Facial Nerve Flashcards
How long does it take for tOO% Wallerian degeneration to occur after a compressive conduction block
14 - 21 days.
Defects greater than ___ cannot be rerouted and require cable grafting
15 - 17 mm.
What is Sutherland’s classification for nerve injury
1st degree: reversible conduction block. 2”d degree: Wallerian degeneration occurs but endoneurium stays intact and recovery is usually complete. Yd degree: endoneurium is destroyed but perineurium stays intact and recovery is incomplete. 4th degree: all is destroyed except for the epineurium; recovery is poor. 5th degree: complete nerve transection; untreated recovery is not expected.
Where on the lid is the implant placed
2 mm above the lash line.
What % of patients with Ramsay Hunt syndrome have Vlllth nerve involvement
20%.
What % of patients with Lyme disease have facial nerve paralysis as the sole manifestation
20%.
How long does it take for 100°/o Wallerian degeneration to occur after complete nerve transection
3 - 5 days.
What is the incidence of diabetes mellitus in patients with recurrent Bell’s palsy
31%.
What is the incidence of facial palsy as the presenting symptom of tuberculous mastoiditis
39%.
What is the minimal time for functional return of the facial nerve after anastomosis or grafting
4 - 6 months.
What is the outcome of these patients who are treated with steroids alone
42% have a good outcome.
After microneurovascular muscle transfer, what is the maximum muscle power attainable compared to normal
55%.
What is the incidence of recurrent facial palsy
5-7%.
Between which days after injury is the degree of axonotmesis and neurotmesis unclear
6 - 14.
What is the mean interval to the 1st recurrence
9.8 years.
What is the outcome of patients with Bell’s palsy who have 90% or more degeneration on ENoG within the 1st 14 days of onset and undergo decompression
91 % have a good outcome (House I or II) 7 months after paralysis.
What is the cog
A ridge of bone that extends inferiorly from the tegmen epitympanum and partially separates the anterior epitympanic compartment from the mesoepitympanum.
What causes hemifacial spasm
A vascular loop, most commonly of the anterior or posterior inferior cerebellar artery, impinging on the root of VI I.
What is the most commonly proposed theory of the etiology of Bell’s palsy
Activation of a latent virus present within the geniculate ganglion leading to entrapment, ischemia, and degeneration of the labyrinthine segment of VII.
What is the recommended treatment for Ramsay Hunt syndrome
Acyclovir 800 mg five times a day x I 0 days and prednisone taper x 14 days.
What is Tangier’s disease
Autosomal recessive disorder of lipid metabolism characterized by low apolipoprotein A-1 and H DL levels. Clinical features include facial diplegia, neuropathy, and coronary artery disease.
Which of these result in Wallerian degeneration
Axonotmesis and neurotmesis.
What is the initial treatment for hemifacial spasm
Baclofen.
When is ENoG evaluation meaningful
Between days 3 and 21 after complete loss of voluntary function.
What happens if the implant is placed too deep
Can damage the levator muscle, causing ptosis.
What are the surgical landmarks for the tympanic segment of VII
Cochleariform process, oval window, pyramidal process, semicanal for the tensor tympani, vertical groove on promontory for the tympanic nerve.
What is the outcome of Bell’s palsy left untreated
Complete recovery in 71 %; permanent diminished function in I 6%; poorer prognosis if>60 years of age and if onset of recovery >3 months after initial onset of paralysis.
How can dynamic rehabilitation be achieved in a patient with a 1 0-year history of facial paralysis following radical parotidectomy
Crossfacial nerve graft plus microneurovascular muscle transfer.
What factors increase the risk of recurrent Bell’s palsy
Diabetes mellitus and family history.
Which methods of facial nerve reconstruction have the potential for spontaneous emotional response
Direct anastomosis and cable grafting.
What electrophysiologic test is more useful 3 weeks after the onset of complete facial paralysis
EMG.
What is the narrowest intratemporal portion of the fallopian canal
Entrance to the fallopian canal at the lateral aspect of the lAC (fundus).
Which anastomotic technique is preferred by most surgeons
Epineural anastomosis using 3 - 8 sutures of 8-0 or I 0-0 synthetic monofilament suture.
What is Heerfordt’s syndrome
Facial nerve palsy with anterior uveitis, parotid gland enlargement, and fever.
T/F: Addition of acyclovir to prednisone for treatment of Bell’s palsy has not been shown to result in significant improvement of facial nerve function
False.
T/F: Evidence of viral etiology for Bell’s palsy is well documented
False.
T /F: There is a consistent topographic representation of fibers from a specific section of a nerve innervating certain parts of the face.
False.
What sort of EMG pattern is associated with nerve degeneration
Fibrillation potentials.
What is the most common cause of unilateral facial palsy in a newborn infant
Forceps delivery.
When the facial nerve is sacrificed, what must be done prior to reconstruction
Frozen section confirmation of negative nerve margins.
What are the limits of the tympanic segment of VII
Geniculate ganglion to the 2nd genu (adjacent to the pyramidal process).
What organisms are most often associated with facial palsy due to chronic otitis media
Gram-negative organisms and Staphylococcus aureus.
Which of these is used most often
Greater auricular nerve.
How is the facial nerve identified using the tympanic nerve
Groove for the tympanic nerve is followed superiorly to the cochleariform process.
What is the advantage of the microneurovascular muscle transfer over the temporalis muscle sling in the treatment of facial paralysis
Has the potential to restore spontaneous muscle expressions.
What viruses are most commonly implicated in the etiology of Bell’s palsy
Herpes simplex and herpes zoster viruses.
What is the best functional outcome of cable grafting
House grade III or IV.
After primary anastomosis, what is the typical return of facial nerve function
House grade ll or II I.
What test should be performed on Afro-Caribbean migrants with idiopathic facial nerve palsy
HTLV-1 antibody screen.
What if the nerve is only partially transected
If greater than 1 /2 remains, reapproximate the remaining nerve and perform regional decompression. If less than 1/2 remains, remove the injured segment and repair as with complete transection.
If a tumor-free proximal nerve stump is unavailable for nerve grafting, what method should be used for optimal functional outcome
If reconstruction is undertaken within 2 years of division, grafting of the proximal portion of another cranial nerve to the distal stump of the facial nerve is the next best choice.
What is the significance of the Bell’s phenomenon prior to gold weight implantation
If the patient has a good Bell’s reflex, then the surgeon can be more conservative, choosing a lighter implant to avoid ptosis.
What is the management of intraoperative facial nerve transection
Immediate repair with primary anastomosis if possible.
What are negative prognostic factors for Ramsay Hunt syndrome
Increased age and a simultaneous onset of paralysis with vesicular eruption.
What are the complications of gold weight implantation
Induced astigmatism, ptosis, migration, extrusion, persistent inflammation.
What is the relationship of the 2”ct genu of the facial nerve to the lateral semicircular canal and short process of the incus
Inferior to the lateral semicircular canal and medial to the short process of the • lOCUS.
Which cranial nerve is most often grafted to the distal facial nerve
Ipsilateral hypoglossal.
What is the primary drawback of hypoglossal-facial nerve grafting
Ipsilateral tongue paralysis.
What is the advantage of the dorsal radial cutaneous nerve
It branches as it approaches the wrist, making distal separation into bundles for facial nerve branch anastomosis easier.
What are the landmarks of the tympanic segment of VII from the mastoid approach
Lateral SCC and the cog.
What are the surgical landmarks for VII in its mastoid segment
Lateral SCC, fossa incudis, and the digastric ridge.
What is the next most accurate test when ENoG is unavailable
Maximal stimulation test.
What is the relationship of VII to the lateral SCC and the fossa incudis
Medial to the fossa incudis and inferior to the lateral canal.
The triad of recurrent facial palsy, oro facial edema, and lingua plicata is classic for what disease
Melkersson-Rosenthal syndrome (orofacial granulomatosis).
What is the procedure of choice for patients with hemifacial spasm
Microvascular decompression.
What are other indications for free muscle transposition surgery for facial reanimation
Mobius syndrome or destruction of muscles secondary to trauma.
Where is the facial nerve most commonly injured during mastoid surgery
Near the 2”d genu as it enters the mastoid cavity.
What are the indications for surgical exploration of the facial nerve following temporal bone trauma
NET >3.5 rnA side-to-side threshold differences or ENoG >90% degeneration.
What are the 3 types of nerve injury
Neuropraxia, axonotmesis, and neurotmesis.
Which of these has a more rapid rate of Wallerian degeneration
Neurotmesis.
What should be done if motor unit potentials are detected on EMG
No further therapy is indicated.
What is a major contraindication to this procedure
Paralysis of 1 X or X.
What prognostic information does ENoG provide
Patients with 95% degeneration or greater have a 50% chance of unfavorable recovery; if at least I 0% function is retained in the I st 21 days of paralysis, 80 - I OO% functional recovery is highly likely.
What is the most common area of facial nerve injury following trauma
Perigenicular area.
What sort of EMG pattern is associated with nerve regeneration
Polyphasic action potentials.
Where are intracranial lesions that cause bilateral facial paralysis located
Pons.
Where does the facial nerve lie in relation to the cochleariform process
Posterosuperior.
What are the limits of the mastoid segment of VII
Pyramidal process to the stylomastoid foramen.
What differentiates herpes zoster oticus from Ramsay Hunt syndrome
Ramsay Hunt syndrome is herpes zoster oticus + facial nerve paralysis.
Which etiology of facial nerve palsy has a worse prognosis: Bell’s palsy or Ramsay Hunt syndrome
Ramsay Hunt syndrome.
What is the most likely cause of bilateral facial palsy in a young adult
Sarcoidosis.
What is lingua plicata
Scrotal tongue.
What is the relation of the lateral SCC to the fossa incudis
Short crus of the incus is inferolateral to the lateral SCC; the fossa incudis is at the tip of the short crus.
What is the outcome of these patients who undergo surgical decompression >14 days after injury
Similar outcome as patients treated with steroids.
What are some other options for improvement of function after facial paralysis
Static fascial slings, dynamic muscle slings, free muscle transfers, gold weight upper lid implants, lid-tightening procedures, brow lift.
Which reconstructive options restore facial nerve function most quickly
Static slings, gold weights, tarsorrhaphies.
Into which plane is a gold weight placed
Suborbicularis.
Which approach is best in patients with normal hearing
Supralabyrinthine approach.
Which of these can provide the most length
Sural nerve (35 em).
What are some possible nerves used for cable grafting
Sural, greater auricular, dorsal radial cutaneous, supraclavicular nerves.
What is a jump graft
The greater auricular nerve is sutured end-to-side to XII and end-to-side to the distal facial nerve.
Why must the dose of acyclovir be larger for patients with varicella zoster virus (VZV)
The thymidine kinase of VZV is much less sensitive to acyclovir than the herpes simplex virus.
What is the most accurate predictor of poor recovery of facial nerve function following injury
Total paralysis of immediate onset.
T/F: Enhancement of the facial nerve is commonly seen on MRI of patients with Bell’s palsy and is likely to resolve in 2 - 4 months
True.
T/F: Evidence of viral etiology for Ramsay Hunt syndrome is well documented
True.
T/F: Primary anastomosis after rerouting generally leads to a better functional outcome than cable grafting
True.
T/F: No improvement in functional outcome has been demonstrated with the use of tubes or conduits in facial nerve anastomosis or grafting
True.
T /F: Postoperative radiation does not significantly affect the outcome after facial nerve grafting.
True.
What if primary anastomosis is not possible
Use a cable graft with great auricular nerve as the donor.
What can be done to ameliorate this problem
Use of a mid-tongue Z-plasty~ use of only part of the hypoglossal nerve (jump graft); reinnervation of the hypoglossal nerve with the ansa cervicalis.
Branches of the facial nerve anterior to ____ do not require reconstruction for return of function.
Vertical line from lateral canthus.
What is the relationship of the tympanic portion of VII to the cog
VII lies anterior to the cog in the floor of the anterior epitympanum.
What test should be performed when 100°/o neural degeneration is recorded with ENoG
Voluntary EMG recording; regenerating nerve fibers conducting at different rates can result in an overestimation of neural degeneration on ENoG.
How is the facial nerve identified using the semicanal for the tensor tympani
When followed posteriorly, its inferior border is continuous with the upper margin of the oval window and the inferior border of VII.
What is the treatment for otogenic facial palsy in association with acute suppurative otitis media
Wide myringotomy, cultures, and IV antibiotics.
Can a patient with a gold weight have an M Rl
Yes.
