Case Studies in CPA/IAC

Transcription

1 Outline Case Studies in CPA/IAC Atul K Mallik MD PhD Department of Radiology and Imaging Sciences University of Utah Health Sciences Center Salt Lake City, Utah, USA Case based review of cerebellopontine angle/ internal auditory canal lesions Prompted differential diagnoses Focus on discriminating features Most common cause of sensorineural hearing loss: Aging (presbyacusis) +/- Noise induced UNIVERSI TY OF UTAH HEALTH, 2017 DEPARTM ENT OF RADIOLOGY AND IMAGING SCIENC ES Case 1: Sensorineural hearing loss (SNHL) Case 1: 61 year old female with SNHL Enhancing T2 heterogeneous CPA/IAC ice cream cone shaped lesion 61 year old female Enhancing T2 heterogeneous CPA/IAC ice cream cone shaped lesion 61 year old female Case 1: Sensorineural hearing loss Case 1: Sensorineural hearing loss IAC Venous Vascular Dural based lesion Useful: Dural Tail sign CSF-vascular cleft Eccentric to porus acousticus ~IAC involvement less likely 1

2 Case 1: Sensorineural hearing loss Case 1: Sensorineural hearing loss IAC Venous Vascular Benign vascular tumor Most common: near the geniculate fossa Best clue: ossifications honeycomb matrix on bone CT. Not sensitive. Avid enhancement Ax CT Cancer history 4 Major Sites: Dural, Leptomeningeal, Choroid Plexus, Flocculus (Intraaxial) Early: Rapid onset ataxia Late: CN VII and VIII out Case 1: Vestibular Schwannoma Most common CPA/IAC mass and lesional cause of SNHL Avid enhancement Larger: Ice cream cone centered at CPA/IAC Variant features: Microhemorrhages common 15% intramural cysts Calcification uncommon Comment on: Fundal CSF cap Cochlear nerve canal involvement Case 1: Vestibular Schwannoma cochlear nerve canal Previously cochlear aperture Worse prognosis for hearing after treatment if cochlear nerve canal/fundal involvement May require middle cranial fossa approach? Transmodialor extension Ax CT Case 2: Sensorineural hearing loss Case 2: Sensorineural hearing loss IAC Venous Another enhancing T2 heterogeneous CPA/IAC lesion 2

3 Case 2: Adult sensorineural hearing loss Case 2: Sensorineural hearing loss IAC Venous Vascular Geniculate fossa most common Ossifications RARE Ax CT IAC Venous Cancer history: Breast 4 Major Sites: Dural, Leptomeningeal, Choroid Plexus, Flocculus (Intraaxial) Case 2: Sensorineural hearing loss Case 2: Sensorineural hearing loss IAC Venous Enhancing T2 heterogeneous CPA/IAC lesion eccentric to the porus acousticus, with dural tail,? hyperostosis Case 2: CPA Meningioma 2 nd Most common CPA/IAC mass and lesional cause of SNHL Useful: Dural based lesion +/- Dural tail sign CSF-vascular cleft Eccentric to porus acousticus CT hyperostosis IAC involvement less common, but can be seen *Brain edema associations: surgical complications recurrence Case 3: Pediatric sensorineural hearing loss Ax T2 Fast Spin Echo (FSE) Bilateral enhancing T2 heterogeneous CPA/IAC lesions 12 year old male 3

4 Case 3: Pediatric sensorineural hearing loss Case 3: Pediatric sensorineural hearing loss Bilateral vestibular s Bilateral meningiomas CPA Metastases Neurosarcoidosis, CPA Bilateral vestibular s Bilateral meningiomas CPA Metastases Older patient, Cancer 4 Major Sites: Dural, Leptomeningeal, Choroid Plexus, Flocculus (Intraaxial) Neurosarcoidosis Case 3: Pediatric sensorineural hearing loss Neurosarcoidosis Multisystem granulomatous disease Dura +/- pia-arachnoid perivascular spaces brain CXR positive in 95% with neurosarcoidosis Cor T1 +C Case 3: Bilateral vestibular s (NF2 - MISME) Merlin mutation (22q) 50-50: Inherited/Sporadic Usually presents years Multiple Inheirted Schwannomas Meningiomas Ependymomas NF2 Criteria Bilateral VSs or 1 VS + relative or Relative + 2 tumors (meningioma, ) Ax T2 FSE Bilateral potential CPA/IAC lesions by age Case 4: History withheld Pediatric and young adult (10-30): NF2 - MISME Over 40 years: Consider metastases Ax T2 Cor T1 +C Expansile non enhancing CSF intensity right CPA lesion 4

5 Case 4: History withheld Arachnoid Cyst Epidermoid Cyst Infection Case 4: History withheld Infection A. Arachnoid Cyst B. Epidermoid Cyst C. Infection Ax T2 Tuberculosis Ax T2 Cor T1 +C Neurocysticercosis Case 4: History withheld Epidermoid Cyst (Congenital Cholesteatoma) Slow growing ectodermal rests May be incidental, silent Presentation age: 40 Helpful: Diffusion restriction FLAIR: Variable, mixed attenuation Insinuating morphology Ax DWI Ax T1 FLAIR +C Separate case Case 4: Arachnoid Cyst Incidental, but can be associated with dizziness, SNHL or CN neuralgia Smooth, sharp margins Helpful: Causes mild mass effect (displaces CNs, vessels) Signal intensity ~ CSF FLAIR: Suppresses completely (even more than CSF in cisterns) No diffusion restriction Ax T2 Cor T1 +C Case 5: Sensorineural hearing loss Case 5: Adult sensorineural hearing loss Diagnostic considerations Singular nerve canal Small IAC Cyst (Arachnoid or Epidermoid) IAC Diverticulum Different, Normal Ax Temporal Bone CT Ax Temporal Bone CT Focal low-attenuation outpouching at the anterolateral IAC Ax Temporal Bone CT 5

6 Case 5: Adult sensorineural hearing loss Diagnostic considerations Case 5: Adult sensorineural hearing loss Diagnostic considerations Singular nerve canal Normal anatomy with CT Useful surgical landmark Transmits: posterior ampullary nerve Between: inferior IAC And: posterior semicircular canal ampulla Ax Temporal Bone Small IAC Cyst Enlarged lateral IAC No abnormal enhancement At lower limit of spatial resolution for DWI Ddx: Arachnoid or Epidermoid Any expansile IAC lesion can enlarge the IAC R Sag Obl T2 IAC L Sag Obl T2 IAC Case 5: IAC Divertuculum Focal low-attenuation outpouching or diverticulum at the anterolateral IAC 807 Temporal bone CTs IAC diverticula in 5% Coexisting with otosclerosis in 1% Suggest including in temporal bone report Associated with (sensorineural) hearing loss Pippin et al. AJNR 2017 Case 6: Sensorineural hearing loss Aneurysm Metastatic Disease Ax CT +C Nodular enhancement at the posterior left porus acousticus Case 6: Sensorineural hearing loss CPA Case 6: Sensorineural hearing loss Aneurysm Metastatic Disease Intracanalicular CPA meningioma Leptomeningeal IAC metastases Anterior L Vert DSA Lateral L Vert DSA 6

7 Case 6: CPA aneurysm (AICA) 3 rd most common CPA/IAC lesional cause of SNHL PICA > VA > AICA Complex MR signals Thrombosed can be T1 hyperintense Ax CT T2 FSE +C Different case AP Ax T1 L Vert -C FS DSA Case 7: 73 year old male with vertigo FS Cor T1 -C Case 7: 73 year old male with vertigo Case 7: 73 year old male with vertigo Thrombosed IAC aneurysm IAC Lipoma Ruptured dermoid Hemorrhagic vestibular White epidermoid FS Thrombosed IAC aneurysm IAC Lipoma Ruptured dermoid Hemorrhagic vestibular Rare, acoustic apoplexy Some enhancment White epidermoid Courtesy: B. Winegar Cor T1 -C Case 7: 73 year old male with vertigo Case 7: 73 year old male with vertigo Thrombosed IAC aneurysm IAC Lipoma Ruptured dermoid Hemorrhagic vestibular White epidermoid Ax T2 FSE FS Thrombosed IAC aneurysm IAC Lipoma Ruptured dermoid Multiple droplets?original midline lesion Hemorrhagic vestibular White epidermoid A ghost! Cor T1 -C FS 7

8 Case 7: IAC Lipoma Case 8: History withheld Symptoms: SNHL, None, dizziness, CN V or VII neuropathy Congenital rest of normal fatty tissue within cistern Lipomatous hamartoma Helpful: Cranial nerves traverse large lipomas Tx: None, Surgery worse than disease FS Ax T1+C Ax CISS Enhancing CN VII and VIII, IAC, labyrinth, EAC, ear, No underlying mass Case 8: History withheld Case 8: History withheld Bell s Palsy Facial Nerve Scwhannoma Ramsay Hunt Syndrome Ax CT Bell s Palsy Clinical diagnosis: No rash Some overlapping imaging features with Rasmsay Hunt Less severe facial palsy Less enhancement (fundal tuft and CN VII) - soft tissue, labyrinth Facial Nerve Scwhannoma Ramsay Hunt Syndrome Ax T1+C Case 8: Ramsay Hunt Syndrome CPA Mass companion case Herpes zoster oticus CN 7, 8 & portion supplied by auriculotemporal nerve External ear vesicular rash Facial paralysis severe Helpful: Enhancing CN VII and VIII, IAC, labyrinth, EAC, ear Labyrinthine FLAIR hyperintensity No mass Ax T1+C Ax Cor T1 +C T1 FS +C FS Ax CISS 8

9 CPA Mass companion case: Ependymoma CPA Mass Companion Case 2 - SNHL Ax FLAIR Ax T1+C Different case Ax CISS Ax T2 CPA Mass Companion Case 2 - SNHL Companion Case 2 Endolymphatic Sac Tumor Ax FLAIR Ax FLAIR Ax CISS Ax T2 Ax CT, Different Pediatric patient Ax CISS Ax T2 Summary Acknowledgments s are the most common CPA-IAC lesion and lesional cause of SNHL Eccentricity to the porus acousticus, dural tail, CSF cleft and hyperostosis can help distinguish a meningioma from a Pt age is important for evaluating potential bilateral CPA/IAC lesions. Metastases, sarcoidosis parenchymal and petrous apex lesion can mimic more common CPA-IAC lesions IAC Diverticula are associated with SNHL; unclear association with otosclerosis Diffusion imaging and insinuating morphology can help differentiate epidermoid from arachnoid cysts Ric Harnsberger Richard Wiggins Richard Nguyen Luke Linscott 9

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