Proefschrift_vd_Beek

Van der Beek: Differences in levels along CI array

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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

CII/HiRes 90K HiFocus 1/1J Progressive: 100; Medication: 4; Meniere’s disease: 5; Meningitis:

Implant type

Etiology

12; Otosclerosis: 4, Trauma: 3; Usher syndrome: 2

Monosyllabic word score at 1 year (%)

57 (avg; range: 5-93)

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 F.B. van der Beek

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