Radiofrequency thermocoagulation of trigeminal meniscus

In 1932, Kirschner first proposed the use of 350 mA current electrocoagulation to destroy the semilunar nerve cells for the treatment of trigeminal neuralgia, but because of the degree of damage is not easy to control, can produce many complications, such as corneal ulcer, blindness, eye movement disorders, subarachnoid hemorrhage, Carotid embolism and injury, even coma, death, etc., so basically stopped after 1944. By 1974, Sweet and Wepsie switched to radiofrequency current and temperature-controlled quantitative destruction of the trigeminal semilunar or post-root pain fibers to treat trigeminal neuralgia. 90% of patients immediately relieve pain and get a cure. They have been widely used in Europe and America. Become the main means of treating trigeminal neuralgia. Applied in China in the early 1980s, it is also widely used in the treatment of diseases such as trigeminal neuralgia and facial muscle twitching. According to the type of nerve fibers and the study of sensory physiology, myelinated A fibers that transmit painful impulses, about 5-8 m in diameter, and unmyelinated Class C fibers. These two types of fibers are more sensitive to RF currents and heat than tactile fibers, so in the case of RF thermocoagulation, the pain fibers are selectively destroyed while the tactile fibers are relatively retained, both to relieve pain and to retain some or all of the tactile sensations. At present, this method is more common. Treating diseases: trigeminal neuralgia Indication Radiofrequency thermocoagulation can be performed in patients with primary trigeminal neuralgia who have been treated for long-term medical treatment. In young patients, after microdecompression of the trigeminal nerve root, there are still painful authors, and radiofrequency thermocoagulation can also be used. Contraindications The semilunar sensory fiber and the trigeminal nerve root resection have been performed, and there are still pains after the operation. Preoperative preparation Patients and their families should be explained to understand the effects of surgery and possible adverse reactions in order to be understood and cooperated. For patients with nervousness, anxiety and anxiety, a neuroleptic sedative such as Innovar (containing fentanyl 0.05 mg/ml and droperidol 2.5 mg/ml mixture) 2 ml can be injected intravenously. Surgical procedure It is usually performed in the radiology department to correct the puncture direction with an X-ray machine if necessary. Take the supine position, under local anesthesia, and also apply ultra-short-time anesthetics such as metholhexital (brand name brevital) when conditions permit, let the patient sleep in a short time during electrocoagulation After the heat setting, the patient feels awake during the test to reduce fear. 1. Draw 3 marker points on the patient's face 1 3 cm in front of the external auditory canal; 2 2 cm below the inside of the pupil; 3 at 2.5 cm outside the mouth. The first and second marker points point to the position of the foramen ovale, and the third marker point points to the percutaneous needle insertion point. 2.X-ray positioning The foramen ovale should be located 15mm before the intersection of the slope and the rock bone. The half moon section is mostly at the intersection of the slope and the rock bone, sometimes slightly higher. On the positive phase, the half moon section is located 7 to 8 mm outside the inner mouth of the inner ear between the upper and lower walls of the inner auditory canal, and is 18 mm away from the midline. Generally, in the lateral phase, the electrocoagulation reaches the intersection of the slope and the rock bone, which is exactly the fiber of the 2, 3 branches of the posterior root of the trigeminal nerve. Or in the lateral position, the trigeminal nerve root is located in the range of 5 to 15 mm at the intersection of the saddle bottom and the slope (0 point), the electrode tip is 10 mm from the 0 point, and the third branch is 5 mm from the slope line. In 1982, Schvarcz considered the needle tip. The apex of the posterior bed should not be <20mm, so as not to damage the motor nerve of the eye. 3. Half moon puncture Use a 19 to 20 needle. The electrode exposure length is limited to 3 to 5 mm for one branch, and when the pain is 2 branches, it is exposed for 7 to 8 mm. When the needle passes through the soft tissue of the cheek, the operator can place the finger in the patient's mouth to avoid piercing the oral cavity, and at the same time, the finger can be touched to the lateral protrusion of the patient's sphenoid wing to determine the puncture direction. Generally, the needle can reach the foramen ovale at 6.5-7.5 cm, and a small amount of local anesthetic is injected outside the foramen ovale to reduce pain. When entering the foramen ovale, there is often a feeling of wearing a fascia or tendon, and when piercing the intrinsic membrane, there is a small breakthrough. The patient felt painful distraction along the jaw. After entering the foramen ovale, push 1~1.5cm to reach the posterior root of the trigeminal nerve. When entering the needle in the foramen ovale, avoid entering from the lateral 1/3 to avoid deep penetration into the temporal lobe; also do not face the saddle to avoid damage to the motor of the eye. If the position is accurate, the cerebrospinal fluid often flows out after the core is pulled out. 4. Electrical stimulation positioning After the puncture is successful, the microelectrode is inserted and the square wave current of 100 to 300 mA and 50 to 70 cycles/s is turned on. In the stimulation zone, the patient can have an ant walking and itching sensation at this time to further determine the exact position of the electrode. 5. Thermocoagulation After the electrical stimulation is accurately positioned, the temperature is first controlled between 42.5 and 44 °C by using radio frequency, and the nerve is stimulated to produce a trigeminal neuralgia, indicating that the electrode position is accurate. At the beginning of thermocoagulation, the temperature is controlled at 45-50 °C, each time 10~20s, the damaged lesions are initially formed, and the skin branching area of the patient's face may appear blushing, indicating that the current affects the internal sympathetic nerve of the cavernous sinus and the shallow rock Nerve and the like cause vasodilation. Then increase 5 °C each time, extend 30 ~ 60s, until the patient's facial pain disappears, the general temperature is 60 ~ 70 ° C, repeated destruction 5 ~ 7 times. The observation should be continued for 15 minutes before the end, and it is determined that the formation of a fixed lesion can be terminated. The patient's facial pain, tactile and chewing muscle strength changes were recorded in detail. Take care to protect your eyes. Then watch for 12 ~ 24h. complication 1. The face appears numb and abnormal. 2. Eye damage, such as nerve paralytic keratitis, ophthalmoplegia and so on. 3. Exercise damage, can produce mandibular deflection and chewing weakness. 4. Herpes zoster, more common in the damaged branch distribution area, can be cured in about 1 week. 5. Internal carotid artery injury. Once the artery is inserted, stop the operation immediately, pull the needle and use your fingers to press the back of the patient's pharynx.