Trigeminal neuralgia

Dr. Shahnawaz Alam
Resident; MCh-
Neurosurgery
Moderated by:
Dr. V. C. Jha
HOD, Dept. of Neurosurgery
TRIGEMINAL NEURALGIA
DEFINITION, DDX, MANAGEMENT, SURGERY AND GKRS

INTRODUCTION
• Recurrent brief episodes of unilateral electric shock like pains, abrupt in onset
and termination, in the distribution of one or more divisions of the trigeminal
nerve that are typically triggered by innocuous stimuli.
• Incidence: 40-50 cases per million; Prevalence: 100-200 cases per million (1)
• Age group: 35-65 years (2); Right side more commonly affected; Gender: twice
as common in females
• Hereditary forms of TGN rare (<5%); B/l TGN have higher hereditary
predisposition
{1} 1. Manzoni G, Torelli P. Epidemiology of typical and atypical craniofacial neuralgias. Neurological Sciences. 2005;26(S2):s65-s67.
{2} Koopman J, Dieleman J, Huygen F, de Mos M, Martin C, Sturkenboom M. Incidence of facial pain in the general population. Pain. 2009;147(1):122-127.

Diagnosis of typical trigeminal neuralgia: five criteria
1. paroxysmal sharp and shooting pain that is characterized by exacerbations
and remissions,
2. pain that follows the distribution of the trigeminal nerve,
3. a normal neurologic examination that includes no significant loss of facial
sensation,
4. Magnetic resonance imaging (MRI) of the brain that demonstrates neither
mass lesions nor demyelinating plaques, and
5. pain that is induced by cutaneous stimulation.

BRIEF HISTORY
• First scientific account: Johannes Laurentius Bausch (1671)
• Synonyms: Suicide disease, Prosopalgia , Tic Douloureux, Fothergill’s
Disease
• 1820 Charles Bell coined Trigeminal Neuralgia
• 1904  Percutaneous alcohol injection by Schloesser
• 1920  Spiller-Frazier technique of selective sectioning of Trigeminal nerve
fibres, Walter Dandy: ‘arterial loop impingement’
• 1940  Bergouinan used antiepileptic in TGN
• 1970 Leksell used stereotactic radiation
• 1996 Peter Janetta: MVD

DEFINITION (ICHD-3, 2018,IHS)
• 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 B and C
• A  All the pain characteristics:
• lasting from a fraction of a second to 2 minutes
• severe intensity
• electric shock-like, shooting, stabbing or sharp in quality
• B Precipitated by innocuous stimuli
• C Not better accounted for by another ICHD-3 diagnosis.

CLINICAL FEATURES
• Pain may radiate to another division; Identification of Trigger
• Usually fail to show sensory abnormalities
• In severe cases can evoke contraction of the facial muscles of the affected side
• Mild autonomic symptoms like lacrimation or redness of eye may be present
• Refractory period
TYPES:
a) Classical Type
b) Secondary Type
c) Idiopathic Type

CLASSICAL TGN
• Classical TGN: Demonstration on MRI/Surgery of Neurovascular Compression and
morphological changes
1) Classical TGN:
Purely Paroxysmal pain free between attacks
2) Atypical TGN/Type II TGN:
Concomitant continuous pain between attacks; Atypical- aching, throbbing, burning,
>50% constant pain.

• Morphological changes: Nerve root atrophy (demyelination, neuronal loss,
microvasculature changes)/ displacement.
• Compression by artery more symptomatic than by compression of vein.

SECONDARY TGN
• Secondary TGN : An underlying disease known to cause neuralgia
1)TGN attributed to MS
2)TGN attributed to SOL
3)TGN attributed to other casues
IDIOPATHIC TGN
• Idiopathic TGN: MRI or electrophysiologic testing showing no abnormalities
• IASP definition: “unilateral painful orofacial condition characterized by brief
duration of electric shock-like sensation with an abrupt onset and termination,
and limited to one or more sensory divisions of the trigeminal nerve”

DIRECT COMPRESSION OF TRIGEMINAL NERVE
• Neurovascular Compression : (80-90% cases)
Vascular Loop; SCA(85%)> AICA > PICA > VA
Venous loop
• MC site: Dorsal Root Entry Zone near Pons
Laminar Arrangement of fibres in Trigeminal nerve
(Medial V2 ,Lateral/caudal V3 , rarely Cranial 
V1 symptoms)
• Tumours(2%) : Meningioma/Vestibular
Schwannoma/epidermoid/Tuberculoma/Arachnoid Cyst
{Tumours at REZ cause neuralgia, peripheral
compression causes more constant pain}
• AVM/Aneurysms

SYSTEMIC DISEASES
• Multiple Sclerosis In 0.9-4.5% patients of MS; young, Bilateral presentation
MR: demyelinating lesion at pontine REZ
• Vascular diseases, Rheumatism, Diabetes, HTN no proven role
• TGN association with atherosclerosis/Arterial hypertonia
• Following previous surgery; Allergic Hypothesis
• TM joint pathology, high position of petrous apex, acute bony angle of
petrous ridge, short trigeminal nerve cisternal length.

PATHOPHYSIOLOGY
• REZ/Redlich-Obersteiner’s Zone:
boundary b/w CNS and PNS
junction between myelin of Schwann and
glial cells
• Visually identified as 1-2.5 mm Zone;
Thin A delta nociceptive fibres are highly
susceptible to pressure
• Long standing compression: membrane
instability and demyelination
interconnection between neurones
• Nerve deviation/distortion: groove
formation nerve atrophy
{Atrophic changes in proportion to
severity of compression}

PATHOGENESIS
• Short Connection Theory: demyelination and cross talk
(Pressure on highly susceptible A delta fibres; ectopic impulse generation;
abnormal non synaptic transmission.
• Ignition Hypothesis: Trigeminal root ganglia neuronal abnormalities
hyperexcitability of neurones and synchronous firing
• Pulsatile mechanical compression by vessel
• Cutaneous stimuli stimulate pain fibres which are in close proximity at REZ
• Focal demyelination not always present
• Central Pathogenetic Mechanism

DIFFERENTIAL DIAGNOSIS
• Deafferentation pain: post surgical injury/trauma {constant itching or burning
pain , sensory loss}
• Dental causes: caries, abscess, periodontitits, cracked tooth
unilateral and localised pain, usually constant, oral mucosal examination for
causes.
• Temporo-Mandibular Joint Disorders  restricted mouth opening or cracking
noises. on prolonged mouth opening, palpation of joint and local examination
• Salivary Gland Disorders  obstruction of flow of saliva :intermittent
pain(tumors, stones) ; infection
• Maxillary sinusitis Acute sinusitis, nasal discharge,tenderness, dull mild to
moderate pain

TRIGEMINAL AUTONOMIC
CEPHALALGIAS
• Primary headache disorders with cranial autonomic symptoms and pain in
Trigeminal nerve distribution.
• Cluster Headache, Paroxysmal Hemicranias, SUNCT, SUNA
• Cluster headache: temporal association with sleep (episodic, u/l typically
periorbital, prolonged course of 15-180 mins, severe throbbing type,
conjunctival injection).
• SUNCT/SUNA : paroxysmal ocular or periocular pain with ipsilateral
autonomic symptoms intense: Conjunctival injection, lacrimation, nasal
congestion, rhinorrhoea, sweating and flushing of forehead
• More common in V1 and least in V3

Difference between TGN and SUNCT/SUNA

DIFFERENTIAL DIAGNOSES
• Post-Herpetic Neuralgia : Usually months after resolution of Herpes
Zoster; Dermatomal Vesicopapular Rash; Allodynia, burning sharp pain;
Sensory loss to pinprick, temperature in affected areas; Continuous pain with
fluctuating severity
• Glossopharyngeal neuralgia: pain in throat- ear areas inferior to angle of
mandible, precipitated by swallowing, chewing
• Nervus Intermedius neuralgia - brief paroxysmal pain in ear canal
• Hemifacial spasm/ Tolosa Hunt syndrome/ Migraine
• Perineural spread of head and neck malignancies

RED FLAG SIGNS IN CLINICAL
EXAMINATION FOR SECONDARY
AETIOLOGIES
 Sensory or motor deficits in cranial nerve examination
 Abnormal oral, dental, or ear examination
 Age younger than 40 years
 Presence of bilateral symptoms
 Dizziness or vertigo
 Hearing loss or abnormality
 Pain episodes persisting longer than two minutes
 Pain outside of trigeminal nerve distribution
 Severe Autonomic symptoms

MRI
• Obersteiner Redlich zone: 1mm for motor root and 3 mm for sensory root
• Visual inspection: thinning of trigeminal myelin sheath
• Ventrolateral pons: two different roots
• Gasserian ganglion

CLINICAL DIAGNOSIS
OF TGN
PHARMACOLOGIC
THERAPY WITH
CBZ/OXZ
DOSE ESCALATION
AND ADDITION OF
2nd/3rd LINE DRUGS
PHARMACORESISTANT
TGN
MRI AND OTHER
SIGNS
NERUOVASCULAR
CONFLICT +
ASA I OR AGE < 75
yrs
MVD
ASA II OR AGE >
75yrs
NEUROVASCULAR
CONFLICT -
SRS, PERCUTANEOUS
PROCEDURES,
NEUROMODULATIVE
PROCEDURES
SECONDARY CAUSES
UNDERLYING CAUSE
TREATMENT

TREATMENT MODALITIES
AVAILABLE

PHARMACOTHERAPY
• First line: CARBAMAZEPINE (Level A evidence)
DOSE: 100 to 200 mg twice daily and increase in 200 mg daily dose as
tolerated upto 600-800 mg daily and maximum of 1200 mg daily; Sodium
channel blockade and membrane stabilisation; Efficacy: 80% pain relief
• HLA-B 1502 individuals higher incidence of Steven Johnson syndrome and
TEN, CBC, Sodium and LFT monitoring; CYP 450 system and failure of
OCPs; 6 to 10% patients are unable to tolerate.
• Oxcarbamazepine: Similar efficacy to CBZ; Pro-drug; Better Tolerability
and fewer drug interactions; Weak enzyme inducer; Dose: 150 mg BD 
increased 300 mg every 3 days to 300-600mg and maximum of 1800 mg.
• 2nd line Drugs :Lamotrigine, Baclofen, Pimozide

SECOND LINE DRUGS
• LAMOTRIGINE: Superior to placebo in CBZ refractory cases; starting dose at
25 mg/day to 200-400 mg/day gradually; slower titration gives slower occurance
of side effects.
• BACLOFEN : GABAb receptor antagomist; dose of 5-10mg TDS and
increased slowly upto a maximum; dose of 90mg per day; Renal excreted drug
• Pimozide :Extrapyramidal side effects; Gabapentin, Pregabalin  moderate
efficacy.
• Phenytoin(60% pain relief); Topiramate(75% pain relief); Levetiracetam(50%
pain relief); TCA: No role in TGN; Quality of evidence poor.
• ACUTE EXACERBATION TREATMENT: initially used local anasthetic and
iv lidocaine; Insufficient evidence and not recommended; Treatment duration:
No definitive evidence of duration of treatment to conclude failure of first line
drugs and indication for surgery

SURGICAL MODALITIES
• Percutaneous: Glycerol Retrogasserian Rhizolysis; Radiofrequency
Thermocoagulation; Percutaneous Microballon Compression.
• Invasive surgery: Microvascular Decompression; Partial sensory Rhizotomy;
Internal Neurolysis; Cryotherapy
• Ablative vs Nonablative procedures.

When to refer for Surgery?
No specific conclusion; 70% patients who failed primary therapy wished
earlier surgery
Failure of first line therapy; ? Second line therapy
Age(old and young) and life expectancy(<20yrs)
Anaesthetic fitness for Surgery; Severity of the Pain
Which Surgical Procedure to choose?
MVD has higher and longer duration of pain control; MVD has 90 % pain
control immediately and 73% at 5 years; Lower chance of hypoesthesia
Peripheral Local anaesthetic techniques not effective.
Gronseth G, Cruccu G, Alksne J, Argoff C, Brainin M, Burchiel K et al. Practice Parameter: The diagnostic evaluation and treatment of trigeminal
neuralgia (an evidence-based review): Report of the Quality Standards Subcommittee of the American Academy of Neurology and the
European Federation of Neurological Societies. Neurology. 2008;71(15):1183-1190

MICROVASCULAR
DECOMPRESSION
• Long term success rate of 89-100%; More effective in classical TGN with only
paroxysmal attacks
• Acute pain relief in 91% and recurrence of 18%; Initial outcome better than
GKRS.
• Better at initial response and lower recurrence rate than partial sensory
rhizotomy
• MVD and PBC has similar initial pain control but MVD has lower recurrence
rate.

MICROVASCULAR DECOMPRESSION
• Supine position, head rotated and fixed to
opposite side, lateral decubitus position
• Linear retromastoid incision of approx. 3-
5 cm with a fourth above the iniomeatal
line
• Retromastoid Craniotomy made starting at
inferior and posterior to the transverse -
sigmoid junction
• Supralateral Cerebellar approach
 Dura opened in inverted L or C shaped fashion; CSF drained by
gentle retraction of the cerebellum.
 Retraction of cerebellum in Inferomedial direction gently just
below petro-tentorial junction (pure medial retraction = more
injury to CN VIII).
 Exposure of Superior petrosal vein and arachnoid membrane just
inferior to this vessel dissected; Superior petrosal venous bleed
coagulated close to cerebellum.

• Correct Identification of cranial nerves:
7th and 8th complex runs superficially, obliquely
• 5th nerve more medially and deeper; Careful arachnoid
dissection with preservation of BS vessels
• Exposure of Trigeminal nerve REZ.
NEUROVASCULAR CONFLICTS
 Most common by SCA or its branches
along the superior shoulder f REZ
 Combined compression between SCA
and AICA; Between Trigeminal and
petrosal veins; By superior Petrosal
vein.

 Decompression requires elevating the SCA upward
and away from the nerve; Arterial loops dissected
along the length of the nerve; Multiple Vascular
loops.
 Implant: Shredded Teflon; Placed at REZ and
pushed ahead parallel to the nerve; Unshredded
Teflon: more chance of displacement; Materials:
Teflon(Polytetrafluoroethylene), Ivalon(Polyvinyl
acetal).
 Partial sensory root sectioning is indicated in negative vessel explorations during
surgery and large intraneural vein.
 Complications
• MC complication is aseptic meningitis(11%); Cranial nerve damage, Transient
conductive hearing loss.
• SNHL major long term complication (prevented by gentle retraction and prevention of
AICA vasospasm)
• Prolonged post-operative vertigo /tinnitus; CSF rhinorrhoea(4%); Cerebellar
contusions.

GKRS
• First used by Dr Leksell in 1971; Procedure: Leksell stereotactic head frame 
MRI(T1w with or without contrast and T2 CISS sequences)Treatment planning
GKRS.
• Single shot, 4 mm beam collimator diameter; Dose: 70-90 Gy.; Higher dose associated
with higher post irradiation complications but better rates of improvement and lesser
recurrence; Higher required doses placed isocentre anteriorly on TGN away from
brainstem
Target Selection:
Options:
1. REZ close to Brainstem(Pollock et al 90% pain control)
2. Marseille point(distal most portion of cisternal CN V close to Meckels cave) (Regis et al. 87% pain
control)
3. Gasserian ganglion anteriorly(Messenger et al higher sensory complications)
• Pain relief better if isocentre located close to REZ; Less complications if target placed
anteriorly; Anterior targets are likely to have same initial pain control.

AGasserian gangliona; B  Marseille point; C REZ; D Dual Centre

• Gradual response Time to response after GKRS better in anterior
retrogasserian target(median -4.1 weeks) vs REZ targets(median – 6.4 weeks).
• Median latency to symptom improvement- 2 months; Need some
medications(although reduced dosage).
• Freedom from pain with medication(84.8%) vs without medication(53.1%);
Long Term outcome: Good pain control of 45-65% by 5 years.
• Abnormal vessel: Doesn’t alter outcome.
• Redo GKRS: Can be done in patients with an earlier good response to GKRS;
Primary GKRS > Secondary GKRS(in pain relief)
• Pain in V1: GKRS safest option as corneal hyposthesia never occur; No
Radioprotectant role of CBZ/OXZ; Treatment failure if no symptomatic
improvement by 180 days.
• Outcome: 75-90% patients had pain relief after 1 year of GKRS.

Predictors of good pain control:
• Type of Pain at presentation, post GK BNI score, Post GK facial numbness
(major predictor of maintenance of pain relief).
• Patients with early response within 3 weeks had longer duration of complete
free pain.
• Length of Cisternal segment of Trigeminal nerve; Target on Trigeminal nerve
5-8 mm away from brainstem
Favourable outcomes:
• young patient, length of trigeminal nerve irradiated, higher dose of radiation,
proximity of isocentre to Brainstem.

Stereotactic RS yields better response if done within 3 years of symptom
onset.
Poor prognosticator factors: atypical facial pain and presence of MS
 Recurrence rate of TGN post GKRS is 23% at approximately 8 to 20 months
Side effects: facial numbness(more in anterior target or longer length of
nerve irradiated or higher doses),parenchymal injuries, vascular injuries.

References:
• Youmans and Winn neurological surgery 8th edition
• Ramamurthi & Tandon's textbook of neurosurgery 3rd edition
• Schmidek and Sweet: Operative Neurosurgical Techniques 6th edition
• Internet
THANK YOU

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