Intra-operative monitoring of cochlear function during cochlear implantation

Abstract

The objective of this study was to determine if intra-operative auditory monitoring is feasible during cochlear implantation and whether this can be used as feedback to the surgeon to improve the preservation of residual hearing. This prospective non-randomised study was set in a paediatric tertiary referral hospital. Thirty eight consecutive paediatric patients undergoing cochlear implantation who had measurable auditory thresholds pre-operatively were divided into two cohorts. The unmonitored cohort included the fi rst 22 patients and the monitored cohort included the last 16 patients. The main outcome measure(s) were pre-operative, intra-operative and more than one month post-operative average auditory thresholds at 500, 1000 and 2000 Hz measured using auditory steady-state response audiometry. The average pre-operative thresholds were 103.5 dB HL and 99.7 dB HL in the unmonitored and monitored cohorts, respectively. These were not statistically different (p > 0.3). In the monitored cohort, we measured auditory thresholds to assess cochlear function at multiple time points during the operation. Compared to baseline, thresholds were increased 0.7 dB after drilling the mastoidectomy and well, 0.2 dB after opening the cochlea and 4.6 dB after inserting the electrode array. One month post-operatively, the average thresholds were 114.0 dB HL in the unmoni-tored cohort but only 98.8 dB HL in the monitored cohort (p < 0.001). Both the use of intra-operative auditory monitoring and higher pre-operative thresholds were associated with improved preservation of residual hearing (p < = 0.001). Intra-operative auditory monitoring is a viable tool that can provide real-time feedback to the surgeon during cochlear implant surgery. These data suggest that this can lead the surgeon to modify his or her surgical technique in ways that can improve the rate of long-term hearing preservation.

Neuroimaging with near-infrared spectroscopy demonstrates speech-evoked activity in the auditory cortex of deaf children following cochlear implantation

“…Even though the CI can be placed in very young children (Lin et al, 2010; Oghalai et al, 2009), it can be difficult to perform the necessary behavioral testing to program the CI, especially if there are co-existent developmental delays which are often found in this patient population (Beauchamp et al; Cristobal et al, 2008; Katzenstein et al, 2009; Kushalnagar et al, 2007; Pierson et al, 2007). Therefore, an objective method to measure brain activity would be give valuable additional information.…”

Electric-Acoustic Stimulation of the Auditory System: A Review of the First Decade

“…The authors mentioned that this technique could also be used as an indicator for the preoperative functional status of the organ of Corti. Oghalai et al [2009] used auditory steady-state response audiometry to assess hearing thresholds during regular cochlear implantation in a cohort of 16 children with some measurable LFH. While there was only a minor increase in the threshold during drilling of the mastoid (0.7 dB) and after opening the cochleostomy (0.2 dB), the main shift occurred when the 'full-length electrode' array was inserted into the scala tympani (4.6 dB).…”

Functional near-infrared spectroscopy for neuroimaging in cochlear implant recipients

“…Such information can supplement behavioral tests, which are often limited in young CI users (Choi and Oghalai, 2005; Katzenstein et al, 2009; Lin et al, 2010; Oghalai et al, 2009; Santa Maria and Oghalai, 2014; Williamson et al, 2009; Ying et al, 2013). However, there are inherent limitations in the use of all of the currently available neuroimaging modalities in CI recipients, as outlined below and summarized in Table 1.…”