Injury of Cranial Nerve

By: Huda Almubarak

Cranial Nerves

• CN I

• CN II

• CN III, IV, & VI

• CN V

• CN VII,

• CN VIII

• CN IX & X

• CN XI

• CN XII

Memorize 2-3 sections/division

Injury of Cranial Nerve

Injury to the cranial nerve is a

frequent complication of a fracture in

the base of the cranium.

some of causes:

Trauma, tumor and aneurysm

CN I Olfactory Nerve

Not real nerves, why?

Directly from the receptor to the center of vision!

Injury of CN I

1. Anosmia

loss of smell.

Causes:

- Loss of olfactory fibers usually occurs whith

aging

- Injury to the nasal mucosa, olfactory nerve

fibers, olfactory bulbs, or olfactory tract may

impair smell

Injury of CN I

2. Olfactory Hallucination:

False preception of smell

Causes:

Lesion in the temporal lobe of the cerebral

hemisphere “temporal lobe epilepsy”

Characterized by:

- Imaginary disagreeable odors

- Involuntary movement of the lips and tongue.

CN II Optic Nerve

• Vision

• Intraocular

movement (+ III)

• Blinking (+ V &

VII)

• Circadian rhythm

Injury of CN II

1. Demyelinateing: Diseases and the Optic

Nerve.

- The optic nerve are actually CNS tract

surrounded by myelin sheath.

Consequently, the optic nerves are susceptible

to the effects of demyelinating disease of the

CNS , such as multiple sclerosis(MS), which

usually don’t affect other nerves of the PNS.

Injury of CN II

2. Optic neuritis

optic neuritis refers to lesions of the optic

nerve that cause diminution of visual

acuity Optic neuritis may be caused by

inflammatory , degenerative , demyelinating

, or toxic disorder

Injury of CN II

3. Visual field defect:

Visual field defects result from lesions that

affect different parts of the visual pathway

Injury of CN III

Ptosis

Causes: A lesion of CN III results in ipsilateral

oculomotor palsy

Characterized by:

- Dilated pupil.

- Pupillary reflex on the side of the lesion will

be lost.

- eyes turned down and out.

Injury of CN IV

- The Trochlear nerve is relay pralyzed alone.

- Lesion of the nerve or it’s nucleus paralysis of

the superior oblique and impair the ability to

turn the affected eyeball inferpmedially

- characteristic sign:

Diplopia “double vision” when looking down.

Injury of the V

Trigeminal Nerve injured by:

- Trauma

- Tumors

- Aneurysm

- Meningeal infection

Injury of the V

Causes the following:

- Paralysis of the muscle of mastication

- Loss of the ability to appreciate soft

tactile, thermal, or painful sensation in the

face.

- Loss of corneal reflex

Injury of the VI

Paralysis of Abducent nerve result from:

- Neurysm of the cerebral arterial circle (at the

base of the brain)

- Pressure from an atherosclerotic internal

carotid artery in the cavernous sinus.

- Septic thrombosis of the sinus subsequent to

infection in the nasal cavities or paranasal

sinus.

Injury of the VII

Injury of Facial nerve result from:

- Laceration or contusion in parotid region

- Fracture of temporal bone

- Intracranial hematoma “stroke”

Injury of the VI

Causes the following:

- Causing paralysis of

the lateral rectus.

- Medial deviation of

the affected eye.

Injury of the VII

Causing:

- Bell’s palsy: paralysis of facial muscle; eye

remains; angle of mouth droops; forehead does

not wrinkle.

- Dry cornea; loss of taste on anterior two third

of tongue.

- Paralysis of contralateral facial muscle.

Injury of the VIII

Lesion of Vestibulocochlear nerve may cause:

- Tinnitus: ringing or buzzing in ear.

- Vertigo: dizziness, loss of balance.

- Impairment or loss of hearing.

Injury of the IX

Isolate lesion of Glossopharyngel nerve is

uncommon. Result from:

- Infection

- Tumors

Injury of the IX

Causing:

- Taste is absent on the posterior third of

tongue.

- Change in swallowing

- Loss of sensation on affected side of soft

palate.

Injury of the X

Injury of Vagus nerve results from:

- Cancer of the larynx and thyroid gland

- Injury during surgery on (thyroid

gland, neck, esophagus, heart, and lungs)

Injury of the X

Injury of Vagus nerve results in:

- Dysphagia: difficulty in swallowing.

- Dysphonia: difficulty in speaking.

- Aphonia: loss of voice.

- Inspiratory stridor: high respiratory sound.

Injury of the XI

Injury to the spinal accessory nerve:

Susceptible to injury durring surgical

procedures such as lymph node

biopsy, cannulation of the internal jugular

vien, and carotid endarterectomy.

Injury of the XII

Injury to the Hypoglossal nerve:

Paralyzes the ipsilateral half of the tongue, it’s

apex deviate toward the paralyzed side.

Fathers of Neuroscience

Camillo Golgi

(1843-1926)

Santiago Ramon y Cajal

(1852-1934)

Father of Neurosurgery

& Father of Neurology

Harvey Williams Cushing

(1869-1939)

Jean-Martin Charcot

(1825-1893)

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