I. Basic knowledge
The trigeminal nerve is the thickest of the cranial nerves and consists mainly of sensory fibers, with a small portion consisting of motor fibers. Trigeminal neuralgia is a recurrent paroxysmal electric shock-like severe pain in the distribution area of the trigeminal nerve, lasting for several seconds or minutes. The pain can be spontaneous or caused by stimulation of trigger points, such as the actions of brushing teeth, washing face, or chewing. The pain is so severe that patients often find it unbearable, and some even have thoughts of lightheartedness, which seriously affects the quality of life of patients.
The etiology and pathogenesis of primary trigeminal neuralgia are still unclear. Most believe that it is caused by ischemia, inflammation or injury of the trigeminal nerve leading to demyelination of the nerve, but most patients do not have an obvious cause. The most common cause is thought to be a blood vessel (mostly the superior cerebellar artery) coiling around its unmyelinated trigeminal nerve root initiation, and microvascular decompression can end the onset of trigeminal neuralgia. Secondary causes of trigeminal neuralgia are usually tumor compression, cerebral arachnoiditis, and multiple sclerosis. Trigeminal neuralgia is common in middle-aged or older patients, with an incidence rate of 1,5 per 10,000 people and a male to female ratio of 2:3. Since the cause of trigeminal neuralgia is unknown, it is difficult to prevent it, but a positive attitude to life, regular habits and good life behavior are still very important for health.
Second, trigeminal neuralgia symptoms
1.Pain site: often limited to one side of the trigeminal nerve distribution area, bilateral simultaneous onset is rare. The second and third branches are most often involved. The first branch pain site is located at the back of the nose and above the orbit, mainly the upper lid and forehead. The second branch is located between the fissure of the eye and the fissure of the mouth and includes the cheek, upper lip, and upper gingiva. The third branch of pain is located in the temporal region and below the orofacial fissure, mainly including the lower lip and lower gingiva. The pain does not cross the midline, and even in bilateral patients, one side does not cross the opposite side during an attack
2. Nature of pain: The pain is episodic electric shock-like, knife-like, tearing-like severe pain, with sudden onset and stop. Each pain lasts for several seconds to tens of seconds, while the interval is completed normally. The interval between attacks is gradually shortened and the pain is gradually increased. Frequent attacks may interfere with eating and rest. A small number of patients can have pain for several hours or even longer. But the pain usually does not come on at night during sleep, and few patients wake up with pain at night.
3, triggering factors: pain attacks are often triggered by talking, chewing, brushing teeth, washing face and other actions, even wind blowing or loud sounds can also cause attacks. Touching the area next to the nose, around the mouth, gums, the inner end of the arch of the eyebrow can cause a pain attack, these sensitive areas are called “trigger points” or “trigger points”.
4, signs: the attack can be accompanied by the same side muscle twitching, facial flushing, lacrimation and salivation, so also known as painful spasms. The patient often rubs the ipsilateral side of the face during painful episodes, and over time the facial skin becomes rough, thickened, and the eyebrows fall off. There are usually no obvious positive neurological signs on physical examination. However, some patients may have rough skin and mild hyperalgesia due to local skin irritation.
Differential diagnosis
1. The difference between trigeminal neuralgia and glossopharyngeal neuralgia mainly lies in that the attack site of glossopharyngeal neuralgia is located in the pharynx and the root of the tongue, which is often triggered by swallowing action. Local anesthesia with cocaine or bupivacaine in the pharynx has a pain-relieving effect.
2. Due to the limitation of the understanding of trigeminal neuralgia, some patients may be misdiagnosed as toothache, but with the improvement of medical level and the quality of doctors, the chance of misdiagnosis is getting less and less. Toothache is a persistent dull pain or swelling, often accompanied by redness and swelling in the gum area, and the pain can be aggravated by knocking on the teeth. The doctor will not misdiagnose the disease by careful physical examination and detailed medical history.
3. Trigeminal neuralgia is a typical painful spasm, which is caused by severe pain leading to spasm of facial muscles, sometimes accompanied by sympathetic symptoms such as facial flushing, lacrimation, salivation and runny nose. In contrast, facial spasm is a condition of involuntary twitching on one side of the face. At the beginning of the disease, it is mostly paroxysmal involuntary twitching of the orbicularis oculi muscle on one side of the face, which gradually and slowly expands to other facial muscles on one side of the face.
IV. Treatment
For patients with initial onset of trigeminal neuralgia, medication is usually chosen. If drug treatment is not effective or has obvious side effects, surgical treatment can be chosen, including peripheral nerve branch and semilunar ganglion block, peripheral branch and semilunar ganglion radiofrequency thermocoagulation, peripheral nerve avulsion, semilunar ganglion balloon compression, gamma knife radiation therapy and microvascular decompression, etc. All the above methods have positive effects and can be chosen according to the local hospital and the patient’s own conditions. The above methods have positive effects and can be selected according to the local hospital and the patient’s own conditions. There is no unified plan for the treatment of trigeminal neuralgia patients who have been cured and relapsed, but the above methods are also feasible.
V. Drug treatment
For patients with first-onset trigeminal neuralgia or those who are in poor general condition and cannot tolerate other methods, medication is usually the first choice, but medication is difficult to cure and the pain often comes back once the medication is stopped. The most common drugs used to treat trigeminal neuralgia are antitussives, whose main mechanism of action is to inhibit the occurrence and spread of abnormal high-frequency firing in neurons by affecting different ion channels in the cell membrane. The first-line drug is carbamazepine. Second-line drugs include phenytoin sodium, gabapentin, baclofen, lamotrigine, oxcarbazepine, and sodium valproate. Additional antidepressants such as amitriptyline have also been reported for trigeminal neuralgia, but the effect is not certain. The common side effects include dizziness and drowsiness, fatigue, nausea, rash, vomiting, occasional granulocytopenia, reversible thrombocytopenia, even aplastic anemia and toxic hepatitis, etc. Blood picture should be checked regularly, and occasional allergic reactions. Tolerance can occur with long-term application. If high-dose carbamazepine is not effective or has significant side effects, the application of second-line drug therapy is an option.
Sixth, nerve block therapy
Nerve block therapy is a method of using nerve block to relieve pain and treat the disease. Nerve block therapy has the characteristics of easy operation, rapid onset of action, precise efficacy, high safety and few adverse reactions, which is the main method of pain treatment. Trigeminal nerve block is used to treat painful diseases in the trigeminal nerve innervation area, especially for patients for whom drug therapy is ineffective. The trigeminal nerve block is divided into branch 1 supraorbital nerve block, branch 2 including infraorbital nerve and maxillary nerve block, and branch 3 including chin nerve and mandibular nerve block.
(a) Supraorbital nerve block
(1) Indications: trigeminal nerve branch 1 pain; ocular pain; ocular postherpetic neuralgia; secondary ocular neuralgia; identification of headache caused by intracranial or extracranial causes.
(2) Operation method: For supraorbital nerve block, the patient is placed in a supine position, the operator is located on the side of the patient’s head, and the puncture point is in the inner 1/3 of the superior orbital rim on the affected side or the supraorbital foramen incisura is palpated in the middle of the eyebrow, about 2 or 5 cm from the ear side of the median line, where most of the pressure pain is present. A 2.5 cm long 22G needle is used to stab vertically with the skin, and the retraction is bloodless, and 0.5 to 1 ml of local anesthetic is injected. If destructive nerve block is required, inject 0,5ml of nerve-destroying drug 5 to 10 minutes after the blocking effect appears. To prevent bleeding after removal of the needle, gauze can be used to compress the puncture site for 5 minutes.
(3) Complications
(1) Eyelid edema and hematoma The edema is severe when ethanol spreads to the soft tissues of the eyelid and takes 4 to 5 days to recover. Hematoma can occur when the supraorbital artery is punctured. Prevention is to compress the skin of the supraorbital notch with the left index finger after injection.
(2) Eyelid ptosis is caused by blocking the superior branch of the oculogyric nerve with medication and can recover after anesthesia.
(ii) Infraorbital nerve block
(1) Indications: trigeminal nerve branch 2 pain; herpes zoster and post-herpetic neuralgia in this area or other causes of pain in the lower eyelid, paranasal, upper lip or maxillary central incisors, cuspids and other areas.
(2) Operation method: For infraorbital nerve block, the patient is placed in a supine or sitting position, and the infraorbital foramen is touched 1 cm directly below the infraorbital rim and 3 cm lateral to the nasal midline, which is the puncture point. When puncturing the infraorbital foramen, the finger of the left hand is lightly pressed on the infraorbital foramen to guide the direction of the needle tip, and the infraorbital foramen is reached by about 1.0-1.5 cm of puncture. When the infraorbital nerve is punctured, a discharge pain from the nose to the upper lip can be produced. No blood is drawn, and 0, 5 to 1 ml of analgesic solution is injected. If destructive nerve block is needed, after 15-20 minutes of numbness in the distribution area of the infraorbital nerve, 0.5ml of nerve destructive drug will be injected again.
(3) Complications
①Facial edema.
(ii) Subcutaneous hemorrhage and hematoma.
(③Visual impairment The needle tip pierces too deeply into the infraorbital canal so that the drug penetrates into the orbit, or bleeds after piercing the blood vessels in the infraorbital canal, which raises the intraorbital pressure and causes diplopia, protrusion of the eye, visual impairment and eye pain.
(C) Maxillary nerve block
(1) Indications: trigeminal nerve branch 2 pain, especially if the pain is widespread and the infraorbital nerve block fails; pterygopalatine neuralgia; secondary neuralgia; maxillary or dental surgical pain, etc.
(2) Operation methods The operation methods of maxillary nerve block are lateral entry method and lateral anterior entry method.
The lateral entry method The lateral entry puncture method is the most commonly used method. The patient is placed in a supine position with the head slightly turned to the healthy side. The puncture point is 3 cm in front of the external auditory foramen and the midpoint of the lower edge of the zygomatic arch. A 7- to 8-cm-long, 22G puncture needle is used. The puncture needle is inserted at a right angle to the skin about 4,5-5 cm into the lateral plate of the pterygoid process, and the marker is placed 1-1,5 cm from the skin, the needle is retreated to the subcutaneous, the direction of puncture is changed, and the needle is inserted in the direction of the ipsilateral pupil, so that the tip of the needle enters the pterygopalatine fossa, at which time the upper lip and the gingiva and the cheek appear to be discharging pain, and 0,5-1 ml of local anesthetic is injected when there is no blood in the full aspiration. If destructive nerve block is needed, after full observation of analgesic effect, disappearance of tactile sensation and no complications, 0.5ml of nerve destructive drug should be injected after 15-20 minutes.
2. Lateral anterior approach The body position is the same as that of the lateral approach. The puncture point is viewed from the side at the intersection of the rostral process of the mandible and the lower edge of the zygomatic bone. The puncture needle is an 8-cm-long 22G blocking needle, which is inserted from the puncture point to the tip of the anterior fossa to a depth of about 4-5 cm. The tip of the needle can touch the back of the jaw bone (the tip of the needle is too far to the front) or touch the root of the lateral plate of the pterygoid process (the tip of the needle is too far to the rear), and after several trials to align the tip of the needle with the midpoint of the two, a depth of about 5-5,5 cm can be reached to the maxillary nerve and the discharge pain of its innervation area can appear. If a destructive nerve block is required, the lateral entry method is performed again and the nerve destructive drug is injected 0.5 ml after 10 to 15 minutes of observation.
(3) Complications
(i) Bleeding, hematoma.
(2) Visual impairment If the artery is injured and blood flows into the orbit, the intraorbital pressure increases, the eye swells, the eye protrudes, and eye pain and diplopia may occur and affect the function of the optic nerve or ophthalmic artery or even blindness.
(iii) Diplopia The puncture needle is too deep into the superior anterior, which may block the motoneurotic nerve or the adductor nerve and cause diplopia.
(iv) Facial nerve palsy caused by blocking the facial nerve.
(⑤) trigeminal nerve full branch block If the puncture needle is too deep or the amount of local anesthetic is too much, the drug enters the semilunar ganglion of the skull from the foramen ovale and causes trigeminal nerve full branch block and other cerebral nerve block, which can lead to respiratory arrest and loss of consciousness if subarachnoid block occurs.
(iv), chin nerve block
(1) Indication: trigeminal nerve branch 3 pain and limited to the chin, lower lip and nearby mucosa.
(2) Operation method: For chin nerve block, the patient is placed in a supine or sitting position with the head turned to the healthy side. The puncture point is located at 0.5 cm lateral to the chin hole and 0.5 cm lateral to the head. The chin foramen can be reached by sliding downward with the left index finger to find the 2nd bicuspid. Inject 0.5 ml of local anesthetic after sufficient aspiration without blood. if a destructive nerve block is performed, inject 0.5 ml of nerve destructive drug 15-20 minutes after the blocking effect appears.
(3) Complications Complications are rare, there may be local bleeding at the puncture site, and the bleeding and tissue swelling can be prevented after several minutes of pressure after needle removal.
(E) Mandibular nerve block
(1) Indications: trigeminal nerve branch 3 pain, or the ineffectiveness of chin nerve and inferior alveolar nerve block; secondary neuralgia and pain after mandibular and dental surgery.
(2) Operation method The mandibular nerve block is usually performed by extra-oral puncture. The patient is placed in a supine position with the head tilted to the healthy side. The puncture point is in the depression below the midpoint of the zygomatic arch. An 8-cm-long, 22G core puncture needle with removable markers is used. The puncture needle was inserted vertically about 4.0-4.5 cm to the outer plate of the pterygoid process, at which point the marker was moved to 1 cm from the skin. Retreat the needle to the subcutaneous, change the direction of the puncture needle pointing to the original contact point 0, 5cm posterior and slightly above the puncture depth of about 5cm, you can get to the mandible, the gingival part of the release of pain. Inject 0.5-1ml of local anesthetic after adequate retraction without blood. In case of destructive nerve block, 0.5ml of nerve destructive drug is injected after 15-20 minutes of confirmed effectiveness.
(3) Complications
(i) Bleeding.
(ii) Facial nerve palsy; (iii) Taste disorder (iv) Taste disorder can be caused when the needle tip is biased downward or when the bulbar nerve is blocked.
(4) Trigeminal nerve full branch block.
Semilunar ganglion block
The trigeminal ganglion block is performed by inserting a puncture needle into the foramen ovale and injecting a local anesthetic or nerve-destroying drug into the trigeminal ganglion intracranially.
1.Indications Trigeminal nerve full branch pain, after the branch block failed to achieve satisfactory results; maxillary cancer and other malignant tumors caused by a wide range of pain.
2.Operation method The patient is placed in a supine position with both eyes looking forward. The puncture point is 2,5~3cm lateral to the corner of the mouth, which is equivalent to the maxillary 2nd molar. A 9- to 10-cm-long, 22G core puncture needle is slowly inserted upward and backward along the horizontal line of the foramen ovale through the gap between the anterior border of the mandibular rostral process and the maxillary ramus. The frontal view of the needle tip is oriented towards the ipsilateral orthoptic pupil, and the lateral view of the needle tip is oriented towards the articular tubercle at the root of the ipsilateral zygomatic arch. About 5-6 cm into the needle, you can touch the flat bone surface in front of the oval foramen at the base of the skull, and then continue to move gently along the bone surface to the deeper part by the touch of the needle tip, or try slightly to the left and right, if the needle tip slides to the oval foramen and pierces the mandibular nerve and the semilunar nodes, there will be radiating pain in the jaw and cheek immediately. After drawing back no blood and cerebrospinal fluid, 0.3~0.5ml of local anesthetic is injected. If destructive nerve block is needed, wait for 10-15 minutes after the blocking effect appears before slowly injecting 0,3-0,5ml of nerve destructive drug.
3.Complications
① Cerebral neuritis.
②Elevated blood pressure Puncture needle into the foramen ovale can produce severe pain and cause elevated blood pressure. Intracranial hemorrhage is very likely to occur in hypertensive patients.
Meningitis caused by infection, attention should be paid to the sterilization and aseptic operation of puncture instruments.
④ Corneal ulceration and keratitis Because the 1st branch is blocked, the cornea loses sensation and is highly susceptible to damage and corneal ulceration.
Seven, radiofrequency thermal coagulation therapy
Radiofrequency thermal coagulation therapy is a minimally invasive technique that uses the voltage difference between electrodes to generate high-frequency current, which causes ions in the tissue to move back and forth and generate heat, and the heat acts on the adjacent ganglion/root/stem, fascia, muscle and other tissues, causing protein coagulation and denaturation and blocking pain transmission. It achieves long-term or permanent pain relief by blocking sensory innervation. The main advantage of radiofrequency technology over other existing nerve destruction techniques is that quantitative and predictable foci of nerve destruction can be obtained. RF currents do not cause tissue adhesions or scorching like direct current, and there is no gas production. The RF electrode needle and puncture sleeve needle are small, durable, and have minimal tissue damage.
The main manipulation and pathway of radiofrequency thermocoagulation of the semilunar ganglion is basically the same as that of nerve block, which is usually operated under the guidance of X-ray C-arm machine or CT, enabling the implementation of sensory and motor stimulation and achieving anatomical localization plus physiological localization of electrical stimulation, increasing the accuracy, safety and comfort of treatment. Although radiofrequency thermocoagulation therapy has a certain recurrence rate, it is widely used in clinical practice because it is easy to operate and can be repeatedly performed. Patients experience severe pain during trigeminal ganglion thermal coagulation destruction, so many hospitals currently use intraoperative intravenous general anesthesia to avoid the pain caused by high temperatures.
Indications for radiofrequency thermocoagulation include.
(1) Patients with primary trigeminal neuralgia who have been treated with regular medications that are ineffective or have significant side effects.
(2) Patients with recurrent primary trigeminal neuralgia after surgery, chemical disruption or radiofrequency thermocoagulation disruption.
Contraindications include.
(1) Infection or presence of tumor at the facial puncture site.
(2) Patients with severe bleeding tendencies.
(3) Patients with severe systemic status failure or with severe cardiovascular or cerebrovascular disease.
(4) Patients who are confused or uncooperative.
Familiarity with the anatomy of the trigeminal and semilunar ganglia is essential for successful oval foramen puncture. Incorrect puncture may enter an abnormal site, such as positioned superiorly and inserted into the inferior orbital fissure, damaging the eye; positioned posteriorly and medially, entering the rupture foramen (carotid artery); positioned posteriorly and inferiorly, entering the inferior jugular foramen or carotid canal, causing intracranial hemorrhage. Other complications include infection and facial sensory disturbance. In addition, keratitis is also a more serious complication, commonly associated with the destruction of the first branch, the disappearance of corneal reflexes, and in severe cases can cause paralytic keratitis, which can eventually lead to blindness in patients. Therefore, attention should be paid to controlling the temperature and time of heating during the operation, and the change of corneal reflex should be checked at any time. If loss of corneal reflex has occurred, the patient should be instructed to wear glasses and use eye ointment to protect the cornea and prevent keratitis.