Chapter 8: Disease of the Facial Nerve

Question 1

Is a peripheral seventh nerve paralysis

Answer 1

Bell’s palsy

Question 2

Innervates facial motion
Provides lacrimation, salivation, impedance regulation of the middle ear
Senses of pain, touch, temperature and taste

Answer 2

Seventh cranial nerve

Question 3

Begins at the brain stem and follows a course through the temporal bone, ending in the muscle of the face

Answer 3

Seventh cranial nerve

Question 4

Seventh cranial nerve is in the region of the…

Answer 4

Pons

Question 5

Innervates the ipsilateral and contralateral forehead

Answer 5

Precentral gyrus of the motor cortex

Question 6

Innervates the contralateral portion of the remainder of the face

Answer 6

Cerebral cortical tracts

Question 7

Innervates only the ipsilateral facial nerve

Answer 7

Motor nucleus

Question 8

Branches of facial nerve

Answer 8

1. Temporal
2. Zygomatic
3. Buccal
4. Mandibular
5. Cervical

Question 9

AKA neuropraxia
Occurs when the conduction of impulses is blocked, damming axoplasm transport (both directions) with some axoplasm transport continuing

Answer 9

1st-degree injury or conduction block

Question 10

Amount of pressure on the nerve is sufficient to completely block the movement of axoplasm past the site of injury over several days
Occurs with loss of axonal continuity
Results in wallerian degeneration distally

Answer 10

Axonetmesis (2nd-degree injury)

Question 11

Axonetmesis and neurotmesis histologic findings

Answer 11

1. Schwann cells become swollen and phagocytic
2. Loses of Nissl substance with swelling of cytoplasm (chromatolysis)
3. Formation of Büngner’s bands (provide a biochemical mode of attraction for new nerves)

Question 12

Repair of a cut facial nerve is more likely to be effective if done…

Answer 12

21 days after the injury

Question 13

Are branchiomeric muscles and greater muscle wasting is seen in somatic muscle than in branchiomeric muscle after loss of motor nerve

Answer 13

Facial muscles

Question 14

Stages of facial nerve after injury

Stage 1

Answer 14

1. Occurs up to 21 days
2. Cell body undergoes metabolic transformation and begins to regenerate to create axoplasm that will inhabit the now empty neurotubules

Question 15

Stages of facial nerve after injury

Stage 2

Answer 15

1. Last up to 2 years
2. Cell body and the proximal segment can regenerate using the Büngner’s bands or reserved endoneural tubes through which the regenerating axons can reach the facial muscles

Question 16

It should be considered plausible to reanatomose the severed nerve, interpose a cable graft between the 2 points of loss of continuity or transfer another functioning motor nerve to the distal nerve segments

Answer 16

Up to 2 years after injury

Question 17

Stages of facial nerve after injury

Stage 3

Answer 17

1. Distal scarring and muscle degeneration

Precludes consideration of restoring neuromuscular continuity

Question 18

Needs to have complete audiogram

Answer 18

Facial nerve palsy

Question 19

Testing must include (facial nerve palsy)

Answer 19

1. Air and bone conduction
2. Tympanometry
3. Stapes reflexes

Question 20

Function of the 8th CN can be evaluated using…

Answer 20

Auditory brain stem evoked response (ABR test)

Question 21

Most helpful in detecting pathology in the internal auditory canal

Answer 21

ABR test

Question 22

Reflex testing

Answer 22

A loud tone is presented, either to the ipsilateral or contralateral ear–>evokes a reflex movement of the stapedius muscle–>changes the tension on the TM—>change in the impedance of the ossicular chain

Question 23

Reflex testing result

Answer 23

Tone is presented to the opposite ear: normal hearing ear and reflex is elicited (intact 7th nerve)
Absence of reflex when either ear is stimulated: abnormality of the afferent 7th CN

Question 24

Tearing function of the eye can be evaluated
Strips are placed over the lower lid into the conjunctival sac on both sides
After 3 minutes, the length of the strip that is moist compared to the opposite side
A difference of greater than 25% suggest potential involvement of 7th CN

Answer 24

Schirmer test

Question 25

The side of less tearing is interpreted to represent greater superficial petrosal nerve activity due to...

Answer 25

Loss of action in the parasympathetic nerve of Wrisberg

Question 26

Is a reliable indicator of interruption of the function of the chorda tympani nerve Loss of taste due to injury is limited to the anterior 2/3 of the tongue and stops at the midline

Answer 26

Measurement of taste

Question 27

Can be performed by cannulating the submandibular glands | Reduction in salivary flow of 25% is considered abnormal

Answer 27

Salivation test

Question 28

Nerve function tests

Answer 28

1. Electromyography (EMG) 2. Electroneuronography (ENOG) 3. Maximal stimulation tests

Question 29

Nerve function test frequently performed | Determining the patient's course in reinnervation responses

Answer 29

EMG

Question 30

A positive sign showing recovery of some fibers | Not seen before 21 days

Answer 30

Fibrillation potentials

Question 31

Carries put a stimulation at one point and measurement of the EMG at a more distal point on the nerve If there is a 90% reduction at ten days, chances of recovery are significantly reduced

Answer 31

ENOG

Question 32

The probe is pressed against the face in the area of the facial nerve Current is slowly increased to 5 ma, or until the patient has discomfort Forehead, eyebrow, periorbital area, cheek, nasal ala and lower lip are tested

Answer 32

Maximal stimulation test

Question 33

1. External and middle ear anomalies 2. Involvement of CN 3, 5, 6, 7 and 12 3. Facial nerve forms (fibrotic tract) 4. Muscle development may be present (rapidly degenerates to fibrosis) 5. No response to any electrical testing 6. Not develop any form of facial movement

Answer 33

Möbius syndrome

Question 34

Congenital lesion (facial nerve paralysis)

Answer 34

1. Möbius syndrome | 2. Childbirth trauma

Question 35

Infections (facial nerve paralysis)

Answer 35

1. Meningitis 2. Ramsay Hunt syndrome (herpes zoster oticus) 3. Bacterial infections of the middle ear 4. Lyme disease

Question 36

Is a common cause of facial palsy

Answer 36

Trauma to the temporal bone

Question 37

Facial nerve evaluation should be performed immediately on any patient with a

Answer 37

Basilar skull fracture

Question 38

Vascular lesion (facial palsy)

Answer 38

1. Aneurysm | 2. Thrombosis of major vessel

Question 39

Neoplasm (facial palsy)

Answer 39

1. Tumors of cerebellopontine angle (acoustic neuroma, meningioma) 2. Glomus jululare 3. Histiocytosis 4. Rhabdomyosarcoma 5. Squamous cell carcinoma

Question 40

Development of facial nerve paralysis in a patient with external otitis suggests

Answer 40

Malignancy

Question 41

Idiopathic causes (facial palsy)

Answer 41

1. DM 2. Melkersson-Rosenthal syndrome 3. Bell's palsy

Question 42

Most common cause of unilateral facial paralysis Recovery of function within 6 months Upper respiratory inflammation symptoms may precede

Answer 42

Bell's palsy

Question 43

When electrical tests show identical responses on both sides...

Answer 43

Prognosis for recovery of nerve function is excellent

Question 44

Complications of facial nerve paralysis

Answer 44

1. Drooling 2. Inability to whistle 3. Trouble with speaking clearly 4. Biting the buccal mucosa (loss of motor tone) 5. Popping of food in the paralyzed buccal pouch

Question 45

When facial nerve grafting is not possible, other cranial nerves in the area can be used

Answer 45

1. Spinal accessory nerve | 2. Hypoglossal nerve

Question 46

Medical therapy for Bell's palsy requires..

Answer 46

Attention to the paralyzed eyelid

Question 47

Medical therapy for Bell's palsy

Answer 47

Prednisone 1 mg/kg/day up to 14 days

Question 48

Surgery treatment for Bell's palsy

Answer 48

1. Transmastoid facial nerve decompression from the geniculate ganglion distally to the level of the stylomastoid foramen 2. Middle fossa decompression