Definition and Overview
Trigeminal neuralgia (TN) is a neuropathic pain syndrome characterized by paroxysmal episodes of excruciating pain on one side of the face, described as electric shock-like or stabbing, lasting several seconds. It occurs in the face, forehead, and jaw regions innervated by the trigeminal nerve (cranial nerve V), and is characteristically triggered by minor everyday stimuli.
The prevalence is reported at approximately 4-13 per 100,000 [1], occurring predominantly after age 50 and slightly more commonly in women. The extreme pain intensity severely impacts patients' quality of life and mental health.
Pathophysiology
Trigeminal Nerve Anatomy
The trigeminal nerve has three major branches.
- Ophthalmic branch (V1): Forehead, eye, upper nose
- Maxillary branch (V2): Cheek, lower nose, upper lip
- Mandibular branch (V3): Jaw, lower lip, anterior tongue
Trigeminal neuralgia most commonly occurs in the V2 distribution alone (approximately 35%), V2+V3 combined (approximately 25%), or V3 alone (approximately 25%) [1].
Primary Trigeminal Neuralgia (Vascular Compression)
The cause of primary (classical) trigeminal neuralgia is vascular compression at the root entry zone of the trigeminal nerve. The superior cerebellar artery is the offending vessel in approximately 75-80% of cases. Chronic pulsatile vascular compression damages the nerve myelin, resulting in ectopic discharge and ephaptic transmission between axons.
Secondary Trigeminal Neuralgia
Causes of secondary trigeminal neuralgia include multiple sclerosis (demyelinating plaques), brainstem or cerebellopontine angle tumors, and arteriovenous malformations. Secondary causes should be investigated when onset occurs before age 40, is bilateral, or presents with atypical features.
Symptoms
Classical Trigeminal Neuralgia
According to the International Headache Society (ICHD-3) classification, the characteristics of classical trigeminal neuralgia are as follows.
- Pain quality: Electric shock-like or stabbing excruciating pain
- Duration: Paroxysmal pain lasting from seconds to less than 2 minutes
- Distribution: Unilateral, following trigeminal nerve branch distribution
- Triggering factors: Chewing, speaking, face washing, tooth brushing, cold wind
- Pain-free intervals: Complete pain resolution between attacks
Atypical Trigeminal Neuralgia
Cases accompanied by persistent pain or dull background pain are classified as atypical trigeminal neuralgia. Treatment response may be lower than in the classical type.
Diagnosis
Clinical Diagnosis
Trigeminal neuralgia is diagnosed based on its characteristic clinical presentation. The key diagnostic elements are the paroxysmal pain characteristics, trigeminal nerve distribution, triggering stimuli, and pain-free intervals.
Imaging Studies
MRI (magnetic resonance imaging) is an essential study to evaluate the following.
- Presence of vascular compression (high-resolution MRI, 3D FIESTA or CISS sequences)
- Differentiation of secondary causes (tumors, multiple sclerosis lesions, vascular malformations)
Differential Diagnosis
| Condition | Differentiating Points |
|------|------------|
| Postherpetic neuralgia | History of herpes zoster, persistent burning pain |
| Cluster headache | Periorbital pain, accompanying autonomic symptoms |
| Dental pain | Dental examination, confirmation of dental cause |
| Temporomandibular joint disorder | Jaw joint tenderness, limited mouth opening |
| Facial migraine | Pulsating headache, accompanying nausea |
Treatment
First-Line Pharmacotherapy
Carbamazepine
The first-line treatment for trigeminal neuralgia, which blocks voltage-dependent sodium channels to suppress ectopic neural discharge. A Cochrane systematic review reported an NNT (number needed to treat) of 1.8 [2]. Doses are titrated within the range of 200-1200 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.
Adjunctive medications
- Lamotrigine: Can be combined with carbamazepine
- Gabapentin/pregabalin: Adjunctive therapy
- Baclofen: GABA-B agonist, can be used in combination
Invasive Treatments
Microvascular Decompression (MVD)
A surgical treatment that relieves vascular compression through suboccipital craniotomy. In primary trigeminal neuralgia patients with confirmed vascular compression, long-term pain relief rates exceed 70%, with approximately 75% maintaining pain-free status at one year or more [3]. It is considered the optimal treatment for patients who can tolerate surgical risks.
Radiosurgery
Focused radiation is delivered to the trigeminal nerve root using Gamma Knife or CyberKnife. Although non-invasive, onset of effect requires weeks to months, and recurrence rates are higher than MVD. It is considered for elderly or high surgical risk patients.
Percutaneous trigeminal ganglion procedures
These include percutaneous balloon compression, glycerol injection, and radiofrequency thermocoagulation. Immediate pain relief can be achieved as outpatient procedures, but complications such as sensory deficit may occur.
Complications and Prognosis
With appropriate treatment, pain control is achievable in most patients. However, the following clinical courses may occur.
- Pharmacotherapy: Long-term diminished drug efficacy or tolerance development
- Natural course: Periods of spontaneous remission occur in some patients
- Post-surgical: MVD has excellent long-term recurrence-free rates, but recurrence is possible
Without treatment, pain-induced eating difficulties, weight loss, depression, and social isolation may develop, making early diagnosis and proactive treatment essential.
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This information is provided for medical educational purposes and does not replace individual medical consultation or treatment.
If you have symptoms, please consult a specialist.
Contact: OSANG Neurosurgery 1599-5453 | osns.co.kr