Cochlear Implant
Considerations
Hearing
Timing
Ear selection
shortest duration of deafness
more consistent use of a hearing aid
most radiographically favorable anatomy
ear of dominant hand, if otherwise equal
Anatomy
well-pneumatized mastoid
normal facial nerve anatomy
normal inner ear development
patent cochlea
Vaccinations
PCV 13 @ 2,4,6,12-15 months of age, at least two weeks prior to implantation
PPSV 23 recommended at 24 months of age
Device
Preparation
Device
Be sure you have the correct device (review the audiologist's notes)
Be sure you have 2 boxed devices (1 backup)
If using Cochlear Americas, make sure NRT device is charged and in room
Operative microscope
Observer viewfinder to opposite side of operated ear
Balance
Facial nerve monitor
Avoid long-acting paralytic
Pre-incision antibiotic
Ancef
Dexamethasone
Shave the hair behind and superior to the ear
Mark the placement for the manufacturer templates for the BTE processor and internal receiver
Dr. Schloegel: Mark the angle of orientation and the anterior edge of the internal receiver
Dr. Y: Ask if the patient commonly wears a hat and mark the hat's position
Mark the incision
Standard post-auricular (mastoid type) incision with postero-superior extension
Drs. Schloegel and Y: "Lazy S" incision, also called "hockey stick" by some
Keep the post-auricular limb ~ 3-5 mm from the sulcus since it is favorable to hug the EAC
Rivero: postauricular incision without superior extension
Local anesthesia
1% lidocaine with 1:100,000 epinephrine
Drape
Mastisol and cut 10-10 behind ear covering hair
Dr. Y: Only the Ioban over the face and ear with the ear folded anteriorly
Rivero: ear drape and thyroid drape
Procedure
Incision
To level of the level of the temporalis fascia superiorly and mastoid periosteum inferiorly
Raise skin flaps
anteriorly to the ear canal
posteriorly to allow for placement of the internal receiver
Raise the musculoperiosteal flap
Drs. Schloegel and Y: Superior based
vs anteroinferiorly based (Palva flap)
Expose spine of Henle
Mastoidectomy, limited vs complete
Dr. Schloegel: The goal is to find the incus
Maintain hard shelf posteriorly and superiorly; Avoid saucerization
Identify Koerner's septum
Enter the antrum
Identify the LSCC
Identify the body of the incus
Drill the facial recess
3 to 1 mm diamond burrs
saucerize the landmarks
chorda tympani
incus buttress
facial nerve
may need to remove bone antero-medial to facial recess
may need to sacrifice the chorda in a narrow facial recess
Expose the round window niche
may need to drill the lip using a 1.5 to 1 mm diamond burr
Plug epitympanum and facial recess
Dr. Schloegel: Epinephrine soaked cotton ball
vs Gelfoam
Irrigate and remove bone dust
50,000 units bacitracin powder dissolved in 1000 mL normal saline solution
Place the dummy internal receiver and mark the bony well and connecting trough
Drill the bony device well, connecting trough, and suture tunnels
Dr. Schloegel: Drill two 4 mm self-tapping screws and tie two 4-0 Ticron sutures to each
Dr. Y: Use 2-0 Silk instead
Enter the cochlea
Drs. Schloegel and Y: Rosen or straight pick to enter the round window membrane
vs drill the cochleostomy with 1 mm diamond burr at slow drill speed
immediately antero-inferior to the round window niche
Place the internal receiver and secure
Insert the electrode array into the scala tympani
Drs. Schloegel and Y: Guide the electrode with the fork and micro grasper
Plug the cochleostomy with temporalis fascia
Dr. Y: Plug the facial recess with muscle
Bury the ground electrode under the temporalis muscle antero-superiorly
Optional: Perform neural-response telemetry and impedence testing
Optional: Perform plain film to evaluate placement in the cochlea
Close in layers
Approximate the musculoperiosteal flap with 3-0 Polysorb
Approximate the deep dermis with buried 4-0 Polysorb
Dr. Y: 4-0 Biosyn
Approximate the skin edge with running 5-0 Fast Gut
Dressing
Drs. Schloegel and Y: Mastisol, steri-strips, Glasscock
vs. Mastoid dressing
Special considerations intra-op
If serous otitis media present
irrigate with saline and given IV cefazolin
post op: Floxin drops
Sample operative report
Findings:
Hearing status on ***: *** hearing loss
Temporal bone anatomy ***
Performed *** sided *** cochlear implantation
Glasscock dressing applied
Procedure in detail:
The patient was transported to the OR and placed in supine position of the OR table. After a time-out, the patient was placed under general endotracheal anesthesia. The table was turned 180 degrees. Facial nerve monitor was placed and tested. Hair was shaved. After cleansing the skin, CI dummy templates were placed and marked. The post-auricular lazy S pattern incision was infiltrated with local anesthesia. The ear was then prepared and draped in standard sterile fashion.
The incision was made with a #15 blade onto the deep temporalis fascia and mastoid periosteum. At the temporalis level, the dissection was then continued inferiorly and the ear was raised forward. The periosteum of the mastoid/temporalis was then incised with to raise a superiorly based flap. A temporalis fascia graft was taken and set aside to dry for later use.
The mastoidectomy was performed, starting with a size 5 cutting burr, and subsequently decreasing in size. Saucerization was not performed, rather a hard edge was created in the mastoid cavity. Facial recess was performed using diamond burrs. The round window niche was identified and the overhanging lip was taken down with the 1 mm diamond burr to expose the membrane.
The well of the implant was then drilled with a 4 cutting burr as was the canal connecting it to the mastoidectomy. Two 4 mm self-tapping screws were used to secure 2-0 Ticron ties.
Attention was then turned back to the cochleostomy. The implant was opened, and the body was secured with the silk ties. The electrode was then inserted. A full insertion was achieved. Temporalis fascia was packed around the cochleostomy site and buffer the electrode from the facial nerve in the recess. Bone wax was used to secure the electrode within the drilled well.
The postauricular incision was closed in 3 layers. The deep tissue, including the periosteum, was closed with interrupted 3-0 Polysorb, the subcutaneous tissue with interrupted 4-0 Polysorb, and the skin with running 5-0 Fast-absorbing gut. Mastisol and Steri-Strips were applied. A Glasscock dressing was applied to the head.
The patient was then returned to the care of Anesthesiology, and the patient was awoken without complication. The facial nerve was found to be fully functional after the conclusion of the procedure.
Post-op
POD 2 remove Glasscock dressing
Dr. S: Antibiotics (anti-streptococcal), such as Augmentin, for 7 days
Acetaminophen PRN pain vs Tylenol with Codeine
Keep the wound dry
RTC POD 7, remove steri-strips
3-4 weeks fit signal processor and activate