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Sinonasal and temporal bone infections may extend to the skull, skull base, meninges, pericerebral spaces, brain parenchyma, dural sinuses, deep cerebral or cortical veins, intracranial arteries and cranial nerves either via contiguous or hematogeneous spread. The site of infection dictates the sites of potential complications: orbital with ethmoid sinusitis, cavernous sinus thrombophlebitis and oculomotor palsies with sphenoid sinusitis, transverse sinus thrombophlebitis with mastoiditis and superior sagittal sinus thrombophlebitis with frontal sinusitis. All may result in brain abscess. Congenital and acquired defects of the skull and meninges, with or without associated meningocele or meningoencephalocele, perilymphatic fistulas, and some anomalies of the inner ear may predispose to the intracranial extension of ENT infections.

Sinonasal and temporal bone infections may extend to the skull, skull base, meninges, pericerebral spaces, brain parenchyma, dural sinuses, deep cerebral or cortical veins, intracranial arteries and cranial nerves either via contiguous or hematogeneous spread. The site of infection dictates the sites of potential complications: orbital with ethmoid sinusitis, cavernous sinus thrombophlebitis and oculomotor palsies with sphenoid sinusitis, transverse sinus thrombophlebitis with mastoiditis and superior sagittal sinus thrombophlebitis with frontal sinusitis. All may result in brain abscess. Congenital and acquired defects of the skull and meninges, with or without associated meningocele or meningoencephalocele, perilymphatic fistulas, and some anomalies of the inner ear may predispose to the intracranial extension of ENT infections.

To assess the value of CT for diagnosis and follow-up of AFS. Evaluation of characteristic CT features of AFS.Retrospective review of 12 cases of AFS presenting with all published diagnostic criteria (1) chronic rhinosinusitis refractory to standard management (2) CT features of chronic sinusitis (3) anatomopathologic, immunoallergologic, biochemical and mycologic criteria. CT findings were correlated with surgical findings and reviewed by one ENT and two radiologists to assess the diagnostic value of different CT features, alone or in association.AFS was isolated in 6 cases, and associated with allergic bronchopulmonary aspergillosis (ABPA) in 6 cases. CT showed pan- or polysinusitis, unilateral or bilateral, with mucosal thickening, sinus opacification frequently heterogeneous, bony changes, fluid trapping, and with pseudotumoral appearance in 3 cases.CT findings alone are not specific or pathognomonic but may suggest AFS in the correct clinical or immunoallergologic setting. It may alert the physician to the need for complementary work-up, exclude the presence of associated lung disease, and better adapt treatment and follow-up.

To identify the anterior ethmoidal artery (AEA) of a skull specimen on CT prior to transnasal endoscopic surgical management of anterior epistaxis.From a medial canthotomy approach, the AEA was located and a marker placed on 9 skull specimens (18 AEA). CT with 2D reformations was then performed. The AEA were then dissected using an endoscopic anterior ethmoidectomy approach. The presence of AEA procidence was recorded.Correlation between CT and surgical findings allowed identification of 2 criteria predictive of AEA procidence: 1) presence of an ethmoid bulla above the AEA canal 2) AEA canal located below (not within) the ethmoid roof, anterior to the bulla.High resolution CT depiction of the AEA provides information regarding its accessibility for endoscopic ligation in patients with severe anterior epistaxis as an alternative to external ligation while demonstrating the upper limit of the anterior ethmoid.

Otosclerosis is a primitive osteodystrophia of the labyrinthine bone. Its diagnosis must be confirmed by a CT scan in order to eliminate the other causes that may lead to conductive hearing loss with an absence of stapedial reflex: fixation of the head of the malleus to the lateral wall of the tympanic cavity, absence of the long process of the incus or stapes, gusher syndrome, primary cholesteatoma, or tympanic facial nerve neuroma blocking the stapes. Particular problems in otosclerosis must be clarified: an extension to the round window (poor postoperative results), and extension to the tympanic cavity blocking the malleus and/or the incus, the labyrinthine lumen, or the internal auditory meatus (very rare). The position of the tympanic facial nerve canal and associated abnormalities must be assessed: stapedial artery, malformations of the ossicles and/or the labyrinth, and chronic otitis media. MRI is indicated in extension to the labyrinthine lumen, the internal auditory meatus, and in postoperative complications with labyrinthitis. MRI can also evaluate the active otosclerotic focus (gadolinium enhancement).

CT and MRI are in most of the cases associated in imaging of tumours and pseudo-tumours of the temporal bone. The tumours of the external auditory meatus particularly the malignant ones are rare. It is of a great interest to delineate a possible extension to the chorda tympani. Secondary cholesteatoma are the most frequent pseudo-tumours of the middle ear: CT and MRI evaluate very well their extension particularly in the giant forms. Others tumours like tuberculosis, histiocytosis, primitive cholesteatoma, tympanic body++ tumours may be diagnosed by imaging as well as the neuroma of the facial nerve, the meningioma or some rarer lesions as the adenoma, or the carcinoid tumour of the middle ear. The adenoma of the endolymphatic sac is the only true tumour of the membranous labyrinth whose diagnosis is nicely made by MRI. The primitive cholesteatoma, the neuroma of the facial nerve may reach the labyrinthine bone and are easily diagnosed by imaging which generally speaking is very good in evaluating the kind of pathology of each cavities, delineating the extension of the lesions and orientating the surgical procedures.

Resume Les traumatismes comportent des fractures, essentiellement translabyrinthiques (7 %), des lesions sans fracture des fenetres ovales et/ou rondes (visibles en TDM) ou des contusions labyrinthiques parfois accessibles en IRM. Les labyrinthites virales bacteriennes, auto-immunes se singularisent par un signal normal ou eleve en Tl sans injection, une diffusion de Gadolinium dans les espaces perilabyrinthiques, un T2 HR normal dans les atteintes virales avec materiel solide dans les etiologies bacteriennes ou auto-immunes (de signal rehausse en Tl apres contraste). Les malformations (TDM, IRM) surtout du labyrinthe posterieur plus ou moins deforme peuvent s’exprimer par une SP. Les anomalies de taille, les defauts de segmentation cochleaire sont plus rares de meme que les hypoplasies ou aplasies du nerf cochleaire (IRM). L’otospongiose est rarement a l’origine d’une SP. Les neurinomes du VIII sont rarement intralabyrinthiques. Toujours rechercher un neurinome du nerf facial qui dans plus de la moitie des cas ne donne pas de paralysie faciale. Dans le CAI, peuvent etre aussi diagnostiques : meningiome, lipome, malformations vasculaires, lymphomes, metastases. Les kystes epidermoides sont en general dans l’angle pontocerebelleux. Toutes les pathologies inflammatoires ou tumorales des regions de voisinage (conduit auditif externe, oreille moyenne, apex petreux, nerf V, VII, mixte, sinus sphenoidal, pharynx) peuvent entrainer des lesions de l’oreille interne visibles en imagerie exprimes par une SP.