SQU Med J, August 2011, Vol. 11, Iss. 3, pp. 369-377, Epub. 15th Aug 11
Submitted 10th Jan 11
Revision ReQ. 11th Apr 11, Revision recd. 4th Jun 11
Accepted 12th Jun 11

Department of Otolaryngology, King Saud University and King Abdulaziz University Hospital, Riyadh, Saudi Arabia.
Corresponding Author email: dhagr90@yahoo.com

<ÌÈiÁí÷]<ÿ√À÷]<ÏÅÖÊ<ÌÈfí√÷]<Ìe^rjâ¯÷<Ç√e<‡¬<å^Èœ÷]
kfnπ^e<Ÿ^}Å˝]<ÌÈflœi<›]Ç~jâ^e<l^È◊€√÷]<ÿ}]Å

ÌÈe]Üi_<ÌÈŒ^fjâ]<Ìâ]ÖÅ<V<Ì√ŒÁœ÷]<Å^€¬<Ìœfi^√⁄Ê<





 30


 16 30
11 354 14




:مفتاح الكلمات

aBstract: Objectives: The development of cochlear implant (CI) electrode arrays has focused on the use of a 
minimally invasive technique involving a modiolus-hugging placement of the electrode. The aim of this study was to 
evaluate the “advance-in-stylet” (AIS) technique compared to the advance-off-stylet (AOS) technique recommended 
for the current cochlear Nucleus® device. In the AIS technique, the stylet is not removed. We evaluated the electrical 
auditory thresholds measured when the stylet was removed (modiolus-hugging) compared to measurements taken 
with the stylet in place (lateral wall cochlea electrode placement). Methods: In this prospective cohort study, 30 
consecutive patients received unilateral Nucleus Freedom® CIs using AIS insertion. Measurement of the acoustic 
reflex (AR) and neural response telemetry (NRT) were performed with the stylet in place (lateral wall placement 
of the electrodes) and then removed (perimodiolar placement), and the results compared. The responses were 
measured in the basal, middle and apical turns in both groups—with and without stylet. Results: The AIS surgery 
was completed without complication in 30 patients (16 males and 14 females, age range 3-54 years [mean 11]). 
Based on neural response telemetry, only apical electrodes showed statistically significant differences in thresholds, 
but the AR was not significantly different before or after stylet removal in any of the electrode groups tested. 
Conclusions: The effects of modiolus-hugging do not seem to result in a large difference in electrical stimulation 
thresholds so, in difficult cases, the stylet may be left in place without significantly changing the thresholds, except 
perhaps at the apical turn. 

Keywords: Cochlear implant; telemetry

Intra-Operative Neural Response Telemetry 
and Acoustic Reflex Assessment using an 

Advance-In-Stylet Technique and 
Modiolus-Hugging
A prospective cohort study

Abdulrahman Hagr

CLINICAL & BASIC RESEARCH

Advances in Knowledge
1. The effects of modiolus-hugging do not seem to result in a large difference in electrical performance in cochlear implant.



Intra-Operative Neural Response Telemetry and Acoustic Reflex Assessment using an  
Advance-In-Stylet Technique and Modiolus-Hugging 

A prospective cohort study

370 | SQU Medical Journal, August 2011, Volume 11, Issue 3

The cochlear implant (CI) is a device that electrically stimulates the auditory nerve via an intracochlear electrode array 
placed in the scala tympani, bypassing the inner ear 
in subjects with severe to profound hearing loss. 
CI technology has improved considerably over the 
past decade as researchers and manufacturers have 
attempted to maximise speech perception. Although 
many advances have already been made, there are 
still several unresolved issues with regard to CI 
surgery, one of which is the utility of the advance-off-
stylet (AOS) technique, with its resulting modiolar 
hugging array morphology. The classic straight CI 
electrode array slides along the lateral wall of the 
scala tympani during insertion, and it remains in 
this location. Newer designs from some companies 
have featured implants with a preformed shape 
memory, which causes the implant to spiral inwards 
towards the modiolus. Different manufacturers have 
achieved modiolus-hugging in different ways, but in 
this study we used the implementation developed 
by Cochlear Corporation (Sydney, Australia), which 
employs a stylet to stent a preformed coiled array 
into a straight shape. The recommendation is to 
insert this electrode to a predefined distance, and 
then advance the electrode off the stylet. This has 
two effects: first, the soft, flexible tip leads and, 
because the stylet has been withdrawn from the 
tip, the distal electrode is no longer stiff, avoiding 
penetration of the basilar membrane or spiral 
ligament; second, it allows the electrode to take up 
its pre-coiled shape and hug the modiolus. This is 
called the advance-off-stylet (AOS) technique. This 
can be a difficult surgical manoeuvre to perform 
because the whole array may be withdrawn instead 
of advanced when the surgeon attempts to slide it 
off the stylet, which is held steady. This can result in 
intraoperative extrusion of the array, and, if it curls 
with the stylet withdrawn, the stylet is not designed 
to be re-introduced. This could potentially waste an 
expensive CI because it is very difficult to insert the 
array once it is coiled. 

Perimodiolar CI electrodes place the electrode 
contacts in closer proximity to the excitable neural 
elements. Theoretically, this offers better resolution 
and improved transfer of the electrical stimuli to the 
neural structures of the VIIIth nerve endings, where 

it results in more specific frequency stimulation, 
reduced electric current spread, increased dynamic 
range and reduced energy consumption.1 These 
combined features result in performance gains 
for the listener and reduced electrical power 
consumption, thereby prolonging battery life. 
Behavioural response studies have found significant 
decreases in average threshold and comfort 
(T&C) levels across electrodes with perimodiolar 
placement when compared to lateral wall cochlea 
arrays,2,3and this placement may also potentially 
improve speech perception.4 Additionally, facial 
nerve stimulation may be reduced by placing the 
electrode further away from the outer wall of the 
scala tympani.5 Most of the early studies showing 
lowered thresholds and a wider dynamic range 
with perimodiolar arrays using electrically evoked 
auditory brainstem responses (EABR) in animals.6,7 
However, some newer studies have shown that these 
supposed benefits are variable.8,9,10 Histological 
studies to assess the cochlear damage resulting 
from insertion of different types of perimodiolar 
electrodes were performed on cadaver temporal 
bones of normal-hearing individuals;11,12 however, 
these studies did not take into account that, with 
time, fibrosis, scarring, and ossification resulting 
from insertion trauma could theoretically alter 
the amount of current necessary for stimulation. 
These factors are independent of the distance of 
the electrode from the modiolus and the remaining 
spiral ganglion cells. Therefore, the impact of 
localised damage to the spiral ligament during 
implantation in humans is uncertain.12,13 In addition, 
many other studies have shown no improvement in 
CI performance in relation to hearing conservation 
or in the dynamic range. 3,14-16

Perimodiolar AOS electrode surgery is relatively 
atraumatic due to the flexible tip, though it may 
result in lower lateral wall stress and forces. It 
may preserve the integrity of the spiral lamina 
and basilar membrane, further preventing the 
subsequent neuronal losses that have been reported 
using conventional straight electrode arrays.11,17As 
mentioned above, the impact of localised damage to 
the spiral ligament during implantation is uncertain 
and may take time to become evident.13 

As noted above, many studies have shown that 

Application to the patient care 
1. The stylet in cochlear implant may be left during electrodes insertion without significantly changes in the threshholds.



Abdulrahman Hagr

Clinical and Basic Research | 371

stimulation in the perimodiolar location using 
EABR results in less power consumption.18-21 Neural 
response telemetry (NRT) is a system that measures 
electrically evoked compound action potential 
(ECAP) thresholds from the auditory nerve using 
the CI. The system applies an electrical pulse to a 
given intracochlear electrode, and the evoked neural 
response is recorded at a neighbouring electrode. 
The measured potentials are telemetered back 
to the system’s interface for clinical analysis. The 
response is probably from the proximal auditory 
nerve, and this method has several advantages over 
EABR. One is that NRT requires a shorter collection 
time which is important for intraoperative use. 
Second, there is little need for patient cooperation 
or sedation, which is required to apply the EABRs’ 
surface electrodes, because NRT uses the CI as 
both the stimulating and recording electrodes. 
Additionally, using NRT, postoperative data can be 
compared to intraoperative data. Moreover, NRT 
can be used to predict the behavioural threshold 
(T levels) and maximum comfort levels (C levels) 
to build stimulation maps for the CI patient and 
facilitate the postsurgical rehabilitation process. 
NRT provides information that reflects the activity 
of a smaller number of auditory neurons, thus 
effectively negating the influence of neural response 
from higher levels in the brain. EABR requires a 
larger number of sweeps and a longer acquisition 
time, it is more difficult to elicit, and it is often 
associated with artefacts.22,23

The acoustic reflex (AR) is the contraction of 
the stapedius muscle, traditionally in response 

to sound stimulation. The ipsilateral pathway for 
the stapedius reflex travels via the VIIIth nerve 
synapses in the ipsilateral cochlear nucleus, and 
then travels to the superior olivary nucleus and the 
facial nerve nucleus, which supplies the stapedius 
muscle by way of the facial nerve. The AR also helps 
to verify implant position and integrity in addition 
to validating the functioning of the auditory and 
facial nerves. To our knowledge, there has been no 
study to date evaluating the effects of perimodiolar 
positioning (by removing the stylet) compared to 
lateral wall placement of the array (by non-removal 
of the stylet) measured using the acoustic reflex 
threshold (ART) and neural response telemetry 
(NRT) performed intraoperatively for the Nucleus® 
(Cochlear Corporation, Sydney, Australia) 
electrode array. The purpose of this study was to 
determine this effect, within the same cochlea and 
using the same array. We will refer to the procedure 
in which the stylet is left in place as the advance-
in-stylet (AIS) technique for the Nucleus Freedom® 
electrode array.

Methods
Thirty patients who received the Nucleus Freedom® 
device between April 2009 and January 2010 were 
studied. Inclusion criteria for this study were age 
greater than 2 years, no inner ear malformation, 
and compliance with our CI candidacy criteria. 
Exclusion criteria were failure of full insertion, 
inability to remove the stylet, the presence of a 
cerebrospinal fluid (CSF) gusher and intra-operative 
measures performed by audiologists other than our 
investigating audiologist.

This prospective study was performed at the 
King Abdulaziz University Hospital in Riyadh, 
Saudi Arabia. A total of 30 consecutive CI patients 
of a single surgeon and a single audiologist were 
recruited and evaluated with intra-operative CI 
testing (ART and NRT) after full insertion with 
stylet in place (AIS). Then, these test results were 
compared with the results of procedures performed 
with the stylet explanted (with perimodiolar 
hugging) in the same patient in a repeated measures 
fashion. The Freedom® CI developed by Cochlear 
Corporation was used in all of our patients. Our 
Institution Research Board (IRB) approved this 
study (Project No. E-10-198).

In our study, NRT responses were recorded at 

Table 1: Characteristics of the sample

Variable Statistic

Age

Minimum
Maximum
Mean
Median
Mode
Standard deviation

3
54
11.47
5.00
5.00
13.68

Sex

Male

Female

16 (53.3%)
14 (46.7%)

Site

Right

Left

14 (46.7%)
16 (53.3%)



Intra-Operative Neural Response Telemetry and Acoustic Reflex Assessment using an  
Advance-In-Stylet Technique and Modiolus-Hugging 

A prospective cohort study

372 | SQU Medical Journal, August 2011, Volume 11, Issue 3

apical, basal, and middle electrodes in each patient. 
The stimulated electrodes ranged from 1 to 7 at the 

basal end, 8 to 15 in the middle, and 16 to 22 at the 
apex. The AR thresholds were observed by the same 
surgeon before and after stylet removal without 
knowing which electrodes were being stimulated. 

In all cases, facial nerve monitoring was used, 
and then the mastoidectomy and transfacial recess 
were done. The middle ear was normal in all cases, 
and a cochleostomy was performed anterior-
inferiorly to the round window. The electrode was 
inserted gently and slowly into the scala tympani 
without using the AOS technique, i.e. insertion with 
the stylet-in-place (AIS technique). This renders the 
array similar to a conventional straight electrode 
array, which will lie against the lateral cochlear wall. 
The cochleostomy site was sealed by muscle after full 
insertion of the electrodes. The ART were evaluated 
by the surgeon, and the lowest stimulation level at 
which visible stapedial contractions could be seen 
was recorded. The AR thresholds were measured 
at the electrodes numbered 1, 6, 11, 16 and 22. 
Then the NRT was measured at the electrodes 
numbered 1, 3, 6, 9, 11, 13, 16 17, 21 and 22. The 
stylet was then removed, allowing the electrode 
array to coil closer to the modiolus. The stimulation 
threshold measurements were then repeated. 
All the patients’ intra-operative evaluations were 
done by the same audiologist. Therefore, identical 
stimulation and recording procedures were used for 
the measurements before and after stylet removal 
within and across subjects.

The next day, an X-ray was taken for all patients 
to confirm intracochlear electrode insertion. All 
statistical analyses were done using SAS (SAS 
Institute, Inc., Cary, NC, USA.). The results of 
t-tests having an alpha P value of 0.05 or less were 
considered statistically significant. 

Results
The patient population consisted of 16 males and 14 
females ranging in age from 3 to 54 years (mean 11). 
For 14 patients, the CI was placed on the right and 
for 16 placed on the left [Table 1]. All patients had 
full CI insertion.

All quantitative variables (except age) were 
proven to follow the normal distribution. The 
Kolmogrov test was used to test normality of data so 
the parametric paired t-test was used for comparison 
of data. The effects of changing electrode placement 
method from the stylet-in procedure (lateral wall 

Table 2: Comparison of the 30 subjects’ means and 
standard deviations of NRT with and without stylet

 
Mean 

difference

95% Confidence 
interval

Lower Upper

Pair 
1
 

NRT3 with
9.59NRT3 

without 0.40 -8.79

Pair 
2
 

NRT9 with
7.20NRT9 

without 2.10 -3.00

Pair 
3
 

NRT13 with
8.71NRT13 

without 4.87 1.02

Pair 
4
 

NRT17 with
10.83NRT17 

without 5.00 -0.83

Pair 
5
 

NRT21 with
10.34NRT21 

without 5.87 1.39

Pair 
6
 

NRT1 with
8.96NRT1 

without 1.17 -6.63

Pair 
7
 

NRT6 with
9.71NRT6 

without 3.07 -3.57

Pair 
8
 

NRT11 with
4.22NRT11 

without 2.87 -9.95

Pair 
9
 

NRT16 with
6.50NRT16 

without 3.27 0.04

Pair 
10
 

NRT22 with
9.02NRT22 

without 5.20 1.38

Pair 
11
 

Mean apical 
with

9.08
Mean apical 
without 5.66 2.23

Pair 
12
 

Mean 
middle with

4.84Mean 
middle 
without

1.37 -2.10

Pair 
13
 

Mean basal 
with

8.26
Mean basal 
without 1.54 -5.17



Abdulrahman Hagr

Clinical and Basic Research | 373

cochlea) to the stylet-out procedure (medial wall 
cochlea) were characterised by comparing AR 

responses and NRTs between the positions. Table 
2 shows the comparison of the 30 subjects’ means 
and standard deviations of NRT with and without 
stylet, while Table 3 shows the threshold measures 
from NRT averaged across subjects for the lateral 
(with stylet) and medial (without stylet) placements 
for the apical, middle, and basal electrodes. 
Standard deviations and P values are indicated for 
each electrode using t-tests. Statistically significant 
differences were found in thresholds with medial 
placement for some electrodes (13, 16, 21, 22) using 
NRT, as indicated with asterisks [Table 3]. However, 
when all subgroups are collapsed into apical, middle 
and basal categories, only the apical electrodes 
showed statistically significant differences in 
thresholds, as indicated with asterisks. 

The effect of perimodiolar electrode placement 
on neural responses was analysed across stimulation 
levels by cross tabulation of the AR responses 
for electrodes 1, 6, 11, 16 and 22, as shown in 
tables 4 to 8, respectively. This cross tabulation 
was performed for each electrode’s AR with and 
without the stylet. Based on a t-test, there was no 
statistical difference between the AR results with or 
without the stylet across all tested electrodes. AR 
comparison (separately for electrode 1, 6, 11, 16 and 
22) was carried out with 2 x 2 table and is presented 
showing odds ratio with 95% confidence in Table 9. 

Discussion
In the current study, we used an efficient method 
to test the impact of modiolus-hugging on 
electrically evoked auditory thresholds in an acute 
intra-operative setting. This method combines 
intraoperative AR and NRT before and after stylet 
removal. The patient group studied in this analysis 
is very typical of the patient population at our large 
CI centre. Because we do not yet have a neonatal 
screening programme for deafness, our patients 
usually present late. 

In this study, we used a single device (Nucleus 
Freedom®), which is the most common type of 
device used in our centre and worldwide. We expect 
other devices to be similar in their performance 
using modiolar hugging or lateral wall placement 
comparisons with the same stimulation parameters. 
There is no reported statistically significant 
difference among the three major manufacturers 
of electrodes (Cochlear Corporation, MEDEL 

Table 3: Comparison of neural response telemetry 
(NRT) for each electrode with and without the stylet in 
place using P value

 Mean
Standard 
Deviation

P 
value

Pair 
1

NRT3 with 184.07 29.56
.930

NRT3 without 183.67 17.51

Pair 
2

NRT9 with 192.97 16.02
.407

NRT9 without 190.87 12.38

Pair 
3

NRT13 with 191.57 16.01
.015*

NRT13 without 186.70 12.26

Pair 
4 

NRT17 with 185.73 17.03
.090

NRT17 without 180.73 15.34

Pair 
5 

NRT21 with 183.20 18.12
.012*

NRT21 without 177.33 16.41

Pair 
6

NRT1 with 186.80 29.87
.762

NRT1 without 185.63 22.23

Pair 
7

NRT6 with 188.30 26.35
.353

NRT6 without 185.23 18.56

Pair 
8 

NRT11 with 187.00 20.62
.415

NRT11 without 189.87 13.92

Pair 
9

NRT16 with 185.00 16.58
.048*

NRT16 without 181.73 15.66

Pair 
10 

NRT22 with 179.67 16.76
.009*

NRT22 without 174.47 17.47

Pair 
11 

Mean apical 
with 184.23 15.59

.002*
Mean apical 
without 178.57 13.84

Pair 
12 

Mean middle 
with 190.51 14.48

.427
Mean middle 
without 189.14 11.38

Pair 
13 

Mean basal with 186.39 25.55
.642Mean basal 

without 184.84 17.69

Note: *Significant.

Table 4: Acoustic reflex (AR) in electrode 1 with and 
without the stylet: cross tabulation

AR1 with Total

No Yes  

AR1 
without

No
Count 17 3 20

% of Total 56.7 10.0 66.7

Yes
Count 2 8 10

% of Total 6.7 26.7 33.3

 
Total

Count 19 11 30

% of Total 63.3 36.7 100.0

Note: P >0.05.



Intra-Operative Neural Response Telemetry and Acoustic Reflex Assessment using an  
Advance-In-Stylet Technique and Modiolus-Hugging 

A prospective cohort study

374 | SQU Medical Journal, August 2011, Volume 11, Issue 3

Table 5: Acoustic reflex (AR) in electrode 6 with and 
without the stylet: cross tabulation

AR6 with Total

No Yes  

AR6 
without

No Count 10 2 12
% of Total 33.3 6.7 40.0

Yes
Count 3 15 18
% of Total 10.0 50.0 60.0

Total
Count 13 17 30
% of Total 43.3 56.7 100.0

Note: P >0.05

and Advanced Bionics) with respect to inner ear 
trauma,12 modiolar wall contact,24,25 or facial nerve 
stimulation rates.26 

Our study did not show a major disadvantage of 
the AIS technique. This procedure is actually easier 
to perform than removal of the stylet in the AOS 
technique. We did not observe any complications 
in our patients as a result of leaving the stylet on 
during insertion of the electrode. This may lower 
the learning and implementation curves for this 
increasingly used surgery and aid in teaching trainees 
in CI insertion. Moreover, the AIS technique may 
be suitable for some difficult cases, such as cochlear 
fracture, re-insertion, and fibrosis of the inner ear, 
where the presence of the stylet may give extra 
rigidity to the implant and prevent early coiling of 
the tip. In addition, not removing the stylet allows 
preservation of the uncoiled implant for a second 
trial if there is difficulty or malplacement of the 
electrode. 

The NRT results only showed significant 
differences between the medial position (modiolar 
hugging) and the lateral position at the apical 
electrodes, which is consistent with other studies.18,27 

This difference may be due to the larger diameter of 
the apical neurons,28 the greater density of surviving 
neural fibres in the cochlear apex, or both.29 Removal 
of the stylet also results in a deeper insertion of the 
electrodes because the inner circle path around 
the modiolus is shorter than the outer circle path 
around the lateral wall, so the same electrode length 
is able to reach further. Theoretically, this would lead 
to stimulation of a larger neural population along 
the apical electrodes. In this study, there was no 
significant difference between the AR thresholds in 
medial (modiolar hugging) and lateral positions at 
all location. However, Mens et al.10 reported lower 
stapedius reflex thresholds in a modiolar hugging 
configuration. One point worth mentioning is that 
we usually turn the facial nerve monitor off after we 
finish the facial recess; therefore, stapedial reflexes 
secondary to direct facial nerve stimulation cannot 
be excluded completely. 

A limitation of this study is its inability to ensure 
that the implant was inserted completely into 
the scala tympani and that removal of the stylet 

Table 6: Acoustic reflex (AR) in electrode 11 with and 
without the stylet: cross tabulation

AR11 with Total

No Yes  

AR11 
without

No
Count 7 0 7

% of Total 23.3 .0 23.3

Yes
Count 3 20 23

% of Total 10.0 66.7 76.7

Total
Count 10 20 30

% of Total 33.3 66.7 100.0

Note: P >0.05

Table 7: Acoustic reflex in electrode 16 with and 
without the stylet: cross tabulation

AR16 with Total

No Yes  

AR16 
without

No
Count 10 0 10

% of Total 33.3 .0 33.3

Yes
Count 1 19 20

% of Total 3.3 63.3 66.7

Total
Count 11 19 30

% of Total 36.7 63.3 100.0

Note: P >0.05.

Table 8: Acoustic reflex in electrode 22 with and 
without the stylet: cross tabulation

 

AR22 with Total

No Yes  

AR22 
without

No Count 11 0 11

% of Total 36.7 .0 36.7

Yes Count 2 17 19

% of Total 6.7 56.7 63.3

 
Total

Count 13 17 30

% of Total 43.3 56.7 100.0

Note: P >0.05.



Abdulrahman Hagr

Clinical and Basic Research | 375

actually resulted in perimodiolar hugging because 
an electrode array that may penetrate the basilar 
membrane could become tethered by the osseous 
spiral lamina, preventing full coiling or close 
perimodiolar proximity. 

One legitimate concern is that it is possible that 
sequential stimulation between the two conditions 
may affect the recordings, as there may be fatigue 
of the AR or evoked compound potentials after 
repeated stimulation. This is more likely to be an 
issue with the AR than with the evoked potentials 
because, in our experience, intraoperative AR and 
NRT recordings are usually very stable.

Although this study only shows a significant 
difference in thresholds at apical regions with 
stylus removal, the psychoacoustic and perceptual 
consequences of this warrant further study, and 
our results need to be confirmed with longer term 
follow-up in cases where the stylet was or was not 
removed to assess the effects of scarring or damage 
to structures such as the basilar membrane and 
spiral ligament.

Conclusion 
According to the result of this study, removal of 
the stylet with the Nucleus Freedom® only results 
in a significant stimulation difference in the apical 
electrodes. We suggest this alternative technique in 
difficult cases and for new CI surgeons.

a c k n o w l e d g m e n t s

This research was financially supported by grants 
from the Prince Sultan Research Chair for hearing 
disability. The author thanks Professor Manohar 
Bance for helpful comments on the manuscript.

c o n f l i c t o f i n t e r e s t
The authors reported no conflict of interest. 

References 
1. Seidman MD, Vivek P, Dickinson W. Neural response 

telemetry results with the nucleus 24 contour in a 
perimodiolar position. Otol Neurotol 2005; 26:620–
3.

2. Parkinson AJ, Arcaroli J, Staller SJ, Arndt PL, Cosgriff 
A, Ebinger K. The nucleus 24 contour CI system: 
Adult clinical trial results. Ear Hear 2002; 23:41–8.

3. Saunders E, Cohen L, Aschendorff A, Shapiro W, 
Knight M, Stecker M, et al. Threshold, comfortable 
level and impedance changes as a function of 
electrode-modiolar distance. Ear Hear 2002; 23:28–
40.

4. Blamey PJ, Pyman BC, Gordon M, Clark GM, 
Brown AM, Dowell RC, et al. Factors predicting 
postoperative sentence scores in postlinguistically 
deaf adult CI patients. Ann Otol Rhinol Laryngol 
1992; 101:342–8.

5. Battmer R, Pesch J, Stover T, Lesinski-Schiedat A, 
Lenarz M, Lenarz T. Elimination of facial nerve 
stimulation by reimplantation in CI subjects. Otol 
Neurotol 2006; 27:918–22.

6. Shepherd RK, Hatsushika S, Clark GM. Electrical 
stimulation of the auditory nerve: The effect of 
electrode position on neural excitation. Hear Res 
1993; 66:108–20.

Table 9: Comparison of acoustic reflex in different electrodes

Electrode Stylet Yes No Odds ratio
95% Confidence interval

Lower Upper

1
With 11 19

0.15 0.04 0.56
Without 10 20

6
With 17 13

0.26 0.10 0.72
Without 18 12

11
With 20 10

0.30 0.12 0.77
Without 23 7

16
With 19 11

0.09 0.01 0.59
Without 20 10

22
With 17 13

0.15 0.04 0.55
Without 19 11



Intra-Operative Neural Response Telemetry and Acoustic Reflex Assessment using an  
Advance-In-Stylet Technique and Modiolus-Hugging 

A prospective cohort study

376 | SQU Medical Journal, August 2011, Volume 11, Issue 3

7. Marsh RR, Yamane H, Potsic WP. Effect of site of 
stimulation on the guinea pig’s electrically evoked 
brain stem response. Otolaryngol Head Neck Surg 
1981; 89:125–30.

8. Frijns JH, Briaire JJ, Grote JJ. The importance of 
human cochlear anatomy for the results of modiolus-
hugging multichannel cochlear implants. Otol 
Neurotol 2001; 22:340–9.

9. Eisen MD, Franck KH. Electrically evoked compound 
action potential amplitude growth functions and 
HiResolution programming levels in pediatric CII 
implant subjects. Ear Hear 2004; 25:528–38.

10. Mens LH, Boyle PJ, Mulder JJ. The Clarion electrode 
positioner: Approximation to the medial wall and 
current focussing? Audiol Neurootol 2003; 8:166–75.

11. Shepherd RK, Clark GM, Pyman BC, Webb RL. 
Banded intracochlear electrode array: Evaluation of 
insertion trauma in human temporal bones. Ann 
Otol Rhinol Laryngol 1985; 94:55–9.

12. Eshraghi AA, Yang NW, Balkany TJ. Comparative 
study of cochlear damage with three perimodiolar 
electrode designs. Laryngoscope 2003; 113:415–19.

13. Linthicum FH, Jr, Galey FR. Histologic evaluation of 
temporal bones with cochlear implants. Ann Otol 
Rhinol Laryngol 1983; 92:610–13.

14. Marrinan MS, Roland JT Jr, Reitzen SD, Waltzman 
SB, Cohen LT, Cohen NL. Degree of modiolar 
coiling, electrical thresholds, and speech perception 
after cochlear implantation. Otol Neurotol 2004; 
25:290–4.

15. Balkany TJ, Connell SS, Hodges AV, Payne SL, 
Telischi FF, Eshraghi AA, et al. Conservation of 
residual acoustic hearing after cochlear implantation. 
Otol Neurotol 2006; 27:1083–8.

16. Hodges AV, Schloffman J, Balkany T. Conservation 
of residual hearing with cochlear implantation. Am J 
Otol 1997; 18:179–83.

17. Fayad J, Linthicum FH Jr, Otto SR, Galey FR, House 
WF. Cochlear implants: Histopathologic findings 
related to performance in 16 human temporal bones. 
Ann Otol Rhinol Laryngol 1991; 100:807–11.

18. Wackym PA, Firszt JB, Gaggl W, Runge-Samuelson 
CL, Reeder RM, Raulie JC. Electrophysiologic effects 
of placing CI electrodes in a perimodiolar position in 
young children. Laryngoscope 2004; 1141:71–6.

19. Firszt JB, Wackym PA, Gaggl W, Burg LS, Reeder RM. 
Electrically evoked auditory brain stem responses for 
lateral and medial placement of the Clarion HiFocus 
electrode. Ear Hear 2003; 24:184–90.

20. Runge-Samuelson C, Firszt JB, Gaggl W, Wackym 
PA. Electrically evoked auditory brainstem responses 
in adults and children: Effects of lateral to medial 
placement of the Nucleus 24 Contour electrode 
array. Otol Neurotol 2009. 30:464–70.

21. Pasanisi E, Vincenti V, Bacciu A, Guida M, Bacciu 
S. The nucleus contour electrode array: An 
electrophysiological study. Laryngoscope 2002; 
112:1653–6.

22. Brown CJ, Hughes ML, Luk B, Abbas PJ, Wolaver A, 
Gervais J. The relationship between EAP and EABR 
thresholds and levels used to program the nucleus 24 
speech processor: data from adults. Ear Hear 2000; 
21:151–63.

23. Abbas PJ, Brown CJ, Shallop JK, Firszt JB, Hughes 
ML, Hong SH, et al. Summary of results using the 
nucleus CI24M implant to record the electrically 
evoked compound action potential. Ear Hear 1999; 
20:45–59.

24. Balkany TJ, Eshraghi AA, Yang N. Modiolar 
proximity of three perimodiolar cochlear implant 
electrodes. Acta Otolaryngol 2002; 122:363–9.

25. Gstoettner WK, Adunka O, Franz P, Hamzavi J Jr, 
Plenk H Jr, Susani M, et al. Perimodiolar electrodes 
in cochlear implant surgery. Acta Otolaryngol 2001; 
121:216–19.

26. Smullen JL, Polak M, Hodges AV, Payne SB, King 
JE, III, Telischi FF, et al. Facial nerve stimulation 
after cochlear implantation. Laryngoscope 2005; 
115:977–82.

27. Tsuji RK, Goffi-Gomez MV, Peralta CO, Guedes 
MC, Magalhaes AT, Neto RB, et al. Neural response 
thresholds in the Nucleus Contour cochlear implant 
before and after stylet removal. Acta Otolaryngol 
2009; 129:1330–6.

28. Tavartkiladze GA, Potalova LA, Kruglov AV, Belov 
A. Effect of stimulation parameters on electrically 
evoked auditory brainstem responses. Acta 
Otolaryngol 2000; 120:214–17.

29. Shallop JK, Beiter AL, Goin DW, Mischke RE. 
Electrically evoked auditory brain stem responses 
(EABR) and middle latency responses (EMLR) 
obtained from patients with the nucleus multichannel 
cochlear implant. Ear Hear 1990; 11:5–15.