Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a chronic neuropathic pain condition characterized by sudden, brief episodes of severe, electric shock–like, lancinating unilateral facial pain in one or more trigeminal nerve distributions, triggered by innocuous stimuli.[1-2] It is classified as classic (neurovascular compression, ~75%), secondary (~15%, due to MS or tumor), or idiopathic (~10%).[1] Average age of onset is 50–60 years, with higher prevalence in women and increasing incidence with age.[2]

1. History

Character of pain: Electric shock–like, shooting, stabbing, sharp — paroxysms lasting a fraction of a second to 2 minutes (usually seconds)[1][3]
Location: Unilateral, most commonly V2 (maxillary) or V3 (mandibular); right side more common than left[1]
Triggers: Light touch to face, talking, chewing, brushing teeth, shaving, wind/breeze across trigger zone. Trigger zones are small, discrete areas — nearly pathognomonic for TN[2][4]
Frequency: Attacks may recur hundreds of times per day; episodes cluster over weeks to months with pain-free intervals lasting months to years[2]
Refractory period: Some patients note a brief period after a paroxysm during which additional pain cannot be triggered[4]
Concomitant continuous pain: A subset has mild-to-moderate background aching/throbbing between paroxysms[2-3]
Important negatives: No numbness (suggests neuropathy), no persistent burning, no bilateral simultaneous pain, no pain outside trigeminal territory[4]

2. Alarm Features

Bilateral pain — raises concern for MS, systemic disease, or non-neurologic cranial pathology[1]
Sensory loss/numbness in the trigeminal distribution — suggests secondary TN (tumor, MS, neuropathy)[2-3]
Other neurologic deficits (weakness, ataxia, visual changes) — concerning for intracranial mass or demyelinating disease[1-2]
Young age at onset (<40 years) — higher suspicion for MS-related TN[1]
First division (V1) involvement alone — less typical; consider alternative diagnoses[5]
Progressive pain with no remission periods — consider malignancy or infiltrative process[1]
Severe exacerbation with inability to eat/drink — risk of dehydration and malnutrition; may require hospitalization[3]

3. Medications

First-line

Carbamazepine — drug of choice; start 200 mg BID, titrate by 200 mg/day every few days to max 1,200 mg/day; NNT ~2 for meaningful pain relief; ~75% initial response rate[1-2][5]
Oxcarbazepine — alternative first-line, 300–1,800 mg/day in divided doses; potentially fewer side effects; high cross-reactivity risk if allergic to carbamazepine[1-2][6]

Second-line / adjunctive

Lamotrigine, gabapentin, pregabalin, baclofen, botulinum toxin type A, phenytoin — used as monotherapy or add-on when first-line fails[6]

Acute exacerbation (ED)

IV fosphenytoin or IV lidocaine — limited evidence but clinical experience supports efficacy; requires monitored setting[3][7]
Opioids are ineffective in safe doses and should be avoided[3]
NSAIDs are generally ineffective for neuralgic pain[7]
Lidocaine injection into trigger zones may provide short-term relief[3]

Contraindications/cautions for carbamazepine

Cardiac conduction abnormalities (AV block)[1]
Hepatic porphyria[8]
HLA-B15:02 screening required before initiation in patients of Southeast Asian, South Asian, or other at-risk ancestry — risk of fatal SJS/TEN. HLA-A31:01 also associated with hypersensitivity in European, Korean, and Japanese populations[9-10]
Side effects: dizziness, diplopia, ataxia, hyponatremia, elevated transaminases, Stevens-Johnson syndrome, aplastic anemia (rare), osteoporosis with long-term use[1-2]
Significant drug-drug interactions (CYP3A4 inducer) — affects oral contraceptives, warfarin, many other medications[1]
Carbamazepine may have a 50% failure rate over 5–10 years[2]

4. Diet

During severe exacerbations, eating and drinking can trigger attacks, leading to dehydration and malnutrition — a key reason for hospitalization[3]
Soft, room-temperature foods may reduce trigger stimulation during flares
No specific long-term dietary modifications are evidence-based for TN
Patients on carbamazepine should be counseled about adequate hydration given hyponatremia risk[8]

5. Review of Systems

Neurologic: Visual changes, diplopia, limb weakness/numbness, gait instability (screen for MS)[1]
Ophthalmologic: Eye redness, tearing (autonomic phenomena can occur during flares)[2]
Dental: Prior dental procedures, tooth pain, jaw pain (>80% of TN patients initially seek dental evaluation)[2]
ENT: Ear pain, hearing changes, nasal congestion, sinus symptoms
Psychiatric: Depression, anxiety, suicidal ideation — TN profoundly impacts quality of life[2][11]
Constitutional: Weight loss from inability to eat during exacerbations

6. Collateral History and Family History

Family history of TN: 1–2% of patients may have a familial link; rare variants in voltage-gated ion channel genes have been identified[1-2]
History of MS in patient or family — TN prevalence is 2–5% in MS patients (20-fold increased risk vs. general population)[1][12]
Collateral from dentist: Prior dental evaluations, procedures, or extractions for presumed dental pain (common misdiagnosis)
Social context: Functional impairment, inability to work, social withdrawal due to fear of triggering pain

7. Risk Factors

Age >50 years — incidence increases with age[2]
Female sex — higher prevalence[1-2]
Multiple sclerosis — strongest disease association (OR 8.9 in one population study)[1][13]
Hypertension — associated with higher TN incidence[2]
Other neurovascular compression disorders (glossopharyngeal neuralgia, hemifacial spasm)[13]
Systemic lupus erythematosus — emerging association (OR 2.84)[13]
Hyperlipidemia and complex diabetes — associated in population-level data[13]

8. Differential Diagnosis

Export Diagnosis Distinguishing Features References Dental pain (caries, cracked tooth, pulpitis) Localized; related to biting or hot/cold foods; visible oral abnormalities[1-2]
Glossopharyngeal neuralgia Pain in tongue, pharynx, or deep ear; triggered by swallowing/coughing[1-2]
TMJ disorder Persistent aching pain near ear/jaw; bilateral possible; jaw clicking[1-2]
Cluster headache Longer-lasting (15–180 min); orbital/supraorbital; prominent autonomic symptoms; restlessness[1-2]
SUNCT/SUNA Periocular; prominent autonomic symptoms; no refractory period; can change sides[1-2]
Paroxysmal hemicrania Forehead/eye pain; autonomic symptoms; responds to indomethacin[1-2]
Postherpetic neuralgia Continuous burning pain; history of herpes zoster; often V1[1-2]
Persistent idiopathic facial pain Dull, aching, constant; poorly localized; no trigger zones[2-3]
Intracranial tumor Progressive; may have other neurologic signs[1, 4]
Giant cell arteritis Persistent temporal pain; jaw claudication; age >50; elevated ESR/CRP[1, 5]
Trigeminal neuropathy Persistent pain with sensory loss; history of trauma or autoimmune disease[1, 4]

9. Past Medical History

Multiple sclerosis — most important associated condition[1]
Prior dental procedures — may have caused post-traumatic trigeminal neuropathy mimicking TN[1]
Facial trauma or maxillofacial surgery[1]
Hypertension — associated with TN and relevant to neurovascular compression[2]
Previous TN episodes — natural history includes remissions and relapses; prior medication trials and responses
Autoimmune conditions (SLE, scleroderma) — can cause trigeminal neuropathy[1][13]

10. Physical Exam

Between attacks, exam is typically normal — this is characteristic of TN[2]
Focused cranial nerve exam: Test all three trigeminal divisions for light touch, pinprick, and temperature; test corneal reflex; assess masseter/temporalis strength
Trigger zone testing: Light touch to perioral/perinasal area may reproduce pain (be cautious — can provoke severe paroxysm)
Facial sensation: Any numbness or hypoesthesia is a red flag for secondary TN[2-3]
Other cranial nerves: Assess hearing (CN VIII — relevant for cerebellopontine angle pathology), facial symmetry (CN VII)
Fundoscopic exam if concern for intracranial pathology
Vital signs: Generally normal; tachycardia/hypertension may be present during acute pain crisis
Oral exam: Rule out dental pathology, mucosal lesions

11. Lab Studies

Blood tests are not recommended to diagnose TN[2]
Pre-carbamazepine labs: CBC (risk of aplastic anemia/agranulocytosis), CMP (hepatic function, sodium baseline), HLA-B15:02 in at-risk populations[9-10]
Monitoring on carbamazepine: Periodic CBC, hepatic function, sodium levels[8]
If secondary TN suspected: ESR/CRP (giant cell arteritis), ANA (autoimmune), consider LP if MS suspected
Serum drug levels of carbamazepine are not routinely needed for efficacy monitoring (unlike epilepsy)[3]

12. Imaging

Brain MRI with and without contrast is recommended for all patients with suspected TN to rule out MS, tumor, cerebral aneurysm, and AVM[2][6]
3D time-of-flight MRA identifies neurovascular compression with 95% sensitivity, 77% specificity[2]
High-resolution sequences (3D CISS, 3D FIESTA, 3D FLASH) improve visualization of neurovascular conflict; 3.0T preferred over 1.5T[3][6][16]
MRI findings in classic TN: neurovascular contact with morphological changes (displacement, indentation, atrophy) of the trigeminal nerve root[3]
Demonstration of neurovascular contact should NOT confirm the diagnosis — it facilitates surgical decision-making[3]
If MRI is contraindicated: CT with contrast to rule out tumors[6]
Imaging is unnecessary to confirm the clinical diagnosis when presentation is classic, but is needed to exclude secondary causes[6]
The following figure outlines the AAFP's recommended diagnostic and treatment algorithm:
View full figure Figure 2. Diagnosis and treatment of trigeminal neuralgia. Adapted with permission from Krafft RM. Trigeminal neuralgia. Am Fam Physician. 2008;77(9):1295. Trigeminal Neuralgia: Rapid Evidence Review. Am Fam Physician. April 30, 2025.

13. Special Tests

Electrophysiologic trigeminal nerve reflex testing: Distinguishes classic from secondary TN with sensitivity 96%, specificity 93% (LR+ 14, LR− 0.04); useful when MRI is contraindicated or atypical features are present[2][17]
Quantitative sensory testing (QST): Can detect subclinical sensory abnormalities; primarily a research tool[3]
Diffusion tensor imaging (DTI): Emerging modality showing microstructural changes in the trigeminal nerve; not yet standard clinical practice[3][16]

14. ECG

Pre-treatment ECG is recommended before starting carbamazepine — contraindicated in patients with AV block or other cardiac conduction abnormalities[1][8]
Carbamazepine has mild anticholinergic activity and sodium-channel blocking properties that can worsen conduction defects[8]
ECG is not part of the diagnostic workup for TN itself

15. Assessment

Clinical summary: TN is a clinical diagnosis based on ICHD-3 criteria — recurrent unilateral paroxysmal facial pain in trigeminal distribution, lasting <2 minutes, electric shock–like quality, triggered by innocuous stimuli.[1][3] Triggered paroxysmal pain is reported by 91–99% of patients and may be pathognomonic.[1]

Classification

Classic TN: Neurovascular compression with morphological nerve changes on MRI (~75%)
Secondary TN: MS, tumor, AVM (~15%) — younger patients, more likely to have sensory loss and bilateral pain[1]
Idiopathic TN: No identifiable cause (~10%)[1]
Subclassification: Purely paroxysmal vs. with concomitant continuous pain[3]
Complications: Depression, anxiety, weight loss, dehydration, social isolation, medication side effects, suicidality[2][11]

16. Treatment Plan

Initial stabilization (ED)

Avoid opioids — ineffective and associated with need for additional drugs in 72% of cases[3][7]
IV fosphenytoin achieved satisfactory relief in 64% of ED cases in one series[7]
IV lidocaine — effective per clinical experience; requires monitored setting[3]
Lidocaine injection into trigger zones for short-term relief[3]
IV fluids if dehydrated from inability to eat/drink[3]

Outpatient pharmacotherapy

Carbamazepine 200 mg BID, titrate by 200 mg/day every several days to effect (max 1,200 mg/day)[1-2]
If intolerant: oxcarbazepine 300–1,800 mg/day[1][6]
Patients should be encouraged to self-adjust doses based on pain severity and side effects, as remission periods occur[3][6]
Second-line add-on: lamotrigine, gabapentin, pregabalin, baclofen, botulinum toxin type A[6]

Surgical options (for medically refractory TN)

Microvascular decompression (MVD) — first-line surgery for classic TN; 62–89% pain-free at 3–11 years; mortality 0.3%. A 5-year prospective study showed 59% of MVD patients were pain-free without medication vs. 19% with medical management alone[1][3][18]
Percutaneous procedures (radiofrequency thermocoagulation, balloon compression, glycerol injection) — ablative; preferred when MRI shows no neurovascular contact[3]
Gamma knife radiosurgery — non-invasive but destructive; 30–66% pain-free at 4–11 years[3]
The following figure illustrates the microvascular decompression procedure:

17. Disposition

Admission criteria

Severe exacerbation with inability to eat or drink (dehydration risk)[3]
Need for IV fosphenytoin or lidocaine infusion (requires monitored setting)[3]
Acute titration of antiepileptic drugs in refractory cases[3]
New neurologic deficits suggesting secondary cause requiring urgent workup

Discharge criteria

Pain adequately controlled with oral medications
Able to tolerate oral intake
Outpatient follow-up arranged
MRI ordered or scheduled

Specialist consultation triggers

Neurology: All new diagnoses (for confirmation, MRI interpretation, and classification)[6]
Neurosurgery: Refractory to ≥2 adequate medication trials, intolerable side effects, or patient preference for surgical evaluation[3][6]
Dentistry/oral surgery: If dental pathology cannot be excluded
Ophthalmology: If V1 involvement with corneal reflex concerns

18. Follow Up / Return Precautions

Follow-up timing

Within 1–2 weeks of starting carbamazepine to assess response, side effects, and check labs (CBC, CMP, sodium)[2][8]
MRI brain with and without contrast should be obtained in all patients[2]
After several symptom-free months, consider a gradual drug-free trial (taper slowly over days)[2][6]
Return precautions — advise patients to seek immediate care for:
Skin rash (risk of SJS/TEN — stop carbamazepine immediately)[9-10]
Inability to eat or drink due to pain
New numbness, weakness, vision changes, or other neurologic symptoms
Dizziness, unsteadiness, or confusion (medication toxicity)
Fever, sore throat, mouth ulcers (signs of agranulocytosis)

Patient counseling

TN is a chronic condition with natural remissions and relapses[2-3]
Medication doses can be self-adjusted within prescribed range based on pain severity[3][6]
80% of patients initially seek dental care — reassure that this is a neurologic condition[2]
Psychological support should be offered given the significant impact on quality of life[6]
Expected recovery: ~75% achieve initial pain control with medication; carbamazepine efficacy may wane over years, and surgical options exist for refractory cases[2]

Diagnosis and treatment of trigeminal neuralgia. Adapted with permission from Krafft RM. Trigeminal neuralgia. Am Fam Physician. 2008;77(9):1295.

References

1. Trigeminal Neuralgia. — Cruccu G, Di Stefano G, Truini A. The New England Journal of Medicine. 2020.

2. Trigeminal Neuralgia: Rapid Evidence Review. — Amaechi O. American Family Physician. 2025.

3. Advances in Diagnosis, Classification, Pathophysiology, and Management of Trigeminal Neuralgia. — Bendtsen L, Zakrzewska JM, Heinskou TB, et al. The Lancet. Neurology. 2020.

4. Clinical Reasoning: A Misdiagnosis of Atypical Trigeminal Neuralgia. — Duvall JR, Robertson CE. Neurology. 2019.

5. Practice Parameter: The Diagnostic Evaluation and Treatment of Trigeminal Neuralgia (An Evidence-Based Review): Report of the Quality Standards Subcommittee of the American Academy of Neurology and the European Federation of Neurological Societies. — Gronseth G, Cruccu G, Alksne J, et al. Neurology. 2008.

6. European Academy of Neurology Guideline on Trigeminal Neuralgia. — Bendtsen L, Zakrzewska JM, Abbott J, et al. European Journal of Neurology. 2019.

7. Treatment of Acute Exacerbations of Trigeminal Neuralgia in the Emergency Department: A Retrospective Case Series. — Pinto MJ, Gomes A, Pinto M, Abreu P, Costa A. Headache. 2022.

8. FDA Drug Label. — Updated date: 2025-10-23. Food and Drug Administration.

9. FDA Drug Label. — Updated date: 2025-12-09. Food and Drug Administration.

10. FDA Drug Label. — Updated date: 2025-12-16. Food and Drug Administration.

11. Trigeminal Neuralgia. — Ashina S, Robertson CE, Srikiatkhachorn A, et al. Nature Reviews. Disease Primers. 2024.

12. Trigeminal Neuralgia in Multiple Sclerosis: Prevalence and Association With Demyelination. — Laakso SM, Hekali O, Kurdo G, et al. Acta Neurologica Scandinavica. 2020.

13. Identifying Associated Comorbidities in the Development of Trigeminal Neuralgia: A Propensity-Matched Analysis of the National Inpatient Sample. — Tang M, Devarajan A, Huo L, et al. Clinical Neurology and Neurosurgery. 2025.

14. Chronic Facial Pain: Trigeminal Neuralgia, Persistent Idiopathic Facial Pain, and Myofascial Pain Syndrome-an Evidence-Based Narrative Review and Etiological Hypothesis. — Gerwin R. International Journal of Environmental Research and Public Health. 2020.

15. Differential Diagnosis of Facial Pain and Guidelines for Management. — Zakrzewska JM. British Journal of Anaesthesia. 2013.

16. Magnetic Resonance Imaging in the Diagnosis of Trigeminal Neuralgia: A Systematic Review of the Imaging Protocol and Diagnostic Accuracy. — Henssen D, van Grinsven M, Vissers K, van Goethem J. European Radiology. 2026.

17. Trigeminal Neuralgia: New Classification and Diagnostic Grading for Practice and Research. — Cruccu G, Finnerup NB, Jensen TS, et al. Neurology. 2016.

18. Five-Year Prospective Outcomes of Medical Management and Microvascular Decompression in Trigeminal Neuralgia. — Worm J, Heinskou TB, Rochat P, et al. Journal of Neurology. 2025.