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Experience and Results with a Custom-Designed
MED-EL Electrode for Common Cavities
MED-EL World-Wide Headquaters, Innsbruck,
Austria, S. Maria del Carmine Hospital, Rovereto, Italy; Crosshouse
Hospital, Kilmarnock, Scotland; Southmead Hospital, Bristol,
England
Author details
Ilona Anderson
ilona.anderson@medel.com
+43-512-288889-543
Introduction
Common cavity is no longer considered a contra-indication
for cochlear implantation. Previous resports suggest good outcomes in children
with common cavities. However there have been issues with CSF gushers and a
need for frequent re-programming due to migrating electrodes. This study documents
results of children with common cavity using the double posterior labyrinthotomy
technique and a custom made electrode.
Procedure
This was a restrospective collection of outcomes data from 3 children who had
been implanted with a custom-made COMBI 40+S electrode using the double posterior
labyrinthotomy technique.
The Custom-Made Electrode
The MED-EL COMBI 40+ short electrode was prolonged with a silicone part ending
with a small platinum ball that can be hooked through the second labyrinthotomy.
The Double Posterior Labyrinthotomy Surgical Technique
With a microscope, the mastoidectomy is completed until the enchondrial bone
of the optic capsule is exposed. A superior labyrinthotomy is made in an area
close to that where the non-ampullated end of the lateral semicircular canal
would normally be seen. An inferior labyrinthotomy is made inferiorly and the
endostium is opened (Figure 1 ).
Figure 1: Schematic cavity with two drilled
openings (cochleostomies) |
The electrode is prepared for insertion. The terminal
non-active part of the electrode array ends with a small ball, which
is needed to hook the electrode array. This non-active part of the
implant is pushed into the superior labyrinthotomy until it is seen
through the inferior labyrinthotomy (Figure 2).
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Fig. 2: Array
inserted in the superior labyrinthotomy of the cavity |
The small terminal ball is hooked through the inferior
labyrinthotomy (figure 3) and the terminal non-active part of the
arry pulled out, leaving a loop within the common cavity (figure
4).
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Figure 3: Array hooked through
the
inferior labyrinthotomy |
Figure
4: Array pushed from the superior labyrinthotomy and pulled from
the inferior |
The electrodes are centralised within the cavity, then
the two arms are advanced together positioning the array along the
inner wall of the cavity (figure 5). Resistance is felt when the loop
covers the internal circumference of the cavity (Figure 6).
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Figure
5: Array pushed from the superior and inferior labyrinthotomy |
Figure
6: Final position of array |
Case Reports
Case 1
A five-year-old girl implanted in December 1998. All 12 electrodes were switched
on,the programme remains stable. Sound detection was reported at 1-month post-fitting.
She also started vocalising at this time. She achieved 100% on discrimination
and closed-set identification by 3 months. At 6 months she was producing CV-CV
words. The 12 month test showed stable, yet static results. After further assessment,
she was diagnosed with Duane`s syndrome which primarily causes visual problems,
as well as skeletal abnormalities of the spine and limbs, otological defects
from the external ear to the acoustic nerve and possible effects on intelligence.
Case 2
A four-year-old boy who was diagnosed with Duane's
Syndrome pre-operatively. He was implanted in March 2000. 2 channels
were switched off initially due to high impedance, the programme
has remained stable. At 3 months post implant, he was alerting to
many environmental sounds and voice, including his name. He demonstrated
a marked increase and change in vocalisations. By 6 months, he tried
to answer the telephone and could complete closed-set discrimination
tasks in an auditory-only test context. At 12-months he demonstrated
a developing vocabulary and reduced reliance in sign. MAIS scores
show an improvement from 20% to 85% from the 3 month to 24 months
test sessions. Similar results are seen with the MUSS scores over
the same period (15% to 83%). His parents are pleased with his improvement
in speech intelligibility.
Case 3
A four-year old girl implanted in March 2001 Electrodes 1 to 4 were switched
off at first fitting. The map has since remained stable. Her three-month
assessment showed she wears her implant constantly. She responds to environmental
sounds, explores sound by babble and is developing vowels and consonant
production Her voice quality is generally good. Her family reports that
she is much more settled now that she has her implant. By 6 months, she
used "non-stop" babble, answers the telephone and babbles into
it. She attempts to say a few common words.
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