Role of CT and MRI in the preoperative evaluation of auditory brainstem implantation in patients with congenital inner ear pathology

Abstract

Preoperative CT and MRI assessment of patients with sensorineural hearing loss is reliable. MRI provided additional information, identifying the possible absence of cochlear nerve and excluding other central nervous system (CNS) diseases.

Bionic ear imaging

“…Da [13][14][15]. Trovano indicazione al trattamento con ABI i pazienti affetti da gravi malformazioni congenite dell'orecchio interno e del pacchetto vestibolo-cocleare, quelli affetti da degenerazione cocleare post-infettiva, in particolare post-meningitica, i pazienti con gravi fenomeni di otospongiosi o che hanno subito gravi traumi che hanno determinato frattura bilaterale della coclea, ed i pazienti affetti da neurofibromatosi di tipo II con interessamento bilaterale del VIII nervo cranico [3,16,17].…”

“…Per poter indicare il più idoneo approccio terapeutico è necessario procedere al corretto inquadramento clinico-strumentale del deficit sensoriale del paziente tenendo conto dell'eziologia, sia essa ipoacusia genetica o acquisita, dell'epoca di insorgenza pre-o post-natale (pre-o post-verbale), della sede, mono o bilaterale, simmetrica o meno, e del tipo di ipoacusia: trasmissiva, neurosensoriale o mista [1][2][3].…”

“…The implant consists of 21 platinum microelectrodes, each with a diameter of about 0.7 mm, mounted on a 3×8.5-mm silicon support in three rows [13][14][15]. The implant is suitable for use in patients suffering from severe congenital malformations of the internal ear and the balance and hearing nerves, patients suffering from postinfectious cochlear degeneration (particularly postmeningitic), patients with severe forms of otospongiosis or who have suffered severe trauma causing bilateral fracture of the cochlea, and patients suffering from neurofibromatosis type II with bilateral involvement of the eighth cranial nerve [3,16,17].…”

“…In order to identify the appropriate therapy, knowledge is required regarding aetiology (genetic or acquired hypoacusis), time of onset (pre-or postnatal, pre-or postverbal), site (uni-or bilateral, symmetrical or not) and type of hypoacusis (transmissive, neurosensory, mixed) [1][2][3].…”

The cochleovestibular nerve identified during auditory brainstem implantation in patients with narrow internal auditory canals: Can preoperative evaluation predict cochleovestibular nerve deficiency?

“…Preoperative radiographic evaluation of cochlear implant candidates is clinically important for determining whether the patient is suitable for implantation and for predicting auditory performance after cochlear implantation together with other prognostic factors. Recent improvement of image resolution and sequence development have made MRI the most important diagnostic tool for detection of the cochlear nerve, and many studies have emphasized the necessity of MRI as a part of the preoperative evaluation before cochlear implantation 17–19. The cross‐sectional images of the IAC make more detailed identification of the neural components possible.…”