What is trigeminal neuralgia?
Trigeminal neuralgia is a chronic pain that occurs in the trigeminal nerve, one of the thickest nerves in the head. It is characterized by intense, intermittent, sudden, burning or electric shock-like facial pain that lasts from a few seconds to 2 minutes per episode and then rapidly resolves. This severe pain is often unbearable and can have severe physical and psychological effects.
The trigeminal nerve is the fifth of twelve pairs of cranial nerves that emanate from the base of the human brain. The trigeminal nerve has three branches that transmit sensations from the face (including the mouth) to the brain in three parts: upper, middle and lower. The first branch, the ophthalmic branch, has its endings distributed to the forehead above the eye fissure; the second branch, the maxillary branch, has its endings distributed to the cheeks, upper jaw, teeth, upper lip, gums, and half of the nose; and the third branch, the mandibular branch, has its endings distributed to the lower jaw, teeth, gums, and lower lip. When trigeminal neuralgia occurs, more than one branch may be involved.
What causes trigeminal neuralgia?
It is generally believed that trigeminal neuralgia is caused by vascular compression of the trigeminal nerve exiting the brainstem, which can lead to wear and tear on the protective coat of the nerve, the myelin sheath. It is possible that trigeminal neuralgia represents an aging process in which blood vessels lengthen and tortuously close to the nerve as we age, and cause the nerve to be impacted by the pulsating blood vessels. Trigeminal neuralgia may also be present in patients with multiple sclerosis, which is caused by the degeneration of myelin sheaths in multiple locations throughout the body. Trigeminal neuralgia may also be caused when the myelin sheath is compressed and destroyed by tumor growth. The degeneration of the myelin sheath can cause abnormal signals from the trigeminal nerve to the brain, which in turn can cause painful symptoms. In some cases, the cause of trigeminal neuralgia is unknown.
What are the symptom characteristics of trigeminal neuralgia?
The typical symptoms of trigeminal neuralgia are sudden, severe, electric shock-like, or knife-like pain, often in one side of the jaw or cheek. The pain may also occur bilaterally, but not at the same time. Frequent episodes of pain that last for several seconds at a time are repeated over and over for several hours or all day. These frequent episodes may suddenly resolve on their own after weeks or months, and the period of remission before another episode may manifest as no pain, tingling, numbness, or persistent aching.
Patients may have severe and sudden pain triggered by ordinary stimuli of daily life such as talking, eating, coughing, washing, shaving, brushing, yawning, or blowing cool air. The pain may be confined to a small area of the face or may spread. Pain episodes rarely occur at night when the patient is asleep. If more than 50% of the pain episodes are sudden, intermittent, cutting or electric shock-like sharp pain, which may be accompanied by a burning sensation, the patient has trigeminal neuralgia type I. If more than 50% of the pain episodes are constant aching or burning sensation, the patient has trigeminal neuralgia type II.
Another characteristic of trigeminal neuralgia is that recurrent attacks stop for a period of time and then reappear, and as this process continues, the condition can gradually worsen and the interval between remissions is gradually shortened. Patients may be extremely careful about their movements, afraid to speak, wash their faces, rinse their mouths, and eat very little to avoid triggering painful episodes.
Who is prone to trigeminal neuralgia?
Trigeminal neuralgia is more common in people over the age of 50, but it can occur in all age groups. It is more common in women than men. Some evidence suggests that trigeminal neuralgia is somewhat familial, possibly due to an inherited pattern of similar blood vessel patterns.
Diagnosis of trigeminal neuralgia
There is no single test that can confirm the diagnosis of trigeminal neuralgia. The diagnosis of trigeminal neuralgia is based on the description of symptoms in the patient’s medical history, physical examination, and a thorough neurological examination. Care must be taken to differentiate it from diseases with similar symptoms. For example, herpes zoster neuralgia may present as facial pain and cluster-like headache; trigeminal nerve injury (caused by surgery, trauma, etc.) may present as neuralgia, which may manifest as dull pain, burning pain, cone pain, etc. Because pain caused by different etiologies can have similar characteristics and these etiologies are relatively broad, it is sometimes difficult to correctly diagnose trigeminal neuralgia. However, it is extremely important to identify the cause of the pain, and the treatment may be different depending on the cause.
Patients with trigeminal neuralgia generally require MRI to exclude symptomatic trigeminal neuralgia due to tumors, multiple sclerosis, and other factors. MRI can sometimes show the relationship between blood vessels and nerves, and enhanced MRI angiography can more clearly show the vascular pathways and nerve compression in adjacent brainstem areas.
Treatment of trigeminal neuralgia
Trigeminal neuralgia is treated with medications, surgery, and some complementary therapies.
Antiepileptic drugs, which generally have the effect of blocking nerve firing, are often effective in the treatment of trigeminal neuralgia. These include carbamazepine, oxcarbazepine, topiramate, clonazepam, phenytoin sodium, lamotrigine, and valproic acid. Gabapentin and baclofen may be used as second-line agents or in combination with other antiepileptic drugs to increase their efficacy.
Tricyclic antidepressants such as amitriptyline and nortriptyline can be used to treat symptoms such as persistent pain, burning, and aching. Typical analgesics and opioid analgesics are usually ineffective in suppressing sharp and periodic pain episodes due to trigeminal neuralgia. Surgical treatment may be considered if medication fails to relieve pain or if intolerable side effects such as excessive fatigue occur.
There are various surgical treatments for trigeminal neuralgia, often chosen based on the patient’s preference, physical condition, previous surgery, presence of multiple sclerosis, and branches of the trigeminal nerve involved. Some procedures can be performed on an outpatient basis, while others require inpatient surgery under general anesthesia. Most surgical procedures cause some degree of facial numbness, and trigeminal neuralgia can recur even after satisfactory results have begun. Depending on the surgical approach, risks such as hearing loss, balance disorders, infection, and stroke may occur.
1.Nerve root dissection
2.Microballoon compression intervention
3.Glycerin injection method
4.Radiofrequency thermal therapy
5.Microvascular decompression
Microvascular decompression is the most invasive surgical method among all surgical treatments for trigeminal neuralgia, but it is also the method with the lowest recurrence rate of pain. This method uses general anesthesia and a small bone window behind the ear to directly expose the trigeminal nerve out of the brainstem under the microscope, where it is found to be compressed by blood vessels, and the direct compression and stimulation of the nerve by the microvessel is released by separating the adhesions with the nerve and placing spacers or similar materials between them, so as to release the trigeminal nerve from compression from the cause and relieve the pain attack. Unlike neurotomy, microvascular decompression does not usually cause facial numbness. However, in some cases, patients who are found to have no intraoperative vascular compression may have their sensory roots partially severed to ensure postoperative relief of painful episodes, which may still result in permanent sensory numbness in the corresponding nerve distribution.
Treatment of trigeminal neuralgia also includes a number of complementary therapies, usually in combination with medication. These methods are each somewhat effective and include acupuncture, biofeedback, hormonal therapy, nutritional therapy, and electrical nerve stimulation.