Paroxysmal, lancinating unilateral facial pain in CN V distribution; first-line therapy is carbamazepine.
Also known as: trigeminal neuralgia, tic douloureux, TN, CN V neuralgia
Overview
Disorder characterized by sudden, recurrent, brief paroxysms of severe, electric-shock-like, lancinating pain in one or more divisions of the trigeminal nerve (CN V), typically triggered by innocuous stimuli to the face.
Epidemiology
Annual incidence ~4-13 per 100,000. Peak in 5th-7th decade. Women > men (~1.5:1). Right side affected slightly more than left. Bilateral involvement (~3%) suggests multiple sclerosis or secondary cause.
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Question 1NeurologyMedium
A 45-year-old man reports recurrent episodes of severe, lancinating right-sided facial pain in the V2 distribution lasting only seconds, triggered by chewing, talking, or light touch to the cheek. Neurologic examination is normal. Which of the following is the most appropriate first-line pharmacotherapy?
AVerapamil
BIndomethacin
CAmitriptyline
DCarbamazepine
Reveal answer & full explanation
Correct answer: D — Carbamazepine
AVerapamil
BIndomethacin
CAmitriptyline
DCarbamazepine✓
Why Carbamazepine is correct
Trigeminal neuralgia presents with brief paroxysms of unilateral lancinating facial pain in a trigeminal branch distribution (V2/V3 most common), triggered by innocuous stimuli such as chewing, talking, or light touch, with a normal neurologic exam between attacks.
Carbamazepine is first-line pharmacotherapy per current AAN/EAN guidance; it dampens the ectopic sodium-channel firing that drives the paroxysms. Oxcarbazepine is an accepted alternative.
Microvascular decompression is reserved for medication-refractory cases.
Why the others are wrong
Verapamil — first-line prophylaxis for cluster headache, whose attacks last 15-180 minutes with ipsilateral autonomic features rather than seconds-long touch-triggered jolts (buzzword-matching severe unilateral facial pain to the wrong syndrome).
Indomethacin — the defining treatment for paroxysmal hemicrania, but those attacks last minutes, occur with ipsilateral autonomic signs, and are not triggered by light touch (confused-with-paroxysmal-hemicrania trap for brief unilateral facial pain).
Amitriptyline — first-line for persistent (atypical) idiopathic facial pain, which is constant, dull, and poorly localized, unlike the seconds-long triggered paroxysms here (confused-with-atypical-facial-pain trap).
Question 2NeurologyMedium
A 45-year-old man reports recurrent episodes of severe, electric shock-like pain over his right cheek and jaw. Each episode lasts only a few seconds and is triggered by chewing, talking, or lightly touching the face, with pain-free intervals between attacks. There is no facial weakness, sensory loss, or autonomic feature, and the neurologic examination is normal. Which of the following is the most likely diagnosis?
ABell's palsy
BCluster headache
CTrigeminal neuralgia
DAtypical facial pain
Reveal answer & full explanation
Correct answer: C — Trigeminal neuralgia
ABell's palsy
BCluster headache
CTrigeminal neuralgia✓
DAtypical facial pain
Why Trigeminal neuralgia is correct
Trigeminal neuralgia causes paroxysms of severe, lancinating unilateral facial pain in the maxillary and mandibular trigeminal divisions
Attacks last seconds, are triggered by chewing, talking, or light touch, and are separated by pain-free intervals
The neurologic examination is normal, with no facial weakness, sensory loss, or autonomic features
First-line therapy is carbamazepine
Why the others are wrong
Bell's palsy — produces unilateral facial WEAKNESS from CN VII dysfunction, not paroxysmal facial pain with a normal motor exam (buzzword-matching on "facial")
Cluster headache — causes longer (15-180 minute) unilateral periorbital pain with prominent autonomic features such as lacrimation and rhinorrhea, not seconds-long touch-triggered jabs (confused-with-another-unilateral-pain)
Atypical facial pain — a constant, poorly localized dull ache without trigger zones or a paroxysmal quality (premature closure when no classic trigger pattern is recognized)
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Most cases (~80-90%) are classical TN due to neurovascular compression of the trigeminal nerve root at the root entry zone (typically by an ectatic superior cerebellar artery), causing focal demyelination and ephaptic transmission ('cross-talk') between large myelinated and pain fibers. Secondary TN from MS plaques in the pontine root entry zone, tumors, or structural lesions. Idiopathic TN: no identifiable cause despite imaging.
Clinical presentation
Symptoms
Sudden, severe, electric-shock-like or stabbing pain lasting seconds to up to 2 minutes per attack
Pain in one or more divisions of CN V — V2 (maxillary) and V3 (mandibular) most common; V1 (ophthalmic) alone rare; bilateral in ~3% (think MS)
Triggered by light touch or innocuous stimuli to the face: shaving, brushing teeth, eating, drinking, talking, cold air, makeup application, kissing
Trigger zones often along nasolabial fold, lip, gum, cheek
Refractory period after attack (cannot be triggered immediately)
Multiple attacks per day or per minute during flares; can have weeks-months of remission
Pain-free between attacks (vs. atypical facial pain or postherpetic neuralgia)
Patients may lose weight (afraid to eat), become depressed, develop suicidal ideation
Signs / physical exam
Normal neurologic examination in classical TN
Sensory loss in CN V territory, weakness of muscles of mastication, hearing loss, or other cranial nerve findings = RED FLAG for secondary cause (tumor, MS)
Trigger zones can be elicited but should be done sparingly (severe pain)
Classic findings
Paroxysmal, unilateral, electric-shock-like facial pain triggered by light touch with normal neurologic exam.
Differential diagnosis
Dental pain / TMJ — Constant aching pain, dental triggers, tenderness on exam, abnormal imaging of teeth/joints
Cluster headache — Severe unilateral periorbital pain with autonomic features (lacrimation, rhinorrhea, ptosis, miosis), 15-180 minutes, circadian pattern
Paroxysmal hemicrania — Brief unilateral pain attacks with autonomic features, MULTIPLE per day; absolute response to indomethacin
SUNCT / SUNA — Short-lasting unilateral neuralgiform attacks with conjunctival injection and tearing (or autonomic features); seconds to minutes, can mimic TN
Glossopharyngeal neuralgia (CN IX) — Lancinating pain in throat, tongue base, ear; triggered by swallowing, talking
Postherpetic neuralgia (V1) — Persistent burning/aching pain in dermatomal distribution after zoster; constant rather than paroxysmal
MS (secondary TN) — Younger patient, bilateral involvement, other demyelinating episodes; MRI lesions
Diagnostic workup
Diagnostic criteria
ICHD-3: (A) recurrent paroxysms of unilateral facial pain in CN V distribution lasting fraction of a second to 2 minutes; (B) severe intensity; (C) electric-shock-like, shooting, stabbing, or sharp in quality; (D) precipitated by innocuous stimuli; (E) not better explained by another ICHD-3 diagnosis. Classical (vascular compression on imaging), secondary (identifiable cause like MS or tumor), or idiopathic.
Labs
Baseline labs prior to carbamazepine: CBC, BMP (sodium), LFTs
HLA-B*15:02 in patients of Asian descent before starting carbamazepine (severe cutaneous reactions; Stevens-Johnson/TEN)
Imaging
MRI brain with thin-slice imaging of the trigeminal nerve and brainstem (FIESTA/CISS sequences) — recommended for ALL patients with new TN to evaluate for neurovascular compression, MS plaques, tumors, vascular malformations
MR angiography may demonstrate the offending vessel
Reassuring if classical compression visualized in symptomatic patient; alarming if MS lesion, mass, or vascular malformation
Diagnostic algorithm
Feature
Trigeminal Neuralgia
Cluster Headache
Postherpetic Neuralgia
Pain quality
Electric-shock, lancinating
Severe burning, boring
Burning, aching, allodynia
Duration
Seconds to 2 min
15-180 min
Constant, persistent
Location
CN V (V2/V3 most often)
Periorbital / temporal
Prior zoster dermatome
Triggers
Light touch, eating, talking
Alcohol, vasodilators
None specific
Autonomic features
Absent (usually)
Present (ipsilateral tearing, rhinorrhea, ptosis)
Absent
First-line treatment
Carbamazepine
Triptans + 100% O2 (acute), verapamil (prevent)
Gabapentin/pregabalin, TCAs
Distinguishing trigeminal neuralgia from common facial pain mimics.
Treatment
First-line
Carbamazepine — first-line drug; start 100-200 mg BID, titrate slowly to 600-1200 mg/day in divided doses; monitor for SIADH (hyponatremia), leukopenia, aplastic anemia, Stevens-Johnson syndrome (test HLA-B*15:02 in Asian patients); check baseline and periodic CBC, BMP, LFTs
Oxcarbazepine — better tolerated alternative; start 150-300 mg BID, titrate to 600-1800 mg/day; lower risk of severe rash but still risk of hyponatremia
If pain controlled and stable, attempt taper after 6-12 weeks pain-free; many patients have recurrent flares requiring chronic therapy
Patient education about triggers and pain diary
Second-line / adjunct
Add-on or alternative medications when carbamazepine/oxcarbazepine fail or are not tolerated:
Acute flare management: IV fosphenytoin or lidocaine infusion in refractory severe pain (specialty setting)
Surgical interventions for medically refractory TN:
• Microvascular decompression (Jannetta procedure) — preferred in younger, healthier patients with documented neurovascular compression; 80-90% initial pain relief, ~70% durable at 10 years; risks include hearing loss, facial weakness, CSF leak, stroke (low)
• Percutaneous procedures (glycerol rhizotomy, radiofrequency thermocoagulation, balloon compression of Gasserian ganglion) — for older or higher-risk patients; high initial success but more recurrence and risk of facial numbness (anesthesia dolorosa)
• Stereotactic radiosurgery (Gamma Knife) — non-invasive; delayed onset of relief (weeks to months); recurrence common over years
Treat underlying cause in secondary TN (MS — disease-modifying therapy; tumor — resection)
Complications
Severe functional and psychological impairment: weight loss (afraid to eat), depression, anxiety, suicidality
Progression to constant background pain (TN type 2) in some patients
PANCE pearls
Carbamazepine is first-line for classical TN — a strong response is itself supportive of the diagnosis.
Bilateral TN, sensory loss, or onset before age 40 should prompt MRI to rule out MS or tumor.
Test HLA-B*15:02 in patients of Asian descent before starting carbamazepine to reduce SJS/TEN risk.
Monitor sodium and blood counts on carbamazepine and oxcarbazepine — hyponatremia is common.
Atypical TN with constant background pain is more difficult to treat and less responsive to MVD.
Microvascular decompression provides the most durable relief but requires posterior fossa surgery — reserved for fit patients.
Postherpetic V1 neuralgia (after zoster ophthalmicus) is NOT trigeminal neuralgia — pain is constant and burning, not paroxysmal; treat with gabapentin/pregabalin, TCAs, topical lidocaine.
TN in a young patient may be the presenting symptom of MS — get an MRI.
References
AAN/EFNS 2008 — Practice Parameter: Diagnostic Evaluation and Treatment of Trigeminal Neuralgia (Gronseth et al., Neurology 2008)
EAN 2019 — European Academy of Neurology Guideline on Trigeminal Neuralgia (Bendtsen et al., Eur J Neurol 2019)
ICHD-3 — International Classification of Headache Disorders, 3rd Edition (Cephalalgia 2018)
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