Definition and Overview
Trigeminal neuralgia (TN) is a neuropathic pain syndrome in which severe pain, like an electric shock or stabbing knife, occurs in one side of the face repeatedly for several seconds. It occurs in the face, forehead, and chin areas served by the trigeminal nerve (fifth cranial nerve), and is characterized by pain caused by minor daily stimulation.
The prevalence is reported to be approximately 4 to 13/100,000, and it occurs mainly after the age of 50 and is slightly more common in women. The pain intensity is extreme and has a serious impact on the patient's quality of life and mental health.
pathophysiology
trigeminal nerve anatomy
The trigeminal nerve has three main branches.
- Ophthalmic branch (V1): forehead, eyes, upper nose
- Maxillary branch (V2): cheeks, lower nose, upper lip
- Mandibular branch (V3): chin, lower lip, front of tongue
Trigeminal neuralgia mainly occurs in V2 alone (approximately 35%), V2+V3 combined (approximately 25%), and V3 alone (approximately 25%).
Primary trigeminal neuralgia (compression of blood vessels)
The cause of primary (classic) trigeminal neuralgia is compression of blood vessels in the root entry zone of the trigeminal nerve. The superior cerebellar artery accounts for approximately 75-80% of the compressed blood vessels. Chronic vascular pulsatile compression damages nerve myelin, resulting in ectopic discharge and ephaptic transmission between axons.
Secondary trigeminal neuralgia
Causes of secondary trigeminal neuralgia include multiple sclerosis (demyelinating plaque), brainstem or cerebellopontine limb tumor, and arteriovenous malformation. If the disease occurs before the age of 40, is bilateral, or has atypical characteristics, secondary causes need to be determined.
symptoms
Typical trigeminal neuralgia
The typical characteristics of trigeminal neuralgia according to the International Headache Society (ICHD-3) classification are as follows.
- Pain characteristics: Severe pain that feels like an electric shock or knife stabbing.
- Duration: Paroxysmal pain lasting from a few seconds to 2 minutes.
- Distribution: Unilateral, following the distribution of the trigeminal nerve branches.
- Triggers: Chewing, talking, washing your face, brushing your teeth, cold wind
- Pain-free interval: complete absence of pain between attacks.
Atypical trigeminal neuralgia
If it is accompanied by persistent pain or dull background pain, it is classified as atypical trigeminal neuralgia. Response to treatment may be lower than in the typical type.
diagnosis
clinical diagnosis
Trigeminal neuralgia is diagnosed based on characteristic clinical features. The nature of the paroxysmal pain, trigeminal nerve distribution, trigger stimulus, and pain-free interval are key diagnostic factors.
imaging test
Magnetic resonance imaging (MRI) is an essential test that evaluates:
- Whether there is vascular compression (high-resolution MRI, 3D FIESTA or CISS techniques)
- Differentiating secondary causes (tumors, multiple sclerosis lesions, vascular malformations)
Differential diagnosis
| disease | Differentiation points | |------|---------------| | Postherpetic neuralgia | Previous history of shingles, persistent burning pain | | Cluster headache | Pain around the eyes, accompanied by autonomic symptoms | | Toothache | Dental examination, confirmation of dental causes | | Temporomandibular joint disorder | Temporomandibular joint tenderness, limited mouth opening | | facial migraine | Pulsating headache, accompanied by nausea |
treatment
Primary drug treatment
Carbamazepine As a first-line treatment for trigeminal neuralgia, it inhibits ectopic nerve firing by blocking voltage-dependent sodium channels. In a Cochrane systematic review, the number needed to treat (NNT) was reported to be 1.8. Adjust the dose in the range of 200 to 1200 mg/day. Side effects include drowsiness, dizziness, hyponatremia, and rarely Stevens-Johnson syndrome.
Oxcarbazepine A keto derivative of carbamazepine, with similar efficacy and improved tolerability. The risk of hyponatremia is higher.
auxiliary medication - Lamotrigine: Can be used in combination with carbamazepine - Gabapentin/Pregabalin: Adjunctive treatment - Baclofen: GABA-B agonist, can be used together
invasive treatment
Microvascular Decompression (MVD) It is a surgical treatment to relieve blood vessel compression through suboccipital craniotomy. In patients with primary trigeminal neuralgia with confirmed vascular compression, the long-term pain disappearance rate is reported to be over 70% and the pain-free maintenance rate for more than one year is approximately 75%. It is considered the optimal treatment for patients who can tolerate surgical risks.
Radiosurgery Focused radiation is irradiated to the root of the trigeminal nerve using a Gamma Knife or Cyberknife. Although it is non-invasive, it takes several weeks to several months to take effect, and the recurrence rate is higher than that of MVD. Consider it in elderly or high-risk groups for surgery.
Percutaneous trigeminal ganglion surgery There are percutaneous balloon compression, glycerol injection, and radiofrequency thermocoagulation. Although immediate pain relief can be achieved with a daily procedure, there are complications such as decreased sensation.
Complications and Prognosis
With appropriate treatment, pain can be controlled in most patients. However, the following may occur.
- Drug treatment: long-term reduction in drug effectiveness or development of resistance
- Natural course: Spontaneous remission may occur in some
- After surgery: MVD has an excellent long-term recurrence-free rate, but recurrence is possible.
If left untreated, pain can lead to eating disorders, weight loss, depression, and social isolation, so early diagnosis and active treatment are important.
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This information is provided for medical educational purposes and is not a substitute for individual medical care or treatment. If you have any symptoms, be sure to seek professional advice. Inquiries: Osang Neurosurgery 1599-5453 | osns.co.kr