Trigeminal neuralgia is a disease that causes severe and disabling chronic facial pain caused by irritation or inflammation of the trigeminal nerve. In most cases this inflammation is secondary to compression of the nerve by an artery inside the skull. The disease usually begins abruptly, with no previous symptoms that might alert the patient to the risk of suffering from it.
What symptoms may indicate that the patient is suffering from trigeminal neuralgia?
The patient has very intense pain discharges that affect the lower face and jaw, and may also affect the perinasal and periocular area. It typically affects only one side of the face. The disease presents with outbreaks of intense pain, described by patients as “electric shocks”, which can be triggered by mechanical stimulation of specific points, called “trigger points”. These triggers can occur in common everyday situations such as eating, brushing teeth, smiling, applying make-up, talking, drinking, etc. Therefore, the quality of life of patients with trigeminal neuralgia is severely compromised.
Although these episodes may initially be of short duration and spaced out over time, they tend to become more continuous and progressively longer in duration, resulting in a worsening of the patients’ quality of life.
Why does trigeminal neuralgia occur?
The trigeminal nerve is the nerve that carries sensory information from the face to the brain. This nerve originates in the brain stem and runs along a short path in the cisterns at the base of the brain until it enters the base of the skull (cisternal segment). Once here it forms a ganglion called Gasser’s ganglion and, at that point, it divides into three branches that collect sensory information from the face (the 1st branch from the periocular area, the 2nd branch from the inferior perinasal area and upper lip, and the 3rd branch from the mandibular area). The trigeminal branches each emerge through a hole in the cranial base (superior orbital fissure in the first branch, round foramen in the second branch and foramen ovale in the third branch), until they reach the corresponding sensory receptors in the face.
Trigeminal neuralgia is caused by chronic irritation of the trigeminal nerve. This irritation is frequently caused (80% to 90% of cases) by contact of the nerve with an artery or vein at the base of the brain. The affected segment of the nerve is usually the cisternal segment. This contact can produce a pressure that alters the normal functioning of the nerve and this emits abnormal signals to the brain, producing lacinating pain crises.
How to treat trigeminal neuralgia?
The initial treatment of trigeminal neuralgia consists of drugs. The most commonly used is Carbamazepine, although other medications are also used, such as Lamotrigine, Gabapentin, Phenytoin, Oxcarbazepine and Topiramate (Wallach, J 2018). Despite this initial medical treatment, which requires daily medication, many patients present with refractory neuralgia, with no improvement despite the combination of several drugs. It is estimated that up to 75% of patients are not adequately controlled with drugs and require some surgical treatment during the course of their disease (Greenberg, 2010). In addition, some patients, given the chronicity of medical treatment and the association between several drugs, often experience adverse or undesired effects of the medication, such as drowsiness, dizziness, alterations in blood tests, intolerance, etc.
In those patients in whom medical treatment is ineffective, produces side effects or present a recurrence of neuralgia once the drugs have been withdrawn, there are safe and effective neurosurgical treatments. These surgical techniques are:
- Vascular microdecompression of the trigeminal nerve.
- Percutaneous procedures on Gasser’s ganglion.
Trigeminal nerve vascular microdecompression.
In most cases, trigeminal neuralgia is directly related to compression exerted by a normal and healthy artery or vein of the brain, but which contacts the trigeminal nerve at the level of the intracranial portion.
The existence or not of a vascular structure in contact with the trigeminal nerve is easily assessed with a cranial MRI.
In patients with trigeminal neuralgia in whom the contact of a vascular structure with the nerve is demonstrated in the MRI and who, because of their age, clinical situation and state of health, do not present a contraindication for brain surgery, are candidates for trigeminal nerve vascular microdecompression.
This surgery is performed in the operating room under general anesthesia. A small incision is made in the retroauricular area on the side of the neuralgia and a craniotomy or skull opening is performed in the occipital bone. Through a minimal incision in the dura mater that covers the brain, and using a surgical microscope, the arteries and veins that contact the trigeminal nerve are separated.
Trigeminal nerve vascular microdecompression is the most effective treatment (Bick SKB, 2017).With this treatment, the highest pain control rates are achieved, reaching 89-90% of pain-free patients after the procedure (KW, 2015). It is also the treatment that shows the longest lasting pain control, with 75-80% of patients completely controlling pain 5 years after treatment.
Percutaneous procedures or minimally invasive techniques.
In those patients who, due to their advanced age or health condition, cannot undergo vascular microdecompression of the trigeminal nerve or whose disease has recurred after a properly performed microdecompression technique, may be candidates for percutaneous procedures.
These treatments for trigeminal neuralgia are minimally invasive techniques. It is possible to perform up to three different techniques, depending on the characteristics of the patient and the disease. Thus, it is possible to perform a mechanical lesion of Gasser’s ganglion, using a device with a small balloon that presses on Gasser’s ganglion; a chemical lesion (using glycerol); or a radiofrequency lesion.
All three techniques are performed in the operating room, under general anesthesia, and require a paralabial puncture on the side of the neuralgia. By means of intraoperative radiographic control, a trocar is introduced up to the foramen at the base of the skull, which is crossed by the third branch of the trigeminal nerve, the foramen ovale. Once the correct position of the trocar in the access to Gasser’s ganglion is verified, the lesion of the ganglion is performed, according to the ideal method in each case.
The percentage of pain control after the procedure is also high with these techniques. About 90% of patients have good pain control after the procedure, but, unlike vascular microdecompression, they have a lower rate of pain control at five years, about 58% of patients (Cheng JS, 2014).
In favor of these techniques it should be noted that they are a simple and fast procedure, they are minimally invasive techniques that require a hospitalization time of only 24 hours. In addition, they are associated with fewer complications, can be performed in patients with severe associated diseases and are a more effective option for patients with multiple sclerosis, for example.
Key points about trigeminal neuralgia and its treatment
- Trigeminal neuralgia is a very disabling condition, characterized by frequent episodes of very severe facial pain.
- In almost 75% of patients with neuralgia, control of the disease is not achieved with medical treatment (drugs).
- Safe and effective neurosurgical treatments are available for the treatment of trigeminal neuralgia.
- Trigeminal nerve vascular microdecompression is the most effective treatment for trigeminal neuralgia.
- Percutaneous procedures are indicated in cases where vascular microdecompression cannot be performed or is ineffective, and also offer a high rate of pain control.
- Surgical treatment should always be individualized according to the patient’s characteristics.