Is hearing preservation possible with the Slim Modiolar electrode?

By Wade Colburn, Product Manager – Cochlear Implants

As we become more confident in cochlear implant outcomes, more patients with residual hearing are being evaluated for cochlear implant candidacy. The questions that often arise include:

1. How do we manage these patients?
2. What electrodes should be used to preserve and maximize acoustic hearing?

The perimodiolar electrode is a rapidly growing category of electrodes, but has historically been categorized as an electrode for traditional cochlear implant candidates with limited residual hearing. With the introduction of the Slim Modiolar electrode, an electrode with a slim atraumatic design with consistent in placement within scala tympani and close to the modiolus^1-3, the question stands – is hearing preservation possible with the Slim Modiolar?

Progress in Preservation

Preservation is not easily defined, but it is well understood that there are two types of preservation: structural and functional.

Structural preservation, meaning the limited disruption of the cochlea and consistent scala tympani placement, is the first step to functional hearing preservation.

Functional preservation maintains residual hearing that can be amplified acoustically. Combining electric and acoustic hearing has been attributed to improvements in sound quality, music and speech in background noise.³

A recently published consensus paper that considered the standardization of hearing preservation and other metrics defined functional hearing as patients with a pure tone average (PTA) > 80 dB HL at 125, 250 and 500 Hz.⁴

Structural Preservation

During the development of the Slim Modiolar electrode researchers looked to take the great hearing outcomes of the Contour Advance, and improve upon them by focusing on key design goals:

• Goal: Thin, atraumatic design

Result: With the world’s thinnest full length perimodiolar electrode, the Slim Modiolar takes up to 60% less volume in scala tympani.⁵ This was achieved by developing a sheath-based system.

• Goal: Insertion via round window

Result: With approval for round window and extended round window insertions, Slim Modiolar allows for the ability to obtain the access to the cochlea desired.

• Goal: Consistent scala tympani placement

Result: The importance of scala tympani placement is well understood. With the Slim Modiolar electrode, consistent scala tympani placement is achieved with a range of studies showing anywhere between 89 to 100% placement within the scala tympani.^3,6

Since the introduction of the Slim Modiolar, outcomes evidence collected has demonstrated successful achievement of atraumatic insertions and structural preservation. For example, in a large bone study, the Slim Modiolar Electrode was able to preserve the delicate structures of the cochlea, with no intracochlear trauma in 98% of the specimens.^1,2

Functional Preservation

In his publication, Surgical Experience and Early Outcomes With a Slim Perimodiolar Electrode, Dr. David Friedmann from NYU explores some implications of functional preservation – specifically 6-month speech perception on CNC word (N=94).⁷

The evidence presented is based on a subset of the 237 Slim Modiolar recipients implanted at NYU since Slim Modiolar was launched in 2016.

Some key findings include:
• 43/94 patients with preoperative unaided LF-PTA < 80 dB⁷
• 16/43 (17 ears) (37%) patients maintained a LF-PTA mean thresholds at 250 and 500 Hz better than 80 dB at initial activation⁶
• Average threshold shifts 20.1 dB at initial activation⁷

Based on presented outcomes, Friedmann states, “Hearing preservation is possible with a number of patients utilizing acoustic low frequency hearing in conjunction with electric stimulation from their CI.”

Setting a New Benchmark

According to a growing compendium of evidence, the Slim Modiolar redefines what is possible with a perimodiolar electrode. With proven structural preservation and published functional preservation⁶ in traditional cochlear implant candidates, it opens the door for further research to be done showing that preservation is possible with the Slim Modiolar.

The Slim Modiolar electrode array is available on the newly released Profile Plus CI600 series (CI632).

To learn more about the Slim Modiolar electrode please watch this video now or visit our website.

About the author: Wade is the Product Manager for Cochlear Implant product portfolio within Cochlear Americas.  Wade’s responsibilities include product positioning and messaging, life-cycle management, new product launches and surgical support and training. Wade has recently joined Cochlear, but comes from an engineering background with the medical device field, including previous otology experience. 

References:

1. Cochlear Limited. 588021.CI532 Temporal Bone Usability Test Report. 2014; Data on file.
2. Cochlear Limited. 415680. EA32 Electrode Insertion Safety and Performance Study. 2015; Data on file.
3. Clinical Evaluation of the Cochlear Nucleus CI532 Cochlear Implants in Adults Investigator Meeting. 2019 Apr.
4. Cochlear Limited. 028-M270-03. Hi-Focus Mid-Scala Electrode brochure and Flex 2. Data on file. https://www.advancedbionics.com/content/dam/ab/Global/en_ce/documents/professional/HiFocusMid-Scala_Electrode_Brochure.pdf
   https://s3.medel.com/downloadmanager/downloads/maestro_2013/en-GB/22676.pdf Aug. 2016
5. Adunka O, Gantz B, Dunn C, Gurgel R, Buchman C. Minimum Reporting Standards for Adult Cochlear Implantation. Otolaryngol Head Neck Surg. 2018 Aug;159(2):215-219. doi: 10.1177/0194599818764329. Epub 2018 Mar 20.
6. Friedmann et al. Surgical Experience and Early Outcomes With a Slim Perimodiolar Electrode. NYU Cochlear Implant Center. Otology & Neurotology, Vol 40, No. 3,2019.
7. Shaul C, Dragovic AS, Stringer AK, O’Leary SJ, Briggs RJ. Scalar localization of peri-modiolar electrodes and speech perception outcomes. J Laryngol Otol 2018; 1-7. https://doi.org/10.1017/S0022215118001871