Overview
Trigeminal Neuralgia
1. Clinical Overview
Summary
Trigeminal Neuralgia (TN), classically known as "Tic Douloureux", is a Unilateral Facial Pain Disorder characterised by Brief, Electric Shock-Like, Paroxysmal Pain in the distribution of one or more divisions of the Trigeminal Nerve (Cranial Nerve V). It is often described as one of the Most Severe Pains Known to Medicine. The pain is typically triggered by Innocuous Stimuli (Trigger Zones) such as touching the face, Chewing, Speaking, Or cold wind. Attacks are Sudden, Stereotyped, and Last Seconds to less than 2 Minutes, occurring multiple times daily. The most commonly affected divisions are V2 (Maxillary) and V3 (Mandibular), while V1 (Ophthalmic) is less common alone. TN is classified as Classical (Due to Neurovascular Compression of the Trigeminal Root, Usually by the Superior Cerebellar Artery), Secondary (Associated with Multiple Sclerosis, Tumour, or Other Structural Lesion), Or Idiopathic. Diagnosis is clinical. MRI is essential to Exclude Secondary Causes. First-line treatment is Carbamazepine or Oxcarbazepine. Microvascular Decompression (MVD) surgery offers the best chance of long-term pain relief for Classical TN refractory to medication. [1,2,3]
Clinical Pearls
"Electric Shock-Like Pain, Seconds Duration, Triggered": Classic TN features.
"V2/V3 Most Common": V1 alone is rare. Always check for sensory loss (Red flag).
"Carbamazepine is First-Line": Highly effective.
"MRI Brain to Exclude Secondary Cause": Essential for all patients.
2. Epidemiology
Demographics
| Factor | Notes |
|---|---|
| Incidence | ~4-13 per 100,000 per year. |
| Age of Onset | Usually >50 years. Peak 50-70. Rare less than 40 (Consider MS). |
| Sex | Female > Male (1.5-2:1). |
| Side | Right > Left. Bilateral less than 5% (Consider secondary cause). |
Aetiology
| Type | Cause |
|---|---|
| Classical TN (~95%) | Neurovascular Compression (NVC) of trigeminal root entry zone by aberrant vascular loop (Usually Superior Cerebellar Artery). |
| Secondary TN (~5%) | Multiple Sclerosis (Demyelinating plaques at root entry zone). Tumour (CPA tumour, Meningioma, Vestibular schwannoma). Arteriovenous malformation. |
| Idiopathic TN | No demonstrable cause on imaging. |
3. Anatomy
Trigeminal Nerve (CN V)
| Division | Sensory Distribution |
|---|---|
| V1 (Ophthalmic) | Forehead, Upper eyelid, Cornea, Nose (Upper), Scalp (Anterior). |
| V2 (Maxillary) | Cheek, Upper lip, Upper teeth, Nasal mucosa, Palate. |
| V3 (Mandibular) | Lower lip, Chin, Lower teeth, Tongue (Anterior 2/3 sensation), Jaw, Temple. (Also motor to muscles of mastication). |
Root Entry Zone
- Where trigeminal nerve enters pons.
- Transition zone between central (CNS) and peripheral (PNS) myelin.
- Particularly susceptible to compression.
4. Pathophysiology
Mechanism (Classical TN)
- Vascular Compression: Aberrant artery (Superior cerebellar artery most common) compresses trigeminal nerve root entry zone.
- Demyelination: Focal demyelination at site of compression.
- Ephaptic Transmission: Cross-talk between adjacent demyelinated sensory fibres.
- Aberrant Signal Generation: Light touch signals (Aβ fibres) activate pain pathways (C and Aδ fibres).
- Paroxysmal Pain: Triggered attacks.
Multiple Sclerosis-Related TN
- Demyelinating plaque at trigeminal root entry zone or brainstem nucleus.
- Bilateral TN more common.
- Younger onset.
5. Clinical Presentation
Pain Characteristics (ICOP Criteria – Key Features)
| Feature | Notes |
|---|---|
| Location | Unilateral. In distribution of V2 and/or V3 (Most common). V1 less common alone. |
| Character | Electric Shock-Like, Stabbing, Shooting, Lancinating. |
| Duration | Paroxysmal – Lasts Seconds to less than 2 Minutes per attack. |
| Intensity | Severe, Excruciating. Often described as "Worst pain imaginable". |
| Frequency | Multiple attacks per day. Can cluster. Periods of remission possible. |
| Trigger Zones / Trigger Factors | Light touch to face (Cheek, Lip, Gum, Nose). Chewing, Talking, Smiling, Brushing teeth, Shaving, Cold wind. |
| Refractory Period | Brief period after attack where further attacks cannot be triggered. |
| Between Attacks | Pain-free OR Mild background ache (TN with concomitant continuous pain). |
| No Sensory Deficit | In Classical TN. Sensory loss = Red flag (Secondary cause). |
Associated Features
| Feature | Notes |
|---|---|
| Facial Grimacing ("Tic") | During attack ("Tic Douloureux"). |
| Avoidance Behaviours | Patients avoid triggers (Not eating, Not touching face). Weight loss. Poor oral hygiene. |
| Depression / Anxiety | Significant impact on quality of life. |
Examination Findings (Classical TN)
| Finding | Notes |
|---|---|
| Neurological Examination Usually Normal | Key feature. |
| NO Sensory Loss | If sensory loss present → Suspect Secondary TN (Tumour). |
| Trigger Zones | May demonstrate during examination (Gentle touch). |
Red Flags (Suggest Secondary TN)
| Red Flag |
|---|
| Age less than 40 years (Consider MS). |
| Sensory loss (Numbness) in trigeminal distribution. |
| Bilateral symptoms. |
| Abnormal trigeminal reflexes (Corneal reflex). |
| Other cranial nerve involvement. |
| Progressive symptoms without remission. |
| Deafness, Vertigo (CPA tumour). |
6. Investigations
MRI Brain (Essential)
| Purpose | Notes |
|---|---|
| Exclude Secondary Causes | MS plaques, CPA tumour, AVMs. |
| Identify Neurovascular Compression (NVC) | High-resolution MRI with CISS/FIESTA sequences. Visualise vascular loop contacting nerve. |
| MRI should be performed in ALL patients with TN. |
Other Investigations
| Investigation | Notes |
|---|---|
| MRI with Gadolinium | If tumour suspected. |
| Lumbar Puncture / CSF | If MS suspected. |
| Trigeminal Reflex Testing | Abnormal in symptomatic TN. Not routine. |
7. Management
Management Algorithm
SUSPECTED TRIGEMINAL NEURALGIA
(Typical paroxysmal facial pain)
↓
MRI BRAIN (Exclude Secondary Causes)
┌────────────────┴────────────────┐
NORMAL OR NVC SECONDARY CAUSE
IDENTIFIED IDENTIFIED (MS, Tumour)
(Classical / Idiopathic TN)
↓ ↓
MEDICAL MANAGEMENT TREAT UNDERLYING CAUSE
(First-Line) + Symptomatic Rx
↓
FIRST-LINE: MEDICAL TREATMENT
┌──────────────────────────────────────────────────────────┐
│ **CARBAMAZEPINE (First-Line)** │
│ - Start 100-200 mg BD, Titrate to 200-400 mg TDS-QDS │
│ (Max 1200-1600 mg/day) │
│ - Highly effective (~70-90% initial response) │
│ - Monitor: FBC, LFTs, Sodium (SIADH) │
│ - Side effects: Drowsiness, Dizziness, Ataxia, Rash │
│ (Stevens-Johnson rare but serious), Hyponatraemia, │
│ Bone marrow suppression. │
│ - HLA-B*15:02 screening (Asian populations) – Risk of │
│ SJS/TEN. │
│ │
│ **OXCARBAZEPINE (Alternative First-Line)** │
│ - Start 300mg BD, Titrate up (Max 1800-2400 mg/day) │
│ - Better tolerated than Carbamazepine in some. │
│ - Similar mechanism. Also causes Hyponatraemia. │
└──────────────────────────────────────────────────────────┘
↓
IF FIRST-LINE FAILS OR NOT TOLERATED
(Second-Line / Add-On Medications)
┌──────────────────────────────────────────────────────────┐
│ - **Gabapentin** (300-1800 mg/day) │
│ - **Pregabalin** (150-600 mg/day) │
│ - **Baclofen** (10-80 mg/day – Useful add-on) │
│ - **Lamotrigine** (Slow titration needed – Rash risk) │
│ - **Phenytoin** (IV for acute severe exacerbation) │
└──────────────────────────────────────────────────────────┘
↓
SURGICAL TREATMENT
(Refractory to Medical Therapy OR Side Effects Intolerable)
┌──────────────────────────────────────────────────────────┐
│ **MICROVASCULAR DECOMPRESSION (MVD)** │
│ - **Procedure of Choice for Classical TN with NVC** │
│ - Open posterior fossa surgery. Move vessel away from │
│ trigeminal nerve, Insert Teflon pad. │
│ - **Best Long-Term Outcomes** (~70-90% initial relief, │
│ ~70% pain-free at 10 years). │
│ - Risks: General anaesthesia risk, Hearing loss, │
│ Facial numbness, CSF leak, Stroke (Rare). │
│ - Preferred for younger, Fit patients. │
│ │
│ **PERCUTANEOUS ABLATIVE PROCEDURES** │
│ - Percutaneous Radiofrequency Thermocoagulation (RFTC) │
│ - Balloon Microcompression │
│ - Glycerol Rhizotomy │
│ - Damage trigeminal ganglion/Root. Cause sensory loss. │
│ - Good initial relief (~90%+), Higher recurrence than │
│ MVD. Suitable for elderly/Frail. │
│ │
│ **STEREOTACTIC RADIOSURGERY (Gamma Knife)** │
│ - Focused radiation to trigeminal root. │
│ - Non-invasive. Delayed onset of effect (Weeks-months). │
│ - Suitable for: MS-related TN, Elderly/Frail, │
│ Contraindication to open surgery. │
│ - Lower initial success than MVD. Recurrence common. │
│ Facial numbness possible. │
└──────────────────────────────────────────────────────────┘
8. Complications
| Complication | Notes |
|---|---|
| Medication Side Effects | Drowsiness, Ataxia, Hyponatraemia (Carbamazepine/Oxcarbazepine), Rash (SJS/TEN risk). |
| Weight Loss / Malnutrition | Avoidance of eating. |
| Depression / Anxiety | Significant QoL impact. Suicide risk. |
| Surgical Complications | MVD: Hearing loss (~1-2%), Facial numbness, CSF leak, Meningitis (Rare), Stroke (Rare). Ablative: Sensory loss (Numbness, Anaesthesia dolorosa – Painful numbness). |
9. Prognosis and Outcomes
| Factor | Notes |
|---|---|
| Natural History | May have periods of remission, But generally progressive without treatment. |
| Medical Therapy | Good initial response (~70-90%). May lose efficacy over time. ~50% eventually need surgery. |
| MVD | Best long-term outcomes (~70% pain-free at 10 years). Recurrence ~20-30% at 10 years. Can repeat or proceed to ablative. |
| Quality of Life | Severely impacted. Successful treatment life-changing. |
10. Evidence and Guidelines
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Trigeminal Neuralgia | EAN/AAN | MRI for all. Carbamazepine/Oxcarbazepine first-line. MVD for refractory Classical TN. |
11. Patient and Layperson Explanation
What is Trigeminal Neuralgia?
Trigeminal Neuralgia is a condition causing severe, Sudden, Electric shock-like pain on one side of the face. The pain follows the path of the trigeminal nerve, Which controls sensation in the face.
What does the pain feel like?
- Very intense, Stabbing or shooting pain.
- Lasts a few seconds but feels extreme.
- Can happen many times a day.
- Often triggered by touching the face, Chewing, Talking, Or brushing teeth.
What causes it?
In most cases, A blood vessel pressing on the trigeminal nerve. In some cases, Conditions like Multiple Sclerosis.
How is it treated?
- Medications: Carbamazepine is the main drug. It helps most people.
- Surgery: If medications don't work or cause too many side effects, Surgery can help. The best operation is called Microvascular Decompression (Moving the blood vessel off the nerve).
What is the outlook?
Trigeminal Neuralgia is usually not dangerous but very painful. With treatment, Most people can get good pain relief.
12. References
Primary Sources
- Cruccu G, et al. Trigeminal neuralgia. N Engl J Med. 2020;383(8):754-762. PMID: 32813952.
- Gronseth G, et al. AAN-EFNS Guidelines on trigeminal neuralgia management. Eur J Neurol. 2008;15(10):1013-1028.
- Headache Classification Committee of the IHS. ICHD-3. Cephalalgia. 2018;38(1):1-211.
13. Examination Focus
Common Exam Questions
- First-Line Drug: "What is the first-line medical treatment for Trigeminal Neuralgia?"
- Answer: Carbamazepine (Or Oxcarbazepine).
- Classic Pain Description: "Describe the classic pain of Trigeminal Neuralgia."
- Answer: Unilateral, Electric shock-like/Lancinating, Paroxysmal (Seconds to less than 2 minutes), Triggered by light touch to face/Chewing/Speaking, In V2/V3 distribution.
- MRI Purpose: "Why is MRI essential in the workup of Trigeminal Neuralgia?"
- Answer: To Exclude Secondary Causes (MS, Tumour) and Identify Neurovascular Compression (For surgical planning).
- Best Long-Term Surgery: "What surgical procedure offers the best long-term outcomes for Classical Trigeminal Neuralgia?"
- Answer: Microvascular Decompression (MVD).
Viva Points
- Sensory Loss = Red Flag: Suggests secondary cause (Tumour). Classical TN has normal neuro exam.
- HLA-B*15:02: Screen before Carbamazepine in Asian populations (SJS/TEN risk).
- Superior Cerebellar Artery: Most common vessel causing compression.
- "Tic Douloureux": Facial grimacing during attack.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.