Evolution of impedance values in cochlear implant patients after early switch-on

Abstract

Cochlear implantation is currently the most effective treatment modality for severe to profound sensorineural hearing loss. Over the past few years, at the Department of Otolaryngology, Cheng Hsin General Hospital (Taipei, Taiwan), cochlear implant devices have been switched on within 24 hours of their implantation. Differences in impedance evolution after early switch-on for different devices have not been previously discussed. The present study aimed to investigate the impedance evolution of one device and the factors influencing this after early activation. Results are compared to published results of other devices. A total of 16 patients who received Advanced BionicsTM devices and had early activation within 24 hours of implantation, were included in the study. Impedance telemetry was recorded intraoperatively and postoperatively at 1 day, 1 week, 2 weeks, 4 weeks and 8 weeks. A stepwise increase was observed in the impedance evolution. To the best of our knowledge, the present study is the first to investigate the impedance evolution of the different devices after early switch-on within 24 hours of implantation and its influencing factors. Further research with a longitudinal design to compare the differences in electrode impedances between patients activated early versus those activated after a few weeks will be necessary for the disclosure of the underlying mechanisms.

Toward neural health measurements for cochlear implantation: The relationship among electrode positioning, the electrically evoked action potential, impedances and behavioral stimulation levels

“…This pattern was not evident for every subject, demonstrating variability in impedances over time among cochleas. Previous studies have also reported a large increase in impedance values after surgery (54)(55)(56). This might be explained by fibrous tissue growth following surgery (57).…”

Very early activation of cochlear implants: A review of the literature

“…Despite the primary concern regarding the rationale behind delayed activation and the mounting body of literature on this subject, there still remains a relative paucity of surgical outcome data. Most studies do not provide granular information on postoperative clinical concerns, electing to use terms such as “no surgical complications.” 3–6,10,12,16,20,21 Other studies did not include any surgical outcome information, as their analysis focused on electrophysiological changes over the postoperative period. 9,13–15,17,18 A handful of studies have published clinical information that sheds some insight on this issue.…”

“…3,6,17 Moreover, early switch-on can help patients return to normal activity and life as soon as possible, with earlier adaptation to their new circumstances. 16…”

“…5 Over the years, several other groups have published their experiences with early activation, ranging from 13 days to the day of surgery in the recovery room. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] An increasing number of publications from a select group of CI centers suggest increased acceptance of these protocols, although no data exist as to how common this practice is in reality.…”

“…Most studies do not provide granular information on postoperative clinical concerns, electing to use terms such as "no surgical complications." [3][4][5][6]10,12,16,20,21 Other studies did not include any surgical outcome information, as their analysis focused on electrophysiological changes over the postoperative period. 9,[13][14][15]17,18 A handful of studies have published clinical information that sheds some insight on this issue.…”