Lecture 9: clinical cases

Question 1

What is Bell;s palsy

Answer 1

a specific form of facial paralysis.

Bell’s palsy presents as idiopathic and acute peripheral nerve palsy resulting in the inability to control facial muscles on the affected side.

Involves the facial nerve [CN VII] - Facial nerve

Question 2

Causes of Bell’s palsy

Answer 2

Inflammation/injury to the facial nerve

Unilateral usually

Etiology; viral infection/ inflammation/ microvascular disease (such as diabetes)

Edema: causes compression, ischemia

Question 3

Innervation of muscles of facial expression

Answer 3

All but one facial muscle are innervated by the facial nerve (VII)

The exception is the levator palperbrae superiors muscle (innervated by oculomotor nerve III)

Question 4

What are the functions of the facial nerves?

Answer 4

1) Motor innervation
2) Sensory information
3) Parasympathetic regulation

Question 5

What does lesion to facial nerves cause?

Answer 5

Paralysis of facial muscles

Deficits depend on location of damage

Question 6

Three divisions of trigeminal nerve

Answer 6

ophthalmic (V1; sensory)

maxillary (V2, sensory)

mandibular (V3, motor and sensory

Question 7

Corneal reflex (pathway and examination)

Answer 7

Blink reflex

Pathway; cranial nerves V and VII are involved.

Examination: light touch of the cornea with a wisp of cotton. Trigeminal
nerve (afferent) and facial nerve (efferent) -> cause corneal/ blink reflex.

See figure

Question 8

Where does the facial nerve exit the skull?

Answer 8

Stylomastoid foramen.

Question 9

What are the functions of the facial nerve (CN VII)

Answer 9

sensory, taste, and parasympathetic qualities.

Question 10

What are the functions of CN V (Trigeminal)

Answer 10

ophthalmic (V1) and maxillary (V2) branch have sensory
qualities

mandibular (V3) branch has motor and sensory qualities.

Question 11

What is the corneal reflex?

Answer 11

The corneal reflex protects the cornea and eye from damage.

It is a monosynaptic reflex circuit between the ophthalmic (V1) branch of the trigeminal nerve (afferent) and the facial nerve [CN VII] which innervates the orbicularis oculi muscle (efferent).

Question 12

Anatomical landmarks for cricothyrodotomy

Answer 12

Cricoid and thyroid cartilages of the larynx

See figure

Question 13

What three axis have to align prior to intubation and how is this accomplished?

Answer 13

oral, pharyngeal and laryngeal axis. This is accomplished by carefully over‐extending the head.

Question 14

What are clinical indications of laryngeal edema?

Answer 14

difficulty breathing

stridor

chest pain

Question 15

What is glaucoma?

Answer 15

increased intra‐ocular pressure in the eye caused by impaired
drainage of aqueous humour by the canal of SCHLEMM at the iridocorneal angle.

Question 16

What can lead to glaucoma?

Answer 16

Diabetes, myopia, family history

Question 17

How does secondary glaucoma occur?

Answer 17

can result from eye injury or inflammation, eye surgery complications, diabetes and the use of certain medications.

Question 18

What can late stage glaucoma result in?

Answer 18

Tunnel vision

Lack of treatment often results in severe vision loss or blindness.

This is due to chronic pressure on the optic nerve with atrophy.

Question 19

Treatment for glaucoma

Answer 19

No cure for glaucoma, despite laser and conventional surgery. Eye drops can be used to lower the intra‐ocular pressure.

Question 20

Trabeculectomy

Answer 20

surgical procedure to drain excess aqueous humour from the eye chambers into a sub‐conjunctival bleb from where the fluid is resorbed by veins.

Question 21

Where is the aqueous humour (AH) of the eye produced and what is the structure called where it is drained?

Answer 21

The aqueous humour (AH) of the eye is produced by the ciliary body located in the posterior eye chamber.

From there the AH flows around the iris into the anterior eye chamber and drains into the SCHLEMM’s canal.

Question 22

What medication can be administered in case of an acute glaucoma?

Answer 22

Pilocarpin causes miosis (smaller pupils) and contraction of the ciliary muscle.

This leads to the opening of the iridocorneal angle and SCHLEMM’s canal and better drainage of AH.

Question 23

What drug can trigger an acute glaucoma attack and should be avoided in glaucoma patient?

Answer 23

Anticholinergics, sympathomimjetics and ipratropium drugs causes mydriasis (wide pupils) and narrows the iridocorneal canal.

This makes drainage of AH difficult and results in intra‐ocular pressure increase.

Question 24

Why should a chronic increase in intra‐ocular pressure be treated?

Answer 24

Chronically increased intra‐ocular pressure can damage the optic nerve and cause vision impairment and/or blindness.