Electrically evoked auditory cortical responses elicited from individually fitted stimulation parameters in cochlear implant users

Figures & data

Table 1. Demographic data.

Participant	Age	Sex	Ear	Implant type	Array	Time of use (months)	Aetiology
S1	58	F	L	CONCERTO	FLEX28	10	Meniere disease
S2	59	F	L	CONCERTO	FLEX28	12	Otosclerosis
S3	59	F	L	CONCERTO	FLEX28	39	Sudden HL
S4	76	F	L	CONCERTO	FLEX28	44	Progressive HL
S5	58	M	L	CONCERTO	FLEX28	66	Possible ototoxicity
S6	36	F	R	CONCERTO	FLEX28	33	Progressive HL
S7	60	F	R	CONCERTO	FLEX28	43	Progressive HL
S8	55	M	R	CONCERTO	FLEX28	51	Meniere disease
S9	70	F	L	CONCERTO	FLEX28	76	Sudden HL
S10	55	F	R	CONCERTO	FLEXSoft	26	Sudden HL
S11	65	F	L	CONCERTO	FLEX28	53	Progressive HL
S12	29	F	L	CONCERTO	FLEX28	22	Progressive HL
S13	43	F	L	SONATA	STANDARD	100	Meningitis
S14	24	M	L	CONCERTO	FLEX28	23	Progressive HL

F: female; M: male; R: right; L: left; HL: hearing loss.

Figure 1. Boxplots showing the distribution of individual fitting parameters at the apical, medial, and basal electrodes used for eliciting eACR. (a) Maximum comfortable loudness level (MCL) values in charge units (1 qu equals approximately 1 nC). (b) Phase duration (µs). (c) Rate of the biphasic pulses (pps) (the pulse rate at the medial and basal electrodes was lower than at the apical electrodes and is shown in a close-up box with a different y-axis). (d) Electrode impedance (kΩ). Horizontal lines represent the mean value of the 14 CI users, the crosses represent outliers. Statistics: ANOVA + Bonferroni multiple comparison test. *p < 0.05; **p < 0.01.

Figure 2. Top panel: (a) Grand-averages of eACR responses for 11 participants who had reproducible eACR, averaged across the three electrodes. Bottom panels: Individual (coloured curves) and total grand-average (black curves) eACR waveforms at different electrodes: (b) apical, (c) medial and (d) basal. Stimulation level was at 90% MCL.

Figure 3. Boxplots showing the distribution of individual values for (a) the N1-P2 eACR amplitudes (µV), (b) the latency of the N1 peak (ms), and (c) the latency of the P2 peak (ms) measured at the apical, medial, and basal electrodes. The horizontal lines represent mean values, the crosses represent outliers. Statistics: two-sample t-tests. *p < 0.05.

Figure 4. Correlation between the eACR parameters, the individual fitting parameters and time of CI use. The panels in the top row show the correlation of the N1 latency at the apical electrode with (a) the charge levels corresponding to 90% MCL and with (b) the phase duration. The panels in the second row show the correlation of the N1-P2 amplitudes with the time of CI use at (c) the apical and (d) the medial electrodes. The panels in the third row show the correlation of the N1 latency with the time of CI use at (e) the apical and (f) the medial electrodes.

Data availability statement

Data available on request from the authors.