This document provides an overview of trigeminal neuralgia (TN), including its classification, causes, clinical features, diagnosis, and treatment options. It defines TN as a painful affliction of the face characterized by brief, intense shock-like pain limited to the trigeminal nerve distribution. The pain is often triggered and generally affects one side of the face. Causes include compression of the trigeminal nerve root near the pons. Diagnosis is based on clinical features and MRI can identify compressing lesions or rule out other causes. Treatment involves pharmacological options like carbamazepine or surgery like microvascular decompression to relieve nerve compression.

1. TRIGEMINAL
NEURALGIA
Presented by
Dr. Rahul Srivastava
Reader
Rama Dental College Hospital
and Research Centre, Kanpur

2. Neuralgia
Neuralgia is pain in the distribution of nerve.
Classification of Neuralgias
The International Headache society has classified neuralgias into two
categories according to etiology:
 Neuralgias associated with compression of the nerve root or
systemic cause, such as multiple sclerosis are considered
symptomatic neuralgias.
 Neuralgias of unknown cause are called Idiopathic Neuralgias.

3. Trigeminal neuralgia (Fothergill's disease/ tic douloureux)
According to the International Headache Society (IHS) the trigeminal
neuralgia may be defined as “painful unilateral affliction of the face
characterized by brief electric shock like pain limited to the
distribution of one or more divisions of trigeminal nerve”.

4. Etiologic/Predisposing factors for trigeminal neuralgia
It is compression of trigeminal nerve root that occurs usually within
few millimeters of entering in to the pons.
The primary demyelinating disorders can also lead to this condition. A
few rare cause of trigeminal neuralgia are:
 Infiltration of nerve root (due to carcinomatous deposit within nerve
root, gasserian ganglion and nerve ).
 Small infarcts or angiomas in the pons or medulla.
 Infiltration of gasserian ganglion or the nerve by a tumour or
amyloid.

5. Compressing lesions responsible for TGN?
 Vestibular schwannomas.
 Meningiomas.
 Epidermoid cyst.
Pre-trigeminal neuralgia
It is the typical initial manifestation that precedes the classic
presentation of TN. A dull continuous, aching pain in the upper or
lower jaw that later develop into classic paroxysmal pain. This
prodromal pain is termed as “pre-trigeminal neuralgia”.

6. Classification of trigeminal neuralgia
A. Based on etiology
1. Classical trigeminal neuralgia – In this, no cause of the
symptoms could be identified other than vascular compression.
2. Symptomatic trigeminal neuralgia -Has the same clinical criteria,
but other underlying cause is responsible for the symptoms.

7. B. Based on specific, objective, and reproducible criteria: A
classification scheme for trigeminal neuralgia (TN) and related facial
pain syndromes is proposed. Such a classification scheme is based on
information provided in the patient’s history and incorporates seven
diagnostic criteria, as follows:
1) and 2) - Trigeminal neuralgia Types 1 and 2(TN1andTN2) refer to
idiopathic, spontaneous facial pain that is predominantly episodic (as
in TN1) or constant (as in TN2) as in nature.

8. 3) Trigeminal neuropathic pain results from unintentional injury to
the trigeminal nerve from trauma or surgery.
4) Trigeminal differentiation pain results from intentional injury to the
nerve by peripheral nerve ablation, gangliolysis or rhizotomy in
attempt to treat either TN or other related facial pain.
5) Symptomatic TN results from multiple sclerosis.

9. 6) Post-herpetic TN follows a cutaneous herpes zoster outbreak in the
trigeminal distribution.
7) The category of atypical facial pain is reversed for facial pain
secondary to somatoform pain disorder and requires psychological
testing for diagnostic confirmation.

10. C. Based on symptoms
From symptomatic point of view the trigeminal neuralgia is classified
in to following:
1-Typical Trigeminal Neuralgia (Tic Douloureux)
This is the most common form of TN, which has previously been
termed Classical, Idiopathic and Essential TN.
2 - Atypical trigeminal neuralgia
Atypical TN is characterized by a unilateral, prominent constant and
severe aching, boring or burning pain superimposed upon otherwise
typical TN symptoms.

11. Clinical features of trigeminal neuralgia
 Recurring episodes of intense, short-lived spasms of pain of the
lower portion of the face and jaw.
 Pain is limited to one side of the face (unilateral).
 The pain has been compared to a series of "electrical shocks"
followed by a steady dull ache.
 The pain often starts and stops rapidly.
 Intense pain usually lessens rapidly (usually with in several
seconds), but the following dull aching pain may persist for as much
as one to two minutes.

12.  Sensitivity in certain areas of face called trigger zone, which when
touched cause an attack. These zones are usually near the nose,
lips, eyes, ears or inside the mouth.
 Pain may be triggered by mild tactile stimuli including brushing
one’s teeth, washing one’s face, shaving, drinking hot or cold
drinks, chewing, talking, blowing one’s nose, a cool breeze, or a
light touch to the face.
 Some episodes may occur without an apparent trigger
(spontaneously). Consequently, episodes can occur repeatedly
throughout the day.

13.  Episodes rarely occur during sleep.
 Attacks typically stop for a period of time and then return.
 Over the time, the pain tends to grow worse with fewer pain-free
periods.

14. Diagnostic criteria for trigeminal neuralgia
The diagnostic criteria of the International Headache Society (IHS)
(1988) are as follows:
 Paroxysmal attacks of facial pain that lasts a few seconds to less
than two minutes.
 Pain has at least 4 of the following characteristics:
A- Distribution along one or more divisions of the trigeminal nerve.
B-Sudden, intense, sharp, superficial, stabbing or burning in quality.
C- Pain intensity is severe.

15. D- Precipitation from trigger areas, or by certain activities such as
eating, talking, washing the teeth or cleaning the face.
E- Between paroxysms the patient is entirely asymptomatic.
 Attacks are stereotyped in the individual patient.
 No neurological deficit and exclusion of other causes.

16. In the second edition the diagnostic criteria for classical
trigeminal neuralgia are as follows:
A. Paroxysmal attacks of pain lasting from fraction of a second to
two minutes, affecting one or more division of trigeminal nerve
and fulfilling criteria B&C.
B. Pain has at least one of the following characteristics:
 Intense, sharp, superficial or stabbing.
 Precipitated from trigger area or by trigger factor.
C. Attacks are stereotype in the individual patients.
D. There is no clinically evident neurological defect.
E. Not attributed to another disorder.

17. The trigeminal neuralgia association, UK has given the following
clues that point to a correct diagnosis:
1- The degree of pain exceeds the evidence.
2- Painkillers do not kill the pain.
3- The pain cannot be pinned down to one specific tooth
Radiologic investigations are important. Secondary TN (e.g. multiple
sclerosis, cysts, vascular pathologies etc.) can be ruled out with help
of MRI.

18.  The diagnosis of TN is essentially clinical.
 Diagnosis is essentially clinically; magnetic resonance imaging is
useful to rule out secondary causes, detect pathological changes in
affected root and neurovascular compression (NVC).
 MRI can diagnose entire course of nerve, root atrophy and
cerebello-pontine angle (CPA) cistern.
Detection of changes in trigeminal root
 Diffusion tensor imaging (DTI) can detect increase in apparent
diffusion coefficient and decrease in fraction of anisotropy (FA) in
trigeminal nerve (TR N).

19.  Coregistration of three-dimensional fast imaging employing steady-
state (3D FIESTA) imaging and DTI facilitates excellent delineation
of cisternal segments of trigeminal nerve (TR Ns).
Vascular conflict detection
 3D FIESTA and contrast-enhanced 3D time-of-flight (TOF)
magnetic resonance angiography (MRA) in combination with
unenhanced MRA could help in the identification of vessel.
 3D T2 high-resolution MRI in combination with 3D TOF-MRA and
3D T1-gadolinium enhanced imaging is reliable in detecting the
degree of the root compression.

20.  3D high resolution MRI and image fusion technology could be
useful for diagnosis of NVC in majority of patients.
 Image fusion of 3D constructive interference in steady-state and
high-resolution MRA is able to depict the complex anatomical
relationships between neural and vascular structures.
 Fusion MRI with multiplanar reconstruction can provide
information about severity of the neurovascular contact.

21. Variants of Trigeminal neuralgia
1- Autonomic signs & SUNCT:
 “Short lasting unilateral neuralgiform headache attacks with
conjunctival injection & tearing”.
 Brief unilateral pain attacks (5- 240 sec in duration) in the orbital
area.
 Facial redness, conjunctival injection, lacrimation & nasal
congestion/ rhinnorrhea.
 These involve the mid-face & orbital region.

22. 2- Cluster- tic syndrome:
Cluster headache together with TN.
(Cluster headache is a well defined craniocervical pain syndrome
characterized by episodes of severe unilateral pain in the orbital
region lasting 15- 180 min. repeated pain episodes occur in
“clusters”)

23. 3- Painful tic convulsif (PTC)
 A combination of ipsilateral hemifacial spasm (HFS) and trigeminal
neuralgia (TN) is known as painful tic convulsif (PTC).
 Cushing first used the term PTC in 1920 to describe this extremely
rare combination of ipsilateral HFS and TN resulting from a
common pathology.

24.  HFS and TN commonly occur in the elderly population as age-
related brain atrophy and sinking of the brain along with elongation
of brain vessels due to arteriosclerosis increase chances of
approximation between cranial nerve roots and nearby vessels,
thereby raising the risk of neurovascular contact.

25. Differential diagnosis
 Migraine, Sinusitis.
 Post herpetic neuralgia.
 Trigeminal neuritis or trigeminal neuropathy.
 Pain of dental origin.
 Trotter’s syndrome.

26. Pharmacological management of TGN.
Pharmacological management can be divided in to:
 First line: Carbamazepine or oxcarbazepine
 Second line: Baclofen or lamotrigine
 Third line: Levetiracetam, gabapentin, pregabalin, topiramate,
Botox-A

27. 1- Drug- Carbamazepine
Mechanism of action: Slow the recovery rate of voltage sensitive
sodium channels, modulates activated calcium channel activity and
activates descending inhibitory modulation system
Dose: 200-1200 mg daily in 2 divided doses
Adverse effect: Memory problems, diplopia, drowsiness, fatigue,
nausea, nystagmus, liver dysfunction, hematosupression

28. 2- Drug: Baclofen
Mechanism of action: It is GABA analogue that activates GABAB
receptors and thus depresses excitatory neurotransmission.
Dose: Initial dose is 5mg TID for3 days and dose may be increased up
to10 to 20mg/day every 3 days and maximum tolerated dose is50 to 60
mg/day
Adverse effects- drowsiness, dizziness, weakness, fatigue and nausea.

29. 3- Drug: Oxcarbazepine
Mechanism of action: Act by blocking voltage sensitive sodium
channel and it modulates voltage activated Ca++ currents.
Dose: 300 to 1800 mg daily in two divided doses
Adverse effect - Dizziness, fatigue, ataxia, fatigue, tremors, diplopia,
diminished concentration.

30. 4- Drug: Phenytoin
Mechanism of action: Promotes sodium reflux from neurons.
Dose: 300 to 500 mg/day
Adverse effects: Nystagmus, ataxia, slurredspeech, mental confusion.
5- Drug: Lamotrigine
Mechanism of action: It acts as a voltage sensitive sodium channel
and stabilizes neural membranes
Dose: Starting dose is 25 mg twice daily and it can be increased
gradually to a maintenance dose of 200-400mg/day in two divided
doses.
Adverse effect - Ataxia, constipation, vomiting and rash.

31. 6- Drug: Levetiracetam
Mechanism of action: Mechanism of action is thought to involve
binding to the high voltage N type calcium channels as well as the
synaptic vesicleprotein 2A (SV2A).
Dose: Effective dose range is1000 – 4000mg/day
Adverse effect - Sleepiness, fatigue, weakness, headache, pain, double
vision, dizziness, coordination difficulties, runny nose or cough,
increased infections, memory difficulties, anxiety, and behavioral
problems.

32. 7-Drug : Gabapentin
Mechanism of action- It is GABA receptor agonist, acts primarily on
presynaptic calcium channels of neurons to inhibit the release of
excitatory neurotransmitters.
Dose - 900 to 1800 mg daily in3 or 4 divided doses
Adverse effect - Dizziness, coordination problems, nausea, vomiting.

33. 8. Drug- Pregabalin
Mechanism of action - Drug binds to the alpha-2-delta subunit of
the voltage gated calcium channels causing decreased presynaptic
calcium entry leading to decreased synaptic release of glutamate.
Dose - 150-600 mg/day.
Adverse effect- Ataxia.

34. 9- Drug: Topiramate.
Mechanism of action - Acts by sodium channel blockade enhancing
GABAA activity by binding to a non-benzodiazepine site on GABAA
receptors, and selectively blocking AMPA/kainite glutamate receptors.
Dose- 100 to 400 mg a day
Adverse effect- Dizziness, sedation, cognitive impairment, fatigue,
nausea, blurred vision and weight loss.

35. Surgical management of TGN
1- Microvascular decompression
 This permits the trigeminal nerve nucleus to recover from its state of
hyperactivity and return to a normal, pain free condition.
 Micro-instruments are used to mobilize the offending vessels away
from the trigeminal nerve root.
 The decompression is permanently maintained by inert implants,
such as those made of shredded Teflon®, between the offending
vessels and nerve.

36. 2- Percutaneous Rhizotomies
Involve inserting a needle through the cheek and into an opening at
skull base (foramen ovale). There, a controlled injury to the trigeminal
nerve and Gasserion ganglion may be produced in one of three ways:
 Percutaneous Glycerol Injection.
 Percutaneous Balloon Compression Rhizotomy.
 Radiofrequency Rhizotomy.

37. 3- Gamma Knife Radiosurgery
Focuses cobalt radiation upon the trigeminal nerve root, producing a
delayed injury to nervous tissue.
4- Peripheral Trigeminal Nerve Blocks, Sectioning and Avulsions
Involve injuring the peripheral portions of the trigeminal nerve external
to the skull.
5- Microsurgical Rhizotomy
Involves surgical exposure and cutting of the trigeminal nerve root near
its entry into the brain stem.

38. References
 Hegarty Anne M, Zakrzewska JM differential diagnosis for orofacial
pain, including sinusitis, TMD, trigeminal neuralgia. Dent
update 2011;38:396-408.
 Migraine and the trigeminal nerve. Migraine Action,Leicester
[Internet].2010 [cited on 2015 Feb 19].Available from: http: // www
.nhs.uk/ipgmedia/ national /migraine % 20 action /assets /
migraineandthetrigeminalnerve.pdf

39.  Jannetta PJ. Arterial compression of the trigeminalnerve at the pons
in patients with trigeminal neuralgia.J Neurosurg.1967;26:159-62.
 George M, Selvarajan S, Indumathi C. Drug therapy for trigeminal
neuralgia. e-Journal of Dentistry. 2011;1:28-31.
 Rhoton AL .The cerebellopontine angle and posterior fossa cranial
nerves by retrosigmoidapproach. Neurosurgery. 2000;47:S93-129
 Yadav YR, Nishtha Y, Sonjjay P, Vijay P, Shailendra R, Yatin K.
Trigeminal Neuralgia. Asian J Neurosurg. 2017;12(4):585-597.
doi:10.4103/ajns.AJNS_67_14