Trigeminal Neuralgia

Question 1

… is characterised by episodes of acute severe facial pain within the distribution of the trigeminal nerve.

Answer 1

Trigeminal neuralgia is characterised by episodes of acute severe facial pain within the distribution of the trigeminal nerve.

Question 2

Trigeminal neuralgia overview

Answer 2

Once termed tic douloureux, trigeminal neuralgia is a rare condition that most commonly affects the maxillary and mandibular branches of the trigeminal nerve.

Episodes normally last seconds to a few minutes and may be triggered by cold wind, talking, vibrations Typically the condition is unilateral though it is bilateral in 3%.

Question 3

Epidemiology of trigeminal neuralgia

Answer 3

Trigeminal neuralgia is a rare condition that is more common in women.
The exact incidence of trigeminal is unclear. Annual incidence in the UK is estimated to be 8 per 10,000 although due to its rarity these estimations can vary wildly. It is around twice as common in women compared to men.

Question 4

The trigeminal nerve is the … cranial nerve.

Answer 4

The trigeminal nerve is the 5th cranial nerve.

Question 5

The trigeminal nerve is composed of three major branches:

Answer 5

Ophthalmic nerve (V1): general somatic afferent. Exits the skull via the superior orbital fissure and provides sensation to the to forehead, anterior scalp, nose and eyes (including conjunctiva).
Maxillary nerve (V2): general somatic afferent. Exits the skull via the foramen rotundum. Provides sensation to the mid-face, lower eyelid, nasal cavity, palate, upper lip and maxillary teeth.
Mandibular nerve (V3): general somatic afferent and branchial (special visceral) efferent. Exits the skull via the foramen ovale. Provides sensation to part of scalp, part of the ear, lower face, tongue, floor of mouth and mandibular teeth. Provides motor input to the muscles of mastication (temporalis, masseter, medial and lateral pterygoids) and the tensor tympani.

Question 6

Vascular … is the most common cause of trigeminal neuralgia.

Answer 6

Vascular compression is the most common cause of trigeminal neuralgia.

Question 7

Primary trigeminal neuralgia

Answer 7

Primary trigeminal neuralgia refers to disease caused by vascular compression. It is thought to account for 80-95% of cases of trigeminal neuralgia. This normally occurs near the root of the nerve at the ‘nerve root entry zone’. The compression is thought to lead to demyelination and abnormal electrical activity in response to stimuli.

Question 8

Secondary trigeminal neuralgia

Answer 8

Secondary trigeminal neuralgia refers to disease occurring secondary to another condition. Compression may be caused by other lesions (e.g. vestibular schwannoma, meningioma, cysts).

Multiple sclerosis can also lead to secondary trigeminal neuralgia due to demyelination of the trigeminal nerve.

Question 9

… … can also lead to secondary trigeminal neuralgia due to demyelination of the trigeminal nerve.

Answer 9

Multiple sclerosis can also lead to secondary trigeminal neuralgia due to demyelination of the trigeminal nerve.

Question 10

Risk factors for trigeminal neuralgia (4)

Answer 10

Female sex
Advancing age
Multiple sclerosis
Family history

Question 11

What do patients describe in trigeminal neuralgia?

Answer 11

Patients describe short-lived episodes of electric shock pain in the distribution of the trigeminal nerve.

Question 12

Red flags in suspected trigeminal neuralgia

Clinicians must be aware that similar symptoms may be seen in other conditions including malignancy.

NICE CKS list the following red flags to be aware of:

Answer 12

Onset before 40 years
Hearing difficulties or other ear problems
Sensory changes
Previous skin/oral lesions that could exhibit perineurally
Isolated involvement of ophthalmic division
Bilateral symptoms
Optic neuritis
Family history of multiple sclerosis

Question 13

The International Classification of Headache Disorders, third edition formally defines the clinical diagnosis of trigeminal neuralgia.

Answer 13

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 2 and 3.

Pain has all of the following characteristics:
Lasting from a fraction of a second to 2 minutes
Severe intensity
Electric shock-like, shooting, stabbing or sharp in quality
Precipitated by innocuous stimuli within the affected trigeminal distribution
Not better accounted for by another ICHD-3 diagnosis

Question 14

What forms the mainstay of management in trigeminal neuralgia?

Answer 14

Carbamazepine forms the mainstay of management.

Question 15

Carbamazepine forms the mainstay of management. Typically a starting dose of 100mg twice day is given and this may be titrated upward depending upon response. Once in remission the dose should be titrated down to the lowest level that maintains remission.

If ineffective, contraindicated or not tolerated patients should be referred to neurology. Second line options include:
(2)

Answer 15

Gabapentin

Lamotrigine

Question 16

Surgical management

In patients in who medical management is ineffective surgical intervention may be considered. The options depend on the underlying aetiology and patient factors. For primary trigeminal neuralgia options include:

Answer 16

Microvascular decompression

Gamma knife radiosurgery

Question 17

Prognosis

Trigeminal neuralgia

Answer 17

The course of trigeminal neuralgia is varied but normally characterised by episodes of attacks followed by remissions.

Question 18

The course of trigeminal neuralgia is varied but normally characterised by episodes of attacks followed by remissions.
Most patients have a relapsing-remitting course though some patients experience a chronic background pain.

Patients may experience remissions that last many months. With time such remissions normally become shorter. Of those with a new diagnosis:

Answer 18

65% will have a further episode in 5 years

77% will have a further episode in 10 years

Question 19

trigeminal neuralgia

The majority of patients experience remission with medical therapy, though up to …% will not respond.

Answer 19

The majority of patients experience remission with medical therapy, though up to 10% will not respond.