2015 Volume 25 Issue 2 Pages 144-149
After the new indication for pediatric cochlear implantation in Japan was announced, several points emerged to be considered during cochlear implantation surgery in young children. The main changes in the new indication are setting the lowest age of implantation as 1 year old, setting the lowest weight of the patient as 8 kg, and approving the bilateral implantation. In this article, four points are discussed from the viewpoints of surgical techniques.
The first point to be considered is about bleeding. Young children have mastoid cavity with less pneumatization and more bone marrow causing much bleeding during mastoidectomy. Considering that young children have small amount of total circulating blood volume and can cause hypovolemic shock with less blood loss than adult, careful hemostasis is necessary in mastoidectomy of young children. To achieve good hemostasis, it is recommended to use diamond bur and bone wax and to complete mastoidectomy in a short time.
Second, skin incision should not be extended toward a mastoid tip in younger children. Stylo-mastoid foramens exist in a more lateral position in young children due to poor development of mastoid tips. Therefore, extended skin incision toward a mastoid tip may cause facial nerve injury in younger children.
Third, careful manipulation is necessary for fixation of the receiver-stimulator. Most surgeons create a bony well for receiver-stimulator and also create small holes for the tie-down suture to secure the receiver-stimulator onto the cranium. However, younger children have thin cranial bone thickness. Therefore, sometimes it is stressful to make suture-retaining holes because this manipulation requires the exposure of dura mater in younger children. One of the resolutions for this problem is to use self-drilling screws to anchor sutures. With 3 mm-length screws, sufficient stability is available even on 1.5 mm thick cranial bone by inserting screws in oblique fashion.
Fourth, bilateral cochlear implantation limits the usage of monopolar cautery due to electrical current passing the body. Instead of monopolar cautery, heated scalpel is useful in the second cochlear implant surgery. Bilateral surgery may cause bilateral vestibular dysfunction, which result in severe dysequilibrium problems. It is possible to avoid these problems by applying minimally invasive cochlear implant surgery including round window approach and usage of a soft and slim electrode array.
In conclusion, cochlear implantation for young children can be performed safely with well understanding of pitfalls of the surgery and with appropriate surgical techniques.
