Inner ear malformations: a practical diagnostic approach. / Malformaciones del oído interno: una aproximación diagnóstica práctica.

Pediatric sensorineural hearing loss is a major cause of disability; although inner ear malformations account for only 20-40% of all cases, recognition and characterization will be vital for the proper management of these patients. In this article relevant anatomy and development of inner ear are surveyed. The role of neuroimaging in pediatric sensorineural hearing loss and cochlear preimplantation study are assessed. The need for a universal system of classification of inner ear malformations with therapeutic and prognostic implications is highlighted. And finally, the radiological findings of each type of malformation are concisely described and depicted. Computed tomography and magnetic resonance imaging play a crucial role in the characterization of inner ear malformations and allow the assessment of the anatomical structures that enable the selection of appropriate treatment and surgical approach.

Imaging diagnostics: congenital malformations and acquired lesions of the inner ear.

INTRODUCTION: Congenital malformations and acquired lesions of the inner ear are characterised by small structural changes in this region. In recent decades, treatment options have improved considerably. At the same time, there has been a great advancement in diagnostic methods, obtaining high-resolution labyrinth images. Currently, we use a 64-multislice computed tomography scanner in spiral mode (Brilliance 64 Phillips, Eindhoven, the Netherlands), with an overlap of 0.66 mm and an interval of 0.33 mm, 120 KV and 300 mA. The magnetic resonance images were taken with Signa HDxt 1.5 and 3.0 T units (GE Healthcare, Waukesha, WI, USA). We reviewed the radiological features of the lesions affecting the inner ear. They are classified as congenital (labyrinth malformation and statoacoustic nerve deficiencies) or acquired (otospongiosis, labyrinthitis, Ménière's disease, inner ear haemorrhage, intralabyrinthine schwannoma and endolymphatic sac tumour). CONCLUSION: Magnetic resonance imaging and computed tomography play an essential role in diagnosing patients with inner ear pathology. The technique selected should be chosen depending on the clinical setting. In a generic way, tomography is the method of choice for the study of traumatic pathology or otospongiosis. When tumour or inflammatory pathology is suspected, magnetic resonance is superior. In cases of congenital malformation, both techniques are complementary.

Cochlear implant: what the radiologist should know / Implante coclear: o que o radiologista deve saber

Cochlear implant is the method of choice in the treatment of deep sensorineural hypoacusis, particularly in patients where conventional amplification devices do not imply noticeable clinical improvement. Imaging findings are crucial in the indication or contraindication for such surgical procedure. In the assessment of the temporal bone, radiologists should be familiar with relative or absolute contraindication factors, as well as with factors that might significantly complicate the implantation. Some criteria such as cochlear nerve aplasia, labyrinthine and/or cochlear aplasia are still considered as absolute contraindications, in spite of studies bringing such criteria into question. Cochlear dysplasias constitute relative contraindications, among them labyrinthitis ossificans is highlighted. Other alterations may be mentioned as complicating agents in the temporal bone assessment, namely, hypoplasia of the mastoid process, aberrant facial nerve, otomastoiditis, otosclerosis, dehiscent jugular bulb, enlarged endolymphatic duct and sac. The experienced radiologist assumes an important role in the evaluation of this condition.

O implante coclear é o método de escolha no tratamento da hipoacusia neurossensorial profunda, notadamente nos pacientes em que os aparelhos de amplificação convencionais não implicam melhora clínica notável. Achados de imagem são fatores decisórios na indicação ou contraindicação desse procedimento cirúrgico. Os fatores que contraindicam absoluta ou relativamente, assim como os que podem complicar de forma significativa o implante, devem ser familiares aos radiologistas na avaliação do osso temporal. Alguns critérios ainda são considerados contraindicações absolutas, como a aplasia do nervo coclear, a aplasia da cóclea e/ou labiríntica, apesar de já existirem relatos que questionam ou contradizem esses dois últimos. As contraindicações relativas são as displasias cocleares, destacando a labirintite ossificante. Outros achados podem ser citados como agentes complicadores na avaliação temporal, tais como hipoplasia do processo mastoideo, nervo facial aberrante, otomastoidite, otosclerose, deiscência do bulbo da jugular, alargamento dos ductos e saco endolinfático. O radiologista experiente na avaliação do osso temporal assume papel de destaque no curso dessa doença.