The terrible journey of a nerve impulse!The terrible journey of a nerve impulse!

Trigeminal Neuralgia

DR UNNIKRISHNAN PNEUROANAESTHESIA

SCTIMSTTRIVANDRUM

INDIA

Demotivating , demoralizing..Demotivating , demoralizing..

one of the most painful neuropathic pains

IASP definition: Sudden, recurrent, severe pain in the

distribution of one or more branches of the fifth

cranial nerve

no universal treatment is capable of reverting

completely

impairment of daily functionality, reduced quality of

life and depression

overwhelming fear that pain can suddenly return

again

Peculiar neuropathic painPeculiar neuropathic pain

not accompanied by sensory deficit

Can be cured by a small nerve or root lesion

Cause ? Now… sound hypothesis of neurovascular

conflict (NVC) [ Are we still hearing sounds of

conflict? ]

tic douloureux = since painful brief muscle spasms

EPIDEMIOLOGYEPIDEMIOLOGY

3-5/ one lac; 52- 69 years most commonMore recent estimates suggest the prevalence is approximately 1.5 cases per 10,000 population, with an incidence of approximately 15,000 cases per yearMultiple sclerosis is found to be a risk factor; ?HTN

5.9/lac3.4/lac

I’m also having..[youngest 12m]

Anatomy - whereabouts

• Emerge as a larger sensory and smaller motor root

• Fibres in sensory root are axons of cells in trigeminal ganglion which occupies Meckels cave

• Neurons of the unipolar cells of the ganglion divides into central and peripheral processes

• Peripheral ophthalmic,maxillary and sensory part of mandibular

• Central fibres of the sensory root

Whereabouts……

origin of the…..pain....nerve

.

Course and relevance in TN

The sensory fibers arise from the gasserian ganglion (lying near the petrous part of the temporal bone in the dura matter), pass backward, enter the pons, and divide into upper and lower roots.

The upper roots end in the principal or superior sensory nucleus and locus caeruleus.

The lower roots descend through the pons and medulla and terminate in the spinal tract nucleus, which consists of subnucleus caudalis, subnucleus inter polates, and subnucleus oralis.

The subnucleus caudalis serves as the principal brainstem relay site for orofacial pain, and the superior sensory nucleus and subnucleus oralis are sites relaying orofacial tactile information.

No monopoly; already a lot of members to control

• 1 motor and 3 sensory nuclei

• Motor upper pons

• Mesencephalic midbrain ; for proprioception

• Main sensory nucleus upper pons ; for touch

• Spinal nucleus in lower pons, medulla and upper

cervical spinal cord; for pain and temperature

Complex routes…..

The Spinal Trigeminal Nucleus

.

Principal brainstem relay sites….

Subnucleus caudalis orofacial painSuperior sensory nucleus , subnucleus oralis Tactile information

The similarity….

Neurons in dorsal horn ThalamusNeurons in subnucleus caudalis Thalamus

Motor root….Motor roots from the superior and lower nucleus then joins the sensory root as it emerges from the pons

Eagerly waiting for chaos..

Nociceptive neurons in subnucleus caudalis respond to noxious stimulation of the

Mechanoreceptive neurons in the superior sensory nucleus

Orofacial tissuesTooth pulpTMJDuraJawTongueNeck muscles

Light tactile stimuli to

SkinMucosateeth

Ophthalmic nerve

Maxillary nerve

Mandibular nerve

ETIOLOGY AND PATHOPHYSIOLOGY

“Pain is temporary. Quitting lasts forever”…Lance Armstrong

His quotes a lso are loos ing integr i ty. . .???

Central vs Peripheral

Central theories emphasize the role of

deafferentation (secondary to compression of the

trigeminal roots or ganglion) in the genesis of neural

hyperactivity.

Peripheral theories note that changes in peripheral

axons and myelin may lead to altered nerve

sensitivity to chemical and mechanical stimuli.

Starts as a peripheral lesion; response of central

synapses to this sets stage for the war; SO BOTH

MECHANISMS PLAY

Painful and annoying conflict…

In 85%, no structural lesion is seen

Classic [idiopathic] form: “Neurovascular conflict”

i.e. vascular compression of nerve most commonly

@ its entry into pons [REZ]

Significant NVC= an artery (not a vein), crossing (not

parallel to) the nerve and provoking

displacement/grooving of it (Casselman,2000)

Amplifying….

compression results in focal trigeminal nerve

demyelination

leads to ephaptic transmission [action potentials

jump from one fiber to another]

A lack of inhibitory inputs from large myelinated

nerve fibers plays a role.

a reentry mechanism causes an amplification of

sensory inputs

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Two types....One feature..

Trigeminal neuralgia is divided into classic [idiopathic] and symptomatic typesThe classic form includes the cases that are due to a normal artery present in contact with the nerve, such as the SCA or even a primitive trigeminal arterySymptomatic forms can have multiple origins: Aneurysms, tumors, chronic meningeal inflammation.An abnormal vascular course of the superior cerebellar artery is often cited as the causeUncommonly, an area of demyelination from multiple sclerosis may be the precipitant

ETIOLOGY

• compression of nerve root [most common-vascular; rarely tumor/vein/avm] usually when pain @ v2 / v3, compression is by SCA ; pain @ v1 by AICA

• Inflammatory causes: multiple sclerosis [in1-5% of patients with MS;more likely if patient with TN is 20-40ys] ; Damage to myelin sheath [Myelin gone….signals blend….nerves may sense light touch as pain!!!!!] ), sarcoidosis, and Lyme disease neuropathy

• traumatic accidents• unsuccessful dental work

ETIOLOGY

Tumor-related causes : (most commonly in the cerebello-pontine angle) include acoustic neurinoma, chordoma at the level of the clivus, pontine glioma or glioblastoma,epidermoid, metastases, and lymphoma and paraneoplastic etiologies. Vascular causes include a pontine infarct and arteriovenous malformation or aneurysm in the vicinity.infections , varicella virusfoci of abscessesbone resorption with irritation of the trigeminal nerve in the maxilla or mandible

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Don’t get deceived by imitations

DIFFERENTIAL DIAGNOSISvariety of tumours and other lesions involving, or impinging on, the trigeminal nerve, ganglion or sensory root tumours of the C-P angle, MCF, cranium or extracranial tissues (often metastatic), and from the envelopes of the Gasserian ganglion.

OTHERS

atypical facial pain syndromes cluster headache postherpetic neuralgia geniculate neuralgia (Ramsay Hunt) sphenopalatine ganglion neuralgia glossopharyngeal neuralgia dental disease, orbital disease temporomandibular dysfunction temporal arteritis

I doubt….you are having….

I doubt….you are having….

Headache Classification Subcommitee of the International Headache Society. Cephalalgia 2004

Difficult to bear

Almost always u/lComes like electric shockBrief; but will recur‘Paralysing’Light pressure on trigger points will trigger the attackUnpredictable symptom free intervalsAtypical pain patterns are thereMy patients’ biggest ambitions:

Eating….Shaving…. Make up face….

Please don’t touch on these areas ..Ok..?

Please don’t touch on these areas ..Ok..?

.

DIAGNOSIS

Keep a low threshold for MRI in

younger patients atypical clinical featuressensory loss dull burning pain between paroxysmspatients who do not respond to initial medical therapy

Imaging

C.T.M.R.I. :

CONVENTIONAL: can rule out tumour / multiple sclerosis3-D VOLUME ACQUISITION, with contrast injection and thin cuts (ie, 0.8 mm) without gaps can see Trigeminal nerve and associated blood vesselsThe trigeminal nerve is easily observed in the axial plane when the MRI series is centered at die midpoint of the 4th ventricle. To ensure adequate evaluation, the nerve should be observed on 3 adjacent cuts. when an offending vessel is present, it will be detected 80% of the timeOTHERS: TOF, CISTERNOGRAPHY

Also look for tumours, multiple sclerosis, abnormalities of the skull base, or AVM

Imaging

Meckel’s cave, the cavernous sinus, the skull base

foramina, the pterygopalatine fossa and the

peripheral trigeminal nerve course

always look for a normal gray and white matter and

brainstem, a normal cisternal segment, a fluid fi lled

Meckel’s cave, a homogeneously enhancing

cavernous sinus, a fat-filled superior orbital fissure

and pterygopalatine fossa, normal foramen

rotondum and ovale, and a symmetrical appearance

of the masticator muscles with normal fat planes of

the skull base

DIFFERENTIATION

• paroxysms of pain last longer• pain tends to be constant• Involvement of forehead alone +/- autonomic

symptoms• neurologic deficit is often detected (cutaneous

hypoesthesia, loss of corneal reflex, masticatory muscle weakness).

Treatment

.

PHARMACOLOGICAL

enormous belief in CarbamazepinePhenytoin is the second treatment of choice

3 weeks over,adequate serum levels obtained…..but no relief DISCONTINUE because higher doses may lead to toxicity. The short-term efficacy rate is 60%; decreases to 30% after 2 years

Lamotrigene useful in failure/intolerance with CarbamazepineGabapentin : benign adverse effect profile, can be used as adjuvant alsoTopiramate: proved to be effective where combination therapy fails

Treatment

Your Text here Take @ mealsUse long acting preparations

fewer drug interactions and side effects; but cross reactivity with carbamazepine +

Treatment

Your Text here

SURGICAL Rx-FACTS

aimed at either destroying parts of nerve fibers or decompressing the trigeminal nerve to relieve painalthough surgical treatment may initially be successful, trigeminal neuralgia may recur retry medical therapy [because drugs that were previously ineffective may become effective later]patients with classic trigeminal neuralgia, evidence of vascular compression, shorter duration of disease, and no previous surgery respond better to all treatment options.In such patients, MVD can be considered the “gold standard” surgical procedure, and it offers the best long term cure rates.

SURGICAL Rx-FACTS

All procedures have high initial response rate, except for stereotactic radiosurgery, which usually takes maximum effect at one to two monthsAblative Rxs are used to a greater extent in patients with high operative risk

Microvascular decompression (MVD) of

the posterior fossajunction of the Vth nerve with the pons is explored

blood vessels and tumors removed from direct

contact with the nerve. The SCA, PICA, VA, and AICA

(& small branches) are separated from the nerve by

a piece of Dacron fabric

Efficacy is reported to be 85% initially, and 80% at 5

years.

carries a relatively low risk of pain recurrence,

dysthesia, corneal analgesia, and trigeminal motor

weakness

.

MVD-Risks

Risks higher in patients who have an ecstatic

(atherosclerotic) and a tortuous vertebrobasilar

arterial tree

the risk for perioperative mortality [around 0.4%],

serious morbidity (eg, stroke, hemorrhage, venous

occlussion, M.I.,HCP), permanent hearing loss, and

facial palsy is higher after MVD than after

percutaneous procedures.

But ablative procedures are less effective in the long

term and more likely to produce facial numbness

and other minor complications than MVD

MVD-Follow up

• OPERATIVE FINDINGS (97%) • arterial channels 374 (80,3%) • venous channels 65 (13,9%) • tumor 12 (2,6%) • negative 15 (3,2%) • total 466 • COMPRESSIVE ARTERY • SCA – 80% • SCA+AICA – 9% • AICA – 8% • Basilar – 2% • Others--1%

Russel R. Lonser and Ronald I. Apfelbaum “Operative Neurosurgical Techniques”

Vol 2, pp 1531-1538 (2006)

MVD-Follow up

• INITIAL RESULTS • complete relief – 91% • pain reduced – 6% • pain not relieved – 2% • death – 1% • COMPLICATIONS • cranial nerve dysfunction – 12,6% • dizziness, ataxia – 3% • infarction – 1,8% • seizures – 1% • death – 1%

Russel R. Lonser and Ronald I. Apfelbaum “Operative Neurosurgical Techniques”

Vol 2, pp 1531-1538 (2006)

MVD-Follow up

• LONG-TERM RESULTS • no recurrence - 62% • mild pain (no medication) - 5% • pain controlled with medication -14% • severe pain not controlled “ - 18% • died - 1%

Russel R. Lonser and Ronald I. Apfelbaum “Operative Neurosurgical Techniques”

Vol 2, pp 1531-1538 (2006)

PREOPERATIVE SIMULATION

fusion imaging technique of three-dimensional (3-D) MR cisternography and co-registered 3-D MRA The presence of offending vessels and compressive site of neurovascular conflict was assessed from the various viewpoints within the cisternsurgeon's-eye view, bird's-eye view

PREOPERATIVE SIMULATION

Presurgical Virtual Endoscopy: is a novel technique

that provides excellent visualization of the three-

dimensional relations between neurovascular

structures and allows simulation of MVD

Percutaneous radiofrequency thermocoagulation of the

gasserian ganglion

A high-frequency current used to destroy precisely

the A-delta and C-fiber nociceptors

based on the theory that lower temperatures

selectively destroys the nociceptive unmyelinated C-

fibers & the poorly myelinated A-delta fibers while

sparing the heavily myelinated A-alpha & A-beta

fibers which convey the touch, proprioceptive &

motor impulses.

Percutaneous radiofrequency thermocoagulation of the

gasserian ganglion

Under fluoroscopic guidance, an insulated needle is

passed through the foramen ovale next to the

gasserian ganglion

The initial efficacy ̴ 90%, with 80% patients

remaining free of pain at 1 year and 50% remaining

pain free at 5 years.

appropriate for elderly and for those with poor

medical conditions

Risks : numbness, paresthesia, and anesthesia

dolorosa,corneal anesthesia [may develop after

lesioning of the ophthalmic division]

Percutaneous radiofrequency thermocoagulation of the

gasserian ganglion

Under fluoroscopic guidance, an insulated needle is

passed through the foramen ovale next to the

gasserian ganglion

Foramen ovale accessed under flouroscopy

Ensure CSF flow…

Needle advanced to petrous clivus junction

Test stimulus which will elicit the patients original

neuralgic pain

Thermocoagulation

Try to reelicit pain and ensure that no pain is there

.

Percutaneous radiofrequency thermocoagulation of the

gasserian ganglion

A

Percutaneous microcompression of the

gasserian ganglioninvolves passing a fine balloon catheter through the foramen ovale.Inflation of the balloon produces an ischemic or mechanical destruction of cells in the ganglion.38 associated with the highest risk for postoperative motor trigeminal weakness. the best choice for patients who have ophthalmic nerve pain and who are not candidates for MVD

Gamma knife irradiation [NIHCE,U.K. APPROVED]

radiation is aimed at the proximal nerve and root entry zone in the ponsgamma knife projects 201 very fine beams of gamma rays (generated by RA Cobalt) through the skull and brain. The dose of radiation along any one beam is too small to effect any change by itselfbut when all 201 beams intersect, a very high dose of radiation can be administered with little or no radiation to surrounding tissue.41

has been shown to affect abnormal ephaptic transmission but not normal axonal conduction

Glycerol injection

Injected behind the ganglion, which destroys small and large myelinated and unmyelinated fibers. Under fluoroscopic guidance, glycerol is injected into the cistern of Meckle's cave.OTHERS METHODS : Laser irradiation of the skin overlying peripheral nerves with a heliium-neon laser

Weighing once more….

Your Text here

Proparacaine eye drops

Is a local anesthetic agent that anesthetizes the eye and possibly the nerves around it.It is shown that it can give short-term relief in some instances usually effective if the pain is in the distribution of the ophthalmic division of the trigeminal nerve. almost certainly ineffective for classic trigeminal neuralgia.relatively harmless, but can damage the eye if used extensivelySo it cannot be considered a long-term treatment.

Final words….

patients with trigeminal neuralgia deserve an

accurate and dispassionate explanation of the merits

and drawbacks of all methods of treatment from the

outset.

References

• Trigeminal neuralgia Pathophysiology and treatment A. JOFFROY, M. LEVIVIER and N. MASSAGER

• Manish K Singh, MD; Chief Editor: Robert A Egan, MD[2012] Medscape

• Pain Management: Trigeminal Neuralgia;Meraj N. Siddiqui, Hospital Physician;Turner White;2003

• BMJ Luke Bennetto, Nikunj K Patel and Geraint Fuller ;2008

• John tew, Mayfield Clinic Update,2012• review on the causes of trigeminal neuralgia

symptomatic to other diseases florin popovici1, ROMANIAN JOURNAL OF NEUROLOGY – VOLUME X, NO. 2, 2011

THANK YOU

HOPING FOR MORE AND MORE WAYS TO COOL THIS HEAD