Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
The Human Cochlea and Cochlear Implantation: Morphological Characteristics and Clinical Correlations
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Otolaryngology and Head and Neck Surgery.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The most common sensory deficit in the world is sensorineural hearing loss. Cochlear implantation (CI) can majorly contribute to restore hearing, not only in patients with severe to profound hearing loss, but also in hearing-impaired patients with residual low-frequency hearing. The overall aims of the present thesis were to study human cochlear anatomy in order to improve structural preservation during CI surgery. An archival collection of temporal bones underwent micro-computer tomography and synchrotron radiation phase-contrast imaging (SR-PCI) with 3D reconstructions, new techniques to digitally image and reproduce the human inner ear. Studying the anatomy of the facial nerve and its interaction with the cochlea revealed that a fusion of the two was found in 1.4 % of the specimens (cochlear-facial dehiscence). This may cause facial nerve excitation after CI. CT-scans and intraoperative electrically auditory brainstem response (e-ABR) measurements were analyzed in patients with cochlear-facial dehiscence. A large evoked late myogenic potential at low stimulation levels during intraoperative e-ABR measurements, can foresee excitation at CI activation. The 3D anatomy of the fundus of the inner acoustic canal was also studied, helping to interpret preoperative imaging of the VIIIth nerve before CI. In a subsequent study, SR-PCI reproduced the soft tissue anatomy at the round window region. Results indicated a high risk for trauma at cochleostomy. For optimal preservation, the round window approach was recommended. In a long-term follow-up the first 21 consecutively operated patients in Uppsala, that underwent hearing preservation CI-surgery, data could be retrieved in 15 patients. Pure tone audiometry was assessed preoperatively and at one, three and >5 years following surgery. Insertion angle, number of electrodes inside the cochlea, user-time of the processor, and stimulation strategies were documented. Results showed that long-term preservation of hearing is possible in most cases. There was a high correlation between insertion depth and preservation of residual hearing. Also, patients with complete hearing loss experienced good performance in speech discrimination and user time.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. , p. 45
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1537
Keywords [en]
cochlear implantation, micro-CT, synchrotron, facial nerve stimulation, hearing preservation, round window
National Category
Otorhinolaryngology
Identifiers
URN: urn:nbn:se:uu:diva-373643ISBN: 978-91-513-0566-0 (print)OAI: oai:DiVA.org:uu-373643DiVA, id: diva2:1282940
Public defence
2019-03-15, Enghoffsalen, Akademiska sjukhuset, ingång 50, Uppsala, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2019-02-19 Created: 2019-01-27 Last updated: 2019-03-18
List of papers
1. Anatomical Characteristics of Facial Nerve and Cochlea Interaction
Open this publication in new window or tab >>Anatomical Characteristics of Facial Nerve and Cochlea Interaction
2017 (English)In: Audiology & neuro-otology, ISSN 1420-3030, E-ISSN 1421-9700, Vol. 22, no 1, p. 41-49Article in journal (Refereed) Published
Abstract [en]

Objective: The aim was to study the relationship between the labyrinthine portion (LP) of the facial canal and the cochlea in human inner ear molds and temporal bones using micro-CT and 3D rendering. A reduced cochlea-facial distance may spread electric currents from the cochlear implant to the LP and cause facial nerve stimulation. Influencing factors may be the topographic anatomy and otic capsule properties.

Methods: An archival collection of human temporal bones underwent micro-CT and 3D reconstruction. In addition, cochlea-facial distance was assessed in silicone and polyester resin molds, and the association between the LP and upper basal turn of the cochlea was analyzed.

Results: Local thinning of the otic capsule and local anatomy may explain the development of cochlea-facial dehiscence, which was found in 1.4%. A reduced cochlea-facial distance was noted in 1 bone with a superior semicircular canal dehiscence but not in bones with superior semicircular canal "blue line." The otic capsule often impinged upon the LP and caused narrowing.

Conclusion: Micro-CT with 3D rendering offers new possibilities to study the topographic anatomy of the human temporal bone. The varied shape of the cross-section of the LP could often be explained by an "intruding" cochlea.

Place, publisher, year, edition, pages
KARGER, 2017
Keywords
Human temporal bones, Cochlea, Facial canal, Micro-CT
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-333425 (URN)10.1159/000475876 (DOI)000406762600006 ()28628917 (PubMedID)
Available from: 2017-11-13 Created: 2017-11-13 Last updated: 2019-01-27Bibliographically approved
2. Peri-operative electrically evoked auditory brainstem response assessment of facial nerve/cochlea interaction at cochlear implantation
Open this publication in new window or tab >>Peri-operative electrically evoked auditory brainstem response assessment of facial nerve/cochlea interaction at cochlear implantation
Show others...
2018 (English)In: Cochlear Implants International, ISSN 1467-0100, E-ISSN 1754-7628, Vol. 19, no 6, p. 324-329Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: Dehiscence between the cochlear otic capsule and the facial nerve canal is a rare and relatively newly described pathology. In cochlear implantation (CI), this dehiscence may lead to adverse electric facial nerve stimulation (FNS) already at low levels, rendering its use impossible. Here, we describe an assessment technique to foresee this complication.

METHODS: Pre- and postoperative computed tomography (CT) scans and intraoperative electrically evoked auditory brainstem response (e-ABR) measurements were analyzed in two patients with cochlear-facial dehiscence (CFD).

RESULTS: Because of the relatively low resolution, the confirmation of CFD with a clinical CT was difficult. The e-ABR displayed a large potential with 6 and 7.5 ms latency, respectively, which did not occur otherwise.

DISCUSSION: Potential strategies to resolve and manage FNS are described.

CONCLUSION: Prediction of FNS by assessing the distance between the labyrinthine portion of the facial nerve and the cochlea is difficult using conventional CT scans. A large evoked late myogenic potential at low stimulation levels during intraoperative e-ABR measurement may foresee FNS at CI activation.

Keywords
Cochlea, Cochlear implantation, Dehiscence, Facial nerve stimulation
National Category
Otorhinolaryngology
Identifiers
urn:nbn:se:uu:diva-373491 (URN)10.1080/14670100.2018.1481179 (DOI)29877144 (PubMedID)
Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-05-27Bibliographically approved
3. Three-Dimensional Analysis of the Fundus of the Human Internal Acoustic Canal
Open this publication in new window or tab >>Three-Dimensional Analysis of the Fundus of the Human Internal Acoustic Canal
2018 (English)In: Ear and Hearing, ISSN 0196-0202, E-ISSN 1538-4667, Vol. 39, no 3, p. 563-572Article in journal (Refereed) Published
Abstract [en]

Objectives: Documentation of the nerve components in the internal acoustic canal is essential before cochlea implantation surgery. Interpretations may be challenged by wide anatomical variations of the VIIIth nerve and their ramifications. Malformations may further defy proper nerve identification. Design: Using microcomputed tomography, we analyzed the fundus bone channels in an archival collection of 113 macerated human temporal bones and 325 plastic inner molds. Data were subsequently processed by volume-rendering software using a bony tissue algorithm. Three-dimensional reconstructions were made, and through orthogonal sections, the topographic anatomy was established. Results: The technique provided additional information regarding the anatomy of the nerve foramina/channels of the human fundus region, including variations and destinations. Channel anastomosis were found beyond the level of the fundus. A foramen of the transverse crest was identified. Conclusions: Three-dimensional reconstructions and cropping outlined the bone canals and demonstrated the highly variable VIIIth nerve anatomy at the fundus of the human inner acoustic canal. Myriad channel interconnections suggested an intricate system of neural interactive pathways in humans. Particularly striking was the variable anatomy of the saccule nerve channels. The results may assist in the preoperative interpretation of the VIIIth nerve anatomy.

Place, publisher, year, edition, pages
Lippincott Williams & Wilkins, 2018
Keywords
Human, Inner acoustic canal, Inner ear, Micro-CT
National Category
Surgery
Identifiers
urn:nbn:se:uu:diva-364017 (URN)10.1097/AUD.0000000000000510 (DOI)000442150400018 ()29117061 (PubMedID)
Available from: 2018-10-24 Created: 2018-10-24 Last updated: 2019-01-27Bibliographically approved
4. Effects of Various Trajectories on Tissue Preservation in Cochlear Implant Surgery: A Micro-Computed Tomography and Synchrotron Radiation Phase-Contrast Imaging Study
Open this publication in new window or tab >>Effects of Various Trajectories on Tissue Preservation in Cochlear Implant Surgery: A Micro-Computed Tomography and Synchrotron Radiation Phase-Contrast Imaging Study
Show others...
2019 (English)In: Ear and Hearing, ISSN 0196-0202, E-ISSN 1538-4667, Vol. 40, no 2, p. 393-400Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES:

The purpose of this study was to evaluate the three-dimensional (3D) anatomy and potential damage to the hook region of the human cochlea following various trajectories at cochlear implantation (CI). The goal was to determine which of the approaches can avoid lesions to the soft tissues, including the basilar membrane and its suspension to the lateral wall. Currently, there is increased emphasis on conservation of inner ear structures, even in nonhearing preservation CI surgery.

DESIGN:

Micro-computed tomography and various CI approaches were made in an archival collection of macerated and freshly fixed human temporal bones. Furthermore, synchrotron radiation phase-contrast imaging was used to reproduce the soft tissues. The 3D anatomy was investigated using bony and soft tissue algorithms, and influences on inner ear structures were examined.

RESULTS:

Micro-computed tomography with 3D rendering demonstrated the topography of the round window (RW) and osseous spiral laminae, while synchrotron imaging allowed reproduction of soft tissues such as the basilar membrane and its suspension around the RW membrane. Anterior cochleostomies and anteroinferior cochleostomies invariably damaged the intracochlear soft tissues while inferior cochleostomies sporadically left inner ear structures unaffected.

CONCLUSIONS:

Results suggest that cochleostomy approaches often traumatize the soft tissues at the hook region at CI surgery. For optimal structural preservation, the RW approach is, therefore, recommended.

National Category
Otorhinolaryngology
Identifiers
urn:nbn:se:uu:diva-373492 (URN)10.1097/AUD.0000000000000624 (DOI)000459769700016 ()29952804 (PubMedID)
Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-06-19Bibliographically approved
5. Cochlear Implantation and Residual Hearing Preservation. Long-term Follow-up of the First Consecutively Operated Patients Using the Round Window Approach in Uppsala, Sweden.
Open this publication in new window or tab >>Cochlear Implantation and Residual Hearing Preservation. Long-term Follow-up of the First Consecutively Operated Patients Using the Round Window Approach in Uppsala, Sweden.
(English)In: Article in journal (Refereed) Submitted
National Category
Otorhinolaryngology
Identifiers
urn:nbn:se:uu:diva-373493 (URN)
Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-01-27

Open Access in DiVA

fulltext(1887 kB)90 downloads
File information
File name FULLTEXT01.pdfFile size 1887 kBChecksum SHA-512
046d5e9049a9047e6a75da8f27ef2e89088581925e04b5e0500b35f3668088e714239f3ef9a8e8adbfd3aacf72af74dc40758a40d1a121cfe880cfe36b17d052
Type fulltextMimetype application/pdf
Buy this publication >>

Search in DiVA

By author/editor
Schart-Morén, Nadine
By organisation
Otolaryngology and Head and Neck Surgery
Otorhinolaryngology

Search outside of DiVA

GoogleGoogle Scholar
Total: 90 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 402 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf