Aspects of temporal bone anatomy and pathology in conjunction with cochlear implant surgery
- 1 June 2003
- journal article
- Published by SAGE Publications in Acta Radiologica
- Vol. 44 (s430), 2-15
- https://doi.org/10.1034/j.1600-0455.44.s430.1.x
Abstract
Cochlear implantation is a treatment for patients with severe sensorineural hearing loss/deafness, who get no help from ordinary hearing aids. The cochlear implant is surgically placed under the skin near the ear and a very thin electrode array is introduced into the cochlea of the inner ear, where it stimulates the remaining nerve fibers (1,2). The operation is complicated; it is performed with the aid of a microscope, and involves drilling very close to vital vessels and important nerves. The method was introduced in Sweden in 1984 by Professor Göran Bredberg, then at Stockholm Söder Hospital. High resolution computed tomography (CT) of the temporal bone is a part of the preoperative evaluation preceding cochlear implantation. It is a method for visualizing the bony structures of the middle and inner ear - to diagnose pathology and to describe the anatomy. In Stockholm, these examinations have usually been performed at the Radiology Department of Stockholm Söder Hospital. Examinations of cochlear implant candidates from other parts of Sweden and from abroad are also sent there for special reviewing. The first work concerns CT of the temporal bone and cochlear implant surgery in children with CHARGE association. This is a rare condition with multiple congenital abnormalities, sometimes lethal. Children with CHARGE have different combinations of disabilities, of which impairments of vision and hearing, as well as balance problems and facial palsy can lead to developmental delay. There have been few reports of radiological temporal bone changes and none of cochlear implant surgery for this group. The work includes a report of the findings on preoperative CT and at surgery, as well as post-implant results in two children. A review of the latest diagnostic criteria of CHARGE and the temporal bone changes found in international literature is also included. The conclusion was that certain combinations of temporal bone changes in CHARGE are, if not specific, at least extremely rare in other materials. CT can visualize these changes and be used as a diagnostic tool. This is important, since some of the associated disabilities are not so obvious from the start. Early treatment is vital for the child's development. This work also shows that cochlear implantation may help some of these often very isolated children to communicate. The second work is a radioanatomic study of one of the structures of the inner ear - the bony canal for the cochlear nerve. It involves measurements of the dimensions of the canal on 117 silicone rubber casts of the temporal bone (from a unique collection of casts at Uppsala temporal bone laboratory) and on 50 clinical CT-studies (100 ears). The purpose was to show the normal variation, which is of use in the appraisal of congenital temporal bone malformations on CT. Based on our results we propose that if the canal is less than 1.4 mm, as measured on CT, the possibility of cochlear nerve abnormality should be considered. This is of interest since aplasia of the cochlear nerve is a contraindication to cochlear implantation. If the canal is wider than 3.0 mm, then other anomalies may coexist, with the risk of CSF gusher when a cochleostomy or stapedectomy is performed.Keywords
This publication has 38 references indexed in Scilit:
- Normal Canals at the Fundus of the Internal Auditory Canal: CT EvaluationJournal of Computer Assisted Tomography, 1999
- Temporal bone: comparison of isotropic helical CT and conventional direct axial and coronal CT.American Journal of Roentgenology, 1999
- Otologic management in children with the CHARGE associationInternational Journal of Pediatric Otorhinolaryngology, 1998
- CHARGE Association: An Update and Review for the Primary PediatricianClinical Pediatrics, 1998
- L'association CHARGEArchives de Pédiatrie, 1996
- A reappraisal of the CHARGE association.Journal of Medical Genetics, 1988
- Auditory and Temporal Bone Abnormalities in Charge AssociationAnnals of Otology, Rhinology & Laryngology, 1986
- Coloboma, congenital heart disease, and choanal atresia with multiple anomalies: CHARGE associationThe Journal of Pediatrics, 1981
- Choanal atresia and associated multiple anomaliesThe Journal of Pediatrics, 1979
- Ocular colobomata, cardiac defect, and other anomalies: a study of seven cases including two sibs.Journal of Medical Genetics, 1975