5Choosing a Nucleus Array: Perimodiolar vs Lateral Wall

TThe Contour Advance

The Contour Advance is the classic perimodiolar array: 22 half-banded platinum contacts inserted with the Advanced Off-Stylet (AOS) technique to hug the modiolus, FDA-approved 2005. Half-banding faces current toward the cochlear nerve, lowering thresholds and channel interaction; base diameter ~0.8 mm, insertion ~18–20 mm reaching ~420–450°, tip-to-most-basal-contact 15 mm.[2020]

CThe Slim Modiolar

The Slim Modiolar (CI532/CI632, launched 2016) is the industry's thinnest perimodiolar array, pre-curved inside a sheath and deployed off-stylet. It occupies ~60% less scala tympani volume than the Contour Advance (tip 0.35 mm, base 0.475 mm), enabling round-window insertion while still reaching a perimodiolar position; Aschendorff et al. (2017) noted it requires surgeon training.[2017]

TThe Slim Straight

The Slim Straight (CI522/CI622, US release 2012) is the lateral-wall array (tip 0.3 mm, base 0.6 mm, ~25 mm) for softer, deeper, structure-sparing insertion. Full ~25 mm insertion gives ~450–540°; a secondary 20 mm depth marker allows a shallower ~360° insertion to preserve apical low-frequency structures.[2005]

CThe 'inside track'

The 'inside track' concept: a shorter perimodiolar array (~18 mm Slim Modiolar) reaches a comparable angular depth (~420–450°) to a longer lateral-wall array (~25 mm Slim Straight at ~450–540°), because the modiolar lane is the inner running lane of the spiral.[2014]

TThe Hybrid L24

The Hybrid L24 is the short hearing-preservation electric-acoustic array (~16 mm, ~240–250° insertion), FDA-approved November 2013 as the first US Hybrid (EAS) CI, deliberately stopping short of the apex to spare native low-frequency hearing (developed in detail in Module 11).

CSpecial and legacy arrays

Older and special arrays round out the family: the Double Array (a basal plus a more apical bundle, now withdrawn) for ossified cochleae, and the earlier full-band straight arrays that preceded today's modiolus-facing half-banded designs. The default coding strategy across the family is ACE, an n-of-m peak-picker (cross-ref Ch.8).