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120 | Chapter 6
MATERIALS & METHODS
Subjects
The clinical data for 130 post-lingually deafened adult cochlear-implant recipients who used either a CII
or an electrically identical HiRes 90K cochlear implant with a fully inserted HiFocus 1/1J electrode array
(Advanced Bionics, Sylmar, CA, USA) were analyzed in this study. These subjects were consecutively
implanted between 2002 and 2008 at the Leiden University Medical Center. Two surgeons performed all
of the implantations during this period. An extended round-window insertion was performed in all cases.
Subjects younger than 16 years old were not included in this study. The demographical information for
the subjects is summarized in Table 1. All of the subjects used the HiRes processing strategy. For a variety
of reasons, 36 post-lingually deafened adult subjects who were implanted during this period were excluded
from the study (Table 2), mainly because of a lack of reconstructable CT data (see below).
Intra-scalar position
All of the implanted patients received a postoperative CT scan to confirm that the cochlear implant had been
properly inserted. To analyze the intra-scalar position, serial multi-planar reconstructions were executed
[Verbist et al., 2005]. The insertion angle and the position of each electrode contact were determined using
a 3D coordinate system based on international consensus [Verbist et al., 2010a;Verbist et al., 2010b] and an
in-house designed post-processing program (Matlab, Mathworks, Novi, MI, USA; Figure 1). The accuracy
Van der Beek: Differences in levels along CI array
24
Table 1:
Patient demographics.
Patient demographics
Number
130
Age (years)
56 (avg; range: 17-84)
Duration of deafness
(years)
22 (avg; range: 0.1 -60)
Sex
83 F/47 M
Implant type
CII/HiRes 90K HiFocus
1/1J
Etiology
Progressive: 100;
Medication: 4; Meniere’s
disease: 5; Meningitis:
12; Otosclerosis: 4,
Trauma: 3; Usher
syndrome: 2
Monosyllabic word score
at 1 year (%)
57 (avg; range: 5-93)
F.B. van der Beek