Minimally Invasive Cochlear Implantation Offers Benefits Over Traditional Procedure

Editor: Cochlear implant surgery is becoming increasingly routine; it's now common to perform it on an outpatient basis. A new surgical procedure promises to further reduce the trauma of the surgery.

Here's the Newswise press release.

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Cochlear implantation carries with it several risks, which include facial nerve injury, meningitis, and flap infection with potential for flap necrosis. The intrinsic difficulty of an operation may be a reflection of the surrounding structures, both the intricacy and complexity of the middle and inner ear. Basically, placing prosthesis into the cochlea and having a receiver/stimulator situated within the skull carries a risk of infection, contamination and tissue breakdown. Traditional cochlear implantation involved a large scalp flap, mastoidectomy (a surgical removal of the mastoid air cells), posterior tympanotomy via the facial recess, creating an opening in the cochlea, and insertion of the electrode into the scala tympani.

Researchers in Texas propose minimally invasive cochlear implantation (MICI) as a technique in which creation of a large scalp flap is avoided, thereby reducing complications. The most common complications with cochlear implantation involve flap breakdown and electrode misplacement. With the MICI, the large scalp flap has been replaced with creation of a subperiostial pocket for the cochlear implant device. MICI requires a 3-4 cm long post auricular incision placed approximately 1.0cm posterior to the postauricular crease. The decreased tissue trauma and edema has permitted postoperative day one programming and use of the cochlear implant (CI).

Their efficacy of this procedure is explained in depth in a new study. The authors of "Complication Rate of Minimally Invasive Cochlear Implantation," are Elias D. Stratigouleas MD, Brian P. Perry, MD FACS, Susan Marenda King MD, and Charles A. Syms III, MD MBS FACS, all from the University of Texas Health Science Center at San Antonio, San Antonio, TX. Their findings are to be presented at the 109th Annual Meeting & OTO EXPO of the American Academy of Otolaryngology-Head and Neck Surgery Foundation, being held September 25-28, 2005, at the Los Angeles Convention Center, Los Angeles, CA.

Methodology: The data for this retrospective study was obtained through a chart review of records at the Ear Medical Group, San Antonio, TX. The patient data recorded included Sex, date of birth, date of inset, cause of hearing loss, side of implant, pre lingual versus post lingual, length of follow up, and implant brand/type. All complications were recorded and divided into life threatening, major, and minor categories. Major complications include those necessitating hospitalization or revision surgery, meningitis and facial nerve injury. Minor complications are those that are managed conservatively on an ambulatory basis.

One hundred seventy-six patients were included in the study. There were 102 females and 74 males included in the study. Age at implantation ranged from 0.9 to 85.5 years of age with an average age of 26.5 and a mean of 12.1 years of age. One hundred seven had right sided cochlear implantation, 65 five patients had left sided, and four patients had bilateral placement.

Results: Seven major complications were recorded; six patients necessitated revision surgery. Three patients had device failure, including intermittent lock, requiring replacement of their cochlear implant. The non-surgical major complication included one facial nerve paralysis secondary to thermal injury. This immediate facial nerve paralysis had a near full recovery. Three out of seven of the major complications were due to cochlear implant device failure, and not attributable to MICI surgery itself.

Minor complications included one patient who had a flap infection requiring oral antibiotics and use of topical bacitracin ointment, complete healing occurred in four weeks. One patient complained of a distinct change in taste, which resolved after the first postoperative visit. Two patients had receiver/stimulator migration that did not require repositioning. One patient complained of increased tinnitus from baseline (while another had resolution of tinnitus). One patient complained of dizziness only with device use, while three others had transient postoperative balance problems. Three patients had a delayed facial palsy (BP) post operatively with complete resolution.

Conclusions: The total complication rate for MICI in this study is 12.5 percent (major: 3.98 percent, minor: 8.52 percent). The lack of a scalp flap seems to eliminate flap tissue death all together, albeit there still were two superficial infections requiring conservative treatment.

Another observation made in this study was the three delayed facial palsies were noted post operatively. These all resolved and were treated as delayed facial palsies at the time. The researchers believe that the surgical trauma of a mastoidectomy and facial recess with resulting inflammation could be enough to allow reactivation of herpes simplex virus II.

The complication rate noted in this study utilizing minimally invasive cochlear implantation is no higher than reported for traditional implantation. The advantages of avoiding a scalp flap include minimizing the chance of infection, tissue death and ultimate flap failure, as well as a smaller and much less noticeable scar made with this technique. The decreased tissue trauma also allowed for programming of their cochlear implant at an earlier interval following surgery. Programming on post operative day number one and expedited use of the cochlear implant, is also a great advantage with this technique. For these benefits, minimally invasive cochlear implantation is suggested as a preferred option for the patient undergoing this procedure.