BAA MAGAZINE SUMMER 2017 DRAFT 4

FEATURE
Single Sided
Deafness: CROS
Aid or BAHA?
KERRY DOWNES
Advanced Audiologist,
St George’s Hospital
Single Sided Deafness (SSD) affects around 9,000 new people
each year in the UK. For many individuals, the condition can
have a profound and debilitating effect on their lives. Sufferers
experience difficulty picking up sounds from their deaf side,
struggle in crowds and background noise and are unable to
localise sounds. Whilst some losses are congenital or acquired
in early childhood, most occur in adulthood and are of sudden
onset. Adjusting to SSD can cause stress and anxiety, and
impact hugely on a person’s well-being. In particular, individuals
report withdrawal from group activities and feelings of isolation
(Wie et al, 2010).
There is some evidence to support the use of intratympanic
steroids for idiopathic sudden SSD (Ferri et al, 2012), but results
have varied widely and research on success rates are limited.
Consequently, SSD remains a predominantly permanent and
untreatable condition. Rehabilitation options include support
groups and counselling, and provision of either Contralateral
Routing of Sound (CROS) or Bone-Anchored Hearing Aids
(BAHA).
CROS/ BiCROS aids and BAHA can help to alleviate the
difficulties caused by the head-shadow effect and provide relief
to some of the difficulties SSD sufferers face (Faber et al, 2013).
Most of the available research comparing the two amplification
options is in regard to older, more cumbersome and cosmetically
unappealing CROS aids with a wire around the back of the neck,
and percutaneous connected abutments for BAHAs which are
also less cosmetically appealing and can be prone to infection.
With the improved technology and cosmetics of CROS aids, and
the release of subcutaneous Cochlear BAHA attracts, this study
aimed to provide an up to date and relevant insight into patient
choice between the two amplification options.
The research also intended to challenge some common
assumptions; such as congenital SSD sufferers not opting for
amplification and elderly patients avoiding BAHA due to the
surgery involved. Factors which may influence the choice were
also investigated; age, cause of deafness, acoustic neuroma
surgery and high frequency thresholds in the hearing ear.
Methods:
30 individuals with SSD were referred to the BAHA service over
the course of 16 months. All were offered back-to-back trials
of wireless Phonak CROS/BiCROS aids (open-fit BTEs) and
Cochlear BAHAs on soft-bands, for at least 2 weeks each. 27
completed trials with both devices, 3 declined trials with BAHAs
as they had no interest in pursuing this option.
Following the trials, the patients attended follow-up
appointments to give their feedback on the devices. Based on
their experiences, the patients then made the decision whether
to:
- Proceed with BAHA and be added to the surgery
waiting list (Group A)
- Continue with the CROS aids (discharged from BAHA
Service) (Group B)
- Decline both options and return to being unaided
(Group C)
Data was collected retrospectively from patient records and
mean averages were calculated. With the “age of patient”
being the age at the time of data collection rather than at the
time of the trials. The 3 patients who refused BAHA trials were
included in Group B.
Findings:
90% of patients reported some level of benefit from either a
CROS system or BAHA on soft-band, and only 3 people (10%)
chose option C - to pursue neither device and return to being
unaided. Of the 27 patients who reported benefit; 37% opted
to be implanted with a BAHA (Group A), and 63% declined
BAHA and chose to stick with their CROS aids (Group B).
High frequency hearing in patients’ better ears were worse
in Group B; with average thresholds at 4kHz and 8kHz: 14.4dB
and 28.1dB compared with Group A; 12.5dB and 20.5dB.
The age of patients varied in both groups. The mean average
was lower in Group A: 45.5 years compared to 50.8 years
in Group B. However the oldest patient assessed (81 years),
chose to proceed with implantation – indicating that age is not
an overriding factor in the decision-making process.
27% of patients involved had long-standing SSD – reporting
that the hearing loss occurred either in childhood or >20 years
ago, and the majority of these did report benefit from either
BAHA or CROS aids; with only one person declining both
options. The main cause of deafness in all groups was the
removal of acoustic neuromas: 50% in Group A, 44% in Group
B and 33% (one person) in Group C.
Conclusions:
Both BAHA and CROS aids were found to alleviate some of
the difficulties associated with SSD for the majority of patients
- with both long-standing and recently acquired hearing losses.
Those with a high-frequency loss in their hearing ear may
experience more benefit from a BiCROS system, due to the
added amplification offered on this side.
All individuals with SSD should be referred to Audiology and
offered trials with both devices as part of their rehabilitation.
Clinicians should be mindful not to influence patient choice
based on out-dated assumptions of which device is more
BAA MAGAZINE / SUMMER 2017 / 10