Neurology & Pain Medicine & Family Medicine
Trigeminal neuralgia (facial neuralgia)
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Trigeminal neuralgia - also known as trigeminal neuralgia, essential trigeminal neuralgia or, in its historical name, tic douloureux de la face (painful tic of the face, a term used by Fothergill in the eighteenth century) - is the most common form of trigeminal neuralgia.e century) - is a paroxysmal facial neuropathic pain of extreme intensity, unanimously described by patients as the most severe pain imaginable, surpassing childbirth, renal colic and burns. It is caused by dysfunction of the trigeminal nerve (Ve The trigeminal nerve (V1 - forehead, eye, nose), the maxillary nerve (V2 - cheek, upper lip, upper teeth) and the mandibular nerve (V3 - jaw, lower lip, lower teeth, tongue) provide sensitivity to almost the entire face and oral cavity, via its three branches: the ophthalmic branch (V1 - forehead, eye, nose), the maxillary branch (V2 - cheek, upper lip, upper teeth) and the mandibular branch (V3 - jaw, lower lip, lower teeth, tongue). The classic form - the most frequent (85 % of cases) - is caused by vascular compression of the trigeminal nerve at its entry into the brain stem (root entry zone, REZ) by an artery or vein in close contact with the nerve, resulting in focal demyelination and ectopic discharges responsible for the painful paroxysms; the superior cerebellar artery (SCA) is the most frequently identified compressive vessel. Trigeminal neuralgia affects around 4 to 5 people out of 100,000 per year, with a clear female predominance (female/male ratio of 1.5 to 2/1) and onset generally after the age of 50 - although earlier forms do exist, notably in the context of multiple sclerosis. Left untreated, the disease progresses in attacks of variable duration, separated by periods of spontaneous remission, with a tendency to worsen progressively - attacks becoming more frequent, longer and periods of remission shorter over the years. Carbamazepine (Tegretol®) remains the first-line drug treatment with a grade A level of evidence, while surgical microvascular decompression (Jannetta procedure) offers the most frequent durable cure for patients who are candidates for surgery.
Pathophysiology and classification
- Neurovascular compression (classic form - 85 % of cases) : direct contact between a blood vessel (superior cerebellar artery in 75 % of cases + anteroinferior cerebellar artery + superior cerebellar vein) and the trigeminal nerve at the root entry zone (REZ) in the prepontic cistern + chronic arterial pulsation leads to focal segmental demyelination of myelinated A- beta fibers (normally non-nociceptive) + this demyelination creates ephapses (aberrant connections between adjacent fibers) and ectopic discharges.beta fibers (normally non-nociceptive) + this demyelination creates ephapses (aberrant connections between adjacent fibers) and ectopic discharges → stimulation of non-painful trigger zones → triggering of intense paroxysmal pain = mechanism of classic neuralgia
- Secondary neuralgia (15 % of cases) : multiple sclerosis (MS) → demyelinating plaque in trigeminal nucleus or root → trigeminal neuralgia in 1 to 2 % of MS patients + often bilateral + occurring at a younger age + posterior fossa tumors (meningioma + acoustic neuroma + cholesteatoma) compressing the nerve + Chiari malformation type I + herpes zoster (herpes zoster ophthalmicus - V1) → postzoster trigeminal neuralgia distinguished from classic trigeminal neuralgia by its continuous component and burning character
- Idiopathic neuralgia: no vascular cause or lesion identifiable on MRI - probably related to subtle myelin sheath abnormalities not visible on standard imaging
- ICHD-3 diagnostic criteria (International Classification of Headache Disorders 3rd edition 2018): at least three unilateral facial pain attacks meeting criteria B and C + pain limited to one or more trigeminal branches without extra-trigeminal irradiation + pain with at least three of the four characteristics: recurrent paroxysmal lasting from a few seconds to 2 minutes + severe intensity + electric shock or stabbing quality + triggered by painless stimuli on the homolateral face (trigger zones) + no clinically evident neurological deficit + not better explained by another ICHD-3 diagnosis
Clinical presentation and trigger zones
| Clinical features | Detailed description | Diagnostic value |
|---|---|---|
| Pain quality | Fulminant electric pain + stabbing pain + electric discharge + red-hot iron burn + sudden electric shock → unanimously rated 10/10 on the numerical pain scale | Pathognomonic - no other pain presents this paroxysmal quality of such intensity on the face |
| Duration of paroxysms | Each seizure lasts from a few seconds (1 to 2 seconds) to a maximum of 2 minutes, according to ICHD-3 criteria + seizures may be repeated in bursts of several dozen to hundreds of seizures per day in severe forms + refractory period between seizures (impossible to trigger a new seizure immediately) | The extreme brevity of the attacks (seconds) is characteristic and distinguishes trigeminal neuralgia from other facial pains (migraine + neuritis + dental osteitis). |
| Unilaterality | Unilateral in 96 % of cases + right side slightly more frequent than left side + bilateral in 3 to 4 % of cases - must systematically search for MS or a central cause | Bilateral neuralgia requires urgent brain MRI to rule out MS or posterior fossa tumor |
| Distribution by trigeminal branch | V2 (maxillary branch) alone or V2+V3 → 60 to 70 % of cases + V3 (mandibular branch) alone → 20 % + V1 (ophthalmic branch) alone → 5 % - isolated involvement of V1 is rare and should prompt a search for ophthalmic shingles + simultaneous involvement of all three branches → rare → tumoral or central cause to be excluded | Distribution in V2 and V3 territory (cheek + jaw + teeth) is the most frequent, and explains the numerous dental treatments carried out unnecessarily prior to correct diagnosis. |
| Trigger zones | Cutaneous or mucosal areas where light mechanical stimulation (touching) triggers the attack: wing of the nose + upper lip + gum + corner of the mouth + cheek + tooth + tongue + lower lip + shaving + chewing + talking + brushing teeth + cold wind on the face + smiling + a kiss can trigger attacks → patients often avoid eating + talking + washing their face → risk of malnutrition and severe social isolation in severe forms | The presence of trigger points is a major diagnostic criterion - distinguishes classic trigeminal neuralgia from dental, sinusitis and TMJ pain |
| Pain-free intervals | Total absence of pain between attacks (except for a rare continuous component in advanced forms) → patients are perfectly asymptomatic between paroxysms + possible spontaneous remissions (weeks to months) between periods of activity | The free interval is characteristic - continuous facial pain without paroxysm points to another diagnosis (neuritis + dental pain + autonomic trigeminal headache). |
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Trigeminal neuralgia is frequently confused with dental pathology - on average, patients consult 3 to 5 dentists and undergo unnecessary tooth extractions or root canals before getting the right diagnosis. The key to diagnosis is the extreme brevity of the attacks (seconds), their electrical quality, strict unilaterality and the presence of trigger zones. A normal dental examination despite intense, recurrent dental pain should systematically raise the suspicion of trigeminal neuralgia, and lead to a neurological consultation.
Diagnosis - workup and imaging
- Clinical diagnosis first: the diagnosis of trigeminal neuralgia is essentially clinical, based on the detailed history and ICHD-3 criteria + the neurological examination must be normal (absence of facial sensory deficit, absence of hypoesthesia, abolition of corneal reflex → if present: evoke a compressive cause) - the presence of an objective sensory deficit should raise suspicion of secondary neuralgia (tumor + MS)
- Cerebral MRI with dedicated sequences (CISS/FIESTA + 3D angio-MRI): routinely recommended for all patients presenting for the first time + objectives: to identify the neurovascular compression responsible (artery-nerve contact at the REZ visible in 80 to 90 % of cases on high-resolution 3T sequences) + to exclude a secondary cause (MS plaque in the trigeminal root + posterior fossa tumor + vascular malformation) + to guide the surgical decision (identification of the compressive vessel before microvascular decompression).
- Lumbar puncture : not routinely indicated + to be considered if MS suspected (oligoclonal bands in CSF) or if carcinomatous meningitis to be excluded
- Differential diagnosis : dental pain (persistent + meal-related + positive dental examination) + postherpetic neuralgia (history of shingles + continuous pain + skin allodynia) + temporomandibular joint (TMJ) pain + autonomic trigeminal headache (SUNCT + SUNA - short attacks with conjunctival injection and lacrimation) + idiopathic trigeminal neuritis (continuous pain + facial hypoesthesia) + persistent idiopathic facial pain + posterior fossa tumour
Drug treatment
| Drug | Dosage and protocol | Efficacy, tolerance and comments |
|---|---|---|
| Carbamazepine (Tegretol®) - first line | Start: 100 to 200 mg/day in two doses + gradual increase from 100 to 200 mg every 3 to 7 days depending on response and tolerance + usual effective dose: 400 to 1,200 mg/day in two to three doses + LP (sustained-release) tablets preferred for better tolerance (Tegretol LP 200 mg + 400 mg). | Initial relief in 70 to 90 % of patients + mechanism: blockade of voltage-dependent sodium channels → neuronal membrane stabilization + grade A recommendation (Cochrane 2014) + frequent side effects: somnolence + dizziness + ataxia + diplopia + nausea + hyponatremia (especially in the elderly - ionograms to be monitored) + serious rare effects : severe hypersensitivity reaction (Stevens-Johnson syndrome - increased prevalence in patients of Asian origin carrying the HLA-B*1502 allele - testing recommended before prescription) + bone marrow aplasia (CBC before and during treatment) + numerous drug interactions (CYP3A4 enzyme inducer) |
| Oxcarbazepine (Trileptal®) - alternative first-line treatment | Start: 150 to 300 mg/day in two doses + gradual increase + effective dose: 600 to 1,800 mg/day in two doses + may be started at a higher dose than carbamazepine due to better initial tolerance | Efficacy comparable to carbamazepine + better tolerability (less drowsiness + fewer drug interactions) + higher risk of hyponatremia than carbamazepine (ionograms to be monitored at 1 month and regularly) + no CYP3A4 enzyme induction + preferred in patients with multiple medications or the elderly + level of evidence slightly lower than carbamazepine in meta-analyses |
| Lamotrigine (Lamictal®) - second line | Very gradual titration required (risk of Stevens-Johnson syndrome): 25 mg/day × 2 weeks + 50 mg/day × 2 weeks + increase of 50 mg every 2 weeks + target dose 200 to 400 mg/day + in combination with carbamazepine or as monotherapy if carbamazepine is poorly tolerated. | Moderate efficacy as monotherapy + useful in combination (synergistic effect with carbamazepine) + slow titration essential (Stevens-Johnson syndrome in 0.1 % if titration too rapid + increased risk if combined with valproate). |
| Baclofen - second-line / adjuvant | 10 to 80 mg/day in three doses + effective as monotherapy or in combination with carbamazepine + start at 5 mg three times a day with gradual increase | GABA-B agonist reduces neuronal excitability + moderate efficacy documented in several open studies + side effects: drowsiness + muscle weakness + do not stop abruptly (risk of withdrawal syndrome + convulsions) |
| Gabapentin / Pregabalin - adjuvants | Gabapentin 300 to 3,600 mg/day in three doses + pregabalin 75 to 600 mg/day in two doses + used as adjuvant or if carbamazepine and oxcarbazepine are contraindicated or poorly tolerated. | Ligands of the α2δ subunits of voltage-gated calcium channels → reduction in the release of excitatory neurotransmitters + efficacy in neuropathic pain in general but less solid evidence specifically in trigeminal neuralgia than for carbamazepine + side effects: drowsiness + dizziness + weight gain |
Interventional and surgical treatments
- Microvascular decompression (Jannetta procedure) - reference curative treatment : retrosigmoid craniotomy under general anaesthesia + identification of the compressive vessel in contact with the trigeminal nerve at the REZ + interposition of a Teflon (or muscle) patch between the vessel and the nerve to relieve compression + initial success rate: 80 to 90 % (complete disappearance of pain) + durability at 10 years: 70 to 80 % without medication + surgical mortality < 0.5 % in experienced centers + complications: ipsilateral hypoacusis (1 to 3 %) + facial hypoesthesia (5 to 10 %) + aseptic meningitis (1 to 2 %) + stroke (rare) + indicated in patients < 70 years with neurovascular compression identified on MRI + relative contraindication: precarious general condition + anticoagulation
- Percutaneous rhizotomy (thermorhizotomy + balloon compression + glycerol rhizotomy): percutaneous procedures performed under light sedation + passage of a needle through the foramen ovale to Gasser's ganglion + thermorhizotomy: selective thermal lesioning of nociceptive fibers by radiofrequency + balloon compression (Mullan procedure): mechanical compression of the ganglion by an inflated balloon + glycerol rhizotomy: injection of absolute glycerol into the trigeminal cistern + initial efficacy: 85 to 95 % + frequent recurrences at 5 years (30 to 50 %) + main sequela: facial hypoesthesia (frequent + sought in thermorhizotomy for efficacy) + exposing keratitis if corneal anesthesia (V1) → to be monitored + preferred in elderly patients or patients in poor general condition who are not candidates for open surgery
- Stereotactic radiosurgery (Gamma Knife / CyberKnife) : high-precision focal irradiation of the trigeminal root at the REZ in external condition + non-invasive (no incision + local anesthesia only) + efficacy time of 1 to 6 months (unlike other procedures with immediate effect) + efficacy at 3 years: 60 to 70 % + frequent recurrences at 5 to 10 years + main complication: delayed facial hypoesthesia (10 to 20 %) + indicated in patients who are not candidates for open surgery or who have refused percutaneous procedures + also used in cases of recurrence after microvascular decompression
- Nerve blocks and botulinum toxin injections: infiltration of corticoids and local anesthetics at the emergence foramen of trigeminal branches (foramen ovale + foramen rond + supraorbital foramen) → temporary relief + injection of botulinum toxin A (onabotulinum toxin A) in cutaneous trigger zones → efficacy documented in several recent randomized studies (2019-2023) → can be used as adjunctive or relay treatment while waiting for a surgical procedure
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Trigeminal neuralgia in the context of multiple sclerosis (MS) has some important particularities: it occurs at a younger age (30-50 years), is more often bilateral (15 % vs. 4 % in the classic form), and is caused by a demyelinating plaque in the trigeminal root rather than vascular compression. Microvascular decompression is less effective in this context (vascular compression less often identifiable) - percutaneous procedures and radiosurgery are generally preferred. Background drug treatment of MS does not cure associated trigeminal neuralgia, which requires specific antineuralgic treatment.
Situations requiring rapid medical consultation
Any intense, unilateral, paroxysmal, electric discharge facial pain triggered by touch or facial movements (chewing + speaking + brushing teeth) and lasting from a few seconds to two minutes should lead to immediate medical consultation to establish the diagnosis of trigeminal neuralgia and initiate treatment - pain of this intensity repeated dozens of times a day is disabling and can lead to severe depression, malnutrition through refusal to eat and complete social isolation.
Facial neuralgia associated with a sensory deficit (hypoesthesia or facial anesthesia) + or bilateral + or occurring before age 40 + or resistant to carbamazepine from the outset requires urgent brain MRI to exclude multiple sclerosis, a posterior fossa tumor or another serious secondary cause.
To evaluate paroxysmal facial pain, prescribe appropriate medication and refer patients to neurology or neurosurgery, Clinique Omicron offers medical consultations at its points of service in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron's specialized physicians and nurse practitioners (NPs) recognize the diagnostic criteria for trigeminal neuralgia, prescribe dedicated brain MRI and first-line drug treatment (carbamazepine or oxcarbazepine with appropriate titration), and refer to neurologist and neurosurgeon for evaluation of interventional options (microvascular decompression + radiosurgery + percutaneous procedures) in patients refractory to medical treatment. Consultations are available at several points of service in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The content of this page is provided for informational purposes only and does not replace the advice of a physician or neurologist. Trigeminal neuralgia requires specialized medical evaluation to confirm the diagnosis, exclude a secondary cause by imaging, and tailor drug or surgical treatment to the individual patient.
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