1. Define the benefits of early implantation of cochlear implants and of bilateral implants in children.

2. Describe the evaluation of music appreciation in patients with cochlear implants.

3. Measure balance, horizontal canal function, and saccular function in children with hearing loss due to bacterial meningitis.

4. Identify the effects of inflammation in patients with cochlear implants.

5. Select candidates for placement of bone-anchored hearing aids and perform the implantation procedure.

Controversies in Pediatric Cochlear Implantation
Erik H. Waldman, MD, Assistant Professor of Pediatric Otolaryngology–Head and Neck Surgery, Department of Otolaryngology –Head and Neck Surgery; Clinical Director of Pediatric Cochlear Implants, Columbia University Medical Center and Children’s Hospital of New York, NY

Background: 4 to 5 infants per 10,000 become bilaterally deaf because of sensorineural hearing loss (SNHL) and require implantation; economic burden >$1 million per person with prelingual deafness; implants approved for adults by United States Food and Drug Administration (FDA) in 1980s and for children >2 yr of age in 1990; now approved for children >1 yr of age

Optimum age: to develop speech and language, children require stimulation of auditory cortex beginning at birth; if no stimulation by 3 to 7 yr of age, difficult for brain to accept and use auditory stimuli; auditory deprivation permanently reduces cortical auditory centers

Benefits of early implantation: improved perception and intelligibility of speech, improved language outcomes, and greater literacy; studies show children implanted at <1 yr of age do better than those implanted between 1 to 2 yr of age

Risks: potential risk from anesthesia; risk for cardiac arrest; increased risk for meningitis; greater exposure of and risk to facial nerve; craniotomy sometimes necessary if skull too thin; programming of implant more difficult in very young patients; experience has shown most risks manageable; minimum age limit may decrease to 8 to 12 mo

Bilateral implants

Benefits: binaural hearing allows interpretation of information from interaural differences; central processing of interaural differences enables localization of sound and improved recognition of speech in noise; “head shadow effect”; bilateral implants improve these attributes (eg, patients report better sound quality and clarity, better acoustic balance, greater ease following group conversations, less fatigue); reduced likelihood that failure of implant will impede development of child

Simultaneous implantation: reduced time between implantations improves ability to use binaural sounds, behavior, and performance in school; unilateral hearing loss in children associated with behavioral and academic problems

Disadvantages: cost; limited ability to apply future innovations (eg, stem cell research, genetic manipulation) because of loss of residual hearing; few adverse vestibular consequences apparent in large trials; technical issues—increased risk for cerebrospinal fluid (CSF) gusher and facial nerve anomalies

Cochlear ossification: increases difficulty of implantation; mainly result of bacterial meningitis; detected by magnetic resonance imaging (MRI); drilling through new ossification, placing implant in scala vestibulae, or drilling out bone useful; split and compressed implant arrays developed for use with ossification

Auditory neuropathy and auditory dyssynchrony: outer hair cells function normally, but signal transmitted incorrectly; patients who receive implants have done well

Multiple disabilities: eg, blindness, Usher’s syndrome, autism, mental retardation, cerebral palsy; difficult to predict ability of these children to develop auditory and linguistic skills; studies show implantation associated with better quality of life; note—patients with anomalous anatomy or borderline indications also benefit from implants

Otitis media (OM): theoretic risk for intracranial complications; implants shown not to increase incidence of meningitis; OM less common after implantation; important not to delay implantation; placement of tubes and adenoidectomy before implantation may benefit children prone to OM; controversial whether child must be free of otorrhea or effusion in middle ear before implantation; sometimes tubes placed intraoperatively

Imaging: high resolution computed tomography (CT)—standard for imaging temporal bone, mastoid air cell system, position of facial nerve, and bony labyrinth (thin cuts required); MRI—reveals abnormalities of soft tissues, detects cochlear obliteration and central processes (scan petrous bone and brain to detect central lesions); disadvantages—MRI requires more sedation; CT involves exposure to radiation; MRI costs more than CT but more reliably diagnoses early cochlear obliteration, cochlear nerve aplasia, and central lesions; CT gives more accurate tracing of facial nerve through temporal bone; algorithm suggests using high resolution CT in addition to MRI if risk factors present for cochlear ossification, craniofacial problems, or central lesions; otherwise, begin with MRI and add CT if location of facial nerve unclear

Disparity in care: changes in reimbursement needed; among 835 potential candidates per year in New York, only 50% to 60% receive implants; studies show 2-fold greater chance of deafness in children from families with lower income, but lower chance of receiving implants

Music Perception in Cochlear Implantees
Jaclyn B. Spitzer, PhD, Professor of Clinical Audiology and Speech Pathology, Department of Otolaryngology–Head and Neck Surgery, Columbia University College of Physicians and Surgeons, New York, NY; Director, Audiology and Speech Pathology, Columbia University Medical Center, New York

Music perception: studies show patients with implants have normal ability to perform tasks related to rhythm; perception of pitch less accurate (7 tones needed for implantee to perceive difference between 2 tones); most implantees have poor (12%) recognition of melody; implantees have 47% level of perception of timbre (allows discrimination among musical instruments); music performance not well correlated with speech perception

Testing music appreciation

Appreciation of Music in Cochlear Implantees (AMICI) study: clinical test with 4 sections (perception of noise vs music, perception of musical instrument played alone vs at low level with other instruments in background, perception of musical styles, and recognition of melody); results—accuracy score reflected difficulty of task; participants with impaired hearing had few errors in discrimination of music and noise; error rate increased as difficulty of task increased, with poor ability to recognize melodies

Multicenter study: used AMICI and similar more difficult test developed by University of Washington; findings with AMICI—eliminated noise vs music section; tested speech recognition and musical enjoyment; participants achieved AMICI test scores of 75% for style and instrument recognition and 50% for melody recognition; results for each test section correlated positively to speech recognition using sentences from Bamford-Kowal-Bench (BKB) test, and 2 sections correlated to words from consonant-nucleus-consonant (CNC) test; no correlation between AMICI and musical enjoyment

Limitations of music testing: development of tests requires recognition of culture of patient population

Vestibular and End Organ Balance Deficits After Meningitis and Cochlear Implantation
Sharon L. Cushing, MD, Resident, Department of Otolaryngology–Head and Neck Surgery, Faculty of Medicine and Hospital for Sick Children, University of Toronto, ON

Study: performed standardized tests of static and dynamic balance in 9 children who had hearing loss due to bacterial meningitis, 8 of whom had unilateral cochlear implants

Horizontal canal function: all participants had abnormal responses to caloric stimuli; no child responded to ice water; 3 had asymmetric responses; 8 had abnormalities in vestibulo-ocular reflex (VOR) gain measured by rotational chair testing, and child with normal test had unilateral hypofunction; among 3 children with asymmetric responses, better function seen in implanted sides; none showed evidence of ossification before implantation; however, 2 showed asymmetrical ossification in nonimplanted ear upon follow-up imaging

Saccular function: most children had bilaterally present and normal vestibular evoked myogenic potentials (VEMP) responses

Subjective results: parents reported abnormalities in dynamic and static balance shortly after child recovered from meningitis, but balance eventually returned to normal

Bruininks-Oseretsky test (BOT-2): normative data available standardized for age and sex; validated for patients with cochlear implants; children with implants showed variable results (ie, those with connexin-related deafness performed best, followed by those with hearing loss of unknown etiology, while those with cochleovestibular anomalies performed poorly); poorest performance among children with hearing loss due to meningitis, although parents perceived their function as normal

Compensatory mechanisms: tested ability to stand on one foot with eyes open, eyes closed, and off and on balance beam; performance reduced when eyes closed, regardless of hearing ability; decrement proportional in children with implants; decrement much greater in children after meningitis; results for children with similar horizontal canal function but congenital sensorineural deafness paralleled those for children with normal hearing or implants; implications— compensatory reliance on vision in children with acquired vestibular loss differs from that in children with congenital loss; supported by VOR gain results in rotational chair testing

Conclusions: horizontal canal function almost universally compromised in profound SNHL due to meningitis (previously shown); saccular function relatively resistant to damage from meningitis; strong reliance on visual cues used by children with meningitis-induced SNHL as compensatory mechanism; in children with asymmetric function, implanted side had better function; bilateral implantation may provide these children more auditory cues for balance

Foreign Body Granuloma of the Inner Ear After Cochlear Implantation
Joseph B. Nadol Jr, MD, Walter Augustus Lecompte Professor and Chair of Otology and Laryngology, Harvard Medical School; Chief of Otolaryngology and Director of Otology Service, Massachusetts Eye and Ear Infirmary, Boston, MA

Delayed failure of cochlear implants: hard failure—delayed failure attributable to electrical change in implant as seen on integrity testing; soft failure—suspected device malfunction, but no electrical change in implant found on integrity testing; auditory symptoms attributed to soft failure but not eliminated by re-implantation may result from inflammatory response

Case example: patient had progressive bilateral SNHL; right cochlear implantation performed at 57 yr of age; CT revealed normal temporal bone; at 8 mo after procedure, patient achieved Central Institute for the Deaf (CID) sentence score of 78%; at 1 yr, score dropped to 18%, and new-onset facial nerve stimulation developed; integrity testing showed device functioning normally; patient underwent left cochlear implantation at 59 yr of age; achieved only sound awareness and suffered facial nerve stimulation on left side at 5 mo after procedure; removal and re-implantation of device on left side resulted in no improvement; at 66 yr of age, CT showed both implants in place, extending 270° on right and 250° on left; device on right located in basal turn just below labyrinth and horizontal segment of facial nerve; device on left in basal turn

Autopsy results: after patient’s death at 71 yr of age, examination of right temporal bone showed inflammatory response, with osteolysis (especially in basal turn juxtaposed to electrode track) and granulomatous response filling cochlea and expanded cochlea; spiral ganglion had degenerated, with no visible organ of Corti, basilar membrane supporting cells, or stria; giant cells and lymphocytic infiltration present; in basal turn, implant track juxtaposed to facial nerve at labyrinthine segment; inflammatory response limited to peri-electrode track through mastoid and middle ear; histopathology similar on left side, with destruction of cribrose area, expansion of capsule by osteolysis, and migration of electrode to position near carotid canal; comparison with temporal bones from 8 other patients revealed giant cells and monocytes extending to or throughout cochlea in 75%

Differential diagnosis: includes Wegner’s granulomatosis, mycobacterial infection, foreign body reaction, or hypersensitivity response; in case example, absence of vasculitis ruled out Wegner’s granulomatosis; negative polymerase chain reaction (PCR) results and histochemical staining made infection unlikely, given bilaterality and limitation to electrode track; delayed erosion of cochlear capsule previously reported in 2 patients on basis of radiographic findings; erosion of cochlear capsule described in another patient 3 yr after implantation attributed to focal inflammatory process; similar histopathology described after implantation of other prostheses containing silicon and attributed to foreign body or hypersensitivity response; testing for allergic response to formulations of silicon used in cochlear implants showed positive results

Bone-anchored Hearing Aid Implantation: “How I do it” for the General Ear-Nose-Throat (ENT) Physician
Jay K. Roberts, MD, Medical Director and Otolaryngologist, Medical Surgical Specialists, Naples, FL

Bone-anchored hearing aid (BAHA): electromechanical portion remains outside body; abutment comes through skin; approved in United States in 1996 for use in patients with conductive and mixed hearing losses; also approved for use in cases of unilateral SNHL; reimbursement only recently established

Indications: potential candidates—conductive loss due to chronic OM; cholesteatoma surgery, mastoid cavities, congenital atresia, otosclerosis surgery, multiple failed tympanoplasties; mixed loss due to ossicular chain reconstructions; unilateral SNHL due to acoustic neuromas, viral infections, autoimmune disorders, or Meniere’s disease

Audiometric testing: patients with mixed and conductive losses—pure tone average 45 decibels (dB) and discrimination of 60% required for insurance coverage; patients with single-sided deafness—pure tone average of 20 dB on good side required

Mechanism: processor transmits sound directly to inner ear, bypassing problems in ear canal, ear drum, or middle ear; absence of occlusion of canal reduces risk for development of fungal otitis

Sound quality: better than conventional hearing aid, with less feedback and discomfort

Procedure: under local anesthesia, mark location; leave skin graft hinged inferiorly; undermine soft tissue down to periosteum; make small cruciate incision through periosteum; employ countersink until outer flange begins to work into bone; place abutment and connector; fold back flaps of periosteum; punch hole in graft; suture edges; apply sponge and mastoid dressings; allow bone to grow into titanium for 3 mo before connection (may be shorter, eg, 6 wk, in some patients)