Search

Purpose: Vestibular implant electrode positioning close to the afferent nerve fibers is considered to be key for effective and selective electrical stimulation. However, accurate positioning of vestibular implant electrodes inside the semicircular canal ampullae is challenging due to the inability to visualize the target during the surgical procedure. This study investigates the accuracy of a new surgical protocol with real-time fluoroscopy and intraoperative CT imaging, which facilitates electrode positioning during vestibular implant surgery. Methods: Single-center case-controlled cohort study with a historic control group at a tertiary referral center. Patients were implanted with a vestibulocochlear implant, using a combination of intraoperative fluoroscopy and cone beam CT imaging. The control group consisted of five patients who were previously implanted with the former implant prototype, without the use of intraoperative imaging. Electrode positioning was analyzed postoperatively with a high-resolution CT scan using 3D slicer software. The result was defined as accurate if the electrode position was within 1.5 mm of the center of the ampulla. Results: With the new imaging protocol, all electrodes could be positioned within a 1.5 mm range of the center of the ampulla. The accuracy was significantly higher in the study group with intraoperative imaging (21/21 electrodes) compared to the control group without intraoperative imaging (10/15 electrodes), (p = 0.008). Conclusion: The combined use of intraoperative fluoroscopy and CT imaging during vestibular implantation can improve the accuracy of electrode positioning. This might lead to better vestibular implant performance. [ABSTRACT FROM AUTHOR]

Objectives: In vestibular implants (VI), the electrode position is thought to be important for optimal neural activation. The objective of this study was to evaluate the stability of the vestibular electrode position over time.Seven patients implanted with a VI were followed for one year. When possible, the fenestrations of the semicircular canals were kept very small (approximately 0.8 mm) to stabilize the electrode lead. Additionally, the electrodes were fixed at their fenestration sites using bone cement. A temporal bone CT scan was performed intraoperatively, and one week and one year postoperatively. In one patient reliable analysis of the intraoperative CT scan was not possible due to a technical error. A displacement of the vestibular electrodes of more than 0.5 mm was considered significant.Fourteen out of 18 electrodes did not show a significant displacement between the intraoperative scan and the first postoperative scan. In the remaining four electrodes, a displacement of ≥ 0.5 mm occurred (mean 0.54 mm, range 0.50–0.58 mm). These four electrodes were found in the two first implanted patients. In both cases, the intraoperative CT scan had a slice thickness of 0.5 mm and showed severe scattering. This might imply that the measured displacement was (partially) related to a higher measurement error. None of the vestibular electrodes migrated outside of the ampulla. No displacement was observed in any of the vestibular electrodes between the first postoperative scan and the one-year follow-up scan.The current surgical technique seems to securely stabilize the vestibular VI electrodes over time.Methods: In vestibular implants (VI), the electrode position is thought to be important for optimal neural activation. The objective of this study was to evaluate the stability of the vestibular electrode position over time.Seven patients implanted with a VI were followed for one year. When possible, the fenestrations of the semicircular canals were kept very small (approximately 0.8 mm) to stabilize the electrode lead. Additionally, the electrodes were fixed at their fenestration sites using bone cement. A temporal bone CT scan was performed intraoperatively, and one week and one year postoperatively. In one patient reliable analysis of the intraoperative CT scan was not possible due to a technical error. A displacement of the vestibular electrodes of more than 0.5 mm was considered significant.Fourteen out of 18 electrodes did not show a significant displacement between the intraoperative scan and the first postoperative scan. In the remaining four electrodes, a displacement of ≥ 0.5 mm occurred (mean 0.54 mm, range 0.50–0.58 mm). These four electrodes were found in the two first implanted patients. In both cases, the intraoperative CT scan had a slice thickness of 0.5 mm and showed severe scattering. This might imply that the measured displacement was (partially) related to a higher measurement error. None of the vestibular electrodes migrated outside of the ampulla. No displacement was observed in any of the vestibular electrodes between the first postoperative scan and the one-year follow-up scan.The current surgical technique seems to securely stabilize the vestibular VI electrodes over time.Results: In vestibular implants (VI), the electrode position is thought to be important for optimal neural activation. The objective of this study was to evaluate the stability of the vestibular electrode position over time.Seven patients implanted with a VI were followed for one year. When possible, the fenestrations of the semicircular canals were kept very small (approximately 0.8 mm) to stabilize the electrode lead. Additionally, the electrodes were fixed at their fenestration sites using bone cement. A temporal bone CT scan was performed intraoperatively, and one week and one year postoperatively. In one patient reliable analysis of the intraoperative CT scan was not possible due to a technical error. A displacement of the vestibular electrodes of more than 0.5 mm was considered significant.Fourteen out of 18 electrodes did not show a significant displacement between the intraoperative scan and the first postoperative scan. In the remaining four electrodes, a displacement of ≥ 0.5 mm occurred (mean 0.54 mm, range 0.50–0.58 mm). These four electrodes were found in the two first implanted patients. In both cases, the intraoperative CT scan had a slice thickness of 0.5 mm and showed severe scattering. This might imply that the measured displacement was (partially) related to a higher measurement error. None of the vestibular electrodes migrated outside of the ampulla. No displacement was observed in any of the vestibular electrodes between the first postoperative scan and the one-year follow-up scan.The current surgical technique seems to securely stabilize the vestibular VI electrodes over time.Conclusion: In vestibular implants (VI), the electrode position is thought to be important for optimal neural activation. The objective of this study was to evaluate the stability of the vestibular electrode position over time.Seven patients implanted with a VI were followed for one year. When possible, the fenestrations of the semicircular canals were kept very small (approximately 0.8 mm) to stabilize the electrode lead. Additionally, the electrodes were fixed at their fenestration sites using bone cement. A temporal bone CT scan was performed intraoperatively, and one week and one year postoperatively. In one patient reliable analysis of the intraoperative CT scan was not possible due to a technical error. A displacement of the vestibular electrodes of more than 0.5 mm was considered significant.Fourteen out of 18 electrodes did not show a significant displacement between the intraoperative scan and the first postoperative scan. In the remaining four electrodes, a displacement of ≥ 0.5 mm occurred (mean 0.54 mm, range 0.50–0.58 mm). These four electrodes were found in the two first implanted patients. In both cases, the intraoperative CT scan had a slice thickness of 0.5 mm and showed severe scattering. This might imply that the measured displacement was (partially) related to a higher measurement error. None of the vestibular electrodes migrated outside of the ampulla. No displacement was observed in any of the vestibular electrodes between the first postoperative scan and the one-year follow-up scan.The current surgical technique seems to securely stabilize the vestibular VI electrodes over time. [ABSTRACT FROM AUTHOR]