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Differential Diagnosis of Cerebellopontine Angle lesions. By: Nour-Eldin A Mohammed Referrence:Stephan Chapman 2003. Cerebellopontine Angle. Extra-axial area lateral to the prepontine cistern containing CSF, arachnoid tissue, cranial nerves and their associated vessels. Borders
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Differential Diagnosis of Cerebellopontine Angle lesions By: Nour-Eldin A Mohammed Referrence:Stephan Chapman 2003
Cerebellopontine Angle • Extra-axial area lateral to the prepontine cistern 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
Differential Diagnosis: • Vestibular Schwannoma (acoustic neuroma). Most Common Cause • Meningioma • Epidermoid cyst • Trigeminal neuroma • Vertebrobasilar system aneurysm • Metastases • Skull base/temporal bone tumours:eg, glomus tumors,metastases,cholesterol granuloma • Skull base infection:osteomyelitis of the petrous apex (Gradengo’s syndrome) , Malignant otitis externa
Acoustic Neuroma • Comprises 60-92% of CPA lesions • Involve the vestibular division of the 8th cranial nerve
Features of Acoustic Neuroma: • Centered over the petrous bone • Acute angle with the petrous bone • Extension into the internal auditory canal • Homogenous enhacement • No dural tail • No calcifications
Meningioma: • Second most common CPA lesion 3-7 % • Arise from cap cells near arachnoid villi which are more prominent near cranial nerve foramina and venous sinuses. • Usually arise from posterior surface of the petrous bone and usually do not extend into IAC
Features of Meningioma: • Broad base over the petrous bone • Homogenous signal • A small toungue extension into the internal auditory canal without widening it • Homogenous enhacement • dural tail • Calcifications , psammoma bodies • Hyperostosis
Epidermoid Cyst: • 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
Features of Epidermoid: • Low density Cyst with lobulated margin • CSF like signal (with high signal in diffusion,flair and proton seq • May exert extensive mass effect • Also occur parasellar and rarely itradiploic TI WI T2 WI Proton WI
Trigeminal Neuroma • Similar to vestibular neuoma but arises from the trigeminal nerve
Vascular Lesions: 1. Vertebrobasilardolichoectasia: 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) GlomusJugulare GlomusTympanicum