Trigeminal neuralgia

Disease Description (Causes and Symptoms)

• Definition: Trigeminal neuropathy (including trigeminal neuralgia) refers to a condition in which severe paroxysmal facial pain or sensory abnormalities occur due to pathological changes in the trigeminal nerve (related to facial sensation and the muscles of mastication).
• Main pathophysiology:
  • Classical (idiopathic) trigeminal neuralgia is often caused by vascular compression (e.g., by the superior cerebellar artery) of the proximal trigeminal nerve, resulting in demyelination and hyperexcitability.
  • Secondary trigeminal neuropathy occurs due to structural or organic causes such as trauma, tumors, infection (e.g., herpes zoster), inflammation, and multiple sclerosis.
• Main symptoms:
  • Paroxysmal, sharp, electric shock-like pain on one side of the face (lasting from fractions of a second to several minutes), occurring most commonly in the distribution of the second (maxillary) and third (mandibular) divisions.
  • Triggered by light stimuli such as speaking, chewing, washing the face, or brushing the teeth, with specific trigger points present.
  • Facial twitching (tic douloureux) may occur during pain attacks.
  • Some patients have accompanying sensory loss or weakness of the masticatory muscles, and pathological causes such as herpes zoster may be accompanied by a rash and neurological deficits.

Treatment Methods

• Medication treatment (initial standard)
  • Carbamazepine: First-line medication. A typical starting dose is 100–200 mg once or twice daily, with divided dose increases according to symptoms; the usual effective range is 200–1200 mg/day. Regular blood tests (CBC, liver function, and electrolytes, especially Na) and monitoring for adverse effects are required during treatment.
  • Oxcarbazepine: An alternative to carbamazepine, with relatively fewer adverse effects and drug interactions.
  • Other adjunctive medications: gabapentin, pregabalin, lamotrigine, baclofen, valproic acid, etc. (selected according to the individual patient).
  • Caution: In Asian patients, testing for HLA-B*1502 is recommended before administering carbamazepine if positive status is suspected or applicable, to prevent severe skin reactions.
• Procedural and surgical treatment
  • Microvascular decompression (MVD): Effective for long-term pain relief in patients with confirmed or suspected vascular compression. It requires general anesthesia and craniotomy, and careful patient selection is important.
  • Percutaneous procedures: Radiofrequency thermocoagulation, glycerol rhizotomy, and balloon compression — provide rapid pain relief, but carry a risk of sensory loss.
  • Gamma Knife (radiosurgery): A noninvasive option; it may take several weeks to several months after the procedure to achieve full effect.
  • Peripheral approaches (local treatment of nerve branches, cryotherapy, etc.): Considered only for symptoms involving specific branches.
• Lifestyle management and precautions
  • Avoid or control pain-triggering activities (cold air, chewing, speaking, etc.) and keep a pain diary.
  • Monitor for drowsiness, dizziness, gastrointestinal symptoms, hematologic abnormalities, and other issues when taking medication.
  • Before dental treatment, consult a physician and undergo evaluation of the cause (to avoid unnecessary tooth extraction, etc.).

Checklist Before an Outpatient Visit (Including Example Questions)

• Items and information to bring
  • A list of all medications currently being taken (including prescriptions, over-the-counter medications, herbal medicines, etc.)
  • History of allergies (especially medications and drug reactions)
  • Previous medical records and imaging test results such as MRI scans (if available, bring the originals or a CD)
  • Symptom diary: frequency, duration, triggers, intensity (pain scale), and behavior during attacks
  • Recent history of head trauma, herpes zoster (blisters), or ear and sinus disease
• Items useful to record during the outpatient visit
  • Actions that trigger the pain (e.g., brushing the teeth, speaking, etc.)
  • Dates and times of starting or stopping medications and their effects/adverse effects
  • Changes in sleep, meals, and stress

Examples of General Questions to Ask the Doctor

• "Is this pain typical of trigeminal neuralgia?"
• "What initial medication do you recommend, and what adverse effects and monitoring should I expect?"
• "Do I need an MRI or additional tests? If so, what tests are needed?"
• "If the pain is not controlled with medication, what procedures or surgeries could be considered?"
• "What activities should I avoid or what precautions should I take in daily life to reduce the pain?"

Examples of Condition-Specific Questions

• "Does the MRI show that a blood vessel is compressing the trigeminal nerve? Am I a suitable candidate for microvascular decompression?"
• "I am planning to start carbamazepine. Should I have an HLA-B*1502 test or blood tests first? What should the testing schedule and monitoring intervals be?"

Additional References

• Diagnosis is primarily clinical (based on symptoms and attack patterns), and brain MRI (focused on the trigeminal nerve pathway) is recommended to rule out suspected secondary causes such as tumors, multiple sclerosis, and infection.
• Complications include medication adverse effects (abnormalities in blood or liver function and skin reactions), as well as sensory loss, corneal anesthesia, and anesthesia dolorosa (coexisting pain and sensory loss) after procedures. The risks of each procedure should be discussed in advance.