Surgery for cochlear prosthesis insertion exposes the patient to several potential risks. We review the surgical complication experience with cochlear implants in the United States. There have been no deaths attributable to these devices, few serious major complications, and relatively few minor complications. Major complications usually have to do with surgical technique and include flap necrosis, improper electrode placement, and rare facial nerve problems. Minor complications include dehiscence of incisions, infection, facial nerve stimulation, dizziness, and pedestal problems with the Ineraid device. Complications were less frequent in children than adults and were more likely to occur in the younger children than those above the age of 7 years. Complications were still fewer in groups of patients operated on within tightly controlled protocols. There was no increased incidence of otitis media in children who received the Nucleus Mini-22 device, and no reported sequelae from such otitis when it occurred.

A questionnaire was sent to 152 surgeons to survey complications associated with the implantation of the Nucleus multichannel cochlear implant. Complications were categorized as life-threatening; major, if they necessitated revision surgery; or minor, if they resolved spontaneously or with minimal treatment. A total of 55 complications occurred in 459 reported operations for an overall complication rate of 11.8%. There were no deaths, but there was one life-threatening complication, a case of meningitis. There were 23 (4.8%) major complications, most of which involved flap design or electrode insertion (and included the case of meningitis). There were 32 (7 %) minor complications. Most of the complications might have been avoided by proper training, planning of the operations, and careful attention to detail. We recommend that all prospective implant surgeons attend a device-specific training course and practice in the temporal bone laboratory.

Cerebrospinal fluid (CSF) leak has been a constant and unresolved complication of acoustic tumor surgery. This study retrospectively reviews 381 primary acoustic tumor surgeries performed by a single, senior, neurotologist and neurosurgeon team from 1979 through 1991. There were 68 cerebrospinal fluid leaks in 66 patients (66/381; 17%). There was no significant difference in the incidence of CSF leak between the translabyrinthine group (21%) and the retrosigmoid transmeatal group (16%). Translabyrinthine leaks were evenly divided between rhinorrhea and the postauricular wound while retrosigmoid transmeatal leaks were predominantly rhinorrhea. Eleven of 14 translabyrinthine wound leaks responded to pressure dressing and suture. The remaining 3 ceased with continuous lumbar cerebrospinal fluid drainage. Ten of 14 cases of translabyrinthine rhinorrhea responded to continuous lumbar cerebrospinal fluid drainage, and those in whom it failed were cured with revision of the mastoidectomy/labyrinthectomy cavity. Twenty-one of 28 cases of retrosigmoid transmeatal rhinorrhea responded to continuous lumbar cerebrospinal fluid drainage, and those in whom it failed were cured with extracranial, transmastoid revision. The incidence of cerebrospinal fluid leak was not influenced by age, sex, size of tumor, postoperative hydrocephalus, or the intraoperative use of autologous fibrin glue. Meningitis was an unusual complication, occurring in 3% of all patients.

Our cochlear revision series are comparable to what is reported in the literature. However, an unexpected relationship between meningitis was identified among our soft failure group. More than one-quarter carried a history of meningitis. Moreover, nearly one-half of all soft failures had some form of inflammatory derangement. We used the soft failure criteria established by the 2005 Consensus Development Conference for our population analysis. Although we agree that audiologic data often are essential for defining soft failure, multiple patients in our series experienced pain that was severe enough to prevent a complete audiometric evaluation, therefore not rigorously fulfilling the criteria set forth by the 2005 Consensus. However, because their symptoms resolved after reimplantation, and their speech performance restored, we propose modifications of the current definition of "soft failure" to include these patients.

Cochlear implantation can be successfully performed in children with inner ear malformations. These children and their parents can expect significant auditory benefits from this intervention. The various types of inner ear malformations may have quite different prognoses for good auditory performance.