Trigeminal Neuralgia

By, Meera Ramesh

TIC DOULOUREUXFOTHERGILLS DISEASESUICIDE DISEASE

OCTOBER 7TH

INTRODUCTION

Disorder characterized by lancinating attacks of severe facial pain

Epidemiology and DemographicsEpidemiology and Demographics

- Incidence of approx 4 in 100,000

- Majority of cases occur spontaneously

- Slight female predominance

- Over age 50

Age of Onset

0

5

10

15

20

25

30

2nd 3rd 4th 5th 6th 7th 8th 9thDecade

More than 70% of patients with TN are over 50 years of age at the time onset

- Pain typically consists of lancinating paroxysms

- Mostly in Second & Third trigeminal divisions

- Right side most often involved

- Pain attack is stereotyped

- Symptom free between attacks

- Lasts for several years if left untreated.

Trigeminal Nerve Anatomy

Distribution of Pain by Division32

17 17 15 14

40.4

0

5

10

15

20

25

30

35

Percent

V2,3 V2 V1,2,3 V3 V1,2 V1 V1,3Trigeminal Division

The pain of TN……

- Paroxysmal attacks- Electric shock like quality- Sudden onset & severe in

intensity facial grimace- Duration btw 1 sec and 2 min- Instantaneous electric shock

sensation that’s over in much less than a sec – ‘lightning bolt’

- Symptom free btw attacks.

Pain is commonly evoked by stimuli including washing, shaving, smoking, talking and/or brushing the teeth (trigger factors) and frequently occurs spontaneously. The pains usually remit for variable periods.”

Trigger zones……

Etiology and Pathogenesis

• Dental pathosis• Excessive traction• Allergic• Ischemia• Mechanical trauma like aneurysms• Compression distortion phenomenon• Anomalies of superior cerebellar artery• Secondary lesion

Clinical Presentation andPhysical Findings

Diagnosis of TN based on distinctive signs & symptoms.

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

ICHD Criteria for Classical TN (13.1.1)A. Paroxysmal attacks of pain lasting from a fraction of a

second to 2 minutes, affecting one or more divisions of the 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. There is no clinically evident neurological deficit.

E. Not attribute to another disorder.

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 stabbing2. 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.

Diagnosis of Trigeminal NeuralgiaALL FACIAL PAIN IS NOT TRIGEMINAL NEURALGIA!

Diagnostic testingDiagnostic testing Diagnostic brain imaging to Diagnostic brain imaging to

visualize anatomic visualize anatomic landmark around trigeminal landmark around trigeminal ganglion and CPAganglion and CPA

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

Imaging in Trigeminal NeuralgiaIn patients with types 1 and 2 trigeminal neuralgia (TN1 and TN2) one can identify:– Presence of (NVC)– Degree of NVC– Nature – Location

Findings can be confirmed during MVD

Right Trigeminal Nerve

Compressing vessel

Right Trigeminal Nerve

Compressing vessel

Pharmacological TreatmentAEDs– Tegretol (carbamazepine)

gold standard– Tripeptal (oxcarbazepine)– Dilantin (phenytoin)– Neurontin (gabapentin)– Lyrica (pregabalin)– Lamictal (lamotrigene)– Topamax (topirimate)– Gabatril (tiagabine)– Keppra (levateracitam)

TCAs– Elavil (amitriptyline)– Pamelor (nortriptyline)– Desipramine (norpramin)

Baclofen (lioresal)

Opioids

Adverse Effects of AEDs

Cognitive changesSedationNystagmus, ataxia, diplopia, dizzinessNausea, vomiting, headacheAllergic reaction – Up to 7% with CBZ– Some cross-reactivity between CBZ

and PHT

Surgical Treatment of TNMicrovascular decompression (MVD)Percutaneous ablative procedures– Radiofrequency thermal lesioning– Glycerol injection– Balloon compression

Stereotactic radiosurgery– Gamma knife– Linac-based

Peripheral ablative procedures (V1 and V2 pain)– Peripheral branch neurectomy– Alcohol neurolysis

Open destructive procedures– Partial sensory rhizotomy– Subtemporal ganglionectomy (Frazier-Spiller procedure)

Advantages of MVDONLY non-destructive procedure.Low risk of facial sensory loss.ONLY operation that addresses vascular compression

Disadvantages of MVD

Requires major surgery

MVD is generally associated with more risks than percutaneous procedures or radiosurgery like CSF leak

More costly

Surgical TechniquePositioningSkin IncisionRetromastoid craniectomyT-shaped dural opening

Surgical TechniqueExposure of CPAVisualization of trigeminal nerve– Visualize the ENTIRE nerve from it’s

exit from the pons to it’s exit laterally from the CPA

Decompression– Mobilize and “pad” arteries– Coagulate and divide veins

Operative FindingsArterial compression– Superior cerebellar artery

(SCA) – most common– AICA– PICA– Vertebrobasilar artery

Venous compression– More common with atypical

TN

Combined arterial and venous compression

Operative Findings

Complications of MVDCerebellar injury <1%Infectious complications– Bacterial meningitis– Aseptic meningitis

CSF leak 0-4%Cranial nerve deficits– Diplopia– Sensory loss or dysesthesias 0.5-17%– Facial weakness 0.5-15%– Hearing loss <1 (0-19%)

StrokeMortality < 1%

Outcome Following Initial MVD(N=1204 patients)

0102030405060708090

Initial 1 yr 10 yrs

Excellent Partial Failure

Barker F, Jannetta P, Bissonette D, et.al.: NEJM, 1996

Repeat MVD for Recurrent TN

All procedures used to initially treat TN CAN be effective for recurrent TN Less than 1/3 of patients undergo repeat MVDLower success ratesFindings: New compressive vessel.Higher incidence of perioperative morbidity– Increased risk of cranial nerve palsy– Increased incidence of facial numbness (8%)

and/or facial dysesthesias

Percutaneous Procedures

Radiofrequency thermal lesioning

Glycerol injection

Balloon compression

Radiofrequency Lesioning

Glycerol Injection

Contrast in trigeminal cistern Contrast under temporal lobe

Balloon Compression

Radiosurgery for TN

Decision-Making in TNWhen should surgery be considered?– Success/failure of medical therapy– Frequency of recurrences– Duration of symptoms

Which operation should be done?– Age and health of patient– Willingness to except facial sensory loss– Previous procedures for TN– Desires of patient– Experience of surgeon

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