Cochlear implantation update: contemporary preoperative imaging and future prospects – the dual modality approach as a standard of care

Abstract

The selection of cochlear implant (CI) candidates requires consideration of a variety of clinical and radiographic factors. The present article reviews the current knowledge regarding the preoperative imaging of CI candidates and explores emerging developments in different imaging modalities. Preoperative radiologic assessment should evaluate the status of the middle/inner ear, auditory nerve and central acoustic pathways. Preoperative computed tomography displays anatomic middle ear variations of surgical importance. MRI can demonstrate fluid/obliteration in the inner ear and depict the retrocochlear auditory pathways. Dual modality imaging with high-resolution computed tomography and MRI of the petrous bone and brain can provide the maximum information regarding surgical landmarks and detect deafness-related abnormalities. Cost-effectiveness issues also justify its use. New systems are now becoming available, offering improved soft-tissue delineation, sophisticated segmentation techniques, volumetric measurements, semitransparent views and superior surface resolution, thus significantly advancing our diagnostic acumen and making the preoperative evaluation of CI candidates more accurate and reliable.

Speech processing in children with cochlear implant

“…Early identification, referral, and diagnosis of children with hearing loss are necessary to initiate the process of auditory rehabilitation [3]. The introduction of auditory stimulation through electronic devices, such as CIs, in individuals with severe to profound HL can partially or totally revert the effects of this sensory deprivation and redirect these auditory cortical structures to their primary function.…”

“…Unlike a hearing aid, the use of CI allows for damaged inner ear by-pass, permitting direct stimulation of the auditory nerve fibers [2]. Cochlear implants represent one of the most important achievements of modern medicine, as for the first time in history an electronic device is able to restore a lost hearing sense [3].…”

Cochlear Implantation in Children with Anomalous Cochleovestibular Anatomy

“…1 For infants and children with severe to profound SNHL, cochlear implant (CI) surgery remains the best habilitative/rehabilitative option, improving sound and speech perception abilities in the vast majority of implant recipients. 2 Although variables such as age at implantation, duration of hearing loss, and the presence of residual hearing are among the most important determinants of CI performance, [3][4][5][6][7][8][9][10][11][12] outcomes vary widely, even among similar cohorts. What is not fully understood is whether the degree of inner ear dysplasia conferred on imaging studies can help predict clinical outcomes.…”

“…Unlike the vast majority of adult CI candidates with postlingual SNHL who have normal anatomy, 20% of pediatric candidates have cochleovestibular anomalies, as described by Jackler et al 13 Therefore, imaging is an important component of the evaluation of a child with congenital SNHL. 5,6 Computed tomography (CT) of the temporal bones remains the modality of choice at most CI centers, [14][15][16] and an absent cochlea or auditory nerve would preclude surgical intervention. 6 In equivocal cases (small or absent cochlear nerve canal, hypoplastic cochlea, or profound thresholds), high-resolution magnetic resonance imaging (MRI) can help complement the CT findings, and reformatted constructive interference steady-state or fast imaging employing steady-state acquisition sequences can help determine the presence of a small but present auditory nerve.…”

Abnormal Cochleovestibular Anatomy and Hearing Outcomes: Pediatric Patients with a Questionable Cochleovestibular Nerve Status May Benefit from Cochlear Implantation and/or Hearing Aids

“…Given the high degree of discordance between imaging finding interpretations in our series, we further recommend that these children be imaged and evaluated at centers with a neuroradiologist experienced with the complexities of these children. Our data also show that a dual imaging workup, e.g., HD CT and sMRI, allows acquisition of the most complete information on the status of the inner ear and nerve, as others have suggested [Westerhof et al, 2001;Sakina et al, 2006;Adunka et al, 2007;Miyasaka et al, 2010;Vlastarakos et al, 2010;Kachniarz et al, 2015]. In a comparison of CT with MRI for detecting clinically significant abnormalities, one imaging modality was not able to identify an abnormality detected by the other modality in 31% of the cases [Simons et al, 2006].…”