Facial sensation is supplied by the trigeminal nerve. This is subdivided into three main branches: the ophthalmic (V1), maxillary (V2) and mandibular branches (V3). This nerve conveys painful sensations, for example a toothache from its origin in the dental pulp chamber into the brain, On rare occasions a malfunctioning of the nerve occurs similar to a ‘shortcircuiting’ of an electrical device.
3. How do I know I have TN?
The pain is classically severe in intensity and electric-like in quality. It may present spontaneously or it can be triggered by a variety of stimuli such as laughing, brushing teeth, talking, eating, applying make-up or by wind simply blowing against the face. These ‘darts’ of pain will generally last for seconds in duration but multiple darts may occur in succession. It may stop you in your tracks momentarily until the painful episode passes over. It is usually unilateral and rarely crosses the midline. Episodes can last for days, weeks, or months at a time and then disappear for months or years. For some patients the attacks often worsen over time, with fewer and shorter pain-free periods before they recur.
4. What signs or symptoms may occur?
TN may be accompanied by trigger zones. These trigger zones are generally located adjacent to the lips or nose and on simulation will elicit a bout of shooting pain. Following stimulation, a refractory period will then occur and further pain is unlikely for a short period of time (secs-mins)
5. What causes TN?
The theory that is generally accepted is that this disorder is triggered by a blood vessel that compresses the trigeminal nerve as it exits the brain. This causes a ‘short circuiting’ within the nerve which clinically manifests as shooting pain. However, any form of trigeminal nerve compression may present with similar symptoms. Such examples may include brain tumors, cysts or multiple sclerosis. Consequently a brain scan is often taken in patients with TN.
7. How do you diagnose TN?
There are no specific tests to diagnose TN. The diagnosis is made from the clinical history. Various investigations can be performed to eliminate the possibility of other facial pain conditions such as a dental / sinus infection i.e. an x ray.
8. What treatments are available?
Once a correct diagnosis is made, a medication trial is indicated. The medications that are utilized in TN are also used for epilepsy. Examples include carbamazepine, and gabapentin. Typical painkillers and opioids are not usually helpful in treating the sharp, recurring pain caused by TN. As a general rule, start with a low dose and slowly titrate until pain relief is achieved. If side-effects are an issue a medication change maybe warranted. A patient may need to try out different medications before pain relief is achieved or indeed two medications can be used in conjunction to provide optimum pain relief. This treatment should only be provided under medical / dental supervision.
Neurosurgical intervention should be considered when pharmacological methods do not provide any significant relief or when side effects are problematic. There are various surgical options. Open brain surgery (microvascular decompression) is performed in cases where a blood vessel is identified rubbing against the trigeminal nerve as it exits the brainstem. An insulating material is ‘glued’ between the blood vessel and nerve to form a protective barrier. Additionally, a number of destructive percutaneous techniques can also be used to partially damage the trigeminal nerve.
9. What is the prognosis?
The disorder is characterized by recurrences and remissions, and successive recurrences may incapacitate the patient. The remission periods can vary from weeks to months and years. Due to the intensity of the pain during an active period, even the fear of an impending attack may prevent activity. Patients are often afraid to shave, brush their teeth or apply make-up with fear that they may precipitate an attack. However Trigeminal neuralgia is not fatal.
10. What other facial pain conditions can resemble TN?
TN is commonly misdiagnosed as toothache, sinus pain, ear pain, or wisdom tooth pain. This is probably due to the fact that it is a rare disorder and a dentist or general medical practitioner may see very few cases in their practicing lifetime. Furthermore, there are a large number of conditions that can cause facial pain and consequently the diagnosis is not always predictable or straightforward.