Cranial Nerves - Clinically Oriented

Question 1

What would a common symptom of damage to the olfactory nerve be?

Answer 1

Anosmia (loss of smell)

Question 2

What can cause damage to the olfactory nerve?

Answer 2

Ethmoid bone fracture or foster-Kennedy syndrome.

Question 3

What is foster-Kennedy syndrome?

Answer 3

Foster-Kennedy syndrome is associated with the finding of tumors in the frontal lobe.

Question 4

What is Rhinorrhea?

Answer 4

Rhinorrhea is the flow of cerebrospinal fluid out through the nose, which is commonly associated with a tear of the olfactory nerves.

Question 5

What is anopia?

Answer 5

Anopia is the term describing loss of vision

Question 6

What is hemianopia?

Answer 6

Hemianopia is the term describing loss of vision in half of the visual field.

Question 7

What is quadranopsia?

Answer 7

Quadranopsia is the term describing loss of vision in one fourth of the visual field.

Question 8

What is homonymous hemianopia?

Answer 8

Homonymous hemianopia is the term describing the loss of vision in half of the visual field in both eyes on the same side.

Question 9

What is the result of optic nerve lesion?

Answer 9

Optic nerve lesion will result in ipsilateral monocular anopia.

Question 10

What is central scotoma and what can cause it?

Answer 10

Central scotoma is covers the reading field of vision which can be caused by retinal damage.

Question 12

What is caused by optic chiasm lesion?

Answer 12

Optic chiasm lesion results in bitemporal hemianopia due to only nasal fibers being affected. It can be caused by pituitary tumor.

Question 13

What is caused by optic tract lesion and what can be the cause of it?

Answer 13

Optic tract lesions can result in contralateral homonymous hemianopia.

Optic tract lesions can be caused by subcortical lesions (lesions within structures like the diencephalon, pituitary gland, limbic structures and the basal ganglia) due to stroke, tumors, infections etc.

Question 15

What is glaucoma?

Answer 15

Glaucoma is a group of eye diseases that results in damage of the optic nerve. It is the leading cause of blindness.

Question 18

What can be caused by optic radiation lesion?

Answer 18

Optic radiation has two pathways: The upper and lower pathway.

Lesion to the upper radiation causes contralateral lower quadrantanopsia.

Lesion to the lower radiation may cause contralateral upper quadrantanopsia.

Question 19

What is subdural and epidural hematoma and what can it cause?

Answer 19

Subdural and epidural hematoma is bleeding below the meninges or around the dura mater which can cause pressure on the brain which again causes outward bulging of the internal carotid and posterior communicating arteries which can result in oculomotor paralysis.

Question 20

What is ptosis?

Answer 20

Ptosis is denervation (loss of nerve supply) to the levator palpebrae which results in the dropping of the upper eyelid. Levator palpebrae are supplied by the oculomotor nerve.

Question 21

What is diplopia?

Answer 21

Diplopia is double vision. Diplopia can be caused by many things, among paralysis of the muscles supplied by the oculomotor nerve.

Question 22

What is cycloplegia and what can cause it?

Answer 22

Cycloplegia is a dilated and fixed pupil and paralysis of accommodation. This can be a result of the loss of parasympathetic innervation of the oculomotor nerve.

Question 23

What are some common symptoms of oculomotor nerve lesion?

Answer 23

Ptosis ( drooping of the eyelid)

Mydriasis (Dilated and fixed pupil due to inefficient constrictor pupillae muscle)

Looking down and out ( due to unopposed left superior oblique and lateral rectus muscle)

Question 24

What is the common symptoms of paralysis of the trochlear nerve?

Answer 24

Paralysis of the trochlear nerve can result in:

• Extorsion (outward ‘‘vridning’’ of the eye)
• Weekness of downward gaze.
• Vertical diplopia increasing when looking up.
• Head tilting to compensate for extorsion.

Question 25

What can the symptoms of the abducent nerve lesion be?

Answer 25

Lesion of the abducent nerve can cause:

• Convergent strabismus (esotropia) - One or both eyes turn inward due to the unopposed action of the medial rectus muscle.
• Horizontal diplopia (maximal separation of the double images when looking toward the paretic lateral rectus muscle)

Question 26

What can the symptoms of lesion of the trigeminal nerve be? (eg. trigeminal neuralgia)

Answer 26

Lesion of the trigeminal nerve can cause:

• Loss of general sensation from the face and mucous membranes of the oral and nasal cavities.
• Loss of corneal reflex (afferent limb)
• Flaccid paralysis of muscles of mastication.
• Deviation of the patient’s jaw to the weak side (due to unopposed action to the lateral pterygoid)
• Paralysis of tensor tympani leading to hypacusis = partial deafness to low pitched sounds.

Question 27

What would lesion to the facial nerve cause?

Answer 27

Lesion to the facial nerve can cause:

• Flaccid paralysis of facial expression muscles.
• Loss of corneal reflex (efferent limb) which may lead to corneal ulceration.
• Loss of taste from the anterior two-thirds of the tongue.

Hyperacusis - increased acuity to sounds due to stapedius paralysis.

Question 28

What is the result of vestibulocochlear nerve lesion?

Answer 28

Vestibulocochlear nerve lesion causes:

• Hearing loss
• Tinnitis
• Disequilibrium
• Vertigo (Dizziness - feeling of you or surroundings is moving)
• Nystagmus (involuntary movements of the eye)

Question 29

What is acoustic neuroma?

Answer 29

Acoustic neuroma is a tumor that grows close to the cerebellopontine angle (where the vestibulocochlear nerve and facial nerve originates) that affects both nerves.

Question 30

What can be the result of glossopharyngeal nerve lesion?

Answer 30

Glossopharyngeal nerve lesion can cause:

• Loss of gag (pharyngeal) reflex due to interruption to the afferent limb.
• Loss of carotid sinus reflex (carotid sinus is the reflex area of the carotid artery. Senses blood pressure and sends signals via the carotid sinus nerve (branch of the glossopharyngeal nerve) to the brain.
• Loss of taste of the posterior 1/3 of the tongue.
• Glossopharyngeal neuralgia (pain in tongue, throat, ear and tonsils)