2. Introduction
○Intra-operative monitoring during
cochlear implant surgery is a tool to assess
integrity of the equipment used, and to
assess the progress of array introduction
and proper placement of the array with
subsequent assessment of proper
functioning of the device.
○Furthermore, Intra-op is used as a
preliminary tool for subsequent CI
mapping later on especially for difficult to
test patients
3. Objectives
of Intra-
operative
monitoring
○Detection of malfunctioning electrode or
failed receiver-stimulator at the time of the
operation provides an opportunity for
immediate action while the patient still under
anesthesia.
○Optimal (correct) and “atraumatic” electrode
placement within the cochlea is well
recognized pre-requisites for maximizing
cochlear implant success.
4.
5.
6.
7. Impedance
measure
○Impedance in general refers to the
resistance to the flow of energy through any
medium.
○In CI electrode impedance refers to the
measure of the opposition to electrical
current flow across an electrode and thus, it is
influenced by the electrode contact and the
electrode lead that is coupled to the contact
as well as by the medium surrounding the lead
8. Impedance
measure
○Impedance measures are important for determining
whether intra-cochlear or extra-cochlear electrodes
are functioning appropriately.
○It provides information about the properties of
electrode-tissue interface.
9.
10. Impedance
measures
findings
○Normal impedances:
◦are not indicators of electrodes being inside the
cochlea, (electrodes in the carotid, SCC can give
normal EI as long as there is good electrode-tissue
interface).
◦Normal impedance has nothing to do with the
post-operative performance and do not influence
the intra-operative decision making.
11.
12.
13. Impedance
abnormalities
○Open circuit:
HI (High impedance) measurement which rely
information about the adjacent tissue environment
such as air bubbles around the electrode, incomplete
insertion or extrusion of the electrode array and more
rarely a faulty or damaged electrode contact.
14. presence if air bubbles can be removes by slight pressure
or by passing current in the array more than one time in
order to obtain within normal impedance levels.
HI in one electrode, it may indicate broken wire.
17. Use of the
back up
○Surgery complication , with some broken
electrodes.
18.
19. ECAP
measures
○ Done to confirm that action potential can be
triggered by stimulation and confirm device
function.
○ Can be useful in post-operative fitting if cannot
be done post-operative in difficult to test cases.
○ The ground electrode must have good contact
with the tissues.
○ Impedance measures must be done first.
○Preconditions;
◦ Electrodes with poor contact (HI) should not be used.
◦ECAP reference electrode should has proper connection to
the tissues.
20.
21.
22. ○Ipsilateral recording in the OR a visual
inspection of stapedius muscle contraction can
be recorded in response to electrical stimulation
via the implanted electrode.
○Contra-lateral recording requires the use of a
tymanometer to record response from the other
non-implanted ear.
23. ○Advantages:
• Strong correlation with the behavioral thresholds.
○Limitations:
• Requires normal middle ear functions,
• Contraction of the muscle can be obscured by anatomic
variation, blood or fibrous tissue,
• Normal variability in AR recording (absence of reflex in
some individuals).
• The need for other equiment.
24.
25. • The electrical auditory evoked potentials test (EABR)
measures the correct functioning of an electrode as well as the
associated nerve response following electrical stimulation.
• 1.5–2 ms earlier due to the direct stimulation of spiral ganglion
cells by the implant electrodes.
26. Disadvantages
○it can be contaminated by other
physiological response such as those
induced by electrical stimulation of facial
or vestibular nerve .
27. Another form of intra-operatively, ‘‘hard’’ failure is loss of
telemetric ‘‘lock’’ or an inability of the external processor
to communicate with the receiver-stimulator. Skin flap
thickness have to be excluded as cause fro this loss of
telemetric lock.
28.
29. X-ray
○Intraoperative radiography of the cochlear
implant is a fundamental tool.
○The use of a portable
device proved to be
fast, practical and low
cost, affordable to
most hospitals.
30. C-arm
○The main advantage in
relation to the use of a
portable X-ray device is
exactly the possibility for
immediate visualization
of the image, having no
need to wait for
processing.
○The images obtained
are shown in real time, in
a monitor.
○The main disadvantages
are: its high cost; its
relatively larger size,
requiring a considerable
space in the operating
room.
○sometimes there is also
the need to adapt the
room and surgical tables
in order to achieve the
necessary views.
○
31. C arm
○C-Arm Tables
○C-arms work in conjunction with patient tables that are
specifically designed for X-ray imaging.
○The table allows free positioning of the C-arm around the
patient.
○Tables also need to be X-ray translucent so they do not interfere
with imaging. Carbon fiber tables are usually used in this role
because they are strong and lightweight.
33. ○The lack of skull
rotation is shown by the
same distance between
the orbit margin and the
lateral border of the
skull in both sides and by
the same distance of the
median sagittal plane
(identified by the crista
Galli) to the external
orbital margin in both
sides.
36. Preservation of residual hearing is of paramount
importance when working on patients with
steeply sloping hearing loss (Hyprid CI).
37. • It has also been suggested also to perform ‘‘soft CI
surgery’’ regardless of the amount of preoperative
residual hearing, reduce cochlear trauma and improve
spiral ganglion cell survival, and, consequently, improve
the long-term outcomes.
• Previously using a short electrode were the solution to
obtain this but more recently, all manufacturers have
focused their engineering efforts on designing and
developing special flexible electrodes with reduced
cross-sectional dimensions to minimize trauma to
cochlear structures during CI.
38. • Monitoring of residual hearing can be made by using a
neurophysiological auditory intraoperative
monitoring(NIM) technique that continuously records
the ongoing cochlear activity elicited by acoustic stimuli.
• Among the different NIM techniques (ie,
electrocochleography [ECoG], auditory brainstem
response [ABR], and auditory steady-state response
[ASSR]) used during hearing preservation, ECoG can
satisfy these needs properly, furnishing large-amplitude
potentials and allowing adequate representation of
evoked potentials after a few sweeps.
39. A series of representative electrocochleography (ECoG) recordings at 1000 Hz (100 dB
hearing level HL) superimposed on the surgical video. The first yellow trace represents the
baseline recording. Temporary changes to the compound action potential (CAP) can be
observed in the second and third rows. Almost complete recovery of CAP latency and
amplitude can be observed in the last recording.
40. Information on the trauma induced by the type of
cochleostomy and of electrode insertion modalities should
be gathered in real time, while surgery is ongoing, so that the
surgeon can understand the causative maneuvers and decide
whether to modify the surgical procedure to minimize
trauma to the cochlea accordingly.
41.
42. • CI is usually a safe and reliable surgical procedure.
• Several studies demonstrated that facial nerve paralysis
following CI is rare (as low as 0.62%) .
• The relatively low incidence of facial nerve injury during CI
surgery is most likely because the facial nerve is in a specific
location (ie, inside the facial canal) for most patients and
because its direction is predictable.
• However, it may take some effort to make judgments on the
direction of the facial nerve and the likelihood of nerve
sheath exposure especially in cases with altered anatomy as
in congenital anomalous cochlea.
43. The width of the facial recess was smaller in the
inferior angle formed by the chorda tympani
nerve (arrow). (A) When right CI surgery was
performed by right-handed surgeon, the shaft of
the drill was closer to the inferior angle of the
facial recess.
(B) When left CI surgery was performed by a
right-handed surgeon, the drilling shaft was
farther from the inferior angle of the facial
recess.
44. • Intraoperative continuous facial nerve monitoring (IFNM)
using an electromyograph (EMG) was first established in
neurotologic surgery.
• This technique monitors muscles innervated by the facial
nerve at risk during surgery. Iatrogenic trauma to nerves
evokes high-frequency bursts of motor unit potentials
called neurotonic discharges that are detected by a
monitor.
• This alerts the surgeon and may help to prevent serious or
irreversible injury.
45. ○A 2-channel EMG system monitors 2 muscles
;orbicularis oculi and orbicularis oris during the
surgery.
○Two subdermal aired electrodes are placed 10
and 15 mm distal to the upper eyelid
(orbicularisoculi), and 10 and 15 mm superior to
the corner of the mouth (orbicularis oris).
○Ground and stimulant return electrodes were
also placed into the dermis of the anterior chest.
46. Remote
Intraoperative
Monitoring
During Cochlear
Implant
Surgery
○The most significant consumer of time for on-site
testing is the travel time required to and from the
OR
○ in addition, there is greater time wasted waiting
for testing to commence once the audiologist has
arrived in the OR.
○With remote monitoring, the audiologist can
multitask and thus reduce unproductive travel and
waiting time.
47. ○Remote testing is also beneficial to the patient as
because all of the computers at the cochlear implant
center and the OR are networked, the data obtained at
the time of surgery is immediately available to the
audiologist at the implant center.
○This allows the audiologist to begin designing the
plan with regard to techniques that they will use during
the initial device stimulation occurring 3 weeks
postoperatively.
48. ○Additionally, any computer networked in the system can
be used as the computer, which, in turn, allows the
audiologist flexibility in location of monitoring.
○Thus, in the future, patients may undergo cochlear implant
surgeries at remote sites in the world where trained
personnel to perform testing may be lacking. while the
intraoperative testing may be performed by available
personnel at distant sites.
○Even more exciting is the possibility of remote
programming of the device itself.
49. ○The most common problem experienced with remote
testing
○was the inability of the off-site computer to
recognize the IP address of the computer in the OR.
○This led to training of the OR personnel in
configuring the IP address and communicating the
correct address to the audiologist at the remote site so
that it is currently not an issue.
○Rarely, the audiologist must come to the OR if a
connection problem cannot be resolved remotely.
