SIMPLIFIED

1. TRIGEMINAL NEURALGIA:
NEW CLASSIFICATION AND
DIAGNOSTIC GRADING FOR
PRACTICE AND RESEARCH
American Academy of Neurology
July, 2016
Dr.Sandra Mosses
*Review article*

2.  Neuropathic facial pain
 characterized by excruciating paroxysms of pain:
 lips
 gums
 cheek
 chin and
 rarely, in the distribution of the ophthalmic division
of the fifth nerve

3. Why new diagnostic grading...??
 existing criteria plagued by terminologic inconsistencies
that compromise the communication among patients,
physicians, and researchers
 latest version of the International Classification of
Headache Disorders created difficulties by abandoning
the term secondary TN, leaving a widely used
designation for TN that is caused by a major neurologic
disease
 hinder the triage of TN patients for therapy and clinical
trials, and hamper the design of treatment guidelines

4.  developed a new definition and diagnostic
classification for TN that integrates an
evaluation of diagnostic certainty based on
criteria equivalent to those applied for
neuropathic pain in general
 added assessment of diagnostic certainty will
be helpful for treatment decisions
 help in the triage of TN patients for therapy
and clinical trials

5. Definition
 TN is orofacial pain restricted to one or more divisions
of the trigeminal nerve
 U/L (except in some cases asso with Multiple
sclerosis)
 abrupt in onset and typically lasts only a few seconds
(2 minutes at maximum)
 Arise spontaneously but these pain paroxysms can
always be triggered by innocuous mechanical stimuli
or movements
 If they report additional continuous pain, in the same
distribution and in the same periods as the

6.  Incidence 4-8/1,00,000
 Middle aged and elderly
 ~60% in females

7. PATHOLOGY
 ectopic generation of action potentials in pain-
sensitive afferent fibers of the fifth cranial nerve root
just before it enters the lateral surface of the pons
 Compression --demyelination of large myelinated
fibers that do not themselves carry pain sensation but
become hyperexcitable and electrically coupled with
smaller unmyelinated or poorly myelinated pain fibers
in close proximity
 Thus tactile stimuli, conveyed via the large myelinated
fibers, can stimulate paroxysms of pain

10. • posterior third of the
scalp
• back of the ear
• angle of the mandible

11. Possible TN
 include notions of brief, sudden, stabbing,
electric shock–like severe pain attacks
 paroxysms last up to few seconds --2
minutes
 Frequency of the pain attacks may range
from 1 to over 50 a day
 periods of complete remission in up to
63% of patients
 may last from weeks to years

12.  always unilateral
 the affected division of the trigeminal nerve and the
side of the face may change over the course of the
disease
 If the neuralgia involves 2 trigeminal divisions, they
should be contiguous
 combination of the maxillary and mandibular
divisions is most frequent
 TN in the ophthalmic division or the tongue --

14. Clinically established TN
 Stimulus-evoked pain is one of the most
striking features of TN, with high diagnostic
value (99%)
 pain is triggered by innocuous mechanical
stimuli within the trigeminal territory, including
the oral cavity
 Subtlety of the trigger maneuvers is another
unique sign of TN. The stimulus may simply be

15.  More complex maneuvers involve both tactile
stimuli and facial movement, e.g., shaving,
application of makeup, brushing teeth, eating,
or drinking
 The location of the evoked pain may differ
from the site of the stimulation and the pain
can be felt as radiating

16. Allodynia
• abnormal painful
response to gentle
stroking of the skin (in
postherpetic neuralgia)
• No trigger zones
• No refractory period
TN
• TN is also often elicited by
normally painless
mechanical stimuli, or a
combination of external
stimuli and orofacial
movements
• Trigger zones and pain
sensation may be
dissociated (cross-
excitation between
somatosensory afferents)
• refractory period of
several seconds or
minutes during which a
second pain paroxysm
cannot be provoked

17. Trigger zones
central
portion of
the face
around nose
and mouth
nasolabial
fold
lips
tongue

19. Classical TN
 MRI demonstrates vascular compression with
morphologic changes of the trigeminal nerve root
 Compression of the trigeminal nerve root by a
blood vessel- superior cerebellar artery or on
occasion a tortuous vein
 Because of its sensitivity to detect pathologic
processes involving brainstem and cranial nerves
running through the base of the skull, MRI is
widely seen as the method of choice to examine
the trigeminal nerve and root

21.  In a recent meta-analysis of 9 high-quality blinded
and controlled studies, neurovascular contact was
found in 471 out of 531 symptomatic nerves (89%)
and 244 of 681 asymptomatic nerves (36%),
indicating high sensitivity but poor specificity
 Nerve dislocation or atrophy raised the specificity to
97%
 Compression of the trigeminal nerve root at its entry
into the brainstem increased specificity and positive
predictive value to 100%
 The degree of morphologic root changes is
therapeutically relevant

22.  However, it is important to acknowledge that all
cited studies relied on a clinical diagnosis of TN
before MRI
 MRI is a valuable diagnostic tool only if preceded
by an evaluation of symptoms and signs that
indicate probable TN.
 Only valuable if suspecting MS or assessing
overlying vascular lesions to plan for
decompression surgeries

23. • Visualise cisternal and cavernous
nerve segments3D T2-weighted MRI
• visualization of arteries3D timeof-flight
magnetic resonance
angiography
• visualization of veins
3D T1-weighted MRI
with gadolinium or
phase-contrast MRI
• detect abnormalities of the trigeminal
nerve root that normalize following
decompression or radiosurgery
Diffusion tensor
imaging (DTI)

24. Secondary TN (15%)
• Benign-compress the root near its
entry into the pons--focal
demyelination and is thought to
trigger paroxysmal ectopic
discharges
• Malignant-more likely to infiltrate
the nerve and lead to axonal
degeneration
tumor at the
cerebellopontine
angle
• TN in 2%–5% of patients with
MS
• MS is detected in 2%–14% of
patients with TN
• presence of demyelinating
plaques in the pons
• increased susceptibility of the
trigeminal nerve root to
neurovascular compression
Multiple sclerosis

25.  Clinical deficits of discriminatory sensory
functions are highly suspicious of TN caused
by a major underlying disease
 occurred in 25 out of 67 patients (37%) with
TN secondary to tumors or MS
 Reverse conclusion is not true: absence of a
sensory deficit does not rule out secondary TN

26. TN with continuous pain (Atypical
TN)
 Pain between attacks
 It occurs in idiopathic, classical, or secondary
TN
 dull, burning, or tingling
 distribution coincides with that of the
paroxysmal pain, and fluctuations in intensity
as well as periods of remission and recurrence

27.  Drugs:
o CARBAMAZEPINE 100mg OD (max1200mg)
o OXCARBAZEPINE 300-1200mg BD
o LAMOTRIGINE 400mg daily
o PHENYTOIN 300-400mg daily
o BACLOFEN 5-10mg TID
 Surgery:
 Microvascular decompression
 Gamma knife radiosurgery
 Radiofrequency thermal rhizotomy

28.  Evaluation and treatment of TN regularly involve
clinicians in diverse fields of medicine, including
neurology, neuroradiology, neurosurgery, dentistry,
maxillofacial surgery, and specialists in pain
medicine
 A classification system for TN must account for
common differential diagnoses in these disciplines
 Diagnostic requirements for idiopathic, classical,
and secondary TN are based on a thorough review
of clinical and etiologic features of TN

29.  proposed new classification provides defined
criteria that offer diagnostic accuracy with the
added value of a grading system for
neuropathic pain
 designed for intuitive implementation in
diagnostic decisions and treatment guidelines
 will be reflected in the upcoming revision of the
WHO’s ICD