1/9/2014

1/9/2014

Answers:

What is the most common extra-axial malignant neoplasm of the CPA?
A) Astrocytoma 
B) Chordoma 
C) Glomus Jugulare 
D) Chondrosarcoma 
E) Metastases

Mets are the most common extra-axial malignant neoplasm of the CPA.

What is "Meckel's Cave"?

Meckel's Cave, aka trigeminal cave, is an arachnoid pouch w/ CSF in it. It is formed by two layers of dura which are part of an evagination of the tentorium cerebelli near the apex of the petrous part of the temporal bone and envelops CN V. Its boundaries are: the cerebellar tentorium, the lateral wall of the cavernous sinus, the clivus and the posterior petrous face.

MC Questions:
What percentage of vestibular schwannoma patients have neurofibromatosis type 2?
A)3% 
B) 15% 
C) 50% 
D) 85% 
E) 97%

Free Response Question:
The NF2 gene encodes what protein? What is the function of this protein?

Quick Facts:
Clinical Findings
Gardner Subtype:
-early onset
-smaller tumors
-few tumors
-slower growing tumors
-hearing loss related to tumor size
Wishart Subtype:
-Later onset
-Larger tumors
-Multiple tumors
-Faster growing tumors
-Hearing loss not related to tumor size
-Usually present in 20-30s, rarely after 60.
-50% of patients present with hearing loss, it is usually progressive and associated
w/ poor speech discrimination scores.
-10% have tinnitus
-acute vertigo is uncommon due to slow growth pattern
-Skin tumors present in 2/3rds of patient as are Cafe-au-lait spots however there are
fewer than six of these (unlike in NF1)
-Juvenile posterior subcapsular lenticular opacities are common (up to 51%). Some are congenital and can be useful in diagnosis.

1/8/2013

1/8/2014

Answers:

What percentage of CPA tumors are not vestibular schwannomas?
A) 5% 
B) 20% 
C) 50% 
D) 80% 
E) 95%

20% of CPA tumors are not schwannomas. Of these ~50% are meningiomas.

What factors should prompt testing for NF2 in a patient who presents w/ a CPA tumor?

If meningiomas are present in a young patient or there are multiple meningiomas, then NF2 testing should be considered.

MC Questions:
What is the most common extra-axial malignant neoplasm of the CPA?
A) Astrocytoma 
B) Chordoma 
C) Glomus Jugulare 
D) Chondrosarcoma 
E) Metastases

Free Response Question:
What is "Meckel's Cave"?

Quick Facts:
Neurofibromatosis Type 2
-Hallmark is b/l vestibular schwannomas.
-often confused with von Recklinghausen syndrome, however this is peripheral
neurofibromatosis and is designated NF1.
-NF2 is much more rare compared to NF1 (1:50,000)
-NF2 is autosomal dominant w/ 95% gene penetrance.
-presents in 2-3rd decade.
-Pts w/ NF2 represent 2-4% of VS.
-NF2 gene encodes for protein called merlin which functions as a membrane-organizing protein.
Pathogenesis
-from inheritance of mutation in merlin protein on chromosome 22.
-Merlin involved in linking cytoskeletal components w/ plasma membrane.
-Loss of this protein could lead to loss of contact inhibition.
-50% of patients have no family hx and are likely new germ line mutations.
-NF2 mutations associated w/ protein truncation are more severe = Wishart
type
-NF2 mutations associated w/ protein missense or splicing are milder = Gardner
type