Trigeminal Neuralgia is an uncommon disorder characterized by recurrent attacks of lancinating pain in the trigeminal nerve distribution. Typically, brief attacks are triggered by talking, chewing, teeth brushing, shaving, a light touch, or even a cool breeze. The pain is nearly always unilateral, and it may occur repeatedly throughout the day. (Krafft. et.al)
According to the beta version of the 3rd edition of the International Classification of Headache Disorders (ICHD-3 Beta), trigeminal neuralgia (TN) is a disorder characterized by recurrent unilateral brief electric shock-like pains, abrupt in onset and termination, limited to the distribution of one or more divisions of the trigeminal nerve and triggered by innocuous stimuli. Since TN pain is located in the maxillofacial region, it can be mistaken for a toothache. To eliminate this confusion, the clinician needs to be aware of TN features to exclude its possibility as a source of pain, and to avoid unnecessary and irreversible dental treatments.
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TN is further subclassified into classical, secondary, or idiopathic, depending on the underlying cause. Here are some unique features that are characteristic of TN pain which can help the clinician in identifying such cases:
- Some pain attacks may be spontaneous but, to be considered TN, a minimum of 3 attacks should be elicited either by a non-painful stimulus like touching the area, blowing air, or even by movement (chewing, talking, turning the head). The duration of each pain episode can vary from a fraction of a second up to 2 minutes, and in many cases, the patient will remember the first time it happened.
- Sensory changes in the affected area are very important and need to be determined carefully; Hypoesthesia or hypoalgesia indicates the presence of neuropathy, and these cases need more diagnostic investigation. On the other hand, if there is a complaint of hyperalgesia, it is the clinician’s responsibility to differentiate between subjective hyperalgesia and objective hyperalgesia in this case.
- The distribution of the pain is very unique and can provide an additional clue for the diagnosis. Usually, TN affects either the maxillary, the mandibular division, or both, but it rarely affects the ophthalmic division of the trigeminal nerve. In classical cases of TN, the pain attack will be on only one side of the face, but when the pain crosses the midline or is on both sides of the face (bilateral), the clinician needs to suspect a secondary cause such as multiple sclerosis.
- A refractory period usually follows the pain episode; the nerve will be hyperpolarized, and the pain cannot be triggered during this period.
- A remission period is also an important feature. The pain attacks might disappear for weeks or even years before it comes back again.
- Muscle contraction or twitching can occur during a paroxysm when the pain is very severe, this is why TN is used to be called “Tic Douloureux”. Also, the patient might have redness or tear in the eye due to the involvement of the autonomic system.
- Over time, pain intervals will decrease, while pain episodes, on the other hand, will get longer in duration and stronger in intensity. When this is the case, they will cause psychological problems like anxiety, depression, and suicidal ideation.
- In some cases, there might be an atypical persistent pain preceding, and gradually maturing to the classical pain of TN. This stage of immature TN is termed trigeminal neuralgia.
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References:
- https://www.ichd-3.org/wp-content/uploads/2016/08/International-Headache-Classification-III-ICHD-III-2013-Beta-1.pdf
- Rehman A, Abbas I; Alamgir, Ghous SM, Ahmad N, Ahmad A. Association Between Trigeminal Neuralgia And Unnecessary Tooth Extraction. J Ayub Med Coll Abbottabad. 2021 Jan-Mar;33(1):116-119. PMID: 33774966.
- Krafft RM. Trigeminal neuralgia. Am Fam Physician. 2008 May 1;77(9):1291-6. PMID: 18540495.