Oculomotor nerve lesion

Lesion results in:

–Lateral squint & Diplopia (eye deviated laterally by the action of unopposed

lateral rectus)

– Ptosis (drooping of upper eye lid) due to paralysis of levator palpebrae

superioris.

– Proptosis (forwards bulging of eye ball) due to relation of paralysis of

extrinsic eye muscle.

-Pupil dilatation & loss of light reflex due to paralysis of constrictor pupillae.

-Loss of accommodation (& convergence) reflex due to paralysis of ciliary

muscle.

- Impaired downward & outward movement of the eye ball on the damaged

side. The preganglionic parasympathetic fibers run superficially in the nerve

and are therefore the first axons to suffer when a nerve is affected by external

pressure. Consequently, the first sign of compression of the occulomotor nerve

is ipsilateral slowness of the pupillary response to light.

Trochlear nerve lesion

Isolated trochlear nerve injury is rare.

Lesion results in diplopia & inability to rotate the eye infero-laterally due to

paralysis of the superior oblique muscle of the same side.

The eye deviates; upward and slightly inward.

Person has difficulty in walking downstairs.

If you asking the patient to look downwards

towards the opposite side of the lesion

Leads to diploplia.

Oculamotor paralysis

Abducent nerve injury

Abducent nerve palsy

Lesion results in: Isolated abducent nerve injury is rare

Isolated abducent nerve leads to medial squint with an inability to direct the

affected eye laterally (due to unopposed action of the medial rectus)

A nuclear lesion may also involve the nearby nucleus or axons of the facial

nerve, causing paralysis of all the ipsilateral facial muscles.

Trigeminal nerve lesion

Complete injury of the trigeminal nerve

1- Paralysis of the ipsilateral muscles of mastication & other muscles supplied

by mandibular nerve.

2- Loss of sensation on the ipsilateral ½ of the face except the area over lateral

½ of the mandible . There is also unilateral loss of sensation of the anterior ½ of

the scalp. Cornea, conjunctiva, mucosa of themouth & anterior 2/3 of the

tongue.

TRIGEMINAL NEURALGIA

Inflammatory condition affecting one or more of the three divisions of

trigeminal nerve. It is characterized by recurring of episodes of intense stabbing

pain, radiating from angle of jaw along a branch of trigeminal nerve. Usually

involves maxillary & mandibular nerves, sparing the ophthalmic division.

Facial nerve injuries

Upper motor neuron (UMN) lesion of

facial nerve:

result from lesion of the pyramid tract above

the level of facial nucleus (supranuclear

lesion)

It commonly occurs with capsular hemiplegia,

There is hemiplegia accompanied by paralysis

of lower ½ of the face of the opposite side

of the capsular lesion.

The upper part of the face is not affected

asIt recieves corticobulbar from both

sides.

While the lower ½ of facial nucleus receives corticobulbar pyramid fibers only from

the opposite side.

II- Lower motor neuron (LMN) lesion of facial nerve (Clinically called Bell s

palsy):

results from affection of the facial nucleus & facial nerve fibers. Manifested by

Complete Paralysis of the facial muscles of the side of lesion.

If the injury is proximal to geniculate ganglion: there is also loss of secrtion from

lacrimal, nasal, buccal, sunmandibular & sublingual glands in addition to loss of taste

sensation from the anterior 2/3 of the tongue on the affected side.

There is hyperacusis (increase sound perception ) due to paralysis of the stapedius

muscle. If the injury is distal to the geniculate ganglion & above the origin of chorda

tympani, glands will not affected.

Bell’s Palsy

BELL’S (FACIAL) PALSY

Lesion of facial nerve (below sytlomastoid foramen) results in paralysis of muscles of

facial expression. It is of the lower motor neuron lesion type (whole face, at same side

of lesion, is affected).

Distortion of face : sagging of angle of mouth, dribbling of saliva, loss of facial

expressions, loss of chewing, blowing, sucking, unable to show teeth or close eye.

Vestibular nerve lesion: leads to:

1- Vertigo: in the form of subjective feeling of rotaion of the individual or his

surroundings.

2- Nystagmus: in the form of oscillating jerk movements of the eyes.

3- Nausea & vomiting.

Cochlear nerve lesion:

1- complete loss of hearing of the same side of the lesion.

Lesion of glossopharyngeal nerve Isolated injury of the glossopharyngeal is rare.

But its lesion result in loss of taste & general sensations from the posterior 1/3 of

the tongue (corresponding side), anaesthesia of the pharynx , partial dryness of the

mouth & loss of carotid sinus reflex.

Vagus Nerve Lesion

Unilateral Injury of the vagus nerve at the base of the skull result in paralysis of

the muscles of the pharynx, palate & larynx on the same side, this leads to:

1- Dysphagis 2- Hoarseness of the voice

3- Loss of pharyngeal reflexes on the affected side & uvula deviation to the healthy

side (palatal paralysis).

Bilateral vagus injury at the base of the skull may be fatal as they lead to bilateral

paralysis of the all laryngeal muscles lead to asphyxia unless emergency

tracheostomy is done. Loss of vagal tone lead to tachycardia, dyspnea & loss of

respiratory reflexes .

Lesion of spinal part of accessory nerve results into:

Difficulty in swallowing and speech

Inability to turn the head and raise the shoulder

Winging of scapula

Lesion of the hypoglossal nerve

Injury of the nerve & its nucleus (LMN paralysis) leads to paralysis of all the muscles

of the tongue on the same side.

The paralyzed tongue atrophy of the muscles & becomes shrunken and furrowed

of its mucosa on the affected side

2- Difficulty in chewing and speech

Unilateral lesion; the protruded tongue deviates to the

affected side.

Bilateral lesion; the person can’t protrude the tongue.

Visual Pathway1. Optic nerve

2. Optic chiasm

3. Optic tract

4. Lateral geniculate body

5. Optic radiation

6. Visual cortex

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Lesion results in: visual field defects

and loss of visual acuity, a defect of

vision is called anopsia

Visual pathway

Optic nerve

Optic chiasma

Optic radiation

Lateral geniculate body

Visual area

Optic tract

1. Right-sided circumferential blindness due to retrobulbar neuritis.2. Total blindness of the right eye due to lesionof right optic nerve.3. Right nasal hemianopia due to partial lesionof right optic chiasm.4. Bitemporal hemianopia due to a completelesion of the optic chiasm.5. Left temporal and right nasal hemianopiasdue to a lesion of the right optic tract.6. Left temporal and right nasal hemianopiadue to a lesion of the right optic radiation.7. Left temporal and right nasal hemianopia dueto a lesion of the right visual cortex.