Trigeminal Neuralgia (TN)

It is characterised by lancination shock like paroxysmal episodes of severe pain that are usually unilateral and occur within the distribution of one or more branches of the trigeminal nerve.  The attacks are brief lasting a few seconds to a minute, and may occurs in clusters without sensory loss involved with the attacks.

It is a chronic pain condition that causes extreme, sporadic, sudden burning or shock-like face pain.  The pain seldom lasts more than a few seconds or a minute or two per episode. The intensity of pain can be physically and mentally incapacitating. TN pain is typically felt on one side of the jaw or cheek. Episodes can last for days, weeks, or months at a time and then disappear for months or years  The attacks often worsen over time, with fewer and shorter pain-free periods before they recur.

The intense flashes of pain can be triggered by vibration or contact with the cheek (such as when shaving, washing the face, or applying makeup), brushing teeth, eating, drinking, talking, or being exposed to the wind.  Trigeminal Neuralgia occurs most often in people over age 50, but it can occur at any age, and is more common in women than in men.  The presumed cause of Trigeminal Neuralgia is a blood vessel pressing on the trigeminal nerve in the brain as it exits the brainstem. Trigeminal Neuralgia may be part of the normal aging process but in some cases it is the associated with another disorder, such as multiple sclerosis or other disorders characterized by damage to the myelin sheath that covers certain nerves.

Trigeminal neuralgia treatment usually starts with medications, and many people require no additional treatment. However, over time, some people with the condition may stop responding to medications, or they may experience unpleasant side effects. For those people, injections Radiofrequency thermal lesioning or Microvascular decompression surgery provide other trigeminal neuralgia treatment options.

• Medications :

To treat trigeminal neuralgia, the doctor usually prescribe medications to lessen or block the pain signals sent to the brain.
Anticonvulsants. Doctors usually prescribe carbamazepine (Tegretol, Carbatrol, others) for trigeminal neuralgia, and it’s been shown to be effective in treating the condition. Other anticonvulsant drugs that may be used to treat trigeminal neuralgia include oxcarbazepine (Trileptal). Other drugs, including clonazepam (Klonopin) and gabapentin (Neurontin, Gralise, others), also may be used.  Antispasmodic agents. Muscle-relaxing agents such as baclofen (Gablofen, Lioresal) may be used alone or in combination with carbamazepine.

• Radiofrequency Thermal lesioning of the Trigeminal Ganglia :

This procedure is the most common percutaneous procedure used to treat TN, especially in elderly patients. The procedure selectively destroys nerve fibers associated with pain. The surgeon inserts a hollow needle through the face and guides it to a part of the trigeminal nerve that goes through an opening at the base of the skull.  Once the needle is positioned, the surgeon inserts an electrode through the needle and sends a mild electrical current through the tip of the electrode. The patient will asked to indicate when and where he feel tingling. Then the electrode is heated until it damages the nerve fibers, creating an area of injury (lesion). If the pain isn’t eliminated, the doctor may create additional lesions.

Technique of RadioFrequency Ablation of the Trigeminal Nerve:

The Patients are fasted for at least 6 h before the procedure. Prophylactic antibiotic is administered 1 h before the procedure. Intravenous access is obtained, and standard monitors including electrocardiogram, blood pressure monitoring, and pulse oximetry are applied. Sedation is usually necessary to increase patient comfort and reduce anxiety.

The procedure is performed under fluoroscopic guidance with the patient in the supine position and head extended. The C-arm is rotated to obtain an oblique submental view to visualize the foramen ovale. The skin entry point is 2 to 3 cm lateral to the commissura labialis (angle of the mouth) on the affected side. The needle trajectory follows a straight line directed toward the pupil when seen from the front and passes 3 cm anterior to the external auditory meatus when seen from the side.

A 22-gauge, 10-cm RF cannula with a 5-mm active tip is used. After administration of local anesthesia, the cannula is advanced in a coaxial manner (tunnel view) to the X-ray beam toward the foramen ovale . A finger can be placed in the oral cavity to make sure that the buccal mucosa has not been perforated. When the cannula enters the foramen ovale, the depth of the cannula inside the Meckelís cavity is ascertained on the lateral fluoroscopic view. The electrode is advanced ~2ñ4 mm further through the canal of the foramen ovale such that the tip of the electrode reaches the junction of the petrous ridge of the temporal bone and the clivus.  The stylet is then removed from the cannula, and aspiration is performed to ensure that there is no CSF or blood.

Test stimulation is mandatory before RF lesioning. The mandibular nerve lies in the lateral portion of the foramen ovale. If the nerve is stimulated at 2 Hz between 0.1 and 1.5 Hz, muscle contraction of the lower jaw may be seen. This confirms that the needle has passed through the foramen ovale and the tip is lying on the trigeminal roots. Next, paresthesia in the concordant trigeminal distribution of the patientís usual symptoms (V1, V2, or V3 divisions) at 50 Hz, 1 msec pulse duration should be reproducible at 0.1 to 0.5 V.2. If paresthesia is only obtained above 0.5 V stimulation, the needle should be redirected to get the same response at a lower voltage. After appropriate stimulation parameters have been achieved, RF lesioning at 60∞C is carried out for 60 sec. The needle can be repositioned to repeat RF lesioning if more than one branch of the trigeminal nerve is involved.

• Surgery (Microvascular Decompression)

In trigeminal neuralgia surgery, surgeons’ goals are to stop the blood vessel from compressing the trigeminal nerve or to damage the trigeminal nerve to keep it from malfunctioning. Damaging the nerve often causes temporary or permanent facial numbness, and with any of the surgical procedures.

Trigeminal Neuralglia Ablation By Radiofrequency

The patient is complaining of chronic extreme, sporadic, sudden burning or shock-like face pain. The pain seldom lasts more than a few seconds or a minute or two per episode.
The procedure is performed in an outpatient setting. The treatment is done with local anesthesia along with IV sedation when needed. The Needle is inserted through the face and guides it to a part of the trigeminal nerve that goes through an opening at the base of the skull, the entire procedure is performed using fluoroscopic (X-ray) guidance. When the needle is in the correct location, an electrode is introduced into the center of the needle. Stimulation is initiated first with sensory stimulation and then with motor stimulation. When the correct needle position is verified. The electrode is heated to 50-80°C and kept at that temperature for several minutes. The needle was removed and puncture site was sterilized and covered.