When you’re considering a cochlear implant, most of the conversation naturally centres on brands, reliability, MRI safety, and the external sound processor. But inside every cochlear implant is the true workhorse: the electrode array. This tiny structure is threaded into the cochlea and delivers electrical stimulation to the hearing nerve. Its shape and placement—most commonly pre-curved (sometimes called “perimodiolar” or mid-scala) or straight (often called “lateral-wall”)—can influence surgical handling, cochlear structure preservation, programming flexibility, and, ultimately, your listening experience.
This guide explains what those electrode terms mean, how they differ, and where Advanced Bionics’ HiFocus™ Mid-Scala (pre-curved) and HiFocus™ SlimJ (straight) options—available on the HiRes™ Ultra 3D implant—fit in. It’s written for Singapore patients and families who want a clear, trustworthy overview before speaking with their ENT surgeon and audiologist. (Nothing here replaces personalised medical advice.)
Electrode basics: pre-curved vs straight (and where they sit in the cochlea)
The cochlea (inner ear) is a delicate, spiral-shaped structure. During cochlear implant surgery, the electrode array is inserted into the scala tympani—one of the fluid-filled chambers.
- Pre-curved (perimodiolar/mid-scala) arrays are designed with a curvature or “memory” so they sit closer to the modiolus (the central core that houses the auditory nerve). The goal is more focused neural stimulation with potentially lower current needs
- Straight (lateral-wall) arrays generally lie along the outer/lateral wall of the scala tympani. Modern straight arrays emphasise smooth handling, flexible insertion, and structure preservation across a wide range of cochlear anatomies.
Across manufacturers, both styles have strong clinical rationales; outcomes depend on surgical technique, patient anatomy, residual hearing, programming, and rehabilitation.
Why the choice matters: practical differences you’ll hear about
- Structure preservation: Gentle, well-controlled insertions that stay in scala tympani help protect delicate membranes—important if you still have residual (low-frequency) hearing that your team aims to preserve.
- Programming flexibility: Arrays that sit closer to the nerve may enable more focused stimulation; lateral-wall designs can provide broad cochlear coverage and are often praised for predictable handling. Evidence is mixed and evolving; your team will match the array to your anatomy, hearing profile, and goals.
- Surgical handling and consistency: Surgeons consider cochlear size, round-window access, desired insertion depth, and how consistently a given array sits where they intend it to.
The platform: Advanced Bionics HiRes™ Ultra 3D implant
HiRes Ultra 3D is Advanced Bionics’ internal implant platform that supports both HiFocus electrode options below. It’s designed for 3 T MRI without magnet removal (3D magnet design) and is extensively tested for reliability and impact resistance—reassuring for active children and adults alike.
At Cochlear Implants by The Listening Lab, we are an authorised Advanced Bionics distributor in Singapore, so we support both electrode options during candidacy discussions and surgical planning.
Pre-curved option: HiFocus™ Mid-Scala (on HiRes™ Ultra 3D)
Design intent: Provide consistent, mid-scalar placement in scala tympani with controlled, surgeon-friendly insertion. AB literature highlights consistent insertion depth (tight standard deviation across cases), dedicated tooling for precise.
What this can mean for patients:
- A placement that aims to balance proximity to neural targets with atraumatic technique.
- Potential for focused stimulation thanks to the contact geometry and mid-scalar trajectory.
Note on claims: Some AB materials historically described Mid-Scala as a unique, pre-curved array targeted to the middle of scala tympani. As other designs continue to evolve, we recommend discussing current, brand-agnostic comparisons with your surgeon.
Straight option: HiFocus™ SlimJ (on HiRes™ Ultra 3D)
Design intent: Deliver a straight, lateral-wall array that combines balanced stiffness with a tapered profile for smooth handling and structure preservation.
What this can mean for patients:
- A widely adopted lateral-wall approach that aims for atraumatic insertion and broad cochlear coverage.
- Emerging clinical literature reports favourable hearing-preservation outcomes with SlimJ in appropriately selected patients and techniques.
Mid-Scala vs SlimJ at a glance
| Feature | HiFocus™ Mid-Scala (pre-curved) | HiFocus™ SlimJ (straight) |
| Intended cochlear position | Mid-scala / closer to the modiolus | Lateral wall |
| Surgical handling | Purpose-built tools for controlled, consistent insertion depth | Balanced stiffness and tapered profile for smooth insertion |
| Clinical emphasis | Placement consistency, focused stimulation | Structure preservation, broad cochlear coverage |
| On HiRes Ultra 3D | Yes | Yes |
(Your actual recommendation will depend on anatomy, residual hearing, and surgeon preference.)
How your Singapore care team decides
In Singapore, candidacy and device selection involve a multidisciplinary team (ENT surgeon, audiologist, speech therapist). You’ll review imaging, discuss hearing goals (e.g., hearing-preservation vs full insertion depth), MRI needs, and lifestyle. Public centres (e.g., SGH) emphasise balanced, family-friendly information and a team-based pathway from evaluation to habilitation—your private clinic will follow similar principles.
Practical tips for patients and caregivers
- Ask about cochlear anatomy: “Do my scans suggest anything that favours a pre-curved (Mid-Scala) or straight (SlimJ) array?”
- Discuss hearing-preservation goals: If you still hear low frequencies, ask how electrode choice and soft-surgery techniques protect structures.
- Confirm MRI needs: If you anticipate frequent MRIs, confirm 3 T MRI workflow with the HiRes Ultra 3D platform.
- Plan for programming: Enquire how electrode style may influence initial activation and map adjustments over time.
- Think long-term care: Understand follow-up schedules, processor upgrades, and rehabilitation support available in Singapore.
When AB’s two options make particular sense
- You value consistent, targeted placement: Your surgeon may lean towards HiFocus Mid-Scala for its mid-scalar intent and controlled insertion tooling—especially if imaging suggests it will deliver stable placement in your cochlea.
- You prioritise a gentle, lateral-wall approach: HiFocus SlimJ is often selected when structure preservation and smooth handling are the primary goals, while still providing robust cochlear coverage.
Conclusion: the “right” electrode is the one matched to you
Both pre-curved and straight electrodes can deliver excellent outcomes when they are well-matched to your anatomy and goals and inserted with atraumatic technique. Advanced Bionics’ HiRes Ultra 3D platform supports both approaches—HiFocus Mid-Scala and HiFocus SlimJ—giving Singapore surgeons flexibility to personalise care.
Next step: Book a consultation with Cochlear Implants by The Listening Lab. As an authorised Advanced Bionics distributor in Singapore, we’ll coordinate with your surgeon and audiologist, review your imaging and hearing profile, and help you choose confidently.
This article is for education only and does not constitute medical advice. Always consult your surgeon and audiologist for personalised recommendations.