2017 Sec 1 Green Book

SINGLE-SIDED DEAFNESS COCHLEAR IMPLANTATION

TABLE 1.

Demographics

sound (CROS) amplification devices or osseointegrated devices such as bone anchored hearing aids (BAHA). Although both of these approaches provide the patients with some access to sound, the configurations do not restore hearing to the deaf ear but rather route the signals so that the benefits of binaural hearing are not maximally achieved as previously demonstrated (5). Even with such technology, improved hearing in difficult listening situ- ations and the ability to localize sound remain elusive to most patients with SSD (6) and may actually make listening more difficult with certain signal-to-noise ratios incident on the unaffected ear. Cochlear implants for SSD were first introduced in the setting of intractable tinnitus (7), but have since been shown to have benefits far beyond tinnitus suppression (8,9). Our purpose in this article was to review our institu- tional experience with selecting appropriate SSD pediatric and adult patients to receive a cochlear implant for various indications and their subjective and objective outcomes to date to determine if 1) there is a functional increase in word and sentence recognition in quiet and in noise and 2) the binaural advantage can be restored by placing a cochlear implant in the poorer ear. Subjects This retrospective chart review was approved by our institu- tional review board (IRB) and included 12 adult patients and 4 children with SSD. All patients had unaidable hearing in the affected ear. There were no strict hearing criteria in the better and all patients were evaluated on an individual basis but the average PTA in the better hearing ear was 12.7 (SD 7.0). All patients contributing data had at least 1 year of CI use. See Table 1 for adult demographic factors. Most subjects were deaf as a result of sudden sensorineural hearing loss (SSNHL) (67%), and did not have any pathology in their normal hearing ear (83%). The PTA of the deaf ear among all subjects was 87.0 (SD 8.3). The mean age at diagnosis among adult patients with SSDwas 47.3 years (SD 12.4) and on average they were implanted 3.1 years (SD 5.7) later. Eleven adult patients received Cochlear Nucleus (Englewood, CO, U.S.A.) devices and one received Advanced Bionics (Valencia, CA, U.S.A.) devices. All four children received Cochlear Nucleus devices. Intraoperatively, all patients had full inser- tions of the electrode array without perioperative or postoperative complications. Speech Perception Patients were evaluated according to our institutional SSD protocol (Table 2). Before the availability of direct connect, a ‘‘plug and muff’’ technique was used to minimize/eliminate the role of better hearing ear (n ¼ 4) in a sound-proof booth using recorded material. To ensure that the poor ear was completely isolated from the ‘‘good’’ ear on the nonimplanted side, the good ear was plugged and muffed using E.A.R. foam earplugs (3M Co., St. Paul, MN, U.S.A.) and TASCO sound shield over- the-head earmuff Model #2900. (TASCO Corp, Riverside, RI, U.S.A.). For the plug, the mean attenuation for frequencies 125 to 8000 Hz was 42.3 dB with a noise reduction rating (NRR) of 29. The muff had a mean attenuation of 33.9 dB for frequencies 125 to 8000 Hz with an NRR of 29. METHODS

Category

n (%)

Sex

Male

6 (50)

SSD ear Left

7 (58)

Etiology of SSD SSNHL

8 (67) 4 (33)

Other

Pathology in normal ear Yes

2 (17)

Mean (SD)

Age at implantation

50.5 (13.4) 47.3 (12.4)

Age at deafness

Pure-tone average (PTA); 0.5, 1, 2 kHz Normal ear

12.7 (7.0) 87.0 (8.3) 3.1 (5.7) 3.4 (1.8)

SSD ear

Duration of deafness to CI (yr) Length postoperative follow-up (yr)

Later in our experience, a manufacturer-specific direct connect system to the cochlear implant sound processor was used to allow isolation of the CI ear for testing with an insert earphone in the unaffected ear. Direct connect (DC) audio- metric testing (Cochlear Americas), via electrical cable con- nection, to the cochlear implant processor allows testing of each ear in isolation or together (binaurally) using tones or speech. This allows elimination of the inadvertent role of the better hearing ear in sound field testing and allows for hearing in noise testing with spatially separated competing signal and sound localization without the need for multispeaker arrays. The generalizability of this system has been validated else- where including precise timing and level cues (10–12). The signals are processed via a head-related transfer function (HRTF) so that it is equivalent to sound field presentation and the software provides calibration to ensure that the signals are delivered at the desired presentation levels. PTA was calculated using air conduction lines. Other etiologies of SSD in the data set include Me´nie`re’s, chronic otitis media, and sequela from CPA meningioma resection. SD indicates standard deviation. Demographics of adult SSD patients who underwent cochlear implantation at our institution (n ¼ 12). Pure-tone air and bone conduction thresholds Imittance measures including tympanometry and acoustic reflexes and otoacoustic emissions MRI or CT imaging confirmation of a cochlea and cochlear nerve and to detect inner ear malformations or evidence of ossification Speech reception thresholds and speech discrimination where age appropriate (CNC, HINT) Adaptive HINT is also done with sound field using CROS amplification and/or the BAHA soft band Localization testing using a manufacturer-specific ‘‘direct connect’’ system Vertigo and tinnitus questionnaires are included in the evaluation All postimplantation testing is performed using a manufacturer- specific direct connect system TABLE 2. Institutional protocol for cochlear implantation in SSD patients

Institutional protocol for cochlear implantation in SSD patients.

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