12/31/2013

12/31/2013

Answers:

What percentage of traumatic TM perforations heal within 30 days?
A) 20% 
B) 50% 
C) 70% 
D) 90% 
E) 100%

~70% of traumatic TM perfs heal on their own in one month. ~95% will heal within 3 months. If a TM perf is still not healed on its own after this time consider performing a paper-patch myringoplasty.

After what length of time dose persistence of a posttraumatic CSF leak significantly raise the chance of developing meningitis?

80% of CSF leaks will close on their own within a week and the risk of meningitis is low, however, CSF leaks that persist longer than 7-10 days the risk of developing meningitis increases dramatically to >20%.

MC Questions:
What is the most common type of CPA tumor?
A) Epidermoid 
B) Glomus 
C) Meningioma 
D) Astrocytoma 
E) Schwannoma

Free Response Question:
Describe the boundaries of the CPA.

Quick Facts:
Clinical
Findings Of Vestibular Schwannoma -Hearing
loss present in 95% of patients.-Mostly
slowly progressive hearing loss w/ noise distortion.-20%
have episodes of sudden hearing loss.-Level
of hearing loss does not predict tumor size.
-Tinnitus
present in 65% of patient, often constant high pitch buzzing.-Pts
often adapt to disequilibrium well because it occurs so slowly but it is present
in 60% of patients.
-Facial/Trigeminal
nerve dysfunction-most
common to see V2 numbness/absent corneal reflex.-can
also see numbness of posterior EAC (Hitselberger sign-Facial
weakness only present in 17%
-Other
complaints include visual complaints, diplopia, headache, AMS, n/v and increased
ICP w/ papilledema however these occur only during rapid expansion.

12/30/2013

12/30/2013

Answers:

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

Facial nerve injury is present in 50% of transverse tbone fractures. Facial nerve injury is present in only 20% of longitudinal t bone fractures. It is always import to delineate whether facial nerve injuries are immediate or delayed as immediate are almost always operative, wheres delayed is usually not.

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

B2 Transferrin is the test of choice to confirm the presence of CSF. B2 transferring is a protein found exclusively in CSF.

MC Questions:
What percentage of traumatic TM perforations heal within 30 days?
A) 20% 
B) 50% 
C) 70% 
D) 90% 
E) 100%

Free Response Question:
After what length of time dose persistence of a posttraumatic CSF leak significantly raise the chance of developing meningitis?

Quick Facts:
-CPA = potential CSF filled space in posterior cranial fossa bounded be temporal
bone, cerebellum and brainstem.-triangle
shaped,-Superior
boundary = tentorium-inferior
boundary = cerebellar tonsil / medullary olives-anterior
border = posterior dural surface of petrous bone and clivus-posterior
border = ventral surface of pons/cerebellum-medial
border = cisterns of pons and medulla-apex
= region of the lateral recess of the fourth ventricle.-The
lateral opening of the fourth ventricle (foramen of luschka) opens into
CPA.-CN
V-XI traverse cephalic and caudal extent of CPA.-Transition
to peripheral myelin (made by schwann cells) occurs at the medial opening of the
IAC.

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.

12/26/2013

12/26/2013

Answers:

Blows to the lateral side of the skull often result in --- fx of t-bone whereas blunt trauma to the occipital skull result in --- fx of t-bone.
A) Longitudinal, Transverse 
B) Longitudinal, Vertical 
C) Transverse, Vertical 
D) Transverse, Longitudinal 
E) Vertical, Longitudinal

What is the most common type of temporal bone fracture?

Longitudinal fractures comprise 80% of tbone fractures. Transverse fracturse comprise 20%. However, transverse fractures are more likely to involve the otic capsule.

MC Questions:
Diagnose this fracture.

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

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

Quick Facts:
Complications of Temporal Bone Fractures

-Conductive Hearing Loss:
-most commonly from hemotympanum but also TM perf or ossicular
discontinuity.
-Most common OD is incudostapedial joint dislocation.
-Ossicular fixation can occur several months after trauma if new bone formation
at the line of the fx fuses to the ossicular chain.

-Sensorineural Hearing Loss and Vertigo
-In transverse temporal bone fxs w/ otic capsule involvement.
-Pneumolabyrinth is often noted on CT.
-Audiogram shows complete SNHL in affected ear.
-Clinical exam reveals nystagmus
-Can get SNHL w/o otic capsule involvement if labyrinthine concussion, traumatic
noise exposure or blast occurs. THought to be due to testing of the cochlear
membrane and/or trauma to hair cell epithelium due to rapid acceleration and
deceleration forces in the inner ear.-Facial


-Nerve Injury:
-Occurs in 20% of longitudinal and 50% of transverse fxs.
-Important to delineate whether facial nerve injury was immediate or delayed.
-Delayed present w/ normal function that worsens slowly over hours-days.
-Likely from edema within facial nerve without disruption of neural integrity.
-Immediate facial nerve palsy likely due to nerve transection

-Cerebrospinal Fluid Leak
-2% incidence of CSF leak in all skull fxs, 20% in Tbone fxs.
-Usually occurs within first 48 hrs.
-Clear fluid from ear/nose. Worse with straining, standing up, bending over.
-Can collect and send of B2 transferrin testing.

Posttraumatic Encephalocele
-Can result if large defect in floor of the middle cranial fossa occurs.
-Dura and temporal lob can herniate down into middle ear.

12/25/2013

12/25/2013

Answers:

A patient presents saying they stuck a bobby pin deep in their left ear to "clean it out" when they felt a pop and suddenly had hearing loss on that side. On exam the patient lateralizes weber to the right and demonstrates some nystagmus. What is the most likely diagnosis?
A) Ossicular Discontinuity 
B) Stapes subluxation 
C) Tympanic Membrane Perforation 
D) EAC laceration 
E) None of the above

Although this patient also has a TM perf her weber lateralizes to the wrong side as it should lateralize to the side of a CHL. Additionally, her nystagmus is concerning for stapes subluxation and perilymphatic fistula which should be urgently treated.

What is the maximum hearing loss caused solely by ossicular chain dislocation?

60 dB is the maximum hearing loss from OCD (or any CHL)

MC Questions:
Blows to the lateral side of the skull often result in --- fx of t-bone whereas blunt trauma to the occipital skull result in --- fx of t-bone.
A) Longitudinal, Transverse 
B) Longitudinal, Vertical 
C) Transverse, Vertical 
D) Transverse, Longitudinal 
E) Vertical, Longitudinal

Free Response Question:
What is the most common type of temporal bone fracture?

Quick Facts:
Special Tests for Tbone fxs
-Audiometry should be done on all pts as an outpatient usually after hemotympanum has resolved (several weeks).
-If otic capsule fx then very likely there will be complete SNHL.
-Consider urgent audiometry if stapes subluxation into vestibule has occured.
-Facial nerve testing should be done if delayed, complete facial palsy occurs.
-Pts w/ >90% degeneration of facial nerve have poorer recovery and benefit
from surgical decompression.
-Nerve excitability test = place two probes of Hilger nerve stimulators across
the stylomastoid foramen and turn up until facial twitch barely visible...a
3.5mA difference between the injured and uninjured sides correlates with a
>90% loss of neural integrity.
-Electroneuronography can by done by a neurophysiologist = stimulating both
facial nerves with equal current and measuring myogenic potential.
-Neither test is accurate within 3 days of injury as it takes 72 hrs for nerve
fibers distal to site of injury to degenerate.

12/24/2013

12/24/2013

Answers:

Fluid lights up on --- and is dark on ---- MRIs.
A) T1; T2 weighted 
B) T2; T1 weighted

Think "black and white TV = T1 and T2 weighted MRI"

What is the dB difference required for Weber to lateralize?  
What is the dB difference required for Rinne to demonstrate BC>AC?

5 dB for Weber to lateralize. 25 dB for Rinne to be negative (i.e. BC>AC).

MC Questions:
A patient presents saying they stuck a bobby pin deep in their left ear to "clean it out" when they felt a pop and suddenly had hearing loss on that side. On exam the patient lateralizes weber to the right and demonstrates some nystagmus. What is the most likely diagnosis?
A) Ossicular Discontinuity 
B) Stapes subluxation 
C) Tympanic Membrane Perforation 
D) EAC laceration 
E) None of the above

Free Response Question:
What is the maximum hearing loss caused solely by ossicular chain dislocation?

Quick Facts:
Temporal Bone Fractures
-Skull base includes frontal, sphenoid, temporal and occipital bones. Fx of skull base involves 1+ of these.
-20% of skull fx involve Tbone, risk factors = male and under 21.
-Blunt trauma to lateral side of skull often = longitudinal fx.
-Blow to occipital skull may = transverse fx.Pathogenesis
-Longitudinal fx involve squamous portion of Tbone.
-They follow the axis of EAC to middle ear the course ant along geniculate ganglion
and eustachian tube ending near foramen lacerum.
-Otic capsule is spared.
-Transverse fx course directly across petrous pyramid, fx otic capsule, and extend
anteriorly along eustachian tube and geniculate ganglion.
-Longitudinal = 80%, Transverse = 20%
Clinical Findings
-hearing loss, n/v/vertigo.
-Battle sign = postauricular ecchymosis (due to extravasation of blood from
postauricular artery (or mastoid emissary vein).
-”Raccoon” sign = periorbital ecchymosis = associated w/ basilar skull fx involving
middle/anterior cranial fossa.
-May see EAC laceration w/ bony debris
-Usually has hemotympanum.
-May see CSF otorrhea or rhinorrhea.
-Also do tuning for test, weber lateralizes to fx ear if CHl present and contralateral
is snhl present.
-Always document facial nerve function.

12/23/2013

12/23/2013

Answers:

What branch of the external carotid artery is most likely to feed a carotid body tumor?
A) Ascending Pharyngeal 
B) Lingual 
C) Facial 
D) Internal Maxillary 
E) Superior Thyroid

The ascending pharyngeal is the artery that supplies carotid body tumors.

What is the likely causes of this patient's hearing loss?

Noise exposure or occupational hearing loss. This audiogram demonstrates the classic "noise notch" that those who experience hearing loss after exposure to hazardous levels of noise show on audiograms.

MC Questions:
Fluid lights up on --- and is dark on ---- MRIs.
A) T1; T2 weighted 
B) T2; T1 weighted

Free Response Question:
What is the dB difference required for Weber to lateralize?  
What is the dB difference required for Rinne to demonstrate BC>AC?

Quick Facts:
Tympanic Membrane Perforation
-Often due to cotton swabs, bobby pins, pencils, or hot metal (welders).
-Presents with pain + hearing loss.
-Dx w/ otoscopy. Note amount of perf.
-Central perf = does not involve annulus
-Marginal perf = involves annulus.
-Fork pt to confirm CHL, also look for nystagmus
-If pt does not lateralize appropriately and pt has nystagmus = stapes
subluxation w/ perilymphatic fistula which requires urgent treatment.
-Perfs usually heal on their own.
-Pt should follow strict dry ear precautions.
-Perform audiogram in 3 months to confirm hearing return to baseline. If perf has not healed in 3 months, will require tympanoplasty.
Ossicular Chain Dislocation
-Manifests as maximal CHL = 60 db.
-Treat w/ middle ear exploration and ossicular chain reconstruction w/
tympanoplasty.

12/20/2013

12/20/2013

Answers:

What complication results from damage to the superior laryngeal nerve?
A) Dysphagia 
B) Strap muscle motor weakness 
C) Aspiration 
D) Inability to abduct vocal folds 
E) More than one of the above

The superior laryngeal nerve provides sensation to the larynx. A decrease in sensation inhibits coughing and leads to aspiration.

Name the seven branches of the external carotid artery.

The mneumonic is "Some Attendings Like Freaking Out Potential Med Students" 

-Superior Thyroid 

- Ascending Pharyngeal 

- Lingual 

- Facial 

- Occipital 

- Posterior Auricular 

- (internal) maxillary 

- Superficial temporal

MC Questions:
What branch of the external carotid artery is most likely to feed a carotid body tumor?
A) Ascending Pharyngeal 
B) Lingual 
C) Facial 
D) Internal Maxillary 
E) Superior Thyroid

Free Response Question:
What is the likely causes of this patient's hearing loss?

Quick Facts:
Basic MRI scans 

T1-weighted MRI
-T1-weighted scans refer to a set of standard scans that depict differences in the spin-lattice (or T1) relaxation time of various tissues within the body. T1 weighted images can be acquired using either spin echo or gradient-echo sequences. T1-weighted contrast can be increased with the application of an inversion recovery RF pulse. Gradient-echo based T1-weighted sequences can be acquired very rapidly because of their ability to use short inter-pulse repetition times (TR). T1-weighted sequences are often collected before and after infusion of T1-shortening MRI contrast agents. In the brain T1-weighted scans provide appreciable contrast between gray and white matter. Water (such as CSF and blood) is dark and white matter is lighter than grey. In the body, T1 weighted scans work well
for differentiating fat from water—with water appearing darker and fat
brighter.  

T2-weighted MRI
-T2-weighted scans refer to a set of standard scans that depict differences in the spin-spin (or T2) relaxation time of various tissues within the body. Like the T1-weighted scan, fat is differentiated from water, but in this case fat shows darker, and water lighter. For example, in the case of cerebral and spinal study, the CSF
(cerebrospinal fluid) will be lighter in T2-weighted images. These scans are therefore particularly well suited to imaging edema, with long TE and long TR. Because the spin echo sequence is less susceptible to inhomogeneities in the magnetic field, these images have long been a clinical workhorse.