STATE OF THE ART IN COCHLEAR IMPLANTATION: CONCEPTS IN MINIMALLY TRAUMATIC SURGERY! Brendan P. O Connell MD! Assistant Professor! Otology and Neurotology- UNC Chapel Hill!
EXPANDING INDICATIONS FOR CONVENTIONAL ELECTRODES
EXPANDING INDICATIONS FOR COCHLEAR IMPLANTATION Preservation of residual hearing Minimization of trauma to cochlear fine structure
OUTLINE Hearing preservation: definitions and audiometric benefits How successful are we in preserving hearing Ways to minimize trauma during cochlear implant insertion
HEARING PRESERVATION COCHLEAR IMPLANTATION Maintenance of low-frequency acoustic hearing post-operatively Should be functional (ie aidable) Allows for combined electricacoustic stimulation or EAS
WHAT BENEFIT DOES EAS LISTENING CONFER? ~15% Speech Perception Sound Localization Music Appreciation
SPEECH PERCEPTION BENEFITS EAS! >! CI! BL HA! EAS!???! BM!
BILATERAL AIDED EAS: EARLY DATA BL HA! EAS! =! BM!
BILATERAL AIDED EAS: SPEECH PERCEPTION 10-17% 3-5 db Ad SRT
BILATERAL AIDED EAS: LOCALIZATION ~ 20 improvement in RMS error
IS THERE BENEFIT TO HEARING PRESERVATION EVEN IF A PATIENT DOESN T USE EAS? Controversial BUT.. 10% improvement in speech perception
HOW OFTEN ARE WE ABLE TO PRESERVE HEARING? Measurable Thresholds 80-90 db in Low Freq. <15 db LFPTA Shift >90% 40-90% 30-90%
LOW FREQUENCY PTA WITH FLEX ELECTRODES
LONG-TERM HEARING PRESERVATION
LOW FREQUENCY PTA SHIFT WITH FLEX ELECTRODES Dillon et al.!
CONCLUSION 1 Hearing preservation confers benefit with respect to speech perception, localization, and music appreciation Acoustic hearing can be preserved in the majority of cases Assuming preservation of hearing correlates with degree of insertional trauma, how can we study trauma?
MECHANISMS OF COCHLEAR TRAUMA
HISTOLOGY Briggs RJ, Tykocinski M, Xu Jet al. 2006!
HISTOLOGY Briggs RJ, Tykocinski M, Xu Jet al. 2006!
HISTOLOGY Wright CG, Roland PS 2013!
MECHANISMS OF COCHLEAR TRAUMA
MECHANISMS OF COCHLEAR TRAUMA
ELECTRODE LOCATION IN VIVO How do we determine where an electrode array is located in vivo?
ELECTRODE LOCATION IN VIVO MicroCT model! EA and SG SG in pre-op CT!! EA in post-op CT!
ELECTRODE LOCATION IN VIVO MicroCT model! EA and SG SG in pre-op CT!! EA in post-op CT!
ELECTRODE LOCATION IN VIVO MicroCT model! EA and SG SG in pre-op CT!! EA in post-op CT!
ELECTRODE LOCATION IN VIVO MicroCT model! EA and SG SG in pre-op CT!! EA in post-op CT!
VALIDATION OF MODEL
SCALA TYMPANI INSERTION
SCALA TYMPANI INSERTION
SCALA VESTIBULI INSERTION
SCALA VESTIBULI INSERTION
TRAUMA GRADING
SCALAR LOCATION AND SPEECH PERCEPTION
SCALAR LOCATION AND SPEECH PERCEPTION
WHY IS SCALA TYMPANI BETTER? SV insertions cause trauma to terminal nerve structures Electrodes in SV may stimulate next most apical turn SV! ST!
SCALAR LOCATION AND HEARING PRESERVATION Retrospective Prospective ST 58% Success Scalar Crossover 0% Success
CONCLUSION 2 Scala tympani insertions are associated with better speech perception and hearing preservation outcomes Do surgical variables/techniques impact our ability to achieve a scala tympani insertion?
SURGICAL FACTORS: ELECTRODE DESIGN Likelihood of ST insertion is 22 times higher with a lateral wall (straight) electrode Functional hearing preservation is 8 times more likely with lateral wall arrays
SURGICAL FACTORS: ELECTRODE DESIGN
WHY ARE LATERAL WALL ELECTRODES GENERALLY LESS TRAUMATIC? Lateral Wall (straight) Perimodiolar (precurved)
PERIMODIOLAR POSITIONING
WHAT ARE OTHER SURGEONS DOING? In non-hearing preservation cases 56% PM vs. 44% LW In hearing preservation cases 14% PM vs. 86% LW Carlson ML, Sweeney AD, O Connell BP, Lohse CM, Driscoll CL. Survey of the American Neurotology Society on Cochlear Implantation. In Press!
SURGICAL FACTORS: SURGICAL APPROACH 70% reduction in crossover rate when round window approaches are used Round window surgeries associated with better longterm hearing preservation
SURGICAL FACTORS: SURGICAL APPROACH
WHY IS COCHLEOSTOMY GENERALLY MORE TRAUMATIC?
WHY DOES COCHLEOSTOMY PREDISPOSE TO CROSSOVER?
WHAT ARE OTHER SURGEONS DOING? In non-hearing preservation cases 90% RW vs. 10% Cochleostomy In hearing preservation cases 95% RW vs. 5% Cochleostomy Carlson ML, Sweeney AD, O Connell BP, Lohse CM, Driscoll CL. Survey of the American Neurotology Society on Cochlear Implantation. In Press!
CONCLUSION 3 Lateral wall electrodes and round window approaches increase likelihood of achieving a scala tympani insertion What else do we do in an attempt to minimize trauma?
POST-OPERATIVE STEROIDS 3 times higher likelihood of long-term hearing preservation when perioperative oral steroids are administered
WHAT ARE OTHER SURGEONS DOING? In hearing preservation cases 96% of respondents use some form of steroids 30% pre-operative PO, 92% intra-operative IV, 55% post-operative PO Carlson ML, Sweeney AD, O Connell BP, Lohse CM, Driscoll CL. Survey of the American Neurotology Society on Cochlear Implantation. In Press!
SPEED OF INSERTION
SPEED OF INSERTION
FUTURE DIRECTIONS
FUTURE DIRECTIONS
FUTURE DIRECTIONS Deeper insertions à better speech perception for LW Increased cochlear coverage Extends range of possible pitch percepts Better frequency match with tonotopic organization of cochlea CNC Score (%) 100 80 60 40 20 Insertion Depth and Performance for MED-EL Electrodes in Scala Tympani 0 200 400 600 800 Angular Insertion Depth (degrees) r=0.48, p<0.001 MED-EL Flex 24 MED-EL Flex 28 MED-EL Standard
FUTURE DIRECTIONS Insertion Depth and Low-Frequency PTA Shift Deeper insertions à worse hearing preservation Results in clinical dilemma Low-frequency PTA Shift (db HL) 60 40 20 r=0.41, p=0.04 MED-EL Flex 24 MED-EL Flex 28 MED-EL Standard 0 200 400 600 800 Angular Insertion Depth ( )
CONCLUSIONS Hearing preservation is associated with better speech understanding, sound localization, and music appreciation Use of lateral wall electrodes and RW/ERW approaches decreases trauma and increases likelihood of hearing preservation Use of perioperative steroids, and slow but steady insertion speeds are recommended