1The Operation in Context: What Implant Surgery Must Achieve

FThe four things the operation must deliver

Every implant operation has the same skeleton: a postauricular flap, a simple (cortical) mastoidectomy, a posterior tympanotomy through the facial recess, an opening into the scala tympani, secure fixation of the receiver-stimulator, and watertight closure. Full insertion of an array within the basal turn corresponds to an insertion depth of roughly 25 to 30 mm depending on array length, with the most apical contacts reaching spiral ganglion cells subserving low frequencies and basal contacts the high frequencies. Atraumatic insertion is a defining modern goal: aggressive advancement risks buckling that injures the spiral ligament and basilar membrane, so resistance is met by withdrawing slightly and reinserting rather than forcing the electrode. Facial nerve preservation is paramount; the most frequent mechanism of injury is heat from the bur shaft rotating over the nerve in the facial recess, mitigated by copious irrigation and keeping a thin bony shell over the nerve.[2009][1997][2005]

FA short-stay, low-morbidity operation

The procedure is performed in the standard otologic position under general anaesthesia using routine aseptic technique, and in experienced hands serious complications are rare and the majority of ears can be safely implanted. Across a multicentre survey of 2,751 implants the major and minor complication rates were 8% and 4.3% respectively, falling in a later 459-patient survey as technique matured. Wound and flap problems are the commonest significant complication; in a combined Hannover-Melbourne series wound breakdown forced device removal in only 2 of 253 ears (0.8%). A light mastoid dressing is typically kept overnight and removed the next morning, and adult patients can generally be discharged the same day of surgery. Some authors now perform the adult operation in an outpatient ambulatory setting, reserving general anaesthesia chiefly for children and for those who cannot tolerate the case awake.[2009][1997][2012]

TWho operates and where it sits in the journey

Implantation is performed by an otologist or neurotologist, ideally one who has rehearsed the specific device in a temporal-bone dissection laboratory before operating, since each manufacturer's array demands slightly different handling. Surgery follows audiological candidacy and imaging clearance and precedes activation; it is one discrete event in a longer pathway dominated by rehabilitation and programming. Candidates and families must understand that the operation alone confers nothing without a sustained course of programming and therapy, and must be physically and psychologically able to complete it. Intraoperative facial nerve monitoring is widely used and is especially valuable in cochlear malformation, where the nerve may run an aberrant course.[2009][2014]

CFrom radical cavities to minimal access

Early surgery favoured a C-shaped postauricular incision that compromised flap blood supply; the modern posteriorly and inferiorly based inverted-J flap reduced flap-related complications. The dominant trend has been toward a minimal approach, with smaller incisions, less undermining and reduced or absent head shaving aimed at cutting flap complications, operative time, pain, and haematoma or seroma. One described simplification uses a horizontal incision as small as 1.5 cm with minimal undermining, and a region only about 3 by 3 cm need be shaved. Postoperative waiting before activation has shortened; a 6-week interval in adults is safe with higher patient satisfaction and no increase in extrusion or fixation failure, and same-day activation is now sometimes possible.[2009][2012][2003]