KEY FACTS Terminology Definition: Congenital inclusion of ectodermal epithelial elements during neural tube closure You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
Terminology The contents of the cerebellopontine angle (CPA) and internal auditory canal (IAC) cisterns include the facial nerve (CNVII), the vestibulocochlear nerve (CNVIII), and the anterior inferior cerebellar artery (AICA) loop. The bony IAC, its fundal crests (vertical and horizontal), and its opening in the porus acusticus are also included as part of this discussion. Embryology The temporal bone forms as 3 distinct embryological events: (1)…
KEY FACTS Terminology Radiation therapy (RT)-induced injury to temporal bone Imaging Bone CT findings Moth-eaten destruction of temporal bone and adjacent skull base ± sequestrum T2 MR findings High-signal mucosal injury of external auditory canal (EAC), middle ear cavity, mastoid High signal of adjacent brain → radiation necrosis Meningitis, abscess, dural sinus thrombosis Top Differential Diagnoses Malignant external otitis Coalescent mastoiditis Aggressive cholesteatoma EAC carcinoma Paget…
KEY FACTS Terminology Hematogenous spread from distant primary neoplasm Rarely leptomeningeal spread from IAC Bony metastatic disease to petrous apex [(PA), most common site] or mastoid/middle ear You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS Terminology Synonyms: Histiocytosis X Old classification: Eosinophilic granuloma, Hand-Schüller-Christian disease, Abt-Letterer-Siwe disease Proliferative disorder of Langerhans-type histiocytes, which form granulomas in T-bone & surrounding soft tissues You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
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KEY FACTS Terminology Fibrous dysplasia (FD) definition: Congenital disorder with defect in osteoblastic differentiation & maturation resulting in progressive replacement of normal cancellous bone by mixture of fibrous tissue & immature woven bone You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS Terminology Definition: Nonvenous sinus-related (aberrant) pseudopodial pia-arachnoid projection into tegmen tympani or posterior wall of temporal bone You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS Terminology Facial nerve venous malformation (FNVM) Older terms: Facial nerve hemangioma/ossifying hemangioma Definition: Benign developmental lesion near intratemporal CNVII in geniculate fossa area You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS Terminology Bell palsy (BP): Herpetic peripheral facial nerve paralysis secondary to herpes simplex virus; rapid onset, all ipsilateral facial nerve branches involved, no other etiology You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
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KEY FACTS Terminology Definition: Normal contrast enhancement on T1 C+ MR along course of intratemporal facial nerve (CNVII) without abnormal bony changes on bone CT You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS Terminology Rare congenital or acquired aneurysm of petrous internal carotid artery (ICA) You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS Terminology Definition: Extension of middle ear-mastoid (ME-M) infection into pneumatized petrous apex (PA) with resulting suppurative apical petrositis You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS Terminology Petrous apex (PA) cholesterol granuloma: Expansile PA lesion resulting from foreign-body giant cell reaction to deposition of cholesterol crystals in apical air cells with fibrosis and vascular proliferation a.k.a. cholesterol cyst, "chocolate" cyst You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS Terminology Mucus-containing, expanded petrous apex (PA) air cells(s) lined by secretory epithelium resulting from chronic ostial obstruction You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here
KEY FACTS Terminology Definition: Sterile residual fluid collection in petrous apex (PA) air cells, sometimes resulting from remote otomastoiditis a.k.a. PA effusion You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here