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Diagnosis and Treatment of
Trigeminal Neuralgia
Trigeminal Nerve Anatomy
Functional Anatomy
GSA – 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
– Male
5.9 per 100,000
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 Neuralgia
Burchiel Type I
Brief (seconds to minutes) episodes of severe, sharp,
stabbing, lancinating, pain
Almost always unilateral
– Bilateral V1 pain sugestive of MS
Pain occurs along one or more trigeminal divisions
Spontaneous or evoked pain
– Cutaneous trigger zones
Multiple attacks may occur over short periods
Asymptomatic between attacks
Normal facial sensation
BurchielClassification of Facial Pain
Spontaneous Onset
TN Type 1 (Classic TN)
– > 50% episodic pain
TN Type 2 (Atypical TN)
– > 50% constant pain
Trigeminal Injury
Symptomatic TN (Multiple sclerosis)
Trigeminal neuropathic pain (post-traumatic)
Trigeminal deafferentation pain (RF lesion, GKR, etc.)
Post-herpetic facial pain
Secondary TN
– Tumors, aneurysm, AVM, etc.
Atypical facial pain (somatiform pain disorder)
Age of Onset
30
25
20
15
10
5
0
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
35
32
30
25
20
17
Percent
17
15
14
15
10
4
5
0.4
0
V2,3
V2
V1,2,3
V3
V1,2
Trigeminal Division
V1
V1,3
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 Treatment
AEDs
–
–
–
–
–
–
–
–
–
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 FSE + Gad
3D T2
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)
side
Sensitivity 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
compression
Highly correlated with
surgical findings
Surgical Treatment of TN
Microvascular 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 comorbidity
MVD is generally associated with more risks
than percutaneous procedures or radiosurgery
More costly than percutaneous procedures
Surgical Technique
Positioning
Skin 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 Technique
Exposure 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 Observations
579 consecutive patients undergoing MVD
97% (560/579) had one or more vessels
Multiple vessels found in 38%
–
–
–
–
SCA
AICA
Vein
Basilar artery
88%
25%
28%
4%
Location of NVC (medial-lateral)
– Trigeminal REZ
– Middle 1/3
– Lateral
52%
54%
10%
Sindou M, et. al.: Acta Neurochir (Wien) 144:1-12, 2002
Intraoperative Observations
Location of NVC
– Supero-medial
– Supero-lateral
– Inferior
53.9%
31.6%
14.5%
Severity of NVC
– Simple contact
– Distorsion of nerve
– Marked indentation
17.6%
49.2%
33.2%
Other Findings
– Global atrophy
– Arachnoid thickening
– Angulation near petrous bone
42%
18%
13%
Sindou M, et. al.: Acta Neurochir (Wien) 144:1-12, 2002
Operative Findings
Complications of MVD
Cerebellar injury
Infectious complications
<1%
– Bacterial meningitis
– Aseptic meningitis
CSF leak
Cranial nerve deficits
–
–
–
–
Diplopia
Sensory loss or dysesthesias
Facial weakness
Hearing loss
Stroke
Mortality
0-4%
0.5-17%
0.5-15%
<1 (0-19%)
< 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
Apfelbaum 1983
406
Kolluri
1984
72
Piatt
1984
103
2%
Zorman
1984
125
4%
Bederson
1989
166
4%
Klun
1992
220
0
Sun
1994
61
Barker
1996
1204
Kondo
1997
281
13%
9%
1%
3%
1%
19%
0
1%
8%
1%
2%
3%
0
3%
5%
5%
0
0.5%
0.5%
4.5%
7%
3%
6%
0
1%
0.5%
1%
0.2%
11%
0.2%
1%
4-7%
Outcome Following Initial MVD
(N=1204 patients)
90
80
70
60
50
40
30
20
10
0
Initial
1 yr
Excellent
Partial
10 yrs
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
70
60
50
40
30
20
10
0
Initial MVD
Repeat MVD
Excellent
Partial
All Operations
Failure
Long-Term Results of MVD
Typical 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*
# of
Pts.
FU
(yrs)
Dysesthesias
(%)
CN
Palsy
Post-Op
Morbidity
Long-Term
Pain 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
Series
*Taha and Tew
Factors Influencing Outcome of MVD
Duration of TN
Kolluri et. al., 1984
– TN > 4 years
– TN < 4 years
Recurrence 25%
Recurrence 15%
Bederson et. al., 1989
– TN > 4 years
– TN < 4 years
Excellent/good 91%
Excellent/good 75%
Broggi, et. al., 2000
– TN > 7 years ONLY poor prognostic factor for favorable outcome
Factors Influencing Outcome of MVD
Previous Ablative Procedures
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
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 MVD
Lower success rates
Findings: New compressive vessel, compression by felt
Higher 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
100
80
60
40
20
0
Immediate Pain Relief
Typical TN
Long-Term Outcome > 5 yrs
Atypical TN
MVD in Elderly Patients
Ashkan K, Marsh H: Neurosurgery, 55:840-850, 2004
Study Group
Control Group
65 (60-75)
46 (20-59)
7 yrs (1-22yrs)
3 yrs (3mos-20yrs)
98%
100%
5.4 days (3-10)
5.3 days (3-9)
Avg. Follow-Up
30 months
33 months
Mortality/Serious
Morbidity
Recurrence
None
None
24%
27%
Age
Time to Diagnosis
Initial Relief
Mean LOS
MVD in Multiple Sclerosis
MS 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 TN
74% - MRI evidence of demyelinating lesion on the
symptomatic side (26 of 35)
46% (16 of 35 patients) had obvious vascular
compression
Long-term outcome
–
–
–
–
Excellent
Good
Fair
Poor
39%
14%
8%
39%
“Results of MVD in MS patients are much less
satisfactory than in the idiopathic group”.
MVD in Multiple Sclerosis
9 patients with MS underwent PF exploration
– 7 – MVD alone
– 2 – MVD + PSR
100% evidence of vascular compression on MRA
Initial pain relief excellent in all patients
Recurrence
– 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 Procedures
INITIAL PAIN RELIEF
MVD
RF rhizotomy
Balloon
Glycerol
98%
98%
93%
91%
RECURRENCE RATES
Glycerol
RF rhizotomy
Radiosurgery
Balloon
MVD
54% (4 years)
23% (9 years)
25% (3 years)
21% (2 years)
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
Keratitis
0.05
7
3.7
1.5
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
2 years
3 years
3.5 years
5 years
75.8 ± 2.9%
71.3 ± 3.3%
67.2 ± 3.9%
65.1 ± 4.3%
55.8 ± 9.3%
63.6 ± 3.3%
59.2 ± 3.5%
56.6 ± 3.8%
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 Neuralgia
Pain most often occurs in the territory of the glossopharyngeal
nerve
GSA 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 decade
Pain relieved by anesthetizing posteior pharynx with 10% cocaine
5% - 8% of cases caused by posterior fossa tumor
Pain may be due to elongated styloid process (Eagle’s syndrome)
GPN vs. TN
TN 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.