CI Surgery Flashcards
(29 cards)
What surgeon performs the CI procedure?
Surgeons with a background in otolaryngology (ENT) and then advanced training in otology and neurotology
In an interdisciplinary setting, the surgeon’s role for routine cases can be limited to making the initial evaluation, monitoring the ongoing workup, reassuring the patient/parents, reviewing scan images, and performing the surgical procedure
How long is the operation?
Typically 1-2 hours
It’s an outpatient procedure done under general anesthetic, with a low risk of problems or complications
IV antibiotics should be given at least 20 minutes before skin incision
Hospital stay is usually one day for adults and 1-2 days for children
What are the general principles for surgery?
To insert the electrode array deeply and atraumatically into the scala tymapni
To place the body of the device against the side of the head in such a way as to render it least vulnerable to external trauma
To secure the electrode and the body of the device in order to prevent migration of either component
To accomplish these ends without endangering the adjacent tissue such as the scalp external auditory canal tympanic membrane or facial nerve and without damaging the device or electrode itself
This must all be accomplished in such a fashion that infection is prevented, and a satisfactory cosmetic result is obtained
Are there special surgical instruments provided by the supplying companies?
Yes, the surgeon can us them or they can not - depending on how experienced they are
Do all implants come in sterile packaging?
Yes
BTE template - used to ensure the implant is positioned with sufficient space for the ear level sound processor
Non-sterile - used to determine/check the optimum implant position and trace it onto the skin prior to incision
Sterile silicone implant template - used to determine/check the shape of the well excavation and the position of the implant
Implant template - used to check the size of the periosteal pocket - how much they have to drill
What is a soft surgery approach?
Refers to cochlear implantation techniques designed to minimize intracochlear trauma, preserve residual hearing, and optimize electrode placement within the ST relative to SGNs
Aims to reduce disruption to delicate cochlear structures such as the basilar membrane, osseous spiral lamina, and modiolar wall
Focuses on preventing blood and bone dust entry, using steroids, careful surgical site selection, minimizing perilymph leakage and suctioning, and controlling insertion depth
How is an incision done?
Mastoid is exposed using a pedicled flap
Several designs of flaps
Examples:
Interiorly based or C-shaped flap
Posteriorly based or inverted J flap
Inferiorly based flap or extended endaural incision
Superiorly and interiorly based flap
What are the goals of the receiver/stimulator placement?
To minimize protrusion thereby reducing vulnerability to external trauma
To strict device movement that can shear connecting leads
Do they use the templates for drilling into the bone?
Yes
Done to create a bed/well
What happens before or after the creation of the well?
A complete mastoidectomy is performed
The mastoidectomy cavity needs to not be excessively large
What are tie-down holes?
Small holes that are drills in the bone above and below the device to allow nonabsorbable stay sutures to pass through
Used to secure down the implant and to ensure stability of the device and to guard against subsequent migration
Stay sutures are then passed through the holes
The transducer is then laid into the well and secured with the stay sutures
Do many surgeons now omit creating a bony seat and device fixation with sutures?
Yes
Eliminating the bony seat and drill holes decreases the likelihood of CSF leaks and intracranial hematomas
Suture fixation can be accomplished without the tie-down holes by placing them through the periosteum above and below the device
A tight subperiosteal pocket is essential to prevent movement
Bony ridge or tie-down suture needs to be placed in front of the device to prevent its anterior displacement
Is the lack of visibility once the electrode array enters the cochlea a challenge?
Yes, which precludes visualization of both insertion dynamics and final electrode array position within the cochlea
What are the two means of accessing the scala tympani for placement of the electrode array?
Via a basal turn cochleostomy
Via the round window membrane
Also an extended RW cochleostomy
What is a cochleostomy?
Drilling through the promontory directly into the basal turn of the scala tympani, thereby avoiding the hook turn of the most proximal basal turn
Correct placement of the cochleostomy, however, appears critical for avoiding damage to inner ear structures
An attempt should be made to limit the amount of bone dust within the cochlea to prevent new bone formation
Is there less risk with round window insertion?
Yes
How are electrodes inserted in the round window?
The round windoe partially hides behind an overhanging oblique ridge from the promontory, which regularly limits visibility during surgery
The facial recess is the route used in posterior tympanotomy to perform cochlear implantation surgery
The major boundaries of the FR are the facial nerve (FN) and chorda tympani (CT)
The orientation of the round window membrane imposes an upward, inward, and forward trajectory on the electrode array during the initial stage of insertion
The crista semilunaris (C) pushes the array upward toward the osseous spiral lamina
What is a facial recess?
A triangular space created by drilling between the chorda tympani anteriorly, the facial nerve posteriorly, and the incus superiorly
It is important to identify the facial nerve but not to expose it - need to monitor it
It is usually possible to spare the chorda tympani
What is the extended round window approach?
To help guide the array straight into the scala tympani and avoid hitting the spiral lamina, surgeons drill a small part of the posterior lip of the round window and the crista semilunaris
Are electrodes slowly and carefully threaded into the cochleostomy?
Yes
Less force is applied when you move slowly
What are the three primary goals of electrode insertion?
Deeper insertion into the scala tympani (ST) to access lower frequency cochlear neurons
Greater operating efficiency, defined as a reduction in the stimulus charge required to produce a comfortable loudness level.
Reduced intracochlear damage associated with surgical insertion
How do you seal a cochleostomy?
Periosteum harvested from the patient’s Palva flap
Good source of soft tissue
Bone wax and other nonbiological sealants are not recommended
What is done with the extra length of the proximal part of the electrode?
It is coiled in the mastoid cavity
What is critically important when sealing a cochleostomy?
May assist with electrode stabilization
Prevent electrode extrusion
Prevent ascending infections after otitis media
Possibly prevent meningitis
