How effective is minimally invasive image-guided surgery for cochlear implantation (CI) in a clinical setting?
Background: Surgical CI typically involves a mastoidectomy with a facial recess approach, after which the cochlea is entered either through the round window or a separate cochleostomy. To date, the vast majority of these surgeries are performed manually, without computer-guided systems. Capitalizing on image-guidance technology, this minimally invasive approach can provide the advantages of traditional CI and suprameatal approaches without the disadvantages.
Study design: Prospective cohort study.
Setting: Vanderbilt University, Nashville, Tenn.
Synopsis: Nine patients consented to the minimally invasive image-guided approach. Once a patient was prepped, three titanium self-tapping anchors were screwed into the skull. The segmented anatomy and drill trajectory from a pre-operative computerized tomography (CT) scan were mapped to the intra-operative CT scan. A specially designed drill press was set to a preplanned distance based on patient anatomy. A stab incision was made where the drill hit the skin, and bone was exposed. Drilling was done with twist drill bits at 50,000 rpm. After lateral drilling, a second intra-operative CT scan confirmed that drilling was on course. A smaller-bore bit was then used for drilling through the facial recess. After securing the internal receiver, the electrode array was passed through the subperiosteal path, into the drilled tunnel, and into the cochlea under direct visualization provided by the tympanomeatal flap. Difficulties encountered included the inability to place the implant, CI electrode damage, tip fold-over, and facial nerve paresis. The most likely injury, despite copious irrigation with saline, was heat injury. Currently, the complication rate and intervention time are greater for image-guided than for traditional CI surgery.
Bottom line: Minimally invasive image-guided CI is clinically achievable, although further clinical study is needed to address technological difficulties encountered during drilling and insertion and to assess potential benefits, including decreased intervention time and decreased tissue dissection.
Citation: Labadie RF, Balachandran R, Noble JH, et al. Minimally invasive image-guided cochlear implantation surgery: first report of clinical implementation. Laryngoscope. 2014:124:1915-1922.