the use of a needle to deliver radiofrequency energy to the Gasserian ganglion, which is a collection of nerve cells located in the skull near the base of the brain. The energy heats up the ganglion, which disrupts the pain signals being sent to the brain.
How the Procedure is performed?
It is performed in OT under sterile condition. Patient is usually kept in lying down porition, then under fluroscopic guidance a specialised needle (RF Cannula) is inserted just by the side of the angle of mouth under local anesthesia or under sedation. On reaching desired position motor and sensory stimulation is done to confirm the needle position. Conventional radiofrequency lesioning with at 65 to 75 degree celcius us usually done for 60 seconds 2-3 cycles.
in case of glycerol rhizolysis needle positioning is the same, but 22 g spinal needle is used in pace of RF needle and 0.5 ml of glycerol is injected.
What are the common complications of Gasserian Ganglion Block?
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Haematoma in Cheek
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Pain at the site of injection.
How Gasserian Ganglion RF Ablation is done for the Trigeminal Neuralgia?
Gasserian Ganglion RF Ablation is performed by inserting a thin needle through the cheek and into the foramen ovale, a small opening in the base of the skull. The needle is guided by X-ray or computerized tomography (CT) imaging to reach the gasserian ganglion, which is a cluster of nerve cells where the trigeminal nerve splits into three branches: the ophthalmic, maxillary, and mandibular nerves. The needle is connected to a radiofrequency generator, which delivers an electric current to the tip of the needle. The current heats up the nerve tissue and creates a lesion, or a small area of damage, in the gasserian ganglion. The lesion blocks the pain signals from reaching the brain, thus reducing or eliminating the pain.
FAQ on Gasserian Ganglion RF
How long it takes to complete the procedure ?
The Procedure takes about 30 minutes to 45 minutes.
Is Gasserian ganglion radio-frequency ablation painful?
Gasserian ganglion ganglion block or radio-frequency ablation is usually done under local ananesthesia, there may be mild pain during the sensory stimulation but in general it is not painful.
When the patient can expect pain relief ?
In some patients there may be immediate pain relief but in most of the patients it takes 3 to 4 weeks for pain relief so drugs needs to be continued for about a month following the procedure. After that the drug may be reduced gradually depending on the patients response.
Understanding the Anatomy Around Gasserian Ganglion
To perform Gasserian Ganglion Radiofrequency Ablation, a thorough understanding of the anatomy surrounding the ganglion is crucial. The Gasserian Ganglion is located within the cranium, specifically in an area known as Meckel's cave at the posteromedial part of the middle cranial fossa, near the apex of the petrous part of the temporal bone.
The relationships of the Gasserian Ganglion include the cavernous sinus, internal carotid artery, trochlear and optic nerves positioned medially to the ganglia. Superiorly, it is adjacent to the temporal lobe of the brain. Posteriorly, it is associated with the brainstem, and anteriorly, it divides into its three branches: Ophthalmic (V1), Maxillary (V2), and Mandibular (V3) branches.
These three branches exit the cranium through three specific foramen: Superior orbital fissure, Foramen Rotundum, and Foramen Ovale, respectively. For Gasserian Ganglion Radiofrequency Ablation, the radiofrequency needle should enter from below through the Foramen Ovale.
Structures passing through the Foramen Ovale include the Mandibular nerve, Lesser petrosal nerve (a branch of the glossopharyngeal nerve), Accessory meningeal artery, and Emissary vein (connecting the cavernous sinus with the pterygoid plexus of veins).
Important Radiological Landmarks For Gasserian Ganglion RF
FORAMEN OVALE
For successfully performing trigeminal ganglion block the most important radiological landmark is foramen oval. Foramen ovale can be seen from the submental view. To see the foramen ovale c arm should be tilted caudally and in an ipsilateral oblique direction. It is seen between the maxilla & and mandible.
ANGLE OF CLIVUS WITH THE PETROUS TEMPORAL
The angle of clivus with the shadow of the petrous part of the temporal bone in a true lateral view of the skull This angle is the direction at which the RF canula needs to be inserted, The tip of the needle should not cross this junction.
GASSERIAN GANGLION RF PROCEDURE
Indications
The indications for Gasserian ganglion RF are Trigeminal neuralgia and Secondary neuralgia due to cancer or multiple sclerosis, when Conservative Therapy does not have adequate response or the patient is unable to tolerate medications.
Contraindications
Contraindications are local infection, sepsis, coagulopathy, increased intracranial pressure, and major psychopathology.
Equipment Required
Equipment that is required for the procedure is a 25-gauge needle (for skin infiltration), a 5-ml syringe (for local anaesthetic solution),RF generator and cables, a 16-gauge intravenous catheter (for introducing the RF needle) RF needles, 10 cm in length 2-mm or 5-mm RF active tip
Preparation
Informed consent should be taken. Prophylactic Antibiotic injected 1/2 hour before the procedure after proper skin test. The patient is asked to fast for sedation during the procedure.
Patient Positioning
The procedure is done in a supine position, with a pillow below the shoulder, so that the neck is extended.
Technique
After positioning the patient's ipsilateral portion of the face to be painted with an antiseptic solution carefully, as pain may be triggered by painting. The area is draped with a surgical drape.
C-arm positioning should start from the AP view then the fluoroscope position will be changed to the cranio-caudal direction to get the submental view. The Fluoroscope is to be rotated in an ipsilateral direction so that the foramen ovale can be seen in between the maxilla and mandible.
The Surface point that corresponds to the foramen ovale should be determined by putting an opaque pointer. The point of entry usually lies 2-3 cm lateral to the angle of the mouth. Local anaesthesia (1% lignocaine) was injected at the entry point.
After the area is anaesthetized a 16-gauge intravenous catheter is first inserted followed by the RF cannula 10 cm in length 2-mm or 5-mm RF active tip by needle through needle technique. While introducing the needle, care should be taken so that it does not passes through the oral cavity.
The needle is progressed towards the foramen ovale under tunnel view. Intermittent checking under lateral fluoroscopic view is to be done to make sure that the needle direction is towards the junction of the clivus and the coincided shadow of the petrous part of temporal bone of the left and right side in true lateral view of the skull. The needle tip is not visible at the lateral view unless the tip has crossed the junction. It should be remembered the tip should not cross more than 2mm above the junction. and in most cases, the desired sensory and motor stimulation is usually found before that. Once close to the ganglion sensory and motor stimulation are checked. Sensory stimulation is usually done at 0.5V and 50Hz, but in some patients, we can get stimulation at a lower voltage. The area of paresthesia should match with the area of pain for the best results. Motor stimulation is usually done at 2Hz and the voltage is double that of motor stimulation to up to 2 volts. Ophthalmic and maxillary do not have motor parts so on motor stimulation we will get the contraction of masseter muscle.
After stimulation, careful aspiration is done to avoid position in blood vessels.
Once the needle position is confirmed by stimulation 0.2 - 0,5ml of local anaesthetic is injected, alternatively sedation can be given, to make the lesioning time pain-free.
Usually, three conventional RF lesions are done successively at 65, 70 and 75 degrees centigrade and for 60-90 seconds.
The case should be taken for ophthalmic division, to not to a lesion at high temperature, which may lead to corneal anaesthesia leading to exposure keratitis. The needle is taken out post-lesioning. The patient is shifted to the post-procedure care unit. And monitored for vitals, corneal reflex is checked and ice is applied in the cheek to avoid hematoma formation.
Complications
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Hematoma in Cheek - Common after percutaneous procedures at gasserian ganglion.
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Loss of corneal reflex - May occur following gasserian ganglion neurolysis. Among the percutaneous procedures, the chance of loss of corneal reflex is highest with RF procedure at 7%, followed by Glycerol Rhizolysis at 3.7%, and at least with balloon Compression at 1.5%.
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Motor Deficit - Motor deficit is found to be highest following balloon compression at 66%, followed by RF rhizotomy at 24%, and least with glycerol injection - 1.7%
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Carotid Artery Puncture. Retrobulbar Hematoma and Meningitis are rare but serious complications