Trigeminal neuralgia is the most common neurological disease of the brain, mainly manifested by recurrent paroxysmal severe pain in the distribution area of the trigeminal nerve on one side of the face, with an incidence rate of 52.2/100,000 in China, slightly more in women than in men, and the incidence rate can increase with age. Trigeminal neuralgia mostly occurs in middle-aged and elderly people, and the right side is more than the left side.
I. Etiology: clinically, trigeminal neuralgia is usually divided into 2 types: primary and secondary. Primary refers to those who do not show neurological signs, and the etiology has not been completely clarified. Most scholars currently support the theory of vascular compression, and this theory has been basically confirmed by surgery. This theory suggests that the formation of local vascular collaterals, which compress and impact the posterior roots of the trigeminal nerve, leads to limited demyelination of the compressed local nerve fibers, resulting in short-circuiting of two adjacent fibers, through which a small touch can be transmitted to the center, and the efferent impulses of the center can also become efferent impulses, and so on, repeatedly reaching the threshold of nociceptive neurons, thus causing pain attacks. Secondary trigeminal neuralgia can manifest as pain-related organic lesions. The more common ones are tumors in the pontocerebellar horn region, with cholesteatoma, nerve sheath tumor, and meningioma being common. In addition, there are trigeminal neuritis, arachnoiditis, cranial tumors and other diseases.
Clinical manifestations: The disease is mostly over 40 years old, with more middle-aged and elderly people. There are more women than men, about 3:2.
The pain is more on the right side than on the left side. The pain spreads from a point on the face, mouth or jaw to one or more branches of the trigeminal nerve, with the second and third branches being the most common, and the first branch is rare.
2. Nature of pain: such as cutting, stabbing, tearing, burning or electric shock-like severe pain, or even painful;
3, the pattern of pain: the onset of trigeminal neuralgia is often without warning, while pain attacks are generally regular. Each pain attack lasts from only a few seconds to 1 to 2 minutes and stops abruptly. At the beginning of the disease, the number of attacks is small, and the interval is long, ranging from several minutes to several hours, with the development of the disease, the attacks are gradually more frequent, the interval is gradually shortened, and the pain is gradually increased and intense. The pain attacks decrease at night. There is no discomfort during the interval;
4, triggering factors: talking, eating, washing, shaving, brushing teeth and wind blowing can trigger pain attacks, so that patients are depressed, careful and cautious actions, and even afraid to wash their faces, brush their teeth, eat, and speak carefully, for fear of causing attacks;
5. Expression and facial changes: when the attack often suddenly stop talking, eating and other activities, the painful side can show spasms, that is, “painful spasms”, frowning and clenching teeth, opening the mouth to cover the eyes, or rubbing the face with the palm of the hand, resulting in local skin roughness, thickening, loss of eyebrows, conjunctival congestion, tearing and salivation. The expression is mental tension and anxiety;
6, neurological examination: no abnormal signs, a few have facial hypesthesia. Such patients should be further questioned about their medical history, especially whether they have a history of hypertension, and a comprehensive neurological examination, including lumbar puncture, skull base and internal auditory tract radiography, cranial CT, MRI and other examinations if necessary, to help differentiate from secondary trigeminal neuralgia.
The disease is characterized by sudden onset, abrupt stopping, lightning-like, knife-like, burning, intractable and severe pain in the trigeminal nerve distribution area of the head and face. The pain can be severe when speaking, washing the face, brushing the teeth or breezing, or even when walking. The pain lasts for a few seconds or minutes, and the pain comes in periodic episodes with the same intervals as normal.
Treatment methods
Drug treatment
1.Carbamazepine: It is effective for 70% of patients, but about 1/3 of patients cannot tolerate its side effects such as drowsiness, dizziness and digestive discomfort. It can be given twice daily at first, and later three times daily. 0.2~0.6g per day, divided into 2~3 doses, with an extreme dose of 1.2g per day.
2.Phenytoin sodium (sodium phenytoin): less effective than carbamazepine.
3.Chinese medicine treatment: has certain efficacy.
Surgical treatment
1.Trigeminal nerve and semilunar ganglion closure
In 1903, Schosser was the first to apply trigeminal nerve peripheral branch closure to treat trigeminal neuralgia. The procedure is performed by injecting drugs directly on the trigeminal nerve to denature it and cause conduction block, thus relieving pain. The commonly used closure drugs are anhydrous alcohol and glycerin. Peripheral branch closure is simple to perform, but the effect is not long lasting, usually lasting 3-8 months, rarely more than 1 year. The operation of meniscal ganglion closure is relatively complex and can cause complications such as neurokeratitis, with an overall efficiency of 72-99%, an early recurrence rate of 20%, and a recurrence rate of 50% in 5-10 years.
2, hemianopia percutaneous radiofrequency thermal coagulation treatment
It is a safe, simple and patient-friendly treatment method with efficacy up to 90%. The rationale is that it can selectively destroy the nociceptive fibers in the trigeminal nerve while preserving the tactile fibers. It is performed by inserting a radiofrequency needle electrode into the semilunar ganglion under X-ray or CT guidance, energizing it and gradually heating it to 65-75 degrees to destroy the target point for a duration of 60 seconds. This method is suitable for patients who cannot or refuse craniotomy due to their advanced age.
3.Microvascular decompression (micorvascular decompression, MVD)
MVD surgery is currently the preferred surgical treatment for primary trigeminal neuralgia, first proposed by Professor Jannetta in 1967. The blood vessel that compresses the trigeminal nerve and produces pain is called the “responsible vessel”.
The common responsible vessels are
The superior cerebellar artery (75%), which can form a vascular loop extending caudally, is in contact with the trigeminal nerve at the brainstem and mainly compresses the nerve root above or above the medial side.
(ii) Anterior inferior cerebellar artery (10%), generally the anterior inferior cerebellar artery compresses the trigeminal nerve from below, and may also form a clamping compression on the trigeminal nerve together with the superior cerebellar artery.
③The basilar artery, with age and hemodynamic effects, the basilar artery may bend to both sides and compress the trigeminal nerve root, generally more bent to the side of the thinner vertebral artery.
④Other rare responsible vessels include posterior inferior cerebellar artery, variant vessels (such as permanent trigeminal artery), transverse cerebral pontine vein, lateral veins and basilar plexus. The responsible vessel can be one or multiple, and can be either an artery or a vein.
Microvascular decompression is performed by making a 4 cm longitudinal incision behind the affected ear and within the hairline under general anesthesia, making a cranial opening of approximately 2 cm in diameter, entering the pontocerebellar horn region under a microscope, exploring the trigeminal nerve pathway, “loosening” all possible compressive vessels and arachnoid cords, and isolating these vessels with Once the responsible vessels are isolated, the source of irritation disappears, and the hyperexcitability of the trigeminal nucleus disappears and returns to normal. In the vast majority of patients, the pain disappears immediately after surgery and normal facial sensation and function are preserved without affecting the quality of life.