The Insertion Results of a Mid-scala Electrode Assessed by MRI and CBCT Image Fusion

Abstract

Objectives: To investigate the results of clinical surgical insertions with a Mid-scala array (HIFocus Mid-Scala Electrode, HFms). Study Design: Consecutive retrospective case study. Settings: Tertiary referral center. Patients: Analyses of imaging data of 26 consecutive patients (31 insertions) implanted with the HFms. Intervention (s): The evaluation of insertion trauma evoked by a previously validated image fusion technique. Electrode reconstructions from postoperative cone-beam computed tomography (CBCT) were overlaid onto preoperative magnetic resonance imaging (MRI) scans to create artifact-free images. Main Outcome Measures: The electrode position was quantified in relation to the basilar membrane. Trauma scaling adopted from Eshraghi was used for evaluating insertion trauma. The results of the visual assessment of the postoperative CBCT were compared to those obtained with the fusion technique. Results: Three insertions had to be excluded due to incompatibility of the imaging data with the fusion software. We found consistent peri- to mid-modiolar placement of the HFms with a mean insertion depth angle of 376°. According to the medical records, a visual examination of the postoperative CBCT indicated that there had been no scala dislocations but when assessed by the image fusion technique, five scala dislocations (17.8%) were found. Additionally, one tip fold-over was detected in the postoperative CBCT even though this was not evident in any intraoperative measurements. Conclusion: HFms showed atraumatic surgical insertion results with consistent mid-modiolar placement. Image fusion enhances the accuracy of the insertion trauma assessment. Routine postoperative imaging is recommended for identifying tip fold-over as well as for quality control and documentation.

Review on cochlear implant electrode array tip fold-over and scalar deviation

“…of electrode per type/brandNo. of cases reported tip fold-overABCTimm et al (2018)275 (CT)––275 (F28, F24, F20, F16)0Sipari et al. (2018)23 (CT)–MS (23)–2Gabrielpillai et al.…”

“…Electrode scalar deviation is another important and the most traumatic event that could happen inside the cochlea during electrode placement. A total of 26 peer-reviewed publications were found reporting on intra-cochlear electrode array scalar deviation in patient cases with the current commercially available electrode types (McJunkin et al., 2018; Mittmann et al., 2017; Koka et al., 2018; Dirr et al., 2013; Sipari et al., 2018; Jia et al., 2018; Aschendorff et al., 2017; Fischer et al., 2015; Shaul et al., 2018; Ketterer et al., 2017; An et al., 2017; O'Connell et al., 2017a; O'Connell et al., 2017b; Lathuillière et al., 2017; O'Connell et al., 2016a; O'Connell et al., 2016b; Wanna et al., 2015; Nordfalk et al., 2016; Mittmann et al., 2015a; Mittmann et al., 2015b; Mittmann et al., 2015c; Boyer et al., 2015; Wanna et al., 2014; Nordfalk et al., 2014; Aschendorff et al., 2011; Wanna et al., 2011; Lane et al., 2007) and were summarized in Table 2.…”

“…of cases reported with scalar deviationABCMHMSLWShaul et al. (2018)110ImagingCA (92), SM (18)––18 (19.5%)––Sipari et al. (2018)23Imaging–MS (23)––5 (22%)–Koka et al.…”

“…Grade 1 and 2 degree of trauma cannot be detected conclusively by the clinical CT due to the image artefact but grade 3 and 4 can be conclusively detected. There is enough number of publications since 2007 that reported on electrode tip fold-over (McJunkin et al., 2018; Sabban et al., 2018; Dirr et al., 2013; Timm et al.; Sipari et al., 2018; Gabrielpillai et al., 2018; Jia et al., 2018; Garaycochea et al., 2017; Aschendorff et al., 2017; Zuniga et al., 2017; Fischer et al., 2015; Cosetti et al., 2012; Grolman et al., 2009) and electrode scalar deviation (McJunkin et al., 2018; Mittmann et al., 2017; Koka et al., 2018; Dirr et al., 2013; Sipari et al., 2018; Jia et al., 2018; Aschendorff et al., 2017; Shaul et al., 2018; Ketterer et al., 2017; An et al., 2017; O'Connell et al., 2017a; O'Connell et al., 2017b; Lathuillière et al., 2017; O'Connell et al., 2016a; O'Connell et al., 2016b; Wanna et al., 2015; Nordfalk et al., 2016; Mittmann et al., 2015a; Mittmann et al., 2015b; Mittmann et al., 2015c; Boyer et al., 2015; Wanna et al., 2014; Nordfalk et al., 2014; Aschendorff et al., 2011; Wanna et al., 2011; Lane et al., 2007) detected with x-ray, clinical CT, NRT and ECochG methods. All the commercially available CI electrodes vary in its size, shape and the method of insertion, the operating surgeon should be well informed about all these variation before the surgery.…”

Preservation of residual hearing after cochlear implant surgery with slim modiolar electrode

“…McJunkin et al [36] described scala translocation in 3 out of 23 insertions (13%), whereas Aschendorff et al [32] reported of no scala translocations. In summary, the translocation rates of the SME appear to be considerably lower than those reported for stylet-type PMEs, in the publications, their translocation rates have varied from 15.8% up to 52.3% [1,2,16,22,40,41].…”