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7/28/2019 Differencial Pathologies Khbw
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By:Nour-Eldin A Mohammed
Referrence:Stephan Chapman 2003
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Extra-axial area lateral to the prepontinecistern containing CSF, arachnoid tissue,cranial nerves and their associated vessels.
Borders
Medial: lateral surface of the brainstem
Lateral : petrous bone
Superior : middle cerebellar peduncle & cerebellum Inferior : arachnoid tissue of lower cranial nerves
Posterior : cerbellar peduncle
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1. Vestibular Schwannoma (acoustic neuroma). Most Common Cause
2. Meningioma
3. Epidermoid cyst
4. Trigeminal neuroma
5. Vertebrobasilar system aneurysm
6. Metastases
7. Skull base/temporal bone tumours:eg, glomus
tumors,metastases,cholesterol granuloma
8. Skull base infection:osteomyelitis of the petrous apex (Gradengos
syndrome) , Malignant otitis externa
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Comprises 60-92% of CPA lesions
Involve the vestibular division of the 8th
cranialnerve
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Features of AcousticNeuroma:1. Centered over the petrous bone
2. Acute angle with the petrousbone
3. Extension into the internalauditory canal
4. Homogenous enhacement
5. No dural tail6. No calcifications
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Second most common CPA lesion 3-7 %
Arise from cap cells near arachnoid villi which
are more prominent near cranial nerveforamina and venous sinuses.
Usually arise from posterior surface of the
petrous bone and usually do not extend into
IAC
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Features of Meningioma:1. Broad base over the petrous bone2. Homogenous signal3. A small toungue extension into
the internal auditory canalwithout widening it
4. Homogenous enhacement5. dural tail6. Calcifications , psammoma
bodies7. Hyperostosis
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Accounts for 2-6 % of CPA masses
Congenital lesions that present in adulthood
Rests of ectodermal tissue containing stratified squamous
lining and keratin
May arise within the temporal bone or in the CPA
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TI WI
T2 WI Proton WI
Features of Epidermoid:1. Low density Cyst with
lobulated margin2. CSF like signal (with high
signal in diffusion,flair andproton seq3. May exert extensive mass
effect4. Also occur parasellar and
rarely itra diploic
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Similar to vestibular neuoma but arises fromthe trigeminal nerve
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1. Vertebrobasilar dolichoectasia:
Enlongation and dilitation of the vertebrobasilar artery.
Symptomas : Facial spasm, trigeminal neuralgia
2. AICA loop
May loop over, under, or between CN VII & CN VIII.
Symptoms - vertigo
3. Giant Aneurysms
4. Hemangioma
5. Paragangliomas (may extend to CPA)
Glomus Jugulare
Glomus Tympanicum
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Anterior inferiorcerebellar arteryGiant aneurysm
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