Overview
Trigeminal neuralgia (TN) describes neuropathic pain restricted to one or more divisions of the trigeminal nerve. It is usually recurrent, sudden in onset and termination and triggered by stimuli that would not otherwise cause pain. The pain is usually described as an electric shock/stabbing/shooting. The maxillary and mandibular branches are most commonly affected.
Epidemiology
- Slightly more common in women than men
- Uncommon in patients <40 years
Causes
- Trigeminal nerve root compression – 80% of cases
- The compression is usually due to a loop of an artery or vein
- In some cases, it may be a tumour causing compression
- Multiple sclerosis
- Skull base abnormalities
- Arteriovenous malformations
Risk Factors
- Increasing age
- Multiple sclerosis and other demyelinating diseases
Presentation
Overview
Patients have unilateral brief stabbing/shooting pain in the distribution of one or more branches of the trigeminal nerve. The features they may have are as follows:
- The pain is usually triggered by innocuous stimuli e.g. shaving/eating/touching the face/exposure to cold air
- The pain is restricted to the divisions of the branches of the trigeminal nerve
- Attacks of pain are short-lived (seconds to minutes) and episodic
- There may be autonomic features:
- Eye redness
- Lacrimation
- Nasal congestion/rhinorrhoea
- Eyelid oedema
- Facial swelling
Red flag symptoms
The following red flag symptoms suggest that the patient may have a serious underlying cause and require an urgent referral to secondary care:
- Sensory changes
- Deafness or other ear problems
- History of skin or oral lesions that could spread perineurally
- Pain only in the ophthalmic division of the trigeminal nerve (eye socket, forehead, and nose), or bilaterally
- Optic neuritis
- Family history of multiple sclerosis
- Age of onset before 40 years
Differential Diagnoses
- Autonomic features are more prominent
- The pain is usually retro-orbital and can be triggered by smoking/drinking
- Cluster headaches may have no clear trigger
Referral
- Diagnosis is usually clinical, however, if there are any red-flag signs or symptoms, urgently refer for specialist assessment
Diagnostic Criteria
Paroxysms of facial pain lasting seconds to minutes with at least 4 of:
- Distribution along ≥1 division of the trigeminal nerve
- Pain is sudden/intense/sharp/superficial/stabbing/burning
- Pain is severe
- Attacks have known triggers
- Patient is asymptomatic between episodes
- No neurological deficits
- Attacks are stereotyped in a given patient
- Other causes have been ruled out through history/examination/studies
Management
- 1st-line: carbamazepine
- If contraindicated/ineffective – refer to a specialist
- Consider specialist pain service/neurologist referral if:
- They have severe pain
- Their pain limits their participation in activities of daily living
Monitoring and Patient Advice
Monitoring
- Patients are followed up regarding dose titration and effectiveness
- Once the pain is in remission, the dosage should gradually be reduced to the lowest possible maintenance dose or discontinued
Patient Advice
- Patients should be advised regarding dose titration and its importance. They should be advised that treatment does not work immediately and it can take weeks to titrate up to an effective dose
- Patients can keep a daily pain diary to help them learn to manage the pain
Complications and Prognosis
Complications
- Psychosocial problems – e.g. depression
- Weight loss if they are unable to eat
- Impaired ability to perform activities of daily living
Prognosis
- ½ of patients experience remission for at least 6 months
- Periods of remission usually get shorter with time and attacks of pain usually get longer
