Trigeminal nerve hemianopsia radiofrequency thermal coagulation Q&A
1.What is “trigeminal neuralgia”?
”Trigeminal neuralgia” refers to the recurrent paroxysmal severe neuralgia in the distribution area of the facial trigeminal nerve, also known as painful convulsions, which is one of the common diseases in neurosurgery and one of the internationally recognized difficult diseases. Most trigeminal neuralgia starts at the age of 40, especially in women. The attacks are unbearable, like lightning or knife cuts. Patients with trigeminal neuralgia often do not dare to wipe their faces, eat, or even swallow saliva, thus seriously affecting their normal life and work.
2.What is the trigeminal nerve?
The trigeminal nerve is the fifth pair of brain nerves, the thickest pair of brain nerves in the cranium, and is a mixed nerve. What is a mixed nerve? The nervous system calls nerves with motor and sensory functions mixed nerves. The trigeminal nerve originates from the pontocerebral center and divides into motor and sensory roots, the former innervates the movement of the temporalis and masticatory muscles; the latter manages the sensation of pain, temperature and touch in the face.
The sensory roots are thicker than the motor roots and are divided into three branches within the trigeminal hemimelia. The perineurium of the anterior medial part of the trigeminal hemimelia forms the first branch, the ophthalmic branch; the middle part forms the second branch, the maxillary nerve; and the posterior lateral part forms the third branch, the mandibular nerve. These three nerves exit the skull via the supraorbital fissure, foramen ovale and foramen ovale, respectively.
3.What is the etiology of trigeminal neuralgia?
From the clinical point of view, trigeminal neuralgia that cannot be identified after systemic examination such as cranial CT and magnetic resonance imaging is called “primary trigeminal neuralgia”. Primary trigeminal neuralgia accounts for the majority of cases and refers to recurrent severe facial neuralgia without organic damage, which is presumed to be related to demyelination of the trigeminal nerve and vascular compression. If the exact cause can be found, it is called secondary trigeminal neuralgia, which accounts for about 5% of trigeminal neuralgia, such as neuralgia caused by intracranial cholesteatoma, nerve sheath tumor, meningioma, hemangioma and other skull base tumors that cause compression of the trigeminal nerve.
4.How to treat trigeminal neuralgia?
For patients with initial onset, the symptoms are often mild and medication can be tried to control the pain, such as oral carbamazepine or Dexedrine. If medication is ineffective, or the dose of medication is high and directly affects liver and kidney function, the following two methods can be chosen for treatment. The first is radiofrequency thermocoagulation of the trigeminal nerve hemianopia, which is simple, safe, low cost, immediate pain relief, effective, and happily accepted by the majority of patients. The second is transcranial trigeminal nerve vascular decompression, which has mature technology and good efficacy, but the cost is higher and patients have to bear the risk of general anesthesia craniotomy.
5.What is “radiofrequency thermal coagulation of the meningeal ganglion”?
The trigeminal ganglion is located at the base of the middle cranial fossa, surrounded by important structures such as the internal carotid artery, cavernous sinus and several pairs of cranial nerves. The penetration of the meningeal ganglion is done from the lateral corner of the mouth, through an oval hole of about 3mm in diameter at the base of the middle cranial fossa, and into the skull, with a penetration depth of 7.5cm. Due to the deep location of the oval hole and the large anatomical variation, it is difficult to ensure the accuracy of the penetration by hand and experience, and it is difficult to ensure the efficacy if the penetration is not in place.
Our hospital carries out “radiofrequency thermal coagulation therapy of trigeminal nerve under stereotactic navigation”, referred to as “radiofrequency thermal coagulation of hemianopia”. It adopts brain stereotactic navigation technology and 16-row spiral CT oval hole three-dimensional reconstruction technology to precisely calculate the target point and ensure that the radiofrequency electrode needle percutaneously passes through the narrow oval hole at the base of the skull accurately to reach the ideal position of the trigeminal nerve meningeal ganglion, and the position of the electrode needle can be clearly displayed and verified by 16-row spiral CT. This ensures a 100% successful puncture rate and ensures the efficacy of the treatment.
Radiofrequency thermocoagulation is an important treatment for trigeminal neuralgia, which includes trigeminal nerve root pulse stimulation and temperature-controlled coagulation techniques. Intermittent pulsed current stimulation is applied prior to disruption to understand whether the stimulation area matches the patient’s pain onset area, making the disruption more delicate and safe.
Since the unmyelinated fine fibers that conduct nociceptive sensations degenerate at 70°-75°C, whereas the myelinated thick fibers that conduct tactile sensations can tolerate higher temperatures, temperature-controlled thermal coagulation is used to control the destruction temperature at 75°C. In this way, the differences in temperature tolerance of different nerve fibers can be exploited to selectively destroy the fine fibers that conduct facial nociceptive sensations in the semilunar ganglion, while preserving the thick fibers that conduct tactile sensations that are more resistant to heat. The pain relief is immediate and the facial pain is preserved. The result is immediate pain relief and preservation of facial sensation.
6.What kind of patients is “radiofrequency thermal coagulation of the semilunar ganglion” suitable for?
(1) Patients with primary trigeminal neuralgia who do not achieve satisfactory results with medication;
(2) Those who have obvious adverse drug reactions to carbamazepine and other painkillers;
(3) Patients with trigeminal neuralgia who are too old and frail to tolerate open-heart surgery;
(4) Patients who are unwilling to undergo cranial trigeminal neurovascular decompression;
(5) Patients with recurrence after cranial trigeminal neurovascular decompression;
(6) Patients with recurrence after controlled radiofrequency thermocoagulation treatment, which can be recoagulated;
(7) Gamma knife treatment is unsatisfactory and pain is not eliminated or reduced;
(8) trigeminal neuralgia due to tumor, the pain is not improved by gamma knife or surgical treatment.
7.What are the advantages of “radiofrequency thermal coagulation of hemianopia” compared with other treatments?
The method is safe and efficient, the operation takes 30-60 minutes, the pain is relieved immediately during the operation, the patient receives the temperature-controlled treatment plan in the awake state, the effect is immediate, and the long-term pain and the trouble of taking painkillers are relieved immediately. It also has a low recurrence rate and low cost, and is gladly accepted by the majority of patients.
The use of stereotactic navigation and 16-row spiral CT foramen ovale three-dimensional reconstruction technology ensures accurate puncture of the foramen ovale and trigeminal nerve hemimelia, significantly improving the treatment effect. After the puncture is in place, the trigeminal meniscus can be stimulated with a weak current to verify whether the proposed target area of destruction matches the patient’s pain-onset area, making the destruction more delicate and safe.
Temperature-controlled thermocoagulation is to gradually increase the temperature in the target area of destruction, taking advantage of the different heat tolerance of nociceptive and tactile nerve fibers to selectively destroy nociceptive nerve fibers, and the treatment process is accurately adjustable, avoiding the blindness of anhydrous alcohol or glycerin injection, and eliminating the paid injury of injecting irritating drugs.
The pain elimination rate of radiofrequency thermocoagulation is 95%, the 2-year recurrence rate is only 20%, the efficacy is consistent with the open vascular decompression surgery method, and avoids the risk of general anesthesia, pain and trauma of surgery, and fatal and disabling craniotomy. Gamma knife treatment mechanism of trigeminal neuralgia is to use γ-radiation to irradiate the trigeminal nerve root or semilunar ganglion, due to the nerve degeneration after γ-radiation, it takes some time to appear, so the pain will not be eliminated immediately after γ-knife treatment, still need to continue to use painkillers, γ-knife after the onset of effect time is 2 days-7 months, the average of 3 months.