2017 Sec 1 Green Book

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.

METHODS

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

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.

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.

TABLE 1.

Demographics