Diagnosis and Treatment of Trigeminal Neuralgia

Trigeminal Nerve Anatomy

Functional AnatomyGSA – general sensation from head and facial structures– Main sensory nucleus

– Descending tract of V to spinal trigeminal nucleus• Functional equivalent of substantia gelatinosa of spinal cord

GSE – muscles of mastication

SVE – branchial arch muscles– Tensor veli palatini

– Tensor tympani

Demographics

Slight female predominance– Female 5.9 per 100,000– Male 3.4 per 100,000

Right side affected slightly more often

Occasional familial occurrences

Slightly elevated risk associated with HTN and multiple sclerosis

Classic Trigeminal NeuralgiaBurchiel Type I

Brief (seconds to minutes) episodes of severe, sharp, stabbing, lancinating, painAlmost always unilateral– Bilateral V1 pain sugestive of MS

Pain occurs along one or more trigeminal divisionsSpontaneous or evoked pain– Cutaneous trigger zones

Multiple attacks may occur over short periods Asymptomatic between attacksNormal facial sensation

BurchielClassification of Facial PainSpontaneous Onset

TN Type 1 (Classic TN)– > 50% episodic pain

TN Type 2 (Atypical TN)– > 50% constant pain

Trigeminal InjurySymptomatic TN (Multiple sclerosis)Trigeminal neuropathic pain (post-traumatic)Trigeminal deafferentation pain (RF lesion, GKR, etc.)Post-herpetic facial painSecondary TN– Tumors, aneurysm, AVM, etc.

Atypical facial pain (somatiform pain disorder)

Age of Onset

0

5

10

15

20

25

30

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

Decade

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

Distribution of Pain by Division

32

17 1715 14

4

0.40

5

10

15

20

25

30

35

Percent

V2,3 V2 V1,2,3 V3 V1,2 V1 V1,3

Trigeminal Division

Diagnosis of Trigeminal Neuralgia

ALL FACIAL PAIN IS NOT TRIGEMINAL NEURALGIA!

Successful treatment of any patient with facial pain in general and TN in particular depends on making the correct diagnosis at the outset

Pharmacological Treatment for Trigeminal Neuralgia

AEDs are the cornerstone of treatment

Start low, titrate to relief or side effects

Monitor side effects and drug interactions

Monitor levels and blood tests if indicated

Rotate other AEDs or add as needed

Tegretol remains the gold standard– Response thought to be diagnostic

Tegretol is the ONLY drug that has been shown to be effective for treatment of TN in a randomized controlled trial

Pharmacological TreatmentAEDs– Tegretol (carbamazepine)– 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 changes

Sedation

Nystagmus, ataxia, diplopia, dizziness

Nausea, vomiting, headache

Allergic reaction – Up to 7% with CBZ– Some cross-reactivity between CBZ and PHT

Imaging in Trigeminal Neuralgia

In patients with types 1 and 2 trigeminal neuralgia (TN1 and TN2) one can identify:– Presence of neurovascular compression (NVC)– Degree of NVC– Nature of the compressing vessel– Location of NVC along the nerve

Findings can be confirmed during MVD

CB - MRA (TOF)

Right Trigeminal Nerve

Compressing vessel

CB - T1 (FSE) Gad

Right Trigeminal Nerve

Compressing vessel

3D TOF

3D T2

3D FSE + Gad

MRI does accurately predict the

symptomatic side

Ho (null hypothesis) = there is no difference between MRI prediction and surgical side

Result: Fail to reject Ho (P= 0.40)MRI does predict the symptomatic (surgical) sideSensitivity of MRI for predicting symptomatic side = 78%

The symptomatic nerve shows a higher degree

of compression than the asymptomatic nerve

Ho (null hypothesis) = there is no difference between degree of compression on symptomatic and asymptomatic side

Reject Ho (P= 0.0003)

MRI does demonstrate a higher degree of compression on the symptomatic side

MRI can accurately detect arterial v. venous

compression

Ho (null hypothesis) = MRI cannot distinguish between arteries and veins compressing the nerve

Reject Ho (P= 0.36)

MRI can differentiate arterial and venous compressionHighly correlated with surgical findings

Surgical Treatment of TNMicrovascular decompression (MVD)Percutaneous ablative procedures– Radiofrequency gangliolysis– Glycerol rhizolysis– 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 MVD

MVD is the ONLY non-destructive procedure for the treatment of TN

Low risk of facial sensory loss with subsequent dysesthesias or anesthesia dolorosa

ONLY operation that addresses what is believed to be the primary underlying pathology; i.e. vascular compression

Long-term results are at least equivalent if not superior to any other procedure

Disadvantages of MVD

Requires major surgery – may not be suitable for patients with significant medical co-morbidity

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

More costly than percutaneous procedures

Surgical TechniquePositioningSkin Incision– Iniomeatal line – transverse sinus– Digastric groove– ¾ - ¼ rule

Retromastoid craniectomy– Expose sigmoid-transverse sinus junction– Mastoid emissary vein– Bevel bone laterally– Sufficient anterior exposure reduces

amount of cerebellar retraction

T-shaped dural opening– Exposure of most superior and lateral

corner

Surgical TechniqueExposure of CPA– “Turning the corner is the most dangerous stage

of the operation and must be executed with patience and the utmost care” (Peter Jannetta)

– CSF drainage– Gentle retraction of ala of cerebellum– Identify and divide petrosal vein

Visualization 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 Findings

Arterial compression– Superior cerebellar artery (SCA) – most common– AICA– PICA– Vertebrobasilar artery

Venous compression– More common with atypical TN

Combined arterial and venous compression

Intraoperative Observations579 consecutive patients undergoing MVD

97% (560/579) had one or more vessels

Multiple vessels found in 38%– SCA 88%– AICA 25%– Vein 28%– Basilar artery 4%

Location of NVC (medial-lateral)– Trigeminal REZ 52%– Middle 1/3 54%– Lateral 10%

Sindou M, et. al.: Acta Neurochir (Wien) 144:1-12, 2002

Intraoperative ObservationsLocation of NVC– Supero-medial 53.9%– Supero-lateral 31.6%– Inferior 14.5%

Severity of NVC– Simple contact 17.6%– Distorsion of nerve 49.2%– Marked indentation 33.2%

Other Findings– Global atrophy 42%– Arachnoid thickening 18%– Angulation near petrous bone 13%

Sindou M, et. al.: Acta Neurochir (Wien) 144:1-12, 2002

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%

Complications of MVD Author and Year N CSF V VII VIII Death

Breeze 1982 52 2% 17% 15% 11% 0

Van Lovern 1982 23 13% 9%

Apfelbaum 1983 406 1% 3% 1%

Kolluri 1984 72 11% 19% 0

Piatt 1984 103 2% 1% 1% 8% 1%

Zorman 1984 125 4% 2% 3% 0

Bederson 1989 166 4% 3% 5% 5% 0

Klun 1992 220 0 0.5% 0.5% 4.5%

Sun 1994 61 7% 3% 6% 0

Barker 1996 1204 0.2% 1% 0.5% 1% 0.2%

Kondo 1997 281 4-7%

Outcome Following Initial MVD(N=1204 patients)

0

1020304050

60708090

Initial 1 yr 10 yrs

Excellent Partial Failure

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

MVD - 10-Year Outcome Barker F, Jannetta P, Bissonette D, et.al.: NEJM, 1996

0

10

20

30

40

50

60

70

Initial MVD Repeat MVD All Operations

Excellent Partial Failure

Long-Term Results of MVDTypical TN

Review of 19 series with 2,747 patients (17-1,204)Average follow-up, 4.4 years (4 months to 10 years)78% with excellent-good results (62-92%)– >90% initial success with positive findings

Failure rate – 22% (8-30%)Complications 4-34%– Facial numbness, 3-29%– Hearing loss, 0-19%

Mortality, 0.5%

Lovely T, Janetta P: Neurosurgery Clinics of North America. 1997

Long-Term Results of MVD*

Series

# of Pts.

FU (yrs)

Dysesthesias(%)

CN Palsy

Post-OpMorbidity

Long-TermPain Relief

(%)

Bederson, 1989 166 5.1 3 3 21 75

Sindou, 1990 120 4.8 NR NR 79

Klun, 1992 178 5.2 0 0.6 88

Cutbush, 1994 109 4.8 0 7 NR 76

Mendoza, 1995 133 5.4 0 1.5 NR 71

Barker, 1996 1204 10 1 2 11 64

Kondo, 1997 281 12.6 NR 5.5 19 87

Lee, 1997 146 7.2 NR NR NR 84

Pagura, 1998 203 5 0.5 1 13 68

TOTAL 2540 7 0.8 3 16 77

*Taha and Tew

Factors Influencing Outcome of MVDDuration of TN

Kolluri et. al., 1984– TN > 4 years Recurrence 25%– TN < 4 years Recurrence 15%

Bederson et. al., 1989– TN > 4 years Excellent/good 91%– TN < 4 years Excellent/good 75%

Broggi, et. al., 2000– TN > 7 years ONLY poor prognostic factor for favorable outcome

Barba et. al., 1984– Success rate of MVD reduced from 91% to 43%

Bederson et. al., 1989– Excellent outcomes reduced from 78% to 63%

Walchenbach et. al., 1994– Past ablative procedure - 50% good result– MVD primary procedure – 86% good result–

Best result appear to be achieved when MVD is performed as the primary procedure for treatment of TN

Factors Influencing Outcome of MVDPrevious Ablative Procedures

Special Considerations

MVD in elderly patients

Typical (Type I) vs. atypical TN (Type II)

Repeat MVD

Role of MVD in patients with MS

MVD following percutaneous procedures

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, compression by feltHigher incidence of perioperative morbidity– Increased risk of cranial nerve palsy– Increased incidence of facial numbness (8%) and/or facial

dysesthesias

Typical vs. Atypical TN Tyler-Cabara E, et.al.: J Neurosurgery 96:527-531, 2002

0

20

40

60

80

100

Immediate Pain Relief Long-Term Outcome > 5 yrs

Typical TN Atypical TN

MVD in Elderly Patients Ashkan K, Marsh H: Neurosurgery, 55:840-850, 2004

Study Group Control Group

Age 65 (60-75) 46 (20-59)

Time to Diagnosis 7 yrs (1-22yrs) 3 yrs (3mos-20yrs)

Initial Relief 98% 100%

Mean LOS 5.4 days (3-10) 5.3 days (3-9)

Avg. Follow-Up 30 months 33 months

Mortality/Serious Morbidity

None None

Recurrence 24% 27%

MVD in Multiple SclerosisMS traditionally considered an absolute contraindication to MVD

Presumption that demyelination is the exclusive causative factor for TN in MS

Neuroimaging has raised the possibility of a role for vascular compression

Add Galligan)

MVD in Multiple Sclerosis Broggi et. al.: Neurosurgery, 55:830-839,2004

35 MS patients with medically-intractable TN74% - MRI evidence of demyelinating lesion on the symptomatic side (26 of 35)46% (16 of 35 patients) had obvious vascular compressionLong-term outcome– Excellent 39%– Good 14%– Fair 8%– Poor 39%

“Results of MVD in MS patients are much less satisfactory than in the idiopathic group”.

MVD in Multiple Sclerosis9 patients with MS underwent PF exploration– 7 – MVD alone– 2 – MVD + PSR

100% evidence of vascular compression on MRAInitial pain relief excellent in all patientsRecurrence– 5 of 7 with MVD alone– 1 of 2 with MVD + PSR

4 of 9 patient had long-term pain relief“Because of the high recurrence rate together with the morbidity….MVD should not be offered to patients with TN and MS”.

Eldridge P, et.al.: Stereotact Funct Neurosurg 81:57-64, 2003

Percutaneous Procedures

Radiofrequency thermal coagulation

Glycerol rhizolysis

Balloon compression

Needle Insertion

Radiofrequency Lesion

Glycerol Injection

Contrast in trigeminal cistern Contrast under temporal lobe

Balloon Compression

MVD vs. Percutaneous ProceduresINITIAL PAIN RELIEF

MVD 98%RF rhizotomy 98%Balloon 93%Glycerol 91%

RECURRENCE RATESGlycerol 54% (4 years)RF rhizotomy 23% (9 years)Radiosurgery 25% (3 years)Balloon 21% (2 years)MVD 15% (5 years)

Taha J, Tew J: Neurosurgery 38:865—871, 1996

Trigeminal Nerve Complications

MVD PRFTG PGR PBC

Numbness 2 98 60 72

Dysesthesia 0.5 24 16 19

AD 0 1.5 1.8 0.1

Corneal reflex

0.05 7 3.7 1.5

Keratitis 0 1 1.8 0

Motor 0 24 1.7 66

Taha J, Tew J: Neurosurgery 38:865—871, 1996

Radiosurgery for TN

Duration and Maintenance of Pain Relief

More than 50% pain relief/Complete relief

1 year 75.8 ± 2.9% 63.6 ± 3.3%

2 years 71.3 ± 3.3% 59.2 ± 3.5%

3 years 67.2 ± 3.9% 56.6 ± 3.8%

3.5 years 65.1 ± 4.3% -

5 years 55.8 ± 9.3% 37.7 ± 15.6%

GKR

GKR

GKR

Decision-Making in TN

When 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

Glossopharyngeal NeuralgiaPain most often occurs in the territory of the glossopharyngeal nerveGSA input from external/middle ear, posterior tongue, and pharnyx– Classic GPN – pain primarily in tongue and pharnyx– Otalgic GPN – pain primarily occurs in ear

Unilateral, paroxysmal, lancinating pain; last seconds to minutes– Pain may occur in clusters– Irregular intervals over days, weeks or months

Spontaneous occurrence or precipitated by swallowing Peak incidence : 5th to 7th decadePain relieved by anesthetizing posteior pharynx with 10% cocaine5% - 8% of cases caused by posterior fossa tumorPain may be due to elongated styloid process (Eagle’s syndrome)

GPN vs. TNTN 70-100x more common than GPN

GPN shows no sex predilection– TN slightly more common in women (3:2)

GPN occurs more commonly on the left side (3:2)– TN more common on the right (5:3)

Bilateral involvement is uncommon in both conditions– TN – 4% GPN – 2%

Clinical presentation of GPN tends to be more variable

10% of patients have BOTH TN and GPN

Secondary GPN usually associated with malignant skull base neoplasms– Secondary TN due to benigng intradural tumor

MS almost never encountered in association with GPN

Treatment of GPN

Medications tend to be less effective than in patients with TN

Microvascular decompression of the 9th and 10th cranial nerves

Intracranial rhizotomy of 9th nerve and upper 1/3 of vagus– 85% success rate– 20% risk of swallowing dysfunction

Percutaneous glossopharyngeal rhizotomy

Summary and Conclusions

All procedures are initially highly effective in alleviating the symptoms of TN

Each case should be treated individually and multiple options should be discussed and offered to each patient.