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Cochlear Implant
Troy A. Hutchins, MD
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KEY FACTS

  • Terminology

    • Imaging

      • Clinical Issues

        • Diagnostic Checklist

          TERMINOLOGY

          • Abbreviations

            • Cochlear implant (CI)
          • Synonyms

            • Cochlear electrode
          • Definitions

            • CI: Multicomponent electronic device that provides auditory information by directly stimulating auditory fibers in cochlea
              • Microphone
                • External component that resides behind ear
                • Receives sound from environment
                • Transforms sound to electrical impulse
                • Transmits impulse to speech processor
              • Speech processor
                • External component that may be attached to microphone or worn separately in clothing
                • Custom programmed computer that emphasizes speech over other sounds
                • Digitally encodes sounds from frequency range of human speech
                • Encoding strategy depends on manufacturer
              • Transmitter
                • External component that resides behind ear, atop subcutaneous receiver
                • Transcutaneously sends magnetic impulses from speech processor to receiver
                • Held in place by magnet in subcutaneous receiver
              • Receiver
                • Thin, subcutaneous component that resides behind ear
                • Surgically implanted
                • Converts magnetic impulses from transmitter to electrical signal for stimulator wire
              • Stimulator
                • Wire placed inside cochlea directly stimulates spiral ganglion cells and cochlear axons
                • Stimulator wire enters cochlea via round window
                • Array of electrodes along wire appear as tiny bumps radiographically

          IMAGING

          • General Features

            • Radiographic Findings

              • CT Findings

                • MR Findings

                  • Imaging Recommendations

                    DIFFERENTIAL DIAGNOSIS

                      PATHOLOGY

                      • General Features

                        • Gross Pathologic & Surgical Features

                          • Microscopic Features

                            CLINICAL ISSUES

                            • Presentation

                              • Demographics

                                • Natural History & Prognosis

                                  • Treatment

                                    DIAGNOSTIC CHECKLIST

                                    • Consider

                                      Selected References

                                      1. Colby CC et al: Standardization of CT depiction of cochlear implant insertion depth. AJNR Am J Neuroradiol. 36(2):368-71, 2015
                                      2. Fischer N et al: Radiologic and functional evaluation of electrode dislocation from the scala tympani to the scala vestibuli in patients with cochlear implants. AJNR Am J Neuroradiol. 36(2):372-7, 2015
                                      3. van der Jagt MA et al: Visualization of human inner ear anatomy with high-resolution MR imaging at 7T: initial clinical assessment. AJNR Am J Neuroradiol. 36(2):378-83, 2015
                                      4. Pearl MS et al: High-resolution secondary reconstructions with the use of flat panel CT in the clinical assessment of patients with cochlear implants. AJNR Am J Neuroradiol. 35(6):1202-8, 2014
                                      5. Vlastarakos PV et al: Cochlear implantation update: contemporary preoperative imaging and future prospects - the dual modality approach as a standard of care. Expert Rev Med Devices. 7(4):555-67, 2010
                                      6. Isaacson B et al: Labyrinthitis ossificans: how accurate is MRI in predicting cochlear obstruction? Otolaryngol Head Neck Surg. 140(5):692-6, 2009
                                      7. Verbist BM et al: Multisection CT as a valuable tool in the postoperative assessment of cochlear implant patients. AJNR Am J Neuroradiol. 26(2):424-9, 2005
                                      8. Aschendorff A et al: Imaging procedures in cochlear implant patients--evaluation of different radiological techniques. Acta Otolaryngol Suppl. (552):46-9, 2004
                                      9. Jain R et al: Cochlear implant failure: imaging evaluation of the electrode course. Clin Radiol. 58(4):288-93, 2003
                                      10. Witte RJ et al: Pediatric and adult cochlear implantation. Radiographics. 23(5):1185-200, 2003
                                      11. Lo WW: Imaging of cochlear and auditory brain stem implantation. AJNR Am J Neuroradiol. 19(6):1147-54, 1998
                                      12. Teissl C et al: Cochlear implants: in vitro investigation of electromagnetic interference at MR imaging--compatibility and safety aspects. Radiology. 208(3):700-8, 1998
                                      13. Johnson MH et al: CT of postmeningitic deafness: observations and predictive value for cochlear implants in children. AJNR Am J Neuroradiol. 16(1):103-9, 1995
                                      14. Shpizner BA et al: Postoperative imaging of the multichannel cochlear implant. AJNR Am J Neuroradiol. 16(7):1517-24, 1995
                                      15. Mukherji SK et al: CT of the temporal bone: findings after mastoidectomy, ossicular reconstruction, and cochlear implantation. AJR Am J Roentgenol. 163(6):1467-71, 1994
                                      16. Harnsberger HR et al: Cochlear implant candidates: assessment with CT and MR imaging. Radiology. 164(1):53-7, 1987
                                      Related Anatomy
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                                      Related Differential Diagnoses
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                                      References
                                      Tables

                                      Tables

                                      KEY FACTS

                                      • Terminology

                                        • Imaging

                                          • Clinical Issues

                                            • Diagnostic Checklist

                                              TERMINOLOGY

                                              • Abbreviations

                                                • Cochlear implant (CI)
                                              • Synonyms

                                                • Cochlear electrode
                                              • Definitions

                                                • CI: Multicomponent electronic device that provides auditory information by directly stimulating auditory fibers in cochlea
                                                  • Microphone
                                                    • External component that resides behind ear
                                                    • Receives sound from environment
                                                    • Transforms sound to electrical impulse
                                                    • Transmits impulse to speech processor
                                                  • Speech processor
                                                    • External component that may be attached to microphone or worn separately in clothing
                                                    • Custom programmed computer that emphasizes speech over other sounds
                                                    • Digitally encodes sounds from frequency range of human speech
                                                    • Encoding strategy depends on manufacturer
                                                  • Transmitter
                                                    • External component that resides behind ear, atop subcutaneous receiver
                                                    • Transcutaneously sends magnetic impulses from speech processor to receiver
                                                    • Held in place by magnet in subcutaneous receiver
                                                  • Receiver
                                                    • Thin, subcutaneous component that resides behind ear
                                                    • Surgically implanted
                                                    • Converts magnetic impulses from transmitter to electrical signal for stimulator wire
                                                  • Stimulator
                                                    • Wire placed inside cochlea directly stimulates spiral ganglion cells and cochlear axons
                                                    • Stimulator wire enters cochlea via round window
                                                    • Array of electrodes along wire appear as tiny bumps radiographically

                                              IMAGING

                                              • General Features

                                                • Radiographic Findings

                                                  • CT Findings

                                                    • MR Findings

                                                      • Imaging Recommendations

                                                        DIFFERENTIAL DIAGNOSIS

                                                          PATHOLOGY

                                                          • General Features

                                                            • Gross Pathologic & Surgical Features

                                                              • Microscopic Features

                                                                CLINICAL ISSUES

                                                                • Presentation

                                                                  • Demographics

                                                                    • Natural History & Prognosis

                                                                      • Treatment

                                                                        DIAGNOSTIC CHECKLIST

                                                                        • Consider

                                                                          Selected References

                                                                          1. Colby CC et al: Standardization of CT depiction of cochlear implant insertion depth. AJNR Am J Neuroradiol. 36(2):368-71, 2015
                                                                          2. Fischer N et al: Radiologic and functional evaluation of electrode dislocation from the scala tympani to the scala vestibuli in patients with cochlear implants. AJNR Am J Neuroradiol. 36(2):372-7, 2015
                                                                          3. van der Jagt MA et al: Visualization of human inner ear anatomy with high-resolution MR imaging at 7T: initial clinical assessment. AJNR Am J Neuroradiol. 36(2):378-83, 2015
                                                                          4. Pearl MS et al: High-resolution secondary reconstructions with the use of flat panel CT in the clinical assessment of patients with cochlear implants. AJNR Am J Neuroradiol. 35(6):1202-8, 2014
                                                                          5. Vlastarakos PV et al: Cochlear implantation update: contemporary preoperative imaging and future prospects - the dual modality approach as a standard of care. Expert Rev Med Devices. 7(4):555-67, 2010
                                                                          6. Isaacson B et al: Labyrinthitis ossificans: how accurate is MRI in predicting cochlear obstruction? Otolaryngol Head Neck Surg. 140(5):692-6, 2009
                                                                          7. Verbist BM et al: Multisection CT as a valuable tool in the postoperative assessment of cochlear implant patients. AJNR Am J Neuroradiol. 26(2):424-9, 2005
                                                                          8. Aschendorff A et al: Imaging procedures in cochlear implant patients--evaluation of different radiological techniques. Acta Otolaryngol Suppl. (552):46-9, 2004
                                                                          9. Jain R et al: Cochlear implant failure: imaging evaluation of the electrode course. Clin Radiol. 58(4):288-93, 2003
                                                                          10. Witte RJ et al: Pediatric and adult cochlear implantation. Radiographics. 23(5):1185-200, 2003
                                                                          11. Lo WW: Imaging of cochlear and auditory brain stem implantation. AJNR Am J Neuroradiol. 19(6):1147-54, 1998
                                                                          12. Teissl C et al: Cochlear implants: in vitro investigation of electromagnetic interference at MR imaging--compatibility and safety aspects. Radiology. 208(3):700-8, 1998
                                                                          13. Johnson MH et al: CT of postmeningitic deafness: observations and predictive value for cochlear implants in children. AJNR Am J Neuroradiol. 16(1):103-9, 1995
                                                                          14. Shpizner BA et al: Postoperative imaging of the multichannel cochlear implant. AJNR Am J Neuroradiol. 16(7):1517-24, 1995
                                                                          15. Mukherji SK et al: CT of the temporal bone: findings after mastoidectomy, ossicular reconstruction, and cochlear implantation. AJR Am J Roentgenol. 163(6):1467-71, 1994
                                                                          16. Harnsberger HR et al: Cochlear implant candidates: assessment with CT and MR imaging. Radiology. 164(1):53-7, 1987