oto facial nerve disorders

Question 1

What are the most common cranial neuropathies

seen with neurosarcoidosis?

Answer 1

● Optic nerve, facial nerve, eighth nerve
● Up to 50% of patients will have a least one cranial nerve
palsy.

Question 2

What are the classic features of Melkersson-

Rosenthal syndrome?

Answer 2

● Recurrent orofacial edema, recurrent facial nerve paraly-
sis, and lingua plicata (fissured tongue)
● The classic triad is seen in only a minority of patients.

Question 3

What is Bell phenomenon?

Answer 3

A reflexive upward and outward movement of the globe
during attempts at eye closure. Patients with incomplete
eye closure resulting from facial palsy with an absent Bell
phenomenon are at higher risk for corneal complications.

Question 4

What is the organism responsible for Lyme disease?

Answer 4

Borrelia burgdorferi

Question 5

How does treatment for facial paralysis secondary to Lyme disease differ from treatment of idio-
pathic facial paralysis (Bell palsy)?

Answer 5

Treatment with antibiotics (IV ceftriaxone or IV/PO doxycycline) has been found to improve outcomes in cases of facial paralysis associated with Lyme disease.

Question 6

How does the prognosis for facial nerve recovery

in Ramsay Hunt syndrome compare with that of Bell palsy?

Answer 6

The long-term facial nerve outcomes of Ramsay Hunt
syndrome are generally worse, with more severe paralysis
and a lower rate of full recovery.

Question 7

Which sensory ganglion is believed to harbor
latent varicella virus that becomes reactivated in cases of herpes zoster oticus (Ramsay Hunt syn-
drome)?

Answer 7

The geniculate ganglion

Question 8

What is the prognosis for facial nerve recovery in

patients with idiopathic facial paralysis (Bell palsy)?

Answer 8

80 to 90% of patients who receive no treatment experience
full recovery. Among those who do not progress to
complete paralysis, the prognosis is even better; 95% or
greater of these patients have complete recovery. Evidence
suggests that corticosteroids with or without antivirals
provide improved outcomes, although the data are not
conclusive, particularly for antivirals.

Question 9

Where is the narrowest point in the fallopian canal?

Answer 9

At the meatal foramen, which marks the start of the labyrinthine segment

Question 10

Describe how electroneuronography is performed.

Answer 10

Electronueronopgraphy ( evoked electromyography) as-
sesses the motor response to supramaximal stimulation of the facial nerve and compares the peak to peak difference
between the abnormal side and the normal side. A bipolar stimulating electrode is placed at the stylomastoid forma-
men and surface electrodes are placed at the nasolabial
fold. Increasing stimulation levels are provided until a
maximal amplitude in the compound muscle action
potential is reached. The difference between the abnormal
and normal side provides the “percent drop.”

Question 11

At what critical electroneurogrphy (ENoG) value is
facial nerve decompression considered in patients
with Bell palsy?

Answer 11

Greater than 90% reduction compared with the opposite

unaffected side

Question 12

What is the significance of polyphasic motor unit

action potentials during EMG testing?

Answer 12

Neural regeneration

Question 13

What is the significance of fibrillation potentials

during EMG testing?

Answer 13

Fibrillation potentials are spontaneous action potentials that
arise from denervated muscle fibers and are generally not
seen until after 21 days beyond denervation.

Question 14

Describe how maximal stimulation testing is

performed.

Answer 14

Transcutaneous electrical stimulation at the stylomastoid
foramen is provided at a level that elicits maximal facial
movement in an attempt to interrogate all functioning
nerves. The response on the side with facial nerve paralysis
is compared with the normal side and graded.

Question 15

Describe how nerve excitability testing is per-

formed.

Answer 15

Surface electrodes are placed near the stylomastoid foramen. Fixed-current pulses of increasing strength are delivered to the unaffected side until facial twitching is
noted. The process is repeated on the affected side, and the difference in current required for stimulation is calculated.

Question 16

What is the expected rate of neural regeneration

following axonal injury?

Answer 16

1 mm/day

Question 17

Describe the five levels of neural injury according

to the Sunderland classification.

Answer 17

● Conduction block without axonal degeneration (neuropraxia)
● Isolated axonal injury that results in wallerian degeneration (axonotmesis)
● Axonal injury with loss of endoneurium, but the perineurium and epineurium remain intact.
● Axonal injury with loss of the endoneurium and
perinerium, but the epineurium remains intact.
● Axonal injury with loss of all surrounding structures
(transection)

Question 18

Describe the three levels of neural injury according

to the Seddon classification.

Answer 18

● Neuropraxia: Axons remain intact but have a temporary
conduction block. Full recovery is expected.
● Axonotmesis: Axons are damaged, but endoneurium
remains intact. Wallerian degeneration will occur, but a
full recovery without synkinesis is expected.
● 3. Neurotmesis: Axons and surrounding support (endo-
neural tubules) are disrupted. Wallerian degeneration will
occur, and recovery is variable.

Question 19

What are the primary indications for rehabilitation
of facial paralysis using dynamic muscle proce-
dures such as temporalis tendon transfer?

Answer 19

Long-standing facial paralysis (> 2 years) is not amenable to
primary reanastamosis, cable grafting, or jump grafts
because facial motor endplates are no longer viable.
Patients in these groups who desire dynamic facial rehabi-
litation may be candidates for muscle transfer techniques (temporalis transfer, masseter transfer, free gracilis, etc.).

Question 20

What are the primary indications for rehabilitation

of the eye in facial paralysis?

Answer 20

The primary goal is to protect the eye and vision from
damage caused by chronic exposure and dryness. Corneal abrasion, ulceration, clouding, and epiphora can occur with facial paralysis and may result in vision loss if not aggressively managed.

Question 21

What subset of patients with facial nerve paralysis are candidates for rehabilitation with facial-hypo-
glossal transfer?

Answer 21

Direct reinnervation (either primary anastomosis or cable
grafting) is preferable, but when the proximal nerve stump
is not available and the target facial motor endplates are
still viable (within 12 to 18 months), facial-hypoglossal
transfer is a viable treatment option.

Question 22

What medical therapies are indicated for patients
with delayed complete facial nerve paralysis after
temporal bone trauma?

Answer 22

Eye care (drops, ointment, nocturnal moisture chamber)
and corticosteroids

Question 23

What is the significance of a completely unre-

sponsive facial nerve after high-level proximal eletrical stimulation at the end of a surgery?

Answer 23

It denotes a complete conduction block, but without a
subsequent examination to determine whether wallerian
degeneration has occurred, a single test at the time of
injury cannot differentiate between a simple neuropraxia
and a transected nerve.

Question 24

What is the mechanism of gustatory lacrimation

after facial nerve injury?

Answer 24

Caused by a lesion proximal to the geniculate ganglion
where fibers destined for the submandibular/sublingual
glands reinnervate the lacrimal gland

Question 25

How can synkinesis after traumatic facial nerve

injury be managed?

Answer 25

Botulinum toxin injections or selective myectomy of

affected muscles

Question 26

During tympanomastoidectomy, the facial nerve is
partially severed, with approximately 75% of its
cross section still intact. What is the next step that should be performed?

Answer 26

With most of the nerve still intact, no further intervention
should be undertaken. Limited proximal and distal facial
nerve decompression could be considered to decrease
ischemia associated with swelling.

Question 27

What is the best outcome one could expect with
primary tension-free nerve anastomosis after
traumatic facial nerve injury?

Answer 27

House-Brackmann grade III function. Patients can achieve symmetric resting tone, good eye closure, and oral sphincter competence.

Question 28

When awakening from a tympanomastoidectomy
for cholesteatoma, a patient has an unexpected
complete facial paralysis. What is the next step in
care?

Answer 28

Consider observing the patient for 4 to 6 hours to allow

local anesthetic injection to wear off.

Question 29

What is the most common presentation of an

intraparotid facial nerve schwannoma?

Answer 29

Asymptomatic enlarging mass

Question 30

What are the common initial symptoms of an

intratemporal facial nerve schwannoma?

Answer 30

Approximately 50% have slowly progressive or intermittent facial nerve paresis, and roughly 75% have some degree of hearing loss.