Faculty Bibliography

OBJECTIVES: Commercially available cochlear implant systems attempt to deliver frequency information going down to a few hundred Hertz, but the electrode arrays are not designed to reach the most apical regions of the cochlea, which correspond to these low frequencies. This may cause a mismatch between the frequencies presented by a cochlear implant electrode array and the frequencies represented at the corresponding location in a normal-hearing cochlea. In the following study, the mismatch between the frequency presented at a given cochlear angle and the frequency expected by an acoustic hearing ear at the corresponding angle is examined for the cochlear implant systems that are most commonly used in the United States. DESIGN: The angular insertion of each of the electrodes on four different electrode arrays (MED-EL Standard, MED-EL Flex28, Advanced Bionics HiFocus 1J, and Cochlear Contour Advance) was estimated from X-ray. For the angular location of each electrode on each electrode array, the predicted spiral ganglion frequency was estimated. The predicted spiral ganglion frequency was compared with the center frequency provided by the corresponding electrode using the manufacturer's default frequency-to-electrode allocation. RESULTS: Differences across devices were observed for the place of stimulation for frequencies below 650 Hz. Longer electrode arrays (i.e., the MED-EL Standard and Flex28) demonstrated smaller deviations from the spiral ganglion map than the other electrode arrays. For insertion angles up to approximately 270 degrees , the frequencies presented at a given location were typically approximately an octave below what would be expected by a spiral ganglion frequency map, while the deviations were larger for angles deeper than 270 degrees . For frequencies above 650 Hz, the frequency to angle relationship was consistent across all four electrode models. CONCLUSIONS: A mismatch was observed between the predicted frequency and the default frequency provided by every electrode on all electrode arrays. The mismatch can be reduced by changing the default frequency allocations, inserting electrodes deeper into the cochlea, or allowing cochlear implant users to adapt to the mismatch. Further studies are required to fully assess the clinical significance of the frequency mismatch.

OBJECTIVE: To assess whether recombinant growth factor (hGH) therapy has an effect on cochlear implant (CI) performance. PATIENTS: Two pediatric CI recipients (S1, S2) who underwent treatment with hGH for short stature were identified for review. S1 has bilateral labyrinthine dysplasia and received implants at ages 10 months (right) and 4 years 3 months (left). S2 was diagnosed with severe to progressive sensorineural hearing loss bilaterally and received a CI at age 9 years 10 months (left). INTERVENTION(S): Case series. MAIN OUTCOME MEASURE(S): Cochlear implant, hGH, and speech perception data were collected. Phonetically Balanced Kindergarten (PBK) and Consonant Nucleus Consonant (CNC) word recognition scores were reviewed to assess auditory perception. Electrode impedances, threshold levels, and comfort levels were also reviewed. RESULTS: After 4 months of hGH, word recognition scores for S1 were observed to decrease from 90 to 72% (right) and were stable at 40% (left). Despite troubleshooting, performance continued to decline bilaterally to 52% (right) and 28% (left), and the decision was made to discontinue hGH. One month after cessation of hGH, word recognition scores began improving to 74% (right) and 68% (left). Word recognition scores for S2 were observed to have decreased from 92% the previous year to 82% after taking hGH for 2 months. Given both our previous experience with S1 and discussions with S2's parents, hGH was discontinued after 10 months of therapy. Two months after cessation of hGH, S2's word recognition had improved to 86% (left). CONCLUSIONS: Our case studies illustrate that implanted children undergoing treatment with hGH may experience a decrease in speech perception, which recovers after the cessation of treatment. Since hGH use has become more prevalent in recent years, it is important to inquire whether children undergoing, or who have undergone, implantation are receiving hGH so that they may be appropriately monitored.

Although the preponderance of cerebellopontine angle lesions are schwannomas, focused attention to patient clinical history, imaging studies, and tissue biopsies when indicated will aid in detection of less common lesions that might otherwise be misdiagnosed. This is most critical for pathologies that dictate different management paradigms be undertaken.

OBJECTIVES/HYPOTHESIS: Trauma to intracochlear structures during cochlear implant insertion is associated with poorer hearing outcomes. One way surgeons can influence insertion trauma is by choosing the surgical approach. We seek to compare cochleostomy (CO), peri-round window (PRW), and round window (RW) approaches using a fresh frozen temporal bone model. STUDY DESIGN: Experiments using fresh frozen temporal bones. METHODS: Cochlear implant insertions using the three aforementioned approaches were performed on 15 fresh frozen human temporal bones using a Cochlear 422 electrode. Insertions were evaluated by examining fluoroscopic recordings of histologic sections. RESULTS: Five cochlear implant insertions were performed using each of the three aforementioned approaches. Fluoroscopic examination revealed that none of the CO or PRW insertions contacted the modiolus during insertion, whereas three of five RW insertions did. RW insertions were less linear during insertion when compared to CO and PRW insertions (P < .05). CO insertions had significantly larger angular depth of insertion (487 degrees ) when compared to PRW (413 degrees ) and RW (375 degrees ) (P < .05). Histologic examination revealed one RW insertion resulted in osseous spiral lamina fracture, whereas the remaining insertions had no evidence of trauma. In the damaged specimen, the inserted electrode was observed to rest in the scala vestibuli, whereas the remaining electrodes rested in the scala tympani. CONCLUSIONS: Due to variability in RW anatomy, a CO or PRW window surgical approach appears to minimize the risk for insertion trauma. However, with favorable anatomy, a Cochlear 422 electrode can be inserted with any of the three approaches. LEVEL OF EVIDENCE: NA Laryngoscope, 125:966-971, 2015.

Motion sickness can be a limiting factor for sea and air missions. We report the experience of a Pararescue (PJ) team on a Pacific Ocean rescue mission in which motion sickness was prevalent. Cinnarizine, an antagonist of H1-histamine receptors, was used to treat affected PJs. We also report findings of a survey of PJs regarding motion sickness. A family of four on a disabled sailboat 900 miles off the coast of Mexico sent out a distress call because their 1-year-old daughter became severely ill with fever and diarrhea. Four PJs were deployed on a C-130, performed a free-fall parachute insertion into the ocean, and boarded the sailboat. All four PJs experienced onset of motion sickness at some point during the early part of the mission and symptoms persisted through the first 24 hours. Three PJs experienced ongoing nausea, vomiting, dizziness, and sensory imbalances. The captain of the sailboat offered the three sick PJs approximately 18mg of cinnarizine two or three times a day with relief of symptoms and improvement on operational effectiveness. A new, anonymous, voluntary survey of Air National Guard PJs and combat rescue officers revealed that 78.4% of Operators have experienced motion sickness at sea. We discuss the current theories on motion sickness, the effect of motion sickness on operational effectiveness, and research on treatment of motion sickness, including the medication cinnarizine.

OBJECTIVE: Is conscious sedation an effective, safe, and efficient anesthetic choice in patients undergoing select neurotologic and otologic procedures? STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Six patients underwent eight neurotologic procedures including cerebrospinal fluid leak and encephalocele repair, and primary and revision cochlear implant surgery. Patients were deemed poor candidates for general anesthesia secondary to medical comorbidities. These were compared to 11 control patients who underwent same procedures under general anesthesia with intubation. INTERVENTION: Dexmedetomidine infusion was utilized as the primary agent for conscious sedation in this high-risk patient population because, unlike other commonly used sedatives, it preserves normal respirations while providing adequate analgesia. MAIN OUTCOME MEASURES: Preoperative Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (P-POSSUM) scores were calculated for the study group. We measured total anesthesia, and perioperative and recovery times. Cost of anesthetic agents was considered and any adverse effects were noted. Patient satisfaction with the operative experience was assessed with telephone surveys. RESULTS: P-POSSUM scores were high for the study group. Postoperative anesthesia was shorter for the study patients undergoing conscious sedation. Difference in cost of anesthetic agents was negligible. The adverse effects were few and as expected for the type of procedure. Patients reported satisfaction and comfort with their operative experience. CONCLUSION: Select neurotologic and otologic procedures can be safely, effectively, and efficiently performed under conscious sedation with dexmedetomidine infusion as the primary anesthetic choice for patients who are deemed poor medical candidates for general endotracheal anesthesia.