12/27/2013

12/27/2013

Answers:

Diagnose this fracture.

A) Mastoid fracture 
B) Transverse Temporal bone fracture 
C) Longitudinal Temporal Bone Fracture 
D) Occipital Bone fracture

This is a classic longitudinal temporal bone fracture extending along the EAC and ending near the foramen lacerum.

After a temporal bone fracture, what degree of delayed facial nerve degeneration is required in order to benefit from surgical decompression.

Patients with delayed facial nerve paralysis who are found to have > 90% degeneration of the nerve on nerve excitability or electroneuronography testing (which cannot be done until at least 3 days post injury) may benefit from surgical decompression. This is controversial however. Patients with <90% degeneration should not be operated on as they are likely to have full and spontaneous recoveries.

MC Questions:
What percentage of transverse temporal bone fractures cause a facial nerve injury?
A) 10% 
B) 25% 
C) 50% 
D) 75% 
E) 90%

Free Response Question:
What test can be done to determine whether clear fluid draining from the ear is CSF or simply rhinorrhea from rhinitis?

Quick Facts:
Treatment of Temporal Bone Fracture Complications

-Conductive Hearing Loss:
-Hemotympanum resolves on its own within 3-4 weeks of the injury.
-Traumatic TM perfs heal well on their own, 68% in 1 months, 94% in 3 months. If
not healed be 3 months can perform paper-patch myringoplasty. (can only do if TM
is <25% and does not involve margin and middle ear mucosa
uninfected/dry)
-Freshen edges of perf w/ Rosen needle (Husseman dose this w/ TCA (some type of
acid) then place paper over hole and bacitracin over paper.
-If perf is large or paper-patch has failed then pt can go to OR for standard
tympanoplasty.


-Facial Nerve Paralysis:
-Mostly conservative treatment for delayed onset palsy (94% recover
fully).
-If pt has >90% degeneration of facial nerve function then recovery is much
worse, likely due to nerve swelling within bony fallopian canal. Management is
controversial.
-Some recommend watchful waiting, other recommend decompression.
-Immediate onset facial nerve palsy should undergo nerve exploration
ASAP.
-If pt has normal hearing a combined middle fossa/transmastoid facial nerve
exploration can be done including subtemporal craniotomy w/ delineation of the
facial nerve within IAC from porus acusticus internus to geniculate ganglion.
-If patient has complete SNHL then translabyrinthine facial nerve exploration
can be done, allows for complete exposure to facial nerve from porus acousticus
to stylomastoid foramen.
-Injuries are most commonly located in the area of the geniculate ganglion.
-If intraneural hematoma appreciated then epineurium should be carefully opened
and hematoma evacuated.
-Remove any bony fragments.
-If obvious fracture of nerve then freshen both ends an anastomosis. If to long
to anastomose w/o tension then interposition nerve graft from greater auricular
or sural nerve can by done.


-CSF Leak and Encephalocele
-80% of posttraumatic CSF leaks close spontaneously after 7 days and risk of
meningitis is low so treat medically at first.
-Med treatment = HOB elevated, stool softeners, acetazolamide (decreases CSF
production) and lumbar drain. Short to abx can decrease meningitis rates.
-Most common organisms for meningitis in these cases are pneumococcus, staph,
strep and H. flu.
-If CSF leak persists 7-10 dys risk of meningitis increases to >20% and surgical repair is needed.
-Most common after transverse tbone fx involving otic capsule as otic capsule
does not heal w/ new bone formation but be fibrous union which is not strong
enough to contain CSF.
-An encephalocele should always be surgically repaired.