Nerve injuries /certified fixed orthodontic courses by Indian dental academy

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

NERVE INJURIES

NERVE: Nerves are solid white cords
made up of bundles of axons
• Each nerve fiber is known as an
axon
• Each axon is bound by fibrous
tissue into small bundles

The nerve trunk is composed of 4
connective tissue sheaths from outside
inwards are:

1.Mesoneurium: Suspends nerve within soft tissue
and
provides segmental blood supply
to it.
2.Epineurium: Protects nerve from mechanical
stress
3.Perineurium
4.Endoneurium
• Group of nerve fibers- FASCICULI
• Each FASCICULI is surrounded by
PERINEURIUM
• Group of FASCICULI forms a NERVE TRUNKwww.indiandentalacademy.com

Etiology of Nerve injuries:
a. LOCAL CAUSES
• Facial bone fractures.
• Treatment of oral pathological conduction.
• Maxillofical reconstructive surgery.
• Removal of impacted lower third molar.
b. CENTRAL DISEASES
- Syringomyelia
- Multiple Sclerosis
- Bulbar Paralysis

Classification of Injuries:
In 1943 SEDDON introduced a classification of
nerve injury based on three types of nerve fiber
injury.
1. Physiologic Disruption
NEUROPRAXIA,
2. Axonal disruption AXONOTEMESIS,
3. Division of the nerve
NEURONOTEMESIS.

Neuropraxia:
1. Least severe form of peripheral nerve injury,
2. Result of contusion of the nerve ( continuity of
epineurial sheath and axons maintained.
3. Blunt trauma, traction stretching of nerve,
inflammation or local ischemia
4. Full recovery of the nerve function within few
days or weeks.

Axonotmesis:
Blunt trauma, nerve crushing, extreme traction of
nerve.
• Afferent fibers degenerate but nerve trunk
intact,
no disruption of endo/peri/Epineurium
• Recovery is good but incomplete (2, 4-
12month)

Tinnel’s sign:
Painful, electric shock like sensation elicited
by tapping directly over the cutaneous
distribution of injured nerve

Neurotmesis:
Severe disruption of connective tissue
component of nerve trunk.
( Loss of nerve continuity)
Prognosis for recovery poor
Sensory recovery is not expected when nerve
in soft tissue, but if within canal minimal
recovery expected

SUNDERLAND (based on degree of tissue injury)
Five degrees based on increasing anatomic severity
of injury.
Classification Description
Grade I Loss of axonal conduction
Grade II Loss of axonal Continuity
Grade III Loss of axonal and endoneurial
continuity
Grade IV Loss of perineurial continuity with
fascicular disruption
Grade V Loss of continuity of entire nerve
trunk

COMPARTMENT SYNDROME:
• Local increase in pressure
(edema/venous stasis) causing decreased
oxygenation.
• Abnormal vibration and touch perception

TESTING FOR NERVE INJURY:
1. Light touch: cotton wisp
2. Two-point discrimination: >10mm abnormal
3. Localization
4. Sharp blunt differentiation
5. Thermal stimuli: 150
c to 500
c

BASIC PRINCIPLES OF NERVE REPAIR:
1. Decompression:
2. Neurorraphy: (Gap of 10mm only)
a. Preparation of nerve stumps
b. Approximation
c. Cooptation
e. Maintaining the cooptation
3. Nerve Grafts:
- Sural nerve
- Greater auricular nerve

TRIGEMINAL NEURALGIA
Synonyms:
·       Tic douloureux- spasmodic contraction of facial
muscles
·       Fother gill’s disease
·       Trifacial neuralgia

Definition:
‘A painful unilateral affliction of the face,
characterized by brief electric shock like (lancinating)
pain limited to the distribution of one or more
divisions of the trigeminal nerve’

PREVIOUSLY CLASSIFIED AS:
1. Classical trigeminal neuralgia or Idiopathic
trigeminal neuralgia
2. Specific trigeminal neuralgia (known etiology)
Pre- trigeminal neuralgia (PTN

INCIDENCE:
    Female affected more than
males (3:2)
   Right > left
   Middle age and elderly
  4% Bilateral
   95% Maxilla + Mandibular nerve
involved
5% Ophthalmic nerve involved

CLINICAL FEATURES:
“WHITE AND SWEETS CRITERIA”
1. PAIN:
Paroxysmal (lasts from few seconds to few minutes)
Extremely intense (stabbing/ lightening/ pricking/
knife like)
Pain free episodes/ intervals

2. TRIGGER ZONES:
        Vermilion/ alae/ cheeks/ periorbital area
        Cutaneous in distribution
        Stimuli includes- touch/ breeze/ talk/ chew/brush/shave
3. PRE-TRIGEMINAL NEURALGIA(PTN):
      Mild, lancinating/pricking type
Months to years before chronic type of trigeminal neuralgia
4. HYPERESTHESIA/ HEPERALGESIA
On routine clinical examination

5. ALWAYS UNILATERAL:
If bilateral, then only one side affected at a time
       Unshaven and unclean face (frozen face)
       Spontaneous remission is unusual
       Attacks do not occur during sleep(characteristic)
       Secondary radiation of pain to adjacent division
HYPOTHESIS:
1. Neural back talk theory – secondary to nerve injury
2. Deafferentation of central processes due to peripheral injury

CLINICAL FEATURES:
      Male = female
      Middle age or late life
      Pain: lancinating pain of
oropharynx or neck, lasts for week-months
      Triggered by swallowing/ cough/ talk
      Unilateral & radiates to ear & or mouth
      Syncope is a feature
      Rarely causes xerostomia/excess salivation
      Disturbs sleep

ETIOLOGY:
1. C-P angle tumors: Acoustic Neuroma/ Cholesteotoma/
Meningioma/ Osteoma/ Angioma
2. Anatomical variation of Petrous bone/ridge
3. Aneurysms and Adhesions
4. Multiple Sclerosis
INVESTIGATIONS:
Nerve functions- sensory and motor (trigger zones)
Diagnostic nerve blocks
Special tests for tumors and systemic diseases

Treatment modalities:
Medical:
(A)
1. Phenytoin sodium (dilantin)
200-600mg/day in divided doses
2. Carbamazepine (tegretol/ carbital)
Initially – 100mg BID
Increase to 200mg TID
3. Max. Dose is 1200mg/day in divided doses
Baclofen or l-baclofen (lioresal)
10-80-mg/ day in divided doses
4. Valproic acid (depakote) 125-250 mg/day
5. Clonazepam (klonopin) 0.5 - 8mg/day
6. Pimiozide (orap) 2-12 mg/day
7. Lamotragine (lamicital) 50-100mg/day

(B) PERCUTANEOUS injections:(2days -1-week interval)
Chemicals used: local anesthesia/ absolute alcohol/ phenol-
glycerin mixture
Injection site: peripheral nerves/trigger zones/gasserian ganglion
(C) percutaneous electro-coagulation
(D) cryosurgery (-900
to –1600
c)
(E) ratners procedure/ osseous curettage
Bone decortication+curettage+triple antibiotic pack
(chloromphenicol+tetracycline+iodoform)

TREATMENT:
▪         Medical: - Carbamazepine/ Phenytoin/ Baclofen
▪         Local: - Cryotherapy/ Alcohol Injection
▪         Surgery: - Section GPN & Upper Rootlets Of Vagus
▪         Central: - Micro vascular Decompression

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Nerve injuries /certified fixed orthodontic courses by Indian dental academy

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