Inner Ear Malformations: Classification, Evaluation and Treatment

377 Pages·2022·22.076 MB·English

by  Levent Sennaroglu

Inner Ear
Malformations
Classification, Evaluation and
Treatment
Levent Sennaroglu
Editor
123
Inner Ear Malformations
Levent Sennaroglu
Editor
Inner Ear Malformations
Classification, Evaluation
and Treatment
Editor
Levent Sennaroglu
Department of Otolaryngology
Hacettepe University
Faculty of Medicine
Ankara
Turkey
ISBN 978-3-030-83673-3 ISBN 978-3-030-83674-0 (eBook)
https://doi.org/10.1007/978-3-030-83674-0
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Foreword
It was not long ago that inner ear malformations were poorly understood,
little studied, and of minimal relevance to practicing otologists. Symptomatic
of this neglect, all inner ear malformations, which have a rich diversity of
types and subtypes, were lumped together under the omnibus term “Mondini”
deformities. Recent advances, driven by the ability to visualize minute struc-
tures of the inner ear during life via progressively more sophisticated imag-
ing, have enabled recognition and definition of patterns of malformation.
Studies correlating clinical features associated with each morphology enable
improved ability to predict hearing loss stability over time. Contemporary
imaging also assists in identifying those at risk for CSF leak and meningitis
and is important in establishing candidacy for cochlear implantation. Using
modern imaging, and an impressive collection of some 700 inner ear malfor-
mations, Dr. Sennaroglu has refined and improved earlier inner ear malfor-
mation classification schemes.
I have always thought it more than a small miracle, given all the precise
biological steps needed to form a human being, that so many infants are born
free of imperfections. The study of inner ear malformations provides clues
into the essential steps of normal embryology of the inner ear. Unraveling the
mysteries of inner ear organogenesis has special relevance not only to birth
defects but also to potential pathways forward to regenerating the organ of
Corti in adult hearing loss. One promising strategy for regeneration is re-
kindling the developmental cascade through upregulation of master regula-
tory genes such as ATOH-1. The lessons learned via study of how embryology
goes wrong provides important clues to help drive research into the steps of
development and their control mechanisms.
It is a sign of maturity of the field of study of inner ear anomalies that the
body of knowledge is now sufficient to merit a book-length treatment of the
subject. I congratulate Dr. Sennaroglu and his coauthors for compiling such a
comprehensive and well-thought-out monograph covering all aspects of inner
ear malformations. Their work lays the foundation for future advances which
will elucidate the crucial biological underpinnings for this family of disorders
v
vi Foreword
and, in time, develop biologically based interventions to restore hearing func-
tion or, ideally, recognize and correct their genetic basis.
Robert K. Jackler
Department of Otolaryngology-Head & Neck Surgery
Stanford University School of Medicine
Stanford, CA, USA
Departments of Neurosurgery and Surgery
Stanford University School of Medicine
Stanford, CA, USA
Preface
Management of Inner Ear Malformations (IEM) constitutes a major part of
the implant teams’ work at the present time. With the precision of new gen-
eration computerized tomography (CT) and magnetic resonance imaging
(MRI), it has been possible to diagnose IEMs more frequently than before.
When I was a research scholar in House Ear Institute in 1997, I had the
opportunity to increase my knowledge about cochlear implantation and all
kinds of ear surgery. In addition, I examined histopathology slides with Prof.
Fred Linthicum, M.D. I learnt to examine the temporal bone slides systemati-
cally from superior to inferior. One day an important event happened which
would have a big impact on my future career. Prof. Antonio De La Cruz,
M.D., offered me to go to the Department of Radiology to consult the images
of a difficult atresia patient. There, he introduced me to Prof. William
W.M. Lo, M.D., who was the radiologist of St Vincent’s Hospital opposite to
House Ear Clinic with a special interest in temporal bone radiology. This was
at the same time my introduction to radiology of the temporal bone. Prof. Lo
was an excellent radiologist. I spent many hours with him. He not only
showed me basic temporal bone CT and MRI images but also opened his
archive of special cases, and we discussed them in his free time. I owe a lot to
this great teacher and I remember him with great respect.
This increased my knowledge of the radiology of the temporal bone. Back
in Turkey, in 1997, we started cochlear implant (CI) surgery. I noticed that the
term “Mondini” was being used to define two completely different anoma-
lies: incomplete partition type I (IP-I) and II anomalies. I checked the litera-
ture. In the excellent book by Prof. Harold Schuknecht, M.D., the term
“Mondini Deformity” was used for these two completely different anomalies:
one was a cystic cochlea without interscalar septa and modiolus, while the
other one had only a cystic apex with almost normal modiolus. Theoretically,
the majority of the spiral ganglion cells are located in the 2/3 basal part of the
modiolus, and I thought it would not be correct to give the same name to these
completely different anomalies.
In the meantime, we started to run into some problems with IEMs in our
young cochlear implant program. Scans with IEMs were usually reported as
normal. I was pointing out that IP-I anomaly was different than “Mondini
deformity” but my remarks were not taken seriously. Prof. Ergin Turan, M.D.
(our senior professor in the implant team), always told me to ask the opinion
of radiologists to make the correct diagnosis. Therefore, I decided to make a
study to show the difference between them and to send the study to
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viii Preface
Laryngoscope, the journal which Prof. Turan had subscription at that time (I
was hoping he would believe me if the article was published). After he saw
the paper published in Laryngoscope, he was impressed with my contribution
and honored me saying that “From now on you will be the only one who will
operate on IEM’s to accumulate the data in one hand and publish it accord-
ingly.” Whenever he had patients with IEMs, he handed them to me for sur-
gery. This honored me greatly and I strongly thank Prof. Turan for urging me
into this field and fully supporting me in this area. This was the beginning of
my journey with IEMs, which would last during all my academic career.
The main outcome of this paper was to create a platform “to talk the same
language all over the world.” In meetings I have seen people talk about
“small” and “big cochleae” or use names with no meaning to the audience. If
we do not have an accepted classification, presentations and scientific work
will not be understood. Classification of IEMs is important for otolaryngolo-
gists, audiologists, radiologists, geneticists, and neurosurgeons dealing with
Auditory brainstem implantation (ABI). After our initial classification, it was
updated in 2010 and finalized in 2013. Since 2013 there has been no more
new anomalies; therefore, the time finally arrived to write a book!
We have been examining some patients with no inner ear development or
cochlear nerve, and nothing could be done at the beginning for these patients.
After the introduction of ABI surgery in children by Prof. Vittorio Colletti,
M.D., in 2001, in 2003 we seriously thought about the first ABI candidate. At
that time, there was not sufficient information in the world about ABI in chil-
dren. When Prof. Richard Ramsden, M.D., started pediatric ABI surgery in
Manchester, with whom we communicated frequently about the indication,
we decided to start ABI in 2006. The first three children were operated
together with Prof. Colletti in Hacettepe University. So far, we have done 125
pediatric ABI surgeries in IEMs, and Hacettepe University has become the
most experienced clinic in pediatric ABI in the world, providing international
support as well. Prof. Burcak Bilginer, M.D., from the Department of
Neurosurgery and his team played a major role in this development. I think
Prof. Colletti opened an era in the management of severe IEMs, and we
believe it is our mission to continue this approach.
In 2006 one of the children that I operated died because of meningitis
3 months after CI surgery. She had gusher during the surgery. I repaired the
leak properly, but 3 months later she developed meningitis and in spite of the
extraordinary support of our hospital she could not be saved. This had a big
impact on me and I designed an electrode with cork like stopper to stop CSF
leakage more efficiently. I had already thought about the design before, but
this made me go ahead and produce the electrodes with cork stopper to more
efficiently manage CSF gusher during surgery. That is the beginning of
FORM electrode series.
In 2013, I received a very honoring invitation from the Department of
Otolaryngology at Massachusetts Eye and Ear Infirmary at Harvard University
to give the “Harold D.  Schuknecht Lecture in Otology.” Prof. Harold
Schuknecht, M.D., is one of the otology legends. Before going to Boston, I
requested to investigate the specimens with IEMs during my stay at Harvard
University. After my lecture, I investigated some specimens with IEMs and I
Preface ix
noticed an extraordinary finding: the meaning of that finding was not noticed
before even though that patient had been published three times before. I told
this with great enthusiasm to the doctors around me, but naturally nobody
was as interested as me in the subject. After 1 year, I took a sabbatical from
my university and went to investigate that specimen. I spent one whole month
in Eastern Temporal Bone Bank which consisted of a small room with more
than 2000 specimens with different temporal bone pathologies, and at the
end, I underlined the pathophysiology of not only IP-II (my main reason to go
back to Harvard) but the whole spectrum of IEMs. This will be a great oppor-
tunity to geneticists because they will have more chance to understand the
etiology of IEM. This in future may develop methods to genetically prevent
these malformations.
One of the main reasons to be invited to Harvard was also to share our
huge ABI experience with the team there. I gave a lecture on IEMs and out-
come of pediatric ABI. During my stay we evaluated possible candidates. I
learnt later that three centers in the USA used the ABI data from Verona
University (Prof. Vittorio Colletti, M.D.) and Hacettepe University to apply
to FDA to get approval to start ABI in children. As Hacettepe Implant Team,
we are very honored that after 6 months they had FDA approval for starting
ABI in children in the USA.
One of the most important factors of the success of Hacettepe Implant
Team is the early setup of audiology unit in our university. Prof. İ. Nazmi
Hosal, M.D., performed his residency in the USA in the 1950s and saw the
importance of audiology in modern otolaryngology. After returning to Turkey,
he set up the audiology department in Hacettepe University in 1967. I think
this is the birth of modern otolaryngology in Turkey. This allowed performing
a large number of cochlear and brainstem implants because decision-making,
programming, and rehabilitation could be done more efficiently with this
experienced group. In the audiological management of patients with IEMs,
Prof. Gonca Sennaroglu, Ph.D., and Prof. Esra Yücel, Ph.D., and their teams
made enormous contributions.
What is next? Classification is very important. If we do not classify phe-
notypes properly, we cannot notice the difference between them. In recent
years I do not see new malformations coming up. This means we may come
to the end of new anomalies. During my 1 month stay at Harvard University
in 2014, my study shed light on understanding the pathophysiology of IEMs.
Geneticists now have a more specific target and if they can identify the genetic
defects responsible for a particular pathology it may be possible to prevent
certain IEM in future.
Levent Sennaroglu
Ankara, Turkey
Acknowledgments
During my childhood I gained important fundamental behaviors from my
family. This had an important influence on my personality as well as my
working habits. My grandfather, who had been a teacher for 42 years, dem-
onstrated to me and my brother the importance of education. My grandmother
who was a housewife spent a lot of time with us from whom we learnt humane
behavior and at the same time received warning if we did something wrong.
I learnt the concept of systematic working from my father, who was a civil
engineer. This not only helped me in surgery working according to certain
principles but in my whole career as well. I wanted to organize and categorize
things around me. Because of this systematic approach, I learnt how to keep
database for everything and categorize things appropriately. This is the reason
for placing different malformations into appropriate places in the classifica-
tion. My mother, who is the first Turkish woman doctor in Cyprus, was very
interested in our education and always created a peaceful atmosphere during
our studies. I thank all of them with all my heart for their efforts in initial
shaping of my character.
We had a very good education in Cyprus from primary school until the end
of the high school. All our teachers built our knowledge brick-by-brick.
I remember all of them with great respect.
I would like to thank my teachers in the Department of Otolaryngology in
Hacettepe University. Particularly important is Professor İ. Nazmi Hosal who
brought modern otolaryngology to Turkey. I learnt basic principles of otolar-
yngology and particularly otology during my residency and initial years of
my practice in Hacettepe University. I started to work in otology with
Professor Bulent Gursel and I would like to thank him for encouraging me to
continue my studies in otology.
Visiting House Ear Clinic had a dramatic influence on my career. I saw the
advantages of working specifically in one topic within otolaryngology. Until
that time, I was practicing different aspects of otolaryngology although I was
interested in otology. When I saw the House Ear specialists working in otol-
ogy for more than half a century with tremendous contribution to the litera-
ture, I decided to practice only one aspect: otology and neurotology. As a
result, I started to see ear-related problems more and recognize repetition of
certain disorders. I thank all the specialists in the House Clinic, but particu-
larly Dr. WWM Lo who taught me the radiology of the temporal bone.
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