First-line standard trigeminal neuralgia treatment is often medication. Refractory cases may be candidates for neurological surgery to better alleviate pain.
The initial evaluation for trigeminal neuralgia is typically in primary care, but patients frequently also present to dental and ear, nose and throat settings, according to Brian M. Plato, D.O., a neurologist and headache specialist with Norton Neuroscience Institute.
The uncommon condition is characterized by facial pain within the distribution of the trigeminal nerve. Abigail J. Rao, M.D., a stereotactic and functional neurosurgeon with Norton Neuroscience Institute, emphasizes that the diagnosis is clinical, and can be challenging to make.
Trigeminal neuralgia types differ in the nature of the pain, a patient’s history and the history of how the pain started. According to a commonly used classification system, there are seven types of trigeminal neuralgia.
- Classic trigeminal neuralgia, or Type 1. This is described as sharp, paroxysmal electrical stabbing attacks of pain. Type 1 trigeminal neuralgia is more common in women than men. Age of onset traditionally has been thought to be between the ages of 50 and 70, but a peak of onset in the 30s recently has been discovered and researched.
- Type 2 trigeminal neuralgia is characterized by predominance of aching, throbbing constant pain
“A patient is going to come in and complain of facial pain or, oftentimes, pain around the teeth and gums,” Dr. Plato said during a recent episode of the “MedChat” continuing medical education podcast, “Recognition and Management of Trigeminal Neuralgia.”
The trigeminal nerve root arises from the pons and branches out into three distributions, supplying sensation to the face: ophthalmic — V1 — is the forehead, eye and upper eyelid; maxillary — V2 — lower eyelid, cheek, nostril, upper lip and upper gum; and mandibular — V3 — along the jawline affecting the lower lip, lower gum, jaw and chewing muscles.
With trigeminal neuralgia, rather than supplying normal sensation to the face, the trigeminal nerve sends pain signals, producing attacks of intense pain which are frequently incapacitating.
Long periods of remission are one of the more common features of Type 1 trigeminal neuralgia. However, over years, the frequency and duration of flares can increase.
Diagnosing trigeminal neuralgia
Trigeminal neuralgia is rare, with an incidence of about 4 or 5 per 100,000 patient years, much less common than dental issues, for example, making diagnosing it a challenge for the general practitioner.
“If a patient has the typical features of trigeminal neuralgia, even if the location of distribution of the pain is around the teeth, it is not necessary to have them evaluated by a dentist,” Dr. Plato said.
Trigeminal neuralgia symptoms also overlap significantly with temporomandibular joint dysfunction, which can result in craniofacial pain or headaches. Multiple headache disorders, too, are mimickers of trigeminal neuralgia.
According to Dr. Plato, important questions to ask patients are:
- When did the pain start?
- How did the pain start?
- Was there anything else happening at the time, such as an outbreak of shingles?
- How frequent is the pain?
- Where is the pain located?
- What’s the quality of the pain?
- What types of things trigger the pain?
Imaging can be helpful in diagnosing trigeminal neuralgia by ruling out such other conditions as a brain tumor, arteriovenous malformation or a process that affects nerves more generally such as multiple sclerosis. Facial numbness typically is not associated with idiopathic trigeminal neuralgia.
With imaging, it’s important that the MRI looks at dedicated slices through the brainstem to show the course of the trigeminal nerve and adjacent blood vessels, according to Dr. Plato. The images should be contrasted as well.
To rule out TMJ, providers can test patient jaw excursion and ask whether the jaw pops or clicks.
Primary care providers who are comfortable evaluating and treating trigeminal neuralgia do not need to refer to a specialist. For other providers, referring to a specialist makes sense, according to Dr. Plato.
Trigeminal neuralgia treatment options
Trigeminal neuralgia can be treated medically or surgically.
The standard first-line treatment option for Type 1 trigeminal neuralgia is the anti-convulsant carbamazepine. Another anti-convulsant, oxcarbazepine, has shown similar efficacy in head-to-head trials, with superior tolerability, lessening the chance of discontinuation.
Starting trigeminal neuralgia patients on a lower dose and gradually increasing the medication helps patients tolerate these medications, which have side effects including drowsiness, incoordination, balance issues and memory issues.
Traditional second- and third-line treatments for refractory trigeminal neuralgia are gabapentinoids such as gabapentin and pregabalin.
The anti-seizure medication lacosamide has emerged recently as a second-line treatment for refractory trigeminal neuralgia. One recent study found pain relief was achieved in two-thirds of the 86 patients studied retroactively. Lacosamide appears to be better tolerated than either carbamazepine or oxcarbazepine and may end up as a first-line treatment.
Benzodiazepines such as clonazepam can work for breakthrough pain and as a rescue medicine. Baclofen, a skeletal muscle relaxant, also can work well. Occasionally, a patient is incapacitated to the point of needing hospitalization. In these cases, IV fosphenytoin can be effective.
“There is no textbook definition of what’s medically refractory,” Dr. Rao said. “But generally speaking, we start thinking about surgical options when adequate medication trials are either ineffective for pain control, or they may be effective but cause adverse side effects to the point where the patient is having balance issues, cannot drive, cannot function and cannot work, for instance.”
Prior to making a surgical recommendation, a high-resolution MRI and a magnetic resonance angiogram, or MRA, is critical to review.
The MRI should include detailed slices through the brainstem to image the trigeminal nerve and evaluate for contrast in veins, arteries and tumors.
. The MRA will help rule out vascular malformations and ascertain whether an artery is in contact with the trigeminal nerve on the painful side of the face. If a neurovascular conflict exists, a post-contrast sequence helps confirm if the blood vessel is an artery or a vein.
If an artery is causing vascular compression of the nerve, touching the nerve or conflicting with the nerve, the patient may be a good candidate for a surgical procedure — a craniotomy for microvascular decompression.
To reach the trigeminal nerve, surgeons make a small opening in the skull and, using the microscope, go around the curvature of the cerebellum (rather than going through the brain) to the trigeminal nerve.
“If we find the artery up against the nerve, we typically just move it a few millimeters away, and we keep it away with a non-absorbable piece of material that looks like a cotton ball,” Dr. Rao said.
In patients with Type 1 trigeminal neuralgia, this surgery has an 80% to 90% chance of immediate nerve pain relief. With this technique, there may never be recurrence of trigeminal neuralgia pain.
Neurovascular conflict is not always the cause of trigeminal neuralgia. Recent research has shown that there is no neurovascular conflict in about 30% of people with trigeminal neuralgia. If this is the case, in a patient with medically refractory trigeminal neuralgia, it does not necessarily mean there is no surgical option. Rather, the decision-making and surgical options are individualized to the patient. Neurovascular conflict present on imaging also does not mean a patient will have or develop trigeminal neuralgia. Studies show that perhaps 5% to 20% of the population has neurovascular conflict on imaging, but has never had facial pain, according to Dr. Rao.
Other surgical treatment options include less-invasive techniques than microvascular decompression. These include focused radiation, such as stereotactic radiosurgery, and percutaneous ablative procedures, which use radiofrequency or mechanical compression to lesion the nerve.
Even after surgery, some patients still require medication, though possibly less than before. Drs. Plato and Rao have found that collaborative care allows them to develop individualized treatment plans for their patients, with the goal of minimizing pain and treatment side effects, and improving quality of life.