Trigeminal neuralgia is a disease with recurrent episodes of severe pain in the distribution of the trigeminal nerve, the cause of which is unknown and can also be secondary to other diseases. It is a common painful disease that seriously affects the quality of life of patients. The disease is easy to diagnose and difficult to treat.
In general, patients can be treated with oral medications, and severe patients who are not treated with medications can opt for chemical destruction of the semilunar ganglion, radiofrequency thermocoagulation destruction and microballoon compression. Among them, chemical disruption of the meningeal ganglion and radiofrequency thermocoagulation disruption are less invasive and more effective. However, due to the deep location of the foramen ovale and the large anatomical variation, the traditional blind percutaneous puncture method is difficult to accurately place, with more complications and poor treatment results, making it difficult to popularize this minimally invasive technique. How to improve the accuracy of puncture is currently a hot spot in clinical research. Other new methods include trigeminal nerve root microvascular decompression at the pontocerebellar angle, trigeminal ganglion and trigeminal root percutaneous microcompression and trigeminal nerve pool glycerol injection block.
I. Brief description of trigeminal neuralgia
1.Etiology
Etiology of trigeminal neuralgia.
(1) Central etiology: the paroxysm of trigeminal neuralgia suggests a sensory epileptiform discharge, and the discharge site may be in the nucleus of the trigeminal spinal tract or other parts of the center.
(2) Peripheral etiology.
(i) Compression of the trigeminal nerve root by an adjacent blood vessel.
(ii) Inadequate blood supply to the trigeminal nerve due to arteriosclerosis.
(3) Multiple sclerosis or spontaneous demyelinating disease.
(4) Familial trigeminal neuralgia.
(3) Vascular compression theory: the relationship between vascular compression and trigeminal neuralgia has been affirmed.
2.Clinical manifestations
Trigeminal neuralgia is a transient, recurrent paroxysmal pain in the distribution area of the facial trigeminal nerve. It occurs mostly in adults and the elderly, with an incidence rate of 1.8 per 1,000, mostly unilateral, more on the right than on the left, and less than 5% bilateral. The pain is sudden, lightning-like p brief and severe pain. Some episodes are accompanied by chewing movements, and severe cases are often accompanied by “painful convulsions”. The attack can last from a few seconds to 1-2 minutes and then stop abruptly, with intervals as normal, and a few may still have a burning sensation. In the upper and lower lip, nose, corner of the mouth and other particularly sensitive places, the slightest touch can cause painful attacks, called “trigger points”. Neurological examination is normal.
3.Treatment methods
There are several treatment methods for primary trigeminal neuralgia, which are divided into three levels and selected according to the condition.
1.Medication
2.Minimally invasive treatment
(1) Drug-destructive block of the semilunar ganglion.
(2) radiofrequency thermocoagulation of the semilunar ganglion.
(3) Micro balloon compression of the semilunar ganglion.
3.Surgical treatment.
(1) peripheral branch dissection.
(2) trigeminal nerve sensory root partial dissection
(3) trigeminal spinal tractotomy
(4) Trigeminal nerve decompression.
(2) CT-guided radiofrequency thermocoagulation of the semilunar ganglion
In recent years, the development of imaging medicine, radiofrequency technology and computer technology has provided conditions for minimally invasive treatment of trigeminal neuralgia under the guidance of imaging intervention, and radiofrequency thermal coagulation destruction has become an important method for the treatment of trigeminal neuralgia. This minimally invasive neurosurgery is mostly used when conservative treatment is ineffective, and it has become more refined and safer through the development of microelectronic technology of trigeminal nerve root stimulation and temperature-controlled coagulation, especially the emergence of intermittent pulsed radiofrequency thermocoagulation. CT-guided radiofrequency thermocoagulation for trigeminal neuralgia has been widely used, which has significantly improved the efficacy and safety.
1.Patient selection
(1) Old and frail patients with trigeminal neuralgia who are not suitable for microvascular decompression treatment.
(2) Patients who have relapsed after microvascular decompression.
(3) Patients who have been taking larger doses of carbamazepine or/and phenytoin sodium for a long time.
(4) Patients who do not wish to be treated with microvascular decompression.
(5) younger patients in good general condition who can be treated with microvascular decompression of the trigeminal nerve root
(6) Patients who have relapsed after controlled coagulation therapy: coagulation therapy may be performed again.
(7) Patients with recurrence after microvascular decompression therapy: controlled thermocoagulation can be used.
2.Pre-operative preparation
(1) CT coronal and axial scans of the foramen ovale and posterior cranial fossa to observe the cerebral pontocerebellar angle site. Diagnose primary trigeminal neuralgia except for secondary pain caused by peri-trigeminal tumor. Enhancement or MRI scan to exclude intracranial lesions if necessary.
(2) Discontinuation of carbamazepine and phenytoin sodium or dose reduction one day prior to surgery.
(3) Treatment with anxiolytics and antidepressants for those with anxiety and depressive symptoms.
(4) Medical therapy to adjust blood pressure to normal levels in patients with hypertension or/and coronary artery disease.
(5) Lowering blood glucose to normal for those with a history of diabetes.
(6) Admission to the ward, routine blood and urine tests, coagulation, electrocardiogram, blood pressure, blood glucose, liver and kidney function and neurological examination.
(7) Explain to the patient and family members the treatment method, expected results and possible complications, and sign the informed consent form.
3.Surgical operation method
(1) Puncture access: Mostly use the anterolateral access puncture method.
(2) Preoperative drug administration: Intramuscular injection of atropine 0.3 mg and valium 5 mg half an hour before surgery.
(3) Position: The patient was placed supine on the CT bed, and ECG, blood pressure and oxygen saturation were monitored continuously.
(4) Puncture point: The puncture point was selected at the outer corner of the affected side of the mouth equivalent to the maxillary 2nd molar above the lower edge of the zygomatic bone, and a body fenestrated metal marker was placed.
The CT scan was used to determine the localization line from the body surface localization point to the anterior line of the external auditory foramen, and the semi-coronal tomography scan (the rack angle was generally 20°-25°) was done in a thin layer in the range of 50px above and below the body surface marker, and the line between the oval foramen and the best body surface puncture point was used as the needle route to measure the depth and angle of the needle and mark the skin puncture point.
(5) Puncture of the foramen ovale.
Disinfect the face, spread the towel, and connect the relevant electrode for negative electrode. After local anesthesia with 1% lidocaine, puncture with a radiofrequency cannula puncture needle, feed the needle according to the puncture route and angle selected by CT scan, feed the needle in sections under CT monitoring until the puncture reaches the foramen ovale, back aspiration without cerebrospinal fluid or blood outflow, inject 10% Uvexan or Onepac lml, and scan to confirm the distribution of contrast agent in the semilunar ganglion.
(6) Electrical stimulation test.
Apply 50 Hz, 0.1-0.3 mV current stimulation test, according to the patient’s response, the depth and direction of the puncture needle can be adjusted appropriately to produce numbness and swelling or throbbing pain in the corresponding distribution area of the trigeminal nerve to confirm the accuracy of the puncture site.
(7) Continuous radiofrequency thermocoagulation.
Start the radiofrequency current to produce heat. Generally from 40 ° C gradually increase the temperature to 50 ° C when the face pain. Increasing the temperature by 10°C for one step, lasting 60 seconds. After the temperature rises to 60°C, the skin of the corresponding area of the face appears obvious redness until 80-85°C, the corresponding area appears numb and the pain disappears. The time and temperature of thermal coagulation can be adjusted according to the different pain ranges and pain levels. It is common to give 60°C thermal coagulation for 60 seconds, followed by 80°C for 60-240 seconds.
During this time the temperature of 60-80°C is maintained and will continue to act for 60 seconds. This form of thermal coagulation will be repeated several times until the electrical stimulation no longer causes neuropathic pain. Generally, the area of neuralgia shows varying degrees of numbness, but there is no complete loss of sensation.
IV antibiotics are given for 3 to 5 days postoperatively to prevent intracranial infection.
(8) Pulsed radiofrequency thermal coagulation
The pulsed radiofrequency thermal coagulation technique applied in recent years is to give the thermal coagulation temperature not more than 42°C, continuous 120 seconds of intermittent pulse frequency heat, compared with the traditional radiofrequency thermal coagulation, the degree of tissue damage is lighter, due to the lower injury temperature, the damage to the motor nerve is lighter, the possibility of complications is low. However, the long-term efficacy of the current pulsed radiofrequency thermal coagulation technique remains to be evaluated.
(9) Postoperative observation index.
Follow-up visits were generally made by telephone and letter on the day, day 7, month 6 and month 12 after the procedure, and the time of puncture treatment operation, pain VAS score, pain relief, quality of life score and complications were recorded respectively. Pain intensity was measured using visual analogue pain scoring (VAS) for pain, which was recorded by the patient’s oral physician, with a VAS value of 0 for no pain and 10 for the most severe pain. VAS values 1-3 were considered mild pain, 4-6 were considered moderate pain, and 7-10 were considered severe pain.
(10) Precautions
①Treatment of elderly patients
Due to the aging of the elderly organism, the function of the systemic organs and their stress function are poorer, coupled with the fear of radiofrequency treatment, various complications may occur in the surgical stress state. Therefore, the elderly with cardiovascular disease should be fully prepared for radiofrequency treatment to avoid or reduce the occurrence of serious complications.
②Treatment of patients with combined cardiovascular disease
For patients with combined heart disease should make a detailed understanding of the condition, for different types of disease, focus on treatment, preoperative should be more understanding of the patient’s cardiac function status, intraoperative ECG monitoring. If ventricular duplex or triplex rhythm, frequent premature ventricular contractions, multi-source premature ventricular contractions, R wave falling on T wave, and complete AV block occur, the operation should be stopped. In case of intraoperative supraventricular tachycardia, atrial fibrillation, atrial flutter, the procedure should be stopped immediately by slow sedation with Cetiran 0.2-0.4 mg diluted in 25% glucose solution. For frequent ventricular premature beats, multi-source ventricular premature beats, diphasic rhythm or R wave falling on T wave should be immediately given lidocaine 50-100mg drip, and then radiofrequency treatment should be performed after stabilization.
The severity of hypertension should be understood in hypertensive patients. RF therapy is safe when the blood pressure is controlled below 24.0/13.3kPa.
③Protection of the cornea
For those who have branch I pain, some scholars think that radiofrequency treatment is not appropriate. In fact, as long as special attention is paid to the temperature below 80°C during thermocoagulation, when the second day after the first branch of radiofrequency temperature-controlled thermocoagulation, corneal slit lamp examination is routinely made, and the presence of corneal reflection is also detected. Early detection and treatment of corneal epithelial detachment is the key to prevent the occurrence of paralytic keratitis.
④Use of electrophysiological monitoring
The key to radiofrequency thermocoagulation is whether the puncture needle can accurately reach the trigeminal meningeal ganglion, and the puncture is often performed from the anterolateral approach. The use of evoked potentials to monitor the process of radiofrequency thermocoagulation of the semilunar ganglion can precisely locate and define the area of destruction and determine the degree of destruction, improving the efficacy of radiofrequency treatment.
⑤ Close cooperation with radiologists
CT-guided hemilunar ganglion dissection is a painful interventional procedure in which radiologists play an important role, and close cooperation with radiologists should be observed to select appropriate puncture sites and routes. The traditional anterolateral approach entry point is chosen for the body surface puncture point. There are no large vessels or nerves in the area, and to facilitate observation of the needle body position during entry, the shank of the puncture needle should be parallel to the CT frame to facilitate observation of the shank during guidance. The angle and depth of the puncture were measured with a homemade locator, and CT scanning was continuously performed during the needle feeding process to adjust the needle direction and ensure the accurate route of the needle feeding. After entering the foramen ovale, the depth of needle entry is strictly controlled, and the action should be gentle not too violent and too deep.
IV. Contraindications
1, uncooperative persons, including those with mental disorders.
2.Persons with infected lesions in the skin and deep tissues of the puncture site.
3.Persons with bleeding tendency or those undergoing anticoagulation therapy
4, those who are allergic to local anesthetics
5.Persons with hypovolemia.
6.Severe cardiovascular and cerebrovascular diseases in the unstable stage.
V. Complications
1.Facial numbness
Facial sensory loss and numbness occur more commonly after radiofrequency thermocoagulation, and some patients have facial abnormal discomfort, which is a manifestation of tactile nerve fiber injury, but the patient can understand it as a treatment reaction, but must be clearly explained to the patient before surgery. Long-standing facial sensory deficits are approximately 12%. Painful sensory deficits have been reported in the recent literature at a rate of only 0.2% to 5%.
2. Sluggish corneal reflexes or paralytic corneal ulcers
It is a common complication of radiofrequency thermocoagulation, postoperative corneal sensory loss, ipsilateral corneal reflex retardation or paralytic corneal ulcer, mostly due to deep needle entry, which occurs less frequently due to accurate positioning in CT-guided radiofrequency thermocoagulation destruction.
3.Masticatory motor disorder
Masticatory weakness or restricted mouth opening is mostly related to the excessive temperature and duration of radiofrequency thermal coagulation that severely damage the motor fibers of the trigeminal nerve. Generally when the temperature is controlled below 80°C, it is less likely to occur.
4.Visual loss and diplopia
Injury to the optic nerve in the direction of the puncture is inward or deep, resulting in vision loss, and injury to the motoneurone nerve or the talocrural nerve causes diplopia.
5.Other complications
Complications such as salivation at the corners of the mouth, postoperative sensation of jumping in the affected area, and facial herpes zoster may occur. The incidence of serious complications (permanent brain function loss, numbness, significant sensory abnormalities) can sometimes be as high as 3%.
The main causes of complications are caused by inaccurate puncture, damage to adjacent tissues by the puncture needle, or damage to adjacent tissues due to improperly positioned puncture needles. These accidents are difficult to avoid when repeated blind punctures are performed. Thus, improving the accuracy of puncture is the main way to avoid complications, and puncture under the surveillance and guidance of CT can ensure the accuracy of puncture, and the location of the needle tip and the extent of thermal coagulation destruction can be judged in advance by observing the extent of contrast agent diffusion, which can reduce complications and ensure the efficacy of treatment.
Sixth, the advantages of radiofrequency thermal coagulation method
1, the procedure is less dangerous, rarely occurring serious complications.
2, available thermocouple electrodes for better monitoring of the degree of damage, the size of the damage can be effectively controlled.
3, electrical stimulation localization and electrical impedance monitoring can be performed.
4, most radiofrequency thermocoagulation procedures can be performed under local anesthesia.
5.When applied correctly, its complication rate is very low.
6.The treatment can be repeated when needed.
7.Compared with microvascular decompression surgery, the operation is relatively easy and the pain relief is good. It can eliminate the pain and preserve the tactile sensation for the most part.
VII. Efficacy of radiofrequency thermocoagulation
A group of 428 patients had 409 cases of pain completely disappeared after radiofrequency temperature-controlled thermal coagulation treatment, accounting for 95.56% of the number of patients treated, among which 5 cases had increased pain after surgery, and the pain disappeared from 2 days to 2 weeks after surgery, which was caused by cortical trace reaction. The pain was reduced in 13 cases, accounting for 3.04% of the number of patients treated. Six cases were ineffective, accounting for 1.40% of the number of patients treated (all of them included those with branch I pain). The total effective rate was 98.59%. 265 cases were followed up from 3 months to 2 years, among which 32 cases showed recurrent symptoms, and the recurrence rate was 12.07%. The pain ceased with re-frequency treatment.
The recent results of radiofrequency temperature-controlled thermocoagulation therapy were very good, with about 96% to 100% of patients achieving pain disappearance after treatment. The recurrence rate is related to the extent of thermal coagulation. The smaller the area of thermal coagulation (the more it is retained), the higher the recurrence rate. The recurrence rate is 55% in patients with mild sensory loss and 25% in patients with significant postoperative sensory loss.
A multicenter study of radiofrequency temperature-controlled thermocoagulation showed that the immediate pain disappeared in 80% to 100%, with a mean of 94%, and the distant pain disappeared in 71% to 94%, with a recurrence rate of about 29%, which depends on whether there are still vessels compressing the nerve root.
A summary of the literature shows that patients achieve pain disappearance in the near future, with a recurrence rate of 25% to 35% in 5 to 10 years. Early onset of hyperalgesia in the trigeminal region and reversible masticatory muscle palsies are normal. 80% of sensory disturbances disappear, but 5% of patients have unpleasant sensory loss or hyperalgesia. Other neurological deficits and death do not occur with correct operation, but incorrect operation can lead to serious complications.
VIII. Related issues
Radiofrequency thermocoagulation destruction of the semilunar ganglion is the primary treatment option for those patients with trigeminal neuralgia who have had poor success with medications, and is significantly less invasive, dangerous, and expensive to treat than open surgical treatment. The main reason why this technique has not been widely carried out in the last hundred years is that the foramen ovale is located deep in the low cranial level, with large anatomical differences, often inappropriately positioned, and repeated punctures often cause bleeding, damage to adjacent tissues or other serious complications. For a long time, physicians have needed to repeatedly perform blind punctures based on bony anatomical landmarks and clinical experience. This traditional blind puncture of the foramen ovale is difficult to determine the depth of the needle tip position, and it is easy to have a shallow puncture that does not enter the trigeminal nerve meniscus and has no lasting effect, and it is also easy to have a deep puncture that damages the nerve tissue and causes serious complications. CT-guided puncture of the semilunar ganglion is more accurate in positioning and more convenient and rapid in operation than the traditional blind puncture method.
The traditional blind puncture method cannot inject local anesthetic during repeated trial punctures in order to judge the position of the needle tip, thus patients are in pain during the puncture process, some refuse treatment in the middle, and some elderly patients induce cardiovascular accidents due to the painful stimulation of the puncture. During CT-guided puncture, because it can be operated under local anesthesia, patients have very little pain during the puncture process, which can avoid serious cardiac and cerebral complications induced by puncture pain and is suitable for elderly patients with other combined systemic diseases to safely pass through treatment.
The results of many controlled studies illustrate that CT-guided percutaneous puncture of the semilunar ganglion with radiofrequency thermocoagulation disruption can achieve better analgesic efficacy than blind puncture methods. Patients showed significant improvement in quality of life indicators such as appetite, sleep, daily life, interaction with others and interest in life after treatment, indicating that CT-guided percutaneous percutaneous hemimelanoglossus disruption can significantly improve the quality of life of patients while relieving pain.
Compared with the traditional blind semilunar ganglion puncture method, CT-guided percutaneous puncture semilunar ganglion radiofrequency temperature-controlled thermocoagulation, as a microinvasive neurosurgery, is more effective in treating trigeminal neuralgia with safe operation and fewer complications, which is easy for physicians to master more quickly.