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Trigeminal neuralgia

Updated: Mar 23, 2022

 

Definitions/Diagnostic criteria (ICHD-3; Padfield, 2014)

IASP 2012: Sudden, usually unilateral, severe brief stabbing recurrent episodes of pain usually in one or more branches of the trigeminal nerve


ICHD-3: 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. It may develop without apparent cause or be a result of another diagnosed disorder. Additionally, there may be concomitant continuous pain of moderate intensity within the distribution(s) of the affected nerve division(s).


ICHD-3: Diagnostic criteria:

Recurrent paroxysms of unilateral facial pain in the distribution(s) of one or more divisions of the trigeminal nerve, with no radiation beyond1, and fulfilling criteria B and C

  1. Pain has all of the following characteristics:

    1. lasting from a fraction of a second to 2 minutes2

    2. severe intensity3

    3. electric shock-like, shooting, stabbing or sharp in quality

  2. Precipitated by innocuous stimuli within the affected trigeminal distribution4

  3. Not better accounted for by another ICHD-3 diagnosis.

Notes:

  1. In a few patients, pain may radiate to another division, but it remains within the trigeminal dermatomes.

  2. Duration can change over time, with paroxysms becoming more prolonged. A minority of patients will report attacks predominantly lasting for >2 minutes.

  3. Pain may become more severe over time.

  4. Some attacks may be, or appear to be, spontaneous, but there must be a history or finding of pain provoked by innocuous stimuli to meet this criterion. Ideally, the examining clinician should attempt to confirm the history by replicating the triggering phenomenon. However, this may not always be possible because of the patient’s refusal, awkward anatomical location of the trigger and/or other factors.

ICHD-3 Sub-types


Classic: Neurovascular compression - requires clear evidence of compression and changes to the trigeminal nerve root either on imaging or at surgery (75% of cases)


Secondary TN: TN from an underlying disease e.g. MS, cerebellopontine angle tumour, and AV malformation (15% of cases)


Idiopathic: Electrophysiological tests nor MRI show abnormalities (10% of cases)

 

Epidemiology (UpToDate 2021)

Rare condition that affects more women than men - 1.5 : 1 (but may be due to longevity of women)

4-13 per 100,000 people

Though rare, it is one of the most common neuralgias seen in older adults

Incidence increases with age. Most classic and idiopathic cases occur > 50 (though can occur earlier)

Familial cases are possible - but even rarer

 

Risk factors (UpToDate 2021)

Maybe hypertension

Maybe migraine

 

Pathophysiology (UpToDate 2021)

Mechanisms:

- Compression of the trigeminal nerve root

- Multiple sclerosis and brainstem lesions

- Central sensitisation


Compression:

Usually an aberrant loop of an artery or vein in 80-90% of cases

Can also be a vestibular schwannoma, meningioma, epidermoid cyst, or rarely a saccular aneurysm or AV malformation


Thought that this compression leads to a focal demyelination. They they set up ectopic impulse generation, possibly causing ephaptic transmission (nerve fibres touch and cause cross talk). May also cause disinhibition of pain pathways in spinal trigeminal nucleus.


(Ephaptic: Of or relating to a form of communication within the nervous system involving the coupling of adjacent (touching) nerve fibers caused by the exchange of ions between the cells, or as a result of local electrical fields, but distinct from direct communication systems such as synapses.) Wiktionary 2021


Multiple Sclerosis

Demyelination of one or more of the trigeminal nerve pathways may be caused by MS, tumours at the cerebellopontine angle, or other structural lesions of the brainstem


Central sensitisation

Due to refractory periods after triggered episode, central sensitisation effects are suspected. They have also found electrophysiological evidence of sensitisation changes in patients with atypical TN.

 

Presentation (UpToDate 2021)


Anatomy revision:

The trigeminal nerve supplies sensation and motor supply to the muscles of mastication

Three branches - Ophthalmic (V1), Maxillary (V2) and Mandibular (V3)

Nerve starts at midlateral surface of the pons, and its sensory ganglion (gasserion ganglion) resides in the Meckel cave in the floor of the middle cranial fossa



Symptoms

Paroxysmal, stabbing, sharp, superficial severe pains in one of the branches of the 5th cranial nerve

Most common in the V2 and V3 branches


Pain is worst generally at onset of a paroxysm. Muscle spasms can also be seen with severe pain (the old name 'tic douloureux')

May recur from 0 to 50 times per day

Refractory period of several minutes is common

Some people experience a dull ache between episodes

It rarely wakes people at night


It is unilateral mainly but has been known to be both sides simultaneously (more common in MS)


Nearly all patients will have a 'trigger zone' - an area often in the midline. Lightly touching these areas often triggers an attack. Trigger zones can be 'fired' through touch/palpation. Otherwise, paroxysms can be triggered by: chewing, talking, brushing teeth, cold air, smiling or grimacing


Autonomic symptoms are more common with V1 involvement - lacrimation, conjunctival injection, and rhinorrhea.


Continuous pain between attacks is also common but is milder than the attacks and is typically dull or tingling


 

Examination:

- Examination can be difficult in some patients due to complete fear of contacting a trigger point for pain

- Neurological examination including facial sensation, masseter bulk and strength, and corneal reflexes should be intact (trigeminal sensory branch, motor is 7).

- There should be no clear sensory persistent deficit (except acutely after an attack)

- Jaw or eating difficulties suggests another etiology

- In MS or other direct causes there is often sensory loss on examination

 

Differential diagnosis (Padfield, 2014; UpToDate 2021)

- Idiopathic facial pain

- TMJ disorders

- Dental pain including periodical abscesses

- Migraines

- Cluster headaches

- Atypical facial pain (More common in face, neck, ears, hours to days of pain, throbbing and dull and more intrusive than electric. There may also be sensory changes)

- Glossopharyngeal neuralgia (pain is usually in the tonsillar or pharynx region)

- Occipital neuralgia (head region)

- Paroxysmal hemicranias (though this will occur directly around the eye and have autonomic features)

- Acoustic neuromas, cerebral aneurysms, trigeminal neuromas and meningiomas

- Herpetic and postherpetic neuralgia

 

Investigations (Padfield, 2014)

Examinations and x-rays improve the diagnosis of dental pain [not TN] (2)

Patients should have an MRI or, in the least, a CT scan to rule out TN secondary to tumours or other compressive causes, and rule out MS (2).

MRI or MRA is much better than CT


In classical TN, HR MRI will indicate neuromuscular compression of the trigeminal nerve in the posterior fossa


 

Treatment (Padfield, 2014; UpToDate 2021)


Carbamazepine has been the standard for a long time. (Can use oxcabazepine)

Other options include topiramate, gabapentin, pregabalin, clonazepam, phenytoin, lamotrigine and valproic acid.

TCAs can be useful

Common analgesics and opioids are not usually helpful but opioids can assist with TN2 in some settings

Unfortunately TN often becomes increasingly resistant to medications over time


Surgical options:

- Destructive percutaneous procedures at the level of the gasserian ganglion

- Balloon compression, glycerol injection, or RF ablation and gamma knife use

-- These may give relief to up to 70% of patients for up to 5 years

-- Can cause facial numbness however


Microvascular decompression may give relief for 70% of patients for 10 years but 0.5% risk of death and 2% risk of hearing loss

 

Prognosis (Heinskou et al., 2019)


103 patients remained medically managed and completed the two-year follow-up. Fifty patients were treated surgically within the first two years of follow-up. Half of the medically managed patients (53 (51%)), had more than a 50% reduction in the overall burden of pain over the two-year period. The overall burden of pain on NRS decreased from mean 5.34 to 3.00, p < 0.01. There was no significant association between primary outcome and sex, depression and/or anxiety, concomitant persistent pain, or neurovascular contact with morphological changes of the trigeminal nerve.

 

Golden pearls (Padfield, 2014)

It is one of the few chronic pain conditions that can be 100% treated with medications or surgery so requires appropriate diagnosis and management (2)


Symptoms commonly lead to secondary depression (Padfield, 2014)

 

Quiz

 

 

References / Articles / Resources

  1. https://ichd-3.org/13-painful-cranial-neuropathies-and-other-facial-pains/13-1-trigeminal-neuralgia/13-1-1-classical-trigeminal-neuralgia/

  2. Padfield, D. (2014). The patient's journey through trigeminal neuralgia. Pain: Clinical Updates, 22(1), 1-8.

  3. Heinskou, T.B., Maarbjerg, S., Wolfram, F. et al. Favourable prognosis of trigeminal neuralgia when enrolled in a multidisciplinary management program - a two-year prospective real-life study. J Headache Pain20, 23 (2019). https://doi.org/10.1186/s10194-019-0973-4

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