mri of internal auditory canal images which cranial

The membranous cochlea completes 2.5 turns. 2):ģrd gestational week (gw): otic placodes arise from the surface ectoderm on each side of the rhombencephalon Ĥth gw: otic placodes invaginate and give rise to the otic pits which, towards the end of the fourth week, form the corresponding otic vescicle (or otocysts) and auditory vesicles formation of statoacoustic ganglion ĥth gw: the otocysts divide in dorsal utricular portion and ventral saccular portion which give rise to the vestibular and cochlear divisions of the labyrinth, respectively the SSCs start to develop (superior, posterior, and lateral canals consecutively) the statoacoustic ganglion dividesĮnd of the 6th gw: the membranous cochlea started forming by elongation of anterior aspect of cochlear ĭivision the SCC is complete the utricule and saccule are present Įnd of the 7th gw: the maculae are present sensory ridges appear in the cochlea duct The embryological development of the IE begins with the focal thickening of the ectoderm (otic placode) and proceeds via multiple stages from 3rd to 24th gestational week (gw) (Fig. The cochlea is responsible for hearing, while the vestibule and SCCs are important for balance. Since prompt intervention has a positive impact on the treatment outcomes, early diagnosis of IEMs is very important in the management of deaf patients. Patients with genetic IEMs usually have bilateral and symmetrical abnormalities and are commonly affected by profound SNHL. Although IEMs may occur in isolation, around 30% of these cases are related to a specific syndrome (Table 1). Indeed the aetiology of IEM can be idiopathic, related to an inborn genetic error, or in response to exposure to a teratogenic agent. Inner ear malformations can be associated with both hereditary and nonhereditary SNHL. However, in the last two decades, MRI has been widely used to study endolymph-filled structures and the eighth cranial nerve (i.e. High-resolution CT is the preferred imaging modality for delineating the osseous anatomy and malformations of the inner ear. In particular, computerised tomography (CT) and magnetic resonance imaging (MRI) are the most commonly used imaging modalities for investigating the auditory system at any level. However, the anatomy and related pathology of the auditory system necessitate the use of specific, dedicated, optimised protocols to ensure good visualisation. Imaging techniques have a long history in supporting the study of the auditory system. Inner ear malformations (IEMs) are caused by interrupted development of the ear during the first trimester of foetal development and are the principal cause of sensorineural hearing loss (SNHL). This article reviews the key concepts of IEMs for clinical radiologists by focusing on recent literature updates, discusses the principal imaging findings and clinical implications for every IEM subgroup, thus providing a practical diagnostic approach. However, in cases of congenital malformation of the inner ear, these techniques should be considered complementary. The most suitable technique should be selected depending on the clinical setting. Dedicated MRI and HRCT protocols play an important role in the diagnosis and treatment of patients with inner ear disease. High-resolution magnetic resonance imaging (MRI) sequences and high-resolution computed tomography (HRCT) are the mainstay imaging techniques in this area. Imaging techniques are important for identifying the presence and defining the type of IEM and the cochlear nerve condition. The complex anatomical landscape of the inner ear, comprising several small structures, makes imaging of this region particularly challenging for general radiologists. In the multidisciplinary management of patients with inner ear malformations (IEMs), the correct diagnosis makes the differences in terms of clinical and surgical treatment.

Mri of internal auditory canal images which cranial