4The Nucleus Family Tree: From CI22 to CI600
The Cochlear Nucleus line is the original multichannel implant and the world's most-implanted, born from Graeme Clark's Melbourne work. This module decodes its receiver-stimulator lineage, the parallel processor generations, and the elegant model-number convention in which one digit names the platform and another names the array.
TClark's Melbourne lineage
Nucleus descends from Clark's University of Melbourne multichannel device, commercialised via Telectronics/Cochlear Ltd (Australia). The Nucleus 22 was the first multichannel CI to gain FDA approval — for adults in 1985 and children in 1990 — and Cochlear is now the world's largest CI manufacturer (cross-ref Ch.1 History).[2020]
CTwenty-two contacts
The defining architectural choice is 22 intracochlear contacts, retained across every generation from CI22M to today (versus MED-EL 12 and Advanced Bionics 16). The extracochlear references are MP1 (a ball electrode under temporalis muscle) and MP2 (a plate on the titanium case); monopolar mode uses MP1+2.[1982]
TThe receiver-stimulator line
The receiver-stimulator lineage runs CI22M → CI24M → CI24R (Contour) → CI24RE (Freedom, US release April 2005) → CI500 series (Profile, e.g. CI512) → CI600 series (Profile Plus, CI612/CI622/CI632). The CI24M added Neural Response Telemetry; the Profile case is described as about 2.5× stronger than the Freedom case.[2008]
CThe model-number code
The model-number suffix names the array: on the Profile platform CI512 = Contour Advance, CI522 = Slim Straight, CI532 = Slim Modiolar; the CI600/Profile Plus renames these CI612/CI622/CI632. The carrier-frequency change (2.5 MHz on CI22M to 5 MHz on all later implants) is encoded in coil compatibility.[2014]
TThe processor lineage
Processors form a parallel lineage: WSP/MSP/Spectra (Nucleus 22 era) → Freedom → Nucleus 5 (CP810) → Nucleus 6 (CP910/CP920) → Nucleus 7 (CP1000, FDA summer 2017, first made-for-iPhone CI processor, 7.9 g) → Nucleus 8 (CP1110); Kanso and Kanso 2 are the off-the-ear single-unit options.
CReliability and MRI
Reliability and MRI: over 170,000 Nucleus Freedom implants were placed with a 99.0% cumulative survival at 12 years; Freedom/Profile support MRI at 3.0 T with the magnet surgically removed and 1.5 T with the magnet in place and a head bandage, while newer Slim Modiolar platforms increasingly allow scanning without magnet removal (verify current labeling).
What does that tell you?
How many intracochlear contacts has every Nucleus generation carried?
In the Nucleus naming convention, what does the model number encode?