This Guidelines summary of Trigeminal neuralgia: a practical guide covers the diagnosis, clinical features, investigations, differential diagnosis, and treatment of trigeminal neuralgia.
For information on pathophysiology, acute treatment for severe exacerbation, surgical treatments, and other considerations, refer to the full practical guide.
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Characteristics of Trigeminal Neuralgia
- Trigeminal neuralgia (TN) is characterised by recurrent, unilateral, brief (<1 second to 2 minutes), very painful, electric shock-like pain episodes in the trigeminal distribution that are abrupt in onset and termination
- TN is a highly debilitating disorder that impacts on basic human functions such as talking, eating, drinking, and touching the face, thereby resulting in a poor quality of life.
Diagnostic Criteria and Classification
- The International classification of headache disorders third edition (ICHD-3) criteria for TN require recurrent paroxysms of unilateral facial pain restricted to the trigeminal distribution, lasting from a fraction of a second to 2 minutes, severe in intensity with an electric shock-like shooting, stabbing, or sharp quality, and precipitated by innocuous stimuli
- TN is further subclassified into classical, secondary, or idiopathic, depending on the underlying cause. The classical type, which is the most common and accounts for 75% of cases, is diagnosed when there is trigeminal neurovascular compression with morphological changes ipsilateral to the side of the pain, demonstrated either on magnetic resonance imaging with appropriate trigeminal sequences or during surgery.
|Box 1: ICHD-3 Diagnostic Criteria for Trigeminal Neuralgia|
|A) Recurrent paroxysms of unilateral facial pain in the distribution(s) of one or more divisions of the trigeminal nerve, with no radiation beyond, and fulfilling criteria B and C|
B) Pain has all of the following characteristics:
D) Not better accounted for by another ICHD-3 diagnosis.
|ICHD=International Classification of Headache Disorders|
Laterality and Site of Pain
- The right side of the face (60%) is affected more than the left side. Bilateral simultaneous pain in TN is rare (1.7–5%) and more often these patients experience side-alternating unilateral pain paroxysms
- The pain of TN most frequently affects the distribution of the maxillary (V2) and mandibular (V3) divisions of the trigeminal nerve, though approximately a quarter of the cases have ophthalmic (V1) division involvement.
Frequency and Duration of Attacks
- The frequency and duration of TN attacks are highly variable. While the pain usually lasts from less than 1 second up to 2 minutes in the majority (74%), a significant minority reports attacks lasting 2–10 minutes. Up to 70% of patients occasionally have series of paroxysms lasting up to 1 hour, which can cause diagnostic confusion
- Obtaining a good descriptive history of frequency and duration of attacks in short-lasting trigeminal neuralgiform pain conditions is often challenging. Using pain diagrams may help to clarify our definition of a single paroxysm as opposed to a group of paroxysms.
Triggers and Trigger Zones
- One of the hallmark clinical features of TN is the triggerability of the attacks by innocuous mechanical stimulation of the face and intraoral mucosa ipsilateral to the side of the pain. Around 91–99% of patients report triggered attacks, and these are often considered to be pathognomonic of TN
- Light tactile stimulation is the most potent trigger and, conversely, painful and thermal stimulation seems ineffective at eliciting pain in TN. Common triggers include light touch, talking, chewing, brushing teeth, washing or drying, drinking, and shaving. Most patients have several trigger factors
- The location of the pain does not always concord with the site of trigger zone. The most common trigger zones include the nasolabial fold, upper lip, lateral part of the lower lip, chin, cheek, and the alveolar gingiva.
- The physical and neurological examinations are generally normal, though approximately 30% of cases can have sensory changes including mild hypoaesthesia
- On rare occasions, during very severe attacks, the pain can evoke ipsilateral facial muscle contraction (tic douloureux).
TN and the Trigeminal Autonomic Cephalalgias
- Since TN attacks are almost invariably precipitated by innocuous stimuli within the affected trigeminal distribution, all the trigeminal autonomic cephalalgias except short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing/short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms can be easily differentiated from TN, as none of the others can be triggered by innocuous stimuli.
Table 1: Differential Diagnosis of Trigeminal Neuralgia
|Salivary gland causes|
|Temporomandibular joint causes|
|Trigeminal autonomic cephalalgias|
|SUNA=short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms; SUNCT=short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing.|
TN and Other Forms of Trigeminal Neuropathic Pain
- The differential diagnosis between TN purely paroxysmal and other forms of trigeminal neuropathic pain is relatively straightforward in view of the lack of the constant facial pain component in TN purely paroxysmal, whereas other trigeminal neuropathic pain disorders are characterised by a constant dull, aching, burning, and/or throbbing pain
- However, it is more challenging to distinguish between TN with concomitant persistent pain and trigeminal neuropathic pain conditions
- Table 2 outlines some useful clinical differences between these conditions.
Table 2: Differential Diagnosis Between TN with Concomitant Facial Pain and Other Trigeminal Neuropathic Conditions
|Features||TN with Concomitant Facial Pain||Idiopathic Neuropathic Pain[A]||Neuropathic Pain with Identifiable Cause[B]||Persistent Idiopathic Facial Pain|
|Precipitating Factor||No||No||Yes (trauma, viral, inflammatory)||No (possible stress)|
|Laterality and Trigeminal Distribution||Unilateral |
|Often bilateral |
|Pain Severity||Severe to very severe||Mild to severe||Mild to severe||Mild to severe|
|Other Sensory Symptoms||None||Yes||Yes||None|
|Cutaneous/Intraoral Triggers||Present||Yes, but rare||Present||None|
|Effective Treatments||Carbamazepine||Tricyclic antidepressants, gabapentinoids||Tricyclic antidepressants, gabapentinoids||Unclear|
|[A] Includes persistent dentoalveolar pain, atypical odontalgia, phantom tooth pain in which the pain location is intraoral only[B] This term mainly includes painful post-traumatic trigeminal neuropathy and post-herpetic neuropathic pain.|
- Abortive treatments are not useful in the management of TN due to the brevity of the attacks. The mainstay of management is pharmacological preventive treatments; however, acute treatments that work rapidly have to be used occasionally for severe exacerbation
- Surgical interventions are reserved for patients who fail to respond to or adequately tolerate medical therapies.
Pharmacological Preventative Treatments
- Though these treatments are not supported by good quality randomised controlled trials, the clinical experience with some of these drugs (particularly carbamazepine, oxcarbazepine, lamotrigine, gabapentin, pregabalin, baclofen, and botulinum toxin type A) is good, resulting in meaningful pain control, although with still a substantial unmet need for more effective and better tolerated drugs
- Table 3 outlines preventative treatments, recommended doses, and titration and tapering regimens.
Table 3: Preventative Treatments in Trigeminal Neuralgia
|Drug||Initiating Dose||Titration[A]||Dose Range||Frequency||Tapering[B]||Specific Side Effects|
|Carbamazepine||200 mg||200 mg every 3 days||200–1200 mg||2–4 times per day||200 mg every 7 days||Dizziness, drowsiness, fatigue, ataxia, diplopia, nausea, cognitive slowing, hyponatraemia, leucopenia, thrombocytopenia, skin reactions, abnormal liver function tests|
|Oxcarbazepine||300 mg||300 mg every 3 days||300–1800 mg||4 times per day||300 mg every 7 days||Dizziness, drowsiness, fatigue, nausea, ataxia, hyponatraemia, skin reaction|
|Lamotrigine||25 mg||25 mg for 2 weeks, 50 mg for 1 week, then increase by 50 mg every week||25–400 mg||2 times per day||50 mg every 7 days||Dizziness, drowsiness, fatigue, headache, gastrointestinal symptoms, irritability, sleep disorders, tremor, cognitive slowing, rash|
|Gabapentin||300 mg||300 mg every 3 days||300–3600 mg||3 times per day||300 mg every 7 days||Dizziness, confusion, fatigue, ataxia, increased risk of infection, gastrointestinal symptoms, weight gain; use cautiously with opioids|
|Pregabalin||150 mg||150 mg every 7 days||150–600 mg||2 times per day||100 mg every 7 days||Dizziness, confusion, ataxia, increased risk of infection, gastrointestinal symptoms, weight gain|
|Baclofen||15 mg||15 mg every 7 days||15–90 mg||3 times per day||15 mg every 7 days||Confusion, dizziness, drowsiness, gastrointestinal symptoms, euphoria, hallucinations|
|Botulinum toxin type A||25–195 units||NA||25–195 units||Every 12 weeks||NA||Transient facial asymmetry, transient bruising at injection site, transient drooling and difficulty chewing|
|[A] The doses can be increased at a slower rate to improve tolerability; the doses are increased until the pain is well controlled, significant side effects intervene, or the maximum dose is achieved[B] The doses can be reduced more gradually and in smaller decrements; the dose is reduced to either the minimum required to control the pain or allow cessation of drug without recurrence of pain.|
Carbamazepine and Oxcarbazepine
- Carbamazepine and oxcarbazepine are the first-line treatment options for TN and offer meaningful initial pain control in almost 90% of patients, although this may not be sustained in the long term
- Contraindications to using these agents include cardiac conduction problems and allergic reactions
- There is a high degree of cross-reactivity between the aromatic antiseizure medications (carbamazepine, oxcarbazepine, phenytoin, phenobarbital).
- Lamotrigine has been reported to be helpful as an add-on therapy in a small, randomised crossover trial
- Lamotrigine can be used in patients who cannot tolerate carbamazepine and oxcarbazepine, or as add-on therapy to increase efficacy. It is generally associated with fewer side effects than carbamazepine and oxcarbazepine.
Gabapentin and Pregabalin
- Clinical experience shows that gabapentin and pregabalin are less effective but have fewer side effects than carbamazepine and oxcarbazepine. They can therefore be used in place of or in addition to carbamazepine or oxcarbazepine. However, there is a risk of dependency, and they are controlled drugs in the UK.
- Baclofen can help in TN, especially in people with multiple sclerosis who may be using the drug for spasticity.
Botulinum Toxin Type A
- Randomised controlled trials of botulinum toxin type A have provided evidence for efficacy in TN. All trials showed consistent significant superiority of botulinum toxin type A compared with placebo; these studies point towards a clear efficacy of botulinum toxin type A in TN.
- Other drugs reported in small open-labelled studies include phenytoin, tizanidine, levetiracetam, misoprostol (especially in patients with multiple sclerosis), topiramate, pimozide, duloxetine, and eslicarbazepine.