trigeminal neuralgia

TRIGEMINAL NEURALGIADr shabeel pn

Dr.Haris PS/OMRDr.Haris PS/OMR

IntroductionIntroduction

Disorder characterized by lancinating Disorder characterized by lancinating attacks of severe facial painattacks of severe facial pain

Diagnosis based primarily on a history of Diagnosis based primarily on a history of characteristic pain attacks that are characteristic pain attacks that are consistent with specific research & clinical consistent with specific research & clinical criteriacriteria


In majority of patients, clinical exam-ination, imaging and lab tests are unremarkable – Classic TN

In a smaller group, signs & symptoms secondary to another disease affecting the trigeminal system – Symptomatic TN


Nicolas Andre, 1756

“Tic douloureux”

commented that it was exclusive & commented that it was exclusive & distinctive from all other diseasesdistinctive from all other diseases

John Fothergill, 1773

outlined major clinical features, clearly outlined major clinical features, clearly establishing the disorder as a discrete establishing the disorder as a discrete syndromesyndrome


Epidemiology and DemographicsEpidemiology and Demographics

- Incidence of approx 4 in 100,000

Familial cases also reported

- Majority of cases occur spontaneously

- Slight female predominance

- Over age 50


- Pain typically consists of lancinating paroxysms

- Mostly in Second & Third trigeminal divisions

- Right side most often involved- Pain attacks stereotyped- Symptom free between attacks- Chronic disorder, most patients will

experience pain attacks for years unless appropriately treated


Etiology and Pathogenesis Etiology and Pathogenesis

Cause – not known

Injury to the nerve root – an initiating factor?

(Benign tumors and vascular anomalies that compress the trigeminal nerve root can produce symptoms clinically indistinguishable from classic TN)


Based on the morphologic and physio-logic changes following partial nerve injury, Devor et al proposed “ignition hypothesis”.

A trigeminal injury induces physiologic changes that result in a population of hyper-excitable and functionally linked primary sensory neurons. The discharge of any individual neuron of this group can quickly spread to activate the entire population.

Such a discharge could underlie the sudden jolt of pain in TN attack.


Clinical Presentation andClinical Presentation andPhysical FindingsPhysical Findings

Diagnosis of TN based on distinctive signs & Diagnosis of TN based on distinctive signs & symptoms.symptoms.

White & Sweet articulated diagnostic criteria articulated diagnostic criteria for TN.for TN.

Consists of 5 major clinical features that Consists of 5 major clinical features that define the diagnosis of TNdefine the diagnosis of TN


Sweet diagnostic criteria

1.1. Pain is paroxysmalPain is paroxysmal2.2. The pain may be provoked by light touch The pain may be provoked by light touch

to the face (trigger zones)to the face (trigger zones)3.3. The pain is confined to the trigeminal The pain is confined to the trigeminal

distributiondistribution4.4. The pain is unilateralThe pain is unilateral5.5. The clinical sensory examination is The clinical sensory examination is

normalnormal


Patients who did not meet all the criteria rarely benefited.

The Sweet criteria were incorporated into the criteria published by IASP & IHS.

ICHD II (IHS) subdivides Trigeminal Neuralgia (code 13.1) into,

- Classic TN (code 13.1.1)

- Symptomatic TN (code 13.1.2)


Classic TN (13.1.1)Most common form- idiopathic, and also Most common form- idiopathic, and also

associated with vascular compression.associated with vascular compression.

““a unilateral disorder characterized by brief a unilateral disorder characterized by brief electric shock-like pains, abrupt in onset and electric shock-like pains, abrupt in onset and termination, limited to the distribution of one or more termination, limited to the distribution of one or more divisions of trigeminal nerve. Pain is commonly evoked divisions of trigeminal nerve. Pain is commonly evoked by trivial stimuli including washing, shaving, smoking, by trivial stimuli including washing, shaving, smoking, talking and/or brushing the teeth (trigger factors) and talking and/or brushing the teeth (trigger factors) and frequently occurs spontaneously. Small areas in the frequently occurs spontaneously. Small areas in the nasolabial fold and/or chin may be particularly nasolabial fold and/or chin may be particularly susceptible to the precipitation of pain (trigger areas). susceptible to the precipitation of pain (trigger areas). The pains usually remit for variable periods.”The pains usually remit for variable periods.”


ICHD Criteria for Classical TN (13.1.1)

A.A. Paroxysmal attacks of pain lasting from a fraction of a Paroxysmal attacks of pain lasting from a fraction of a

second to 2 minutes, affecting one or more divisions of second to 2 minutes, affecting one or more divisions of

the trigeminal nerve and fulfilling criteria B and Cthe trigeminal nerve and fulfilling criteria B and C

B.B. Pain has at least one of the following characteristics:Pain has at least one of the following characteristics:

1. intense, sharp, superficial or stabbing1. intense, sharp, superficial or stabbing

2. precipitated from trigger areas or by trigger 2. precipitated from trigger areas or by trigger

factorsfactors

C.C. Attacks are stereotyped in individual patient.Attacks are stereotyped in individual patient.

D.D. There is no clinically evident neurological deficit.There is no clinically evident neurological deficit.

E.E. Not attribute to another disorder. Not attribute to another disorder.


Symptomatic TN (13.1.2)

- Results from another disease process (MS or a cerebellopontine angle tumor)

“Pain indistinguishable from 13.1.1 classic TN but caused by a demonstrable structural lesion other than vascular compression.”


ICHD Criteria for Symptomatic TN (13.1.2)

A. Paroxysmal attacks of pain lasting from a fraction of a second to 2 minutes, with or without persistence of aching between paroxysms, affecting one or more divisions of trigeminal nerve and fulfilling criteria B and C.

B. Pain has at least one of the following characteristics:

1. Intense, sharp, superficial or stabbing

2. Precipitated from trigger areas or by trigger factors.

C. Attacks are stereotyped in individual patient.

D. A causative lesion, other than vascular compression, has been demonstrated by special investigations and/or posterior fossa exploration.


The pain of TN……

- Paroxysmal attacksParoxysmal attacks- Electric shock like qualityElectric shock like quality- Sudden onset & severe in intensity Sudden onset & severe in intensity facial facial

grimacegrimace- Duration btw 1 sec and 2 minDuration btw 1 sec and 2 min- Instantaneous electric shock sensation that’s Instantaneous electric shock sensation that’s

over in much less than a sec – ‘lightning bolt’over in much less than a sec – ‘lightning bolt’- Symptom free btw attacks.Symptom free btw attacks.


Trigger zones……

A TN “trigger zone” is an area of facial skin or oral mucosa where a low intensity mechanical stimulation can elicit a typical pain attack.

- Only a few mm in size- In perioral region- First division trigger zones are very rare.- Presence of trigger zone pathognomonic.- May result from ephatic coupling btw partially

damaged trigeminal axons.


- Pain confined to trigeminal zonePain confined to trigeminal zone- Most frequently in 3Most frequently in 3rdrd division division- Less frequently in 2Less frequently in 2ndnd or in both divisions or in both divisions- Pain attacks are stereotypedPain attacks are stereotyped- UnilateralUnilateral- Bilateral in MSBilateral in MS- Clinical sensory examination is normalClinical sensory examination is normal


Clinical evaluationClinical evaluation

Diagnosis based on clinical history, supplemented by physical examination findings and cranial imaging studies.

Detailed intraoral examination to rule out odontogenic and non odontogenic source for the pain

Examination of CN V, VII & VIIISymptomatic TN from a CPA mass often

shows facial weakness and hearing loss on that side


Diagnostic testingDiagnostic testing

Diagnostic brain imaging to visualize Diagnostic brain imaging to visualize anatomic landmarks around trigeminal anatomic landmarks around trigeminal ganglion and CPAganglion and CPA

CT, MRI – to rule out CPA lesions and to CT, MRI – to rule out CPA lesions and to visualize subtle vascular anomalies visualize subtle vascular anomalies causing compressioncausing compression


Medical Management and Medical Management and TreatmentTreatment

TN unique – majority of patients respond to TN unique – majority of patients respond to treatment and may have total elimination treatment and may have total elimination of pain attacksof pain attacks


Pharmacologic therapyPharmacologic therapy

Primary drug therapy

Bergouignan, 1942 found that the , 1942 found that the anticonvulsant anticonvulsant phenytoin effectively effectively controlled attacks of TNcontrolled attacks of TN

Similarity in mechanisms between epilepsy & Similarity in mechanisms between epilepsy & TN pain attacks.TN pain attacks.


Routine therapy begins with single agent, in Routine therapy begins with single agent, in gradually increasing doses until pain gradually increasing doses until pain attacks are suppressed or satisfactorily attacks are suppressed or satisfactorily reduced.reduced.

Carbamazepine (CBZ)

Baclofen (BCF)

Lamotrigine (LTG)


CBZ superior to PhenytoinCBZ superior to Phenytoin

CBZ monotherapy provides symptom control CBZ monotherapy provides symptom control in up to 80% patientsin up to 80% patients

BCF equally effective, better toleratedBCF equally effective, better tolerated

OthersOthers

- - Clonazepam, Gabapentin, Topiramate, Oxcarbazepine, Tiagabine, Levetiracetam and Zonisamide..


Multiple drug therapy

- When a patient respond only partially to When a patient respond only partially to single drug therapy at dosages that evoke single drug therapy at dosages that evoke side effects……side effects……

- When patients do not satisfactorily respond When patients do not satisfactorily respond to 2 AED’s, they should be considered for to 2 AED’s, they should be considered for surgical interventions.surgical interventions.


Surgical options

Highly effective and well toleratedHighly effective and well tolerated

Cumulative risk of multiple pharmacological Cumulative risk of multiple pharmacological agents may exceed the risk of surgical agents may exceed the risk of surgical complications, especially in the elderlycomplications, especially in the elderly


3 SURGICAL APPROACHES

1. Percutaneous stereotactic radiofrequency thermal lesioning of the trigeminal ganglion and/or root (RFL)

2. Posterior fossa exploration and microvascular decompression (MVD) of the trigeminal root

3. Gamma knife radiation to the trigeminal root entry zone (GKR)

Produce satisfactory relief of TN symptoms in 80 – 90% of patients. Incidence of complications is low and specific for the technique employed.


1. RFL

- Produce mild injury to the sensory fibers in the trigeminal root.

- Minimally invasive- Controls symptoms in > 85% of patients- Principal side effect – sensory loss and

occasional dysesthesia


2. Posterior fossa exploration and MVD

- More complex and invasive

- Directly treats the hypothetical cause while minimizing any sensory damage


3. GKR

- Relatively recent- Employs computerized stereotactic

methods to concentrate gamma radiation on the trigeminal root entry zone

- Could be highly effective- Long term benefits to be established


RFL for patients who are elderly or medically frail.

Posterior fossa exploration and MVD for younger healthier patients who can tolerate the longer more invasive surgical procedure.

GKR as an alternative to RFL in frail or elderly patients. MVD or RFL remains the standard for surgical treatment of younger patients who have considerable life expectancy


Conclusion

- Many fundamental questions about patho-Many fundamental questions about patho-physiology of the disorder remain unansweredphysiology of the disorder remain unanswered

- Development of drugs specific for TNDevelopment of drugs specific for TN

- Lack of objective testing remains as a problemLack of objective testing remains as a problem

- ffMRIMRI – potential future diagnostic tool– potential future diagnostic tool

trigeminal neuralgia

Education

paroxysmal attacks of

tn trigger zone

tn attack

sweet diagnostic criteria

classical tn

trigger factors attacks

classic tn code

sudden jolt of pain