Clinical Trial to Compare Two Surgical Approaches to the Cochlea (BULLS-I)

Multicenter Randomized Controlled Trial Comparing Surgical Approaches to the Cochlea for the Slim Modiolar Electrode: Assessing Intracochlear Trauma Using Intraoperative Electrocochleography Measurements and Preservation of Residual Hearing

This is a prospective multicenter multinational randomized control trial. The duration of the study for the individual patient will be approximately 1 year (pre-operative assessments, 1 week, 3 months and 12 months follow-up assessments). Participants will be randomized to one of two surgical approaches: eRW or CO, with a 1:1 allocation in a parallel design.

Study Overview

• Status: Recruiting
• Conditions: Hearing Loss, Sensorineural; Cochlear Implants
• Intervention / Treatment: Procedure: Surgical approach: cochleostomy or extended round window

Detailed Description

Rationale: Preserving residual hearing in cochlear implant (CI) surgery has gained significant attention. It not only signifies minimally invasive implantation but also supports natural sound perception and enables electrical-acoustic stimulation, enhancing sound localization, music appreciation, and speech recognition in noisy environments. Using the Cochlear™ Nucleus® CI with Slim Modiolar electrode (Cochlear Ltd., Sydney, Australia), potential sites of residual hearing loss in surgery include approaches to the cochlear lumen, potential damage during entry, and damage during electrode insertion. Studies comparing different surgical approaches (cochleostomy (CO) and extended round window (eRW)) show varied results. Electrocochleography (ECochG) can be used to indicate intracochlear damage during electrode insertion, however, the variability observed in ECochG responses during cochlear implantation remains significant. Moreover, ECochG has not yet been used to monitor cochlear functions throughout every phase of surgery, including the insertion of the sheath or stabilization of the electrode lead.

Objective: The aim of this study is to investigate whether the type of surgical approach to the cochlea; CO or eRW using the CI632 affects the final residual hearing and secondarily, intracochlear trauma and electrode position, as determined by pure tone audiometry, EcochG and imaging.

Study population: Adult CI candidates with post-lingual onset of severe to profound hearing loss, who are scheduled to receive a Nucleus CI632 with a slim modiolar electrode array and have a preoperative audiometric low-frequency average air conduction threshold of <80 decibel (dB) hearing level at 500 Hz in the ear to be implanted.

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Coby Lindeboom, MD; Phone Number: 024 361 14934; Email: Coby.lindeboom@radboudumc.nl
• Study Contact Backup: Name: Emmanuel Mylanus; Email: Emmanuel.Mylanus@radboudumc.nl

Study Locations

• Netherlands
  • Nijmegen, Netherlands
    • Recruiting
    • Radboud University Medical Center
    • Contact: Lindeboom; Email: Coby.lindeboom@radboudumc.nl

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Individuals aged 18 years and older who have clinically established post-linguistic sensorineural hearing loss.
• CI candidate based on local or national reimbursement criteria.
• Cochlear implantation with a CI632.
• Preoperative 500 Hz pure-tone air conduction threshold <80 dB hearing level (HL) in the ear to be implanted.
• Willing and able to provide written informed consent.

Exclusion Criteria:

• Previous or existing CI recipient.
• Ossification or other anatomical abnormalities of the cochlea or its windows possibly affecting normal electrode array insertion.
• Abnormal cochlear nerve anatomy on preoperative CT or MRI.
• Subjects who are unable to undergo CT or MRI.
• Deafness due to acoustic nerve or central auditory pathway lesions.
• Diagnosis of auditory neuropathy.
• Active middle ear infection.
• Additional handicaps that would prevent participation in study evaluations.
• Unrealistic expectations from the participant regarding the possible benefits, risks, and limitations inherent to the CI procedure and the investigation.
• Cochlear employees or employees of Contract Research Organisations or contractors engaged by Cochlear for the purposes of this investigation.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Cochleostomy; When employing the cochleostomy approach, a carefully positioned opening will be drilled anterior-inferior to the eRW membrane.	Procedure: Surgical approach: cochleostomy or extended round window; Surgical placement of a cochlear implant electrode array
Active Comparator: extended Round Window; In case of the extended round window approach, the scala tympani will be accessed through the extended round window technique, involving the creation of a round window margin cochleostomy.	Procedure: Surgical approach: cochleostomy or extended round window; Surgical placement of a cochlear implant electrode array

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Residual hearing	The difference in residual hearing per group (eRW or CO) between pre- and postoperative pure tone thresholds, averaged at 500, 750 and 1000 Hz (PTAlow).	3-months postoperatively

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
ECochG thresholds after multiple surgery stages	ECochG thresholds with a promontory recording electrode after the following surgery stages: a) posterior tympanotomy (baseline), b) drilling for RW membrane exposure, c) completion of the approach to implantation (CO or eRW), d) sheath insertion, e) electrode array insertion, f) sheath withdrawal, and g) positioning of the electrode lead.	Intraoperatively
Intracochlear electrode position	The position of electrode contacts relative to the modiolus and the angular insertion depth (AID), as assessed with pre- and post-operative CT-scan.	3-months postoperatively

Collaborators and Investigators

• Sponsor: Radboud University Medical Center
• Collaborators: Universitaire Ziekenhuizen KU Leuven; GZA Ziekenhuizen Campus Sint-Augustinus

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2025
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): November 1, 2027

Study Registration Dates

• First Submitted: April 29, 2024
• First Submitted That Met QC Criteria: June 10, 2024
• First Posted (Actual): June 11, 2024

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: February 21, 2025
• Last Verified: February 1, 2025

More Information

Terms related to this study

• Keywords: Imaging; Surgical approach; Electrocochleography; Round Window; Cochleostomy; Residual hearing preservation
• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Otorhinolaryngologic Diseases; Sensation Disorders; Ear Diseases; Hearing Disorders; Hearing Loss; Hearing Loss, Sensorineural
• Other Study ID Numbers: NL85808.091.23

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No