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Trigeminal Neuralgia

Key clinical highlights

  • Trigeminal neuralgia (tic douloureux) is a neuropathic condition characterised by recurrent bouts of unilateral electric shock-like pain, distributed over the path of the trigeminal nerve.1-4
  • The pain associated with trigeminal neuralgia may be spontaneous or evoked from normally innocuous activities such as washing, shaving, talking and/or brushing teeth.2,3,5,6
  • Trigeminal neuralgia is commonly the result of vascular compression of the trigeminal nerve; however other causes such as trauma, unsuccessful dental work, infection, and (rarely) tumour growth may also be responsible for nerve compression.3,5,7,8
  • The management of trigeminal neuralgia can involve pharmacotherapy or surgery; when choosing an appropriate therapy it is important to consider the patient’s age, life expectancy, associated medical conditions, psychiatric conditions, compliance, and the possibility of any adverse events associated with therapy.3,4
  • Early and accurate diagnosis of neuropathic pain conditions is crucial to initiating appropriate management strategies and improving patient health outcomes.9

Definition

The International Classification of Headache Disorders 3rd edition (ICHD-3) defines trigeminal neuralgia (tic douloureux; “painful spasm”3) as:

A disorder characterized by recurrent unilateral brief electric shock-like pains, abrupt in onset and termination, limited to the distribution of one or more divisions of the trigeminal nerve and triggered by innocuous stimuli.”1

This definition is similar to the International Association for the Study of Pain (IASP) definition, which states that trigeminal neuralgia is a “sudden usually unilateral severe brief stabbing recurrent pains in the distribution of one or more branches of the fifth cranial nerve”.4

Diagnostic criteria

Diagnosis of trigeminal neuralgia can only be made based on clinical assessment – as yet there are no electrophysiological, radiological or laboratory investigations that can be used to diagnose the condition.7

The ICDH-3 Criteria classify trigeminal neuralgia as either:

  • Classical trigeminal neuralgia;
  • Purely paroxysmal classical trigeminal neuralgia (i.e. trigeminal neuralgia without persistent background facial pain); or
  • Classical trigeminal neuralgia with concomitant persistent facial pain.1

Classical trigeminal neuralgia typically starts in the second or third divisions of the trigeminal nerve (cranial nerve V), usually affecting the cheek or the chin (Figure 1).1,2

PFILY0850_website-update_2-1-1-4_trigeminal_v1b3-figure-1.png

The diagnostic criteria for the three variants of trigeminal neuralgia are outlined in Table 1. The patient’s description of their pain, as well as sensory testing during physical examination are crucial to determining whether the diagnostic criteria have been fulfilled.7The pain never crosses to the other side of the face, but may (rarely) occur bilaterally.1

It is also important to exclude any other painful facial conditions.7

PFILY0850_website-update_2-1-1-4_trigeminal_v1b-table-1.png

Painful episodes generally only last a few seconds, but several may occur in quick succession.3

Patients may report that their pain occurs spontaneously, however it may be triggered by innocuous stimuli such as washing, shaving, talking and/or brushing the teeth.2,3,5,6

Epidemiology

Trigeminal neuralgia is relatively uncommon. Estimates of its incidence rate vary from between 4.3 to 8 per 100,000 head of population.7

The lifetime prevalence of trigeminal neuralgia has been estimated at 70 per 100,000.7

Trigeminal neuralgia is more common in women than men, with an incidence ratio of approximately 2:1. It is also more common amongst older patients – the incidence rates for both sexes increase with age, and are highest amongst those aged 60 years or older (Figure 2).6-8

The clinical course may also change as a patient ages. Trigeminal neuralgia is characterised by periods of exacerbations and remission – the periods of remission usually get shorter as patients age.8

PFILY0850_website-update_2-1-1-4_trigeminal_v1b4-figure-2.png

The aetiology of trigeminal neuralgia is yet to be completely elucidated, however the most consistent explanation is that trigeminal neuralgia arises as a result of vascular compression. This most likely occurs near the trigeminal nerve root proximal to the pons, where it exits the CNS.3,7,8

Aetiology

A major artery, usually the superior cerebellar artery, is most commonly responsible for compressing the nerve, and the location of the pain may be suggestive of the aetiology (Table 2).3

PFILY0850_website-update_2-1-1-4_trigeminal_v1b2-table-2.png

Other possible causes include compression by tumours, veins and arteriovenous malformations (however this is rarely the case), or traumatic injury, infection or unsuccessful dental surgery.3

Demyelination is also another potential cause, as in the case of patients with Multiple Sclerosis.3

Pathophysiology

Due to a paucity of robust data, the pathophysiology of trigeminal neuralgia is poorly understood. This is primarily because most studies examining the cellular processes of neuropathic pain do not use trigeminal ganglia, and there are no animal models of trigeminal neuralgia.7

Currently, the most extensive and systematic hypothesis is the “ignition hypothesis”. This suggests that the paroxysmal nature of trigeminal neuralgia cannot be explained by the generation of ectopic nerve impulses at the site of the compression or nerve damage.7

Rather, the symptoms are most likely the result of discharges from select neurons, whose threshold for repetitive firing has been altered (see Sensitisation).7

Management

A number of therapeutic options exist for the management of trigeminal neuralgia, ranging from symptomatic pharmacological therapy to surgery.3,4

Invasive procedures, such as surgery, are generally reserved for patients who are refractory to pharmacotherapy or who experience unacceptable adverse effects.3,4

Surgical options can be subdivided into two categories:

  • Ablative (i.e. destruction of the nerve using physical or chemical methods); or
  • Non-ablative (decompressing the nerve and thus preserving nerve function).4

There currently isn’t any data to indicate the prognosis of untreated trigeminal neuralgia; nor is there data comparing the outcomes of surgical vs. non-surgical treatment.4

A 2011 Cochrane Review revealed that while surgical intervention does offer pain relief, and in some instances, patients were able to stop taking medications, many of the procedures were associated with sensory side effects.4

Thus, a number of factors should be taken into consideration when deciding upon a management strategy. These include:

  • The patient’s age (adult or child);
  • Life expectancy;
  • Associated medical and/or psychiatric conditions;
  • Likelihood of compliance with medical therapy; and
  • The tolerability of any adverse events that may result from pharmacotherapy.

Clinical Tip
When managing neuropathic pain conditions, an early and accurate diagnosis is crucial so that appropriate management strategies can be introduced early. This may improve patients’ health outcomes.9

Links and resources

Patient information resources

You may find some of the following patient information resources helpful for use with your trigeminal neuralgia patients:

External links

Trigeminal Neuralgia Assocation Australia

A not-for-profit organisation providing information and newsletters relevant to trigeminal neuralgia, its diagnosis and management.

References:

  1. Headache Classification Committee of the International Headache Society. Cephalalgia. 2013; 33(9) 629–808.
  2. International Headache Society. Classical trigeminal neuralgia. Available at http://ihs-classification.org/en/02_klassifikation/04_teil3/13.01.01_facialpain.html. Accessed on 17th July 2014.
  3. Siddiqui MN, et al. Hospital Physician. 2003; 39(1): 64-70.
  4. Zakrzewska JM & Akram H. Cochrane Database Syst Rev. 2011; 9: CD007312. doi: 10.1002/14651858.CD007312.pub2.
  5. Nurmikko TJ & Eldridge PR. Br J Anaes. 2001; 87(1): 117-132.
  6. Ritter PM, et al. J Neurosci Nurs. 2009; 41(4): 211-214.
  7. Nurmikko TJ. Trigeminal neuralgia and other facial neuralgias. In Cervero F & Jensen TS. Handbook of Clinical Neurology. Vol. 81 (3rd series). Philadelphia: Elsevier; 2006.
  8. Bagheri SC, et al. J Am Dent Assoc. 2004; 135(12): 1713-1717.
  9. Haanpää ML, et al. Am J Med. 2009; 122 (10 Suppl): S13-21.

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Key clinical highlights Trigeminal neuralgia (tic douloureux) is a neuropathic condition characterised by recurrent bouts of...

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