Simulations of high-frequency vocoder on Mandarin speech recognition for acoustic hearing preserved cochlear implant
BACKGROUND In June 2002, the Food and Drug Administration received reports of bacterial meningitis in patients with cochlear implants for treatment of hearing loss. Implants that included a positioner (a wedge inserted next to the implanted electrode to facilitate transmission of the electrical signal by pushing the electrode against the medial wall of the cochlea) were voluntarily recalled in the United States in July 2002. METHODS We identified patients with meningitis and conducted a cohort study and a nested case-control investigation involving 4264 children who had received cochlear implants in the United States between January 1, 1997, and August 6, 2002, and who were less than six years of age when they received the implants. We calculated the incidence of meningitis in the cohort and assessed risk factors for meningitis among patients and among 199 controls, using data from interviews with parents and abstracted from medical records. RESULTS We identified 26 children with bacterial meningitis. The incidence of meningitis caused by Streptococcus pneumoniae was 138.2 cases per 100,000 person-years--more than 30 times the incidence in a cohort of the same age in the general U.S. population. Postimplantation bacterial meningitis was strongly associated with the use of an implant with a positioner (odds ratio, 4.5 [95 percent confidence interval, 1.3 to 17.9], with adjustment for medical, surgical, and environmental factors) and with the joint presence of radiographic evidence of a malformation of the inner ear and a cerebrospinal fluid leak (adjusted odds ratio, 9.3 [95 percent confidence interval, 1.2 to 94.5]). The incidence of meningitis among patients who had received an implant with a positioner remained higher than the incidence among those whose implants did not have a positioner for the duration of follow-up (24 months from the time of implantation). CONCLUSIONS Parents and health care providers should ensure that all children who receive cochlear implants are appropriately vaccinated and are then monitored and treated promptly for any bacterial infections after receiving the implant.