Synonym: tic douloureux
Trigeminal neuralgia (TN) can be described as a chronic, debilitating condition resulting in intense and extreme episodes of pain in the face. The episodes are sporadic and sudden and often like 'electric shocks', lasting from a few seconds to several minutes.
TN results from a neuropathic disorder of the Vth cranial nerve (trigeminal nerve). The trigeminal nerve senses mixed modalities including:
- Motor supply to the muscles of mastication
Most commonly, the maxillary and/or mandibular branch are involved.
- Peak incidence lies between the ages of 50 and 60 years, with prevalence increasing with age.
- There is a reported annual incidence in the UK of about 27 cases per 100,000.
- It is more common in females.
- There may also be a genetic predisposition, as there have been observations of familial clustering. However, the exact method of transmission is unclear, although there is a lack of penetrance.
In nearly all cases, TN is thought to be caused by compression of the trigeminal nerve by a loop of artery or vein; another 5-10% of cases are attributed to tumours, multiple sclerosis, abnormalities of the skull base, or arteriovenous malformations.
TN is a sudden, unilateral, brief, stabbing, recurrent pain in the distribution of one or more branches of the Vth cranial nerve. Pain occurs in paroxysms which last from a few seconds to two minutes. The frequency of the paroxysms ranges from a few to hundreds of attacks a day. Periods of remission can last for months to years, but tend to shorten over time.
- There may be preceding symptoms - eg, tingling or numbness.
- Patients may have certain triggers that set the pain paroxysm off (see 'Diagnostic criteria', below).
- This is followed by sharp, severe, shock-like pains.
- These pains are usually on one side in the cheek or face but pain can involve the eyes, lips, nose and scalp.
- Episodes are intermittent but can last days, weeks or months on end and then not return for months or even years.
- 3-5% of patients will have bilateral pains.
- Site: pain is unilateral in the distribution of the trigeminal nerve, bilateral in only 3% of patients, and rarely is the pain active on both sides at the same time.
- Periodicity: episodic and sudden onset of pain, lasting a few seconds to minutes and stopping suddenly, with many attacks a day. There is a refractory period between each attack. Pain might then go into remission for weeks or months; pain-free intervals gradually shorten between episodes.
- Character: electric shock-like, sharp, shooting.
- Severity: very severe attacks, but attacks can get milder when patients are given drug treatment.
- Factors affecting pain: can be provoked by light touch to the face, eating, cold winds, or vibrations.
- Associated factors: rarely associated with history of other chronic pain or migraine. Some forms have more continued aching background pain after main attack. Rarely associated with autonomic features.
- Skin contact - eg, shaving, washing.
- Brushing teeth.
- Oral intake.
- Exposure to wind.
Patients in this subgroup have relentless underlying pain like a migraine associated with superimposed stabbing pains. There may also be an intense burning sensation. This condition is particularly difficult to treat.
- Sensory changes, deafness or other ear problems.
- Difficulty achieving pain control, poor response to carbamazepine.
- History of any skin lesions or oral lesions that could lead to perineural spread.
- Ophthalmic division only or bilateral as suggestive of benign or malignant lesions or multiple sclerosis.
- Age of onset under 40 years.
- Optic neuritis.
- Family history of multiple sclerosis.
- Dental pathology.
- Temporomandibular joint dysfunction.
- Giant cell arteritis (temporal arteritis) (TN rarely affects the forehead alone).
- Cluster headaches.
- Multiple sclerosis and other disorders of myelin.
- Overlying aneurysm of a blood vessel.
- Tumour in the posterior fossa - eg, meningiomas.
- Arachnoid cyst at the cerebellopontine angle.
- Postherpetic neuralgia after shingles.
The diagnosis is clinical and it can be difficult to make. No investigations are required initially unless there is uncertainty regarding the diagnosis. Patients who are referred on for specialist review will usually have a brain MRI scan.
MRI scan of the brain is indicated to rule out other potential causes of pain if the diagnosis is uncertain or if red flags are present. MRI may be used to identify:
- Extracranial masses along the course of the trigeminal nerve.
- Pathological enhancement of the trigeminal nerve that could indicate perineural spread of malignancy.
- Cavernous sinus masses.
- Demyelination plaques that might indicate multiple sclerosis.
- Intrinsic brain lesions in the thalamus or trigeminal brain stem pathways such as lacunar infarctions.
- Cerebellopontine angle mass lesions such as tumour, epidermoid, dermoid, or arachnoid cyst, aneurysm, or arteriovenous malformation.
Unfortunately, there is no definitive cure at present (relapses and recurrences occur); however, newer surgical procedures are promising. Management involves three aspects: support and education, medical and surgical.
Support and education
- Patients need to be made aware that the condition is not life-threatening.
- There is a need, however, also to express empathy towards severity of the condition.
- Education as to the causes and potential therapies.
- Reassurance and support groups.
Consider referring the person to a specialist pain service or a relevant clinical speciality (for example, neurology, diabetology, or oncology services) at any stage if:
- They have severe pain.
- Their pain significantly limits their participation in daily activities (including self-care, general tasks and demands, interpersonal interactions and relationships, mobility, and sleeping).
- Atypical clinical features (for example, burning pain between paroxysms, loss of sensation, or any abnormal neurological signs) are present.
- Typical analgesics and opioid analgesics are unfortunately not effective.
- Carbamazepine has the most evidence for efficacy and should be used first-line.It should be tried initially and the dose titrated to achieve pain control. There is consensus that oxcarbazepine is also an effective treatment in TN, although there is a lack of randomised control trial-based data to confirm this.
- There is low-quality evidence that the effect of tizanidine is not significantly different to that of carbamazepine. Pimozide is more effective than carbamazepine, although the evidence is of low quality. Overall there is insufficient evidence to show significant benefit from non-antiepileptic drugs in TN.
- Once patients have been in remission for one month, the drug should be gradually withdrawn.
- Tricyclic antidepressants (eg, low-dose amitriptyline) - the data supporting their use at present are lacking.
- Other drugs that might be used in a specialist setting include lamotrigine and baclofen, although lamotrigine needs to be titrated over many weeks and has limited value in severe pain.
Failure of these agents should prompt a review of the diagnosis and, if pain control cannot be achieved or drugs cause unacceptable adverse effects, surgical options should be considered.
Most of the improvements in the management of TN have occurred because of advances in surgical treatments. Surgery involves either relieving pressure on the trigeminal nerve or damaging it to prevent any pain transmission.
There are various types of surgical procedures that can be used in TN. However, there is little evidence to identify the best surgical procedure.Microvascular decompression seems to be the most effective treatment in terms of patient satisfaction and long-term cost-effectiveness. Newer modalities like stereotactic radiosurgery and botulinum injections have shown promising results.
The aim is to damage the trigeminal nerve. This is an alternative to the more invasive decompression. These methods include:
- Percutaneous glycerol rhizotomy (under a local anaesthetic).
- Percutaneous balloon compression rhizotomy (under a general anaesthetic).
- Radiofrequency rhizotomy (performed under sedation).
Stereotactic radiosurgery (gamma knife)
This is also a form of rhizotomy that uses radiation targeted at the trigeminal nerve root and thus injures it. Pain relief is usually delayed for a few days and there can be associated facial numbness. At present, the number of locations providing this treatment is limited.
- Surgery to be considered if there is severe pain or there are side-effects from medication.
- A systematic review commissioned by NICE reported that between 33% to 90% achieved immediate pain relief with this procedure - only an average of 14% had recurrence of symptoms at 18 months.
- Microvascular decompression aims to decompress the trigeminal nerve, and deals with the cause of TN in the 95% of cases not caused by other lesional causes.
- Blood vessels are compressing the trigeminal nerve and lifting these blood vessels away reduces the pressure. This requires a general anaesthetic. The approach is behind the ear into the posterior fossa on the affected side. Patients are usually assessed by MRI beforehand to look for the presence of compression.
- 90% of patients obtain pain relief, with over 80% still pain-free at one year.
- This procedure, however, is not without risks and the average mortality associated with the operation is 0.2%. There is a risk of a cerebrovascular event, deafness and even death.[13, 14] The rates of complication depend on the surgeon's expertise.
- Up to 4% of patients have major problems, such as CSF leaks, infarcts or haematomas. Aseptic meningitis is the most common complication (11%). Diplopia due to IVth or VIth nerve damage is often transient and VIIth nerve palsy is rare. Sensory loss occurs in 7% of patients. The major long-term complication is ipsilateral hearing loss, which can be as high as 10%.
Percutaneous microballoon compression is safe for elderly patients. However, nearly all procedures cause some numbness and, in a few, this can be associated with intense pain obviating the whole point of the surgery ('anaesthesia dolorosa').
Due to the lack of curative measures, the use of complementary therapies in TN has evolved quite rapidly. These include the following:
- Transcutaneous electrical nerve stimulation (TENS).
- Vitamin therapies - eg, vitamin B.
- Nutritional therapies - eg, garlic.
There is no evidence available that supports the use of these measures.
The pain of TN can be so intense that it can lead to a poor quality of life due to mental and physical incapacity. Patients may require psychosocial input - eg, counselling.
One third of patients will have mild symptoms and some will only ever have one episode. Many people have periods of remission with no pain for months or years. There is anecdotal evidence that in many people it becomes more severe and less responsive to treatment with time.
Further reading and references
; National Institute of Neurological Disorders and Stroke, February 2011
; NICE Interventional Procedure Guideline, March 2011
; Trigeminal neuralgia. BMJ. 2014 Feb 17348:g474. doi: 10.1136/bmj.g474.
; Online Mendelian Inheritance in Man (OMIM)
; NICE CKS, February 2013
; Trigeminal neuralgia. Clin Evid (Online). 2009 Mar 122009. pii: 1207.
; NICE Clinical Guideline (November 2013, updated February 2017)
; Non-antiepileptic drugs for trigeminal neuralgia. Cochrane Database Syst Rev. 2013 Dec 312:CD004029. doi: 10.1002/14651858.CD004029.pub4.
; Neurosurgical interventions for the treatment of classical trigeminal neuralgia. Cochrane Database Syst Rev. 2011 Sep 7(9):CD007312. doi: 10.1002/14651858.CD007312.pub2.
; Comparative Evaluation of Surgical Procedures for Trigeminal Neuralgia. J Maxillofac Oral Surg. 2013 Dec12(4):400-409. Epub 2012 Nov 29.
; Percutaneous microballoon compression for trigeminal neuralgia. Chin Med J (Engl). 2007 Feb 5120(3):228-30.
; Trigeminal neuralgia and its management. BMJ. 2007 Jan 27334(7586):201-5.
; NICE (2004)
; European Federation of Neurological Societies (2008)
; Brain stem infarction: a complication of microvascular decompression for trigeminal neuralgia. Neurol India. 2006 Sep54(3):325-6.
; Brain-stem auditory evoked responses during microvascular decompression for trigeminal neuralgia: predicting post-operative hearing loss. Neurol India. 2006 Sep54(3):250-4.
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