Trigeminal Neuralgia
Trigeminal neuralgia (TN), also known as tic douloureux, is one of the most painful disorders of the orofacial region and medical practice [1]. It is usually felt as unilateral, recurrent and abrupt pain along with the innervation of the Trigeminal Nerve – typically radiating to the maxillary and mandibular branches [2]. Patients presenting with TN often describe the pain as electric shock-like pains accompanied by a brief facial spasm or tic. Trigeminal neuralgia may occur spontaneously or initiated by non-noxious stimuli such as eating, talking, brushing teeth or even a cool breeze [1], [3].
EPIDEMIOLOGY
Presentation of trigeminal neuralgia is rare, and adequate study on the subject lacking [3]. Available data, however, shows that in 90% of cases, symptoms are more likely to present in ages over 40 years with incidence increasing progressively with age, ranging from 17.5/100,000/year of adults between 60 to 69 years to 25.6/100,000/year after 70 years [3].
Even though there is no known racial or geographic difference in TN incidence, there are studies that suggest that some patient populations are at higher risk [4]. In multiple sclerosis (MS), TN occurs frequently and precedes the diagnosis of MS by as much as 15.0% of individuals [3], [4].
Genetics was even rarer in TN cases, accounting for only about 1-2% of all cases [3].
AETIOLOGY
Trigeminal neuralgia is said to commonly occur in cases of compression of the trigeminal nerve by nearby blood vessels [5]. Some studies have even suggested that hypertension may be a predisposing factor for TN, however, because of contradictory data, results are still listed as inconclusive [3].
Onset may also be caused by a dental procedure or by trauma or damage to the trigeminal nerve by other medical conditions, such as multiple sclerosis, or a tumour [6], [5].
SIGNS AND SYMPTOMS
Trigeminal neuralgia manifests more often in women than men with both sexes experiencing episodes of unilateral short-lasting pain attacks involving one or more branches of the trigeminal nerve [2], [3].
Interestingly, pain on the right side has been reported more often than on the left. Pain may be spontaneous or be stimulated by non-noxious activities such as a light touch, talking, eating, shaving, or even a cool breeze [5]. These sharp, lancinating, electric-like attacks may occur several times per day, lasting a few seconds up to two minutes [3], [2]. Duration, frequency, and severity may worsen over time [3].
Patients also experience periods of relief between episodes but may develop anxiety from the thought of recurrent pain [6]. Oftentimes, psychological distress causes a notable reduction in a patient’s quality of life [3].
DIAGNOSIS
There are several painful facial conditions that may delay the diagnosis of trigeminal neuralgia. Dentoalveolar or musculoskeletal origin may be easily differentiated, however, some rare headaches, migraines, and neuropathic pain, in addition to the rareness of TN, may confound the clinician [3].
According to the International Headache Society (IHS), diagnosis of TN should have at least 3 pain episodes with: 1) Recurrent paroxysms of unilateral facial pain in one or more of the branches of the trigeminal nerve, with no radiation beyond; 2) Pain lasting from less than a second to two minutes, severe intensity and electric shock-like, shooting, stabbing or sharp in quality; 3) Precipitated by innocuous stimuli within the affected trigeminal [3].
The main differentiating features of TN from other forms of orofacial pain are the short duration of pain attacks, affecting only one side of the face, and being restricted to the branches of the trigeminal nerve [3].
Magnetic Resonance Imaging (MRI) techniques can also be used to identify any possible symptomatic causes such as multiple sclerosis or tumours, and if surgery would be needed [3].
TREATMENT
Pharmacological Treatment
Due to the chronic nature of TN, pharmacological treatment may take a longer duration. The anticonvulsant, carbamazepine, is usually the first treatment recommended [5]. Carbamazepine is highly effective in reducing pain by slowing electrical impulses, mainly in the blockade of sodium channels in the nerves, thereby reducing their ability to transmit pain signals [5]. Onset is rapid, but because of side effects experienced from prolonged use, other drugs for the treatment of TN are being tested [3].
Surgical Interventions
Surgical interventions are indicated for patients with severe symptoms of TN, recurrent TN, or for patients with intolerable adverse reactions to pharmacological treatment [3]. Surgical management of TN may include either non-ablative, which is the decompression of nerve, or ablation, which is where the sensory function of the trigeminal nerve is inhibited by damaging the nerve fibres [3], [6].
There are different surgical techniques used, each with its own benefits and risks, as well as different rates of success and indications for patients [3]. Careful consideration should be done before any procedure is carried out [3].
CONCLUSION
Trigeminal neuralgia is a rare and extremely painful condition. There are still many studies needed to properly understand this disorder. Although the condition is not fatal, the psychological distress on the patient may severely affect their quality of life. It is therefore very important to care for and help those who may be living with trigeminal neuralgia.
References
[1]
M. K. Singh, G. H. Campbell, S. Gautam and H. L. Lutsep, "Trigeminal Neuralgia," Medscape, 11 July 2019. [Online]. Available: https://emedicine.medscape.com/article/1145144-overview. [Accessed 13 May 2021].
[2]
I. P. D. Toledo, J. C. Reus, M. Fernandes, A. L. Porporatti, M. A. Peres, A. Takaschima, M. N. Linhares, E. Guerra and G. D. L. Canto, "Prevalence of trigeminal neuralgia: A systemic review," Journal of the American Dental Association, vol. 7, no. 147, 2016.
[3]
E. I. Araya, R. F. Claudino, E. J. Piovesan and J. G. Chichorro, "Trigeminal Neuralgia: Basic and Clinical Aspects," Current Neuropharmacology, vol. 18, no. 2, pp. 109-119, 2020.
[4]
A. Fallata, A. Salter, T. Tyry, G. R. Cutter and R. A. Marrie, "Trigeminal Neuralgia Commonly Precedes the Diagnosis of Multiple Sclerosis," International Journal of MS Care, vol. 19, no. 5, pp. 240-246, 2017.
[5]
"Trigeminal neuralgia," NHS, 6 August 2019. [Online]. Available: https://www.nhs.uk/conditions/trigeminal-neuralgia/. [Accessed 13 May 2021].
[6]
"Trigeminal Neuralgia," Johns Hopkins, [Online]. Available: https://www.hopkinsmedicine.org/health/conditions-and-diseases/trigeminal-neuralgia. [Accessed 13 May 2021].