Safety and functional results of early cochlear implant switch-on in children.

OBJECTIVE: To assess the safety and the possible advantages of early (1-wk) cochlear implant switch-on in children and to compare impedance and ECAP threshold changes between subjects undergoing early switch-on and those undergoing traditional, 1-month switch-on. STUDY DESIGN: Prospective cohort study. SETTING: Tertiary care referral pediatric center. PATIENTS: Seventeen children receiving a unilateral or bilateral Nucleus Freedom cochlear implant were included, for a total of 20 ears. Ten ears were assigned to the early (1-wk) switch-on group and 10 to the control group (switch-on after 4 wks). INTERVENTIONS: Common ground impedance values and electrically evoked compound action potential thresholds were measured from intraoperation until 9 months postoperatively. Speech perception improvements over time were also assessed. MAIN OUTCOME MEASURES: Complication rate, impedance levels (kΩ), and electrically evoked compound action potentials (current levels) RESULTS: Early switch-on was well tolerated by patients and did not cause complications. Impedances dropped significantly after switch-on in both groups. They also seemed to achieve an earlier stability in the early switch-on patients, although the difference between groups was not significant. ECAP thresholds showed a similar, nonsignificant decreasing trend over time in both groups. Speech perception improvements did not differ between groups. CONCLUSION: This is the first study investigating the safety and the effects of an early cochlear implant switch-on in children. Results show that such a procedure is well tolerated by pediatric subjects and free from complications. Impedance measurements suggest that the earlier switched-on subjects benefit of lower and more stable impedances than subjects undergoing 1-month switch-on.

Clinical and audiological follow up of a family with the 8363G>A mutation in the mitochondrial DNA.

Hearing loss is relatively common in mtDNA-related disorders. While auditory function has been assessed fully in the syndrome of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes, few studies have investigated the degree of progressive hearing deficit in individuals bearing other mtDNA mutations. We performed a 4-year clinical and audiological follow up in a family carrying the 8363G>A mutation in the mitochondrial transfer ribonucleic acid lysine (tRNA(Lys)) gene who displayed a progressive neuromuscular disease. In addition to pure tone audiometry, we considered distortion products of otoacoustic emissions, a sensitive indicator of cochlear dysfunction, as well as brainstem auditory evoked responses. A generalized increase in the auditory threshold at follow up, indicating a cochlear impairment in three cases, was noted. Distortion products of otoacoustic emissions may reveal sub-clinical cochlear dysfunction, even in oligosymptomatic patients. A complete and periodical assessment of the hearing function should be encouraged in asymptomatic relatives of patients carrying the tRNA(Lys) 8363G>A mutation.