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Posted by CCF Neuro MD on April 08, 1997 at 09:10:23:
In Reply to: Duane's Syndrome in 1 Identical Twin Girl posted by Johnnie M. on April 08, 1997 at 09:09:02:
: This Message was posted by: Johnnie M. - 4/2/97 8:04:07 PM
I hope you can answer a couple of questions for me that no one
else can seem to provide. I have identical twin girls, age 4,
one of whom has been diagnosed with Duane's syndrome involving
her left eye. The pediatric opthalmologist said her case was
mild, that since it involved the nerve and not the muscle,
that there was really no way to correct it and he did not
recommend surgery. She also has a small skin tag on her right
ear(which I understand may involve the same cranial nerve), her
hearing has tested fine.
My first question is what is the criteria for corrective
surgery for Duane's syndrome and which leading medical centers
would perform them? I'm afraid there might be a new, innovative
procedure being performed that we might miss out on'.
Also, how can 1 identical twin have this and not the other?There
is no previous family history, but her male first cousin ,age 1,
was just diagnosed with Duane's syndrome too. My twins have not
had DNA testing for mono-zygotisity, but the placenta was
analysed,(different amniotic sacs, but a single chorion).
The only factor which could have differed in-utero was that I
had an amniocentesis,but they could only reach 1 twin.
I apologize for the length of this letter, but this is matter
which both concerns and intrigues me.
Thank you for your help, Johnnie M.
Your questions are interesting and allow for a discussion into some of the intricacies of Duane's syndrome. To begin with so
called Duane's retraction syndrome is a disorder of ocular motitilty (or eye movements). The disorder seems to involve the left
eye most commonly, however it can involve the right eye and less frequently it can be bilateral. There is a limitation of moving
the affected eye outward and there is an associated pulling of the eye inward into the orbit. This abnormality disrupts the
otherwise synchronous movemets of the eyes and causes visual images to blur and become double. The reason for this
abnormality of eye movements is explained by the fact that the nerve which supplies the eye muscle which turns the eye
outward is poorly developed and so that muscle is innervated by one of the other cranial nerves which typically supplies the
other eye muscles. There are other cognital abnormalies that can be found in association with Duane's syndrome and so it is
possible that the skin tag at the ear maybe associated in some way with the syndrome but it is not associated with the specific
nerve which is involved in Duane's syndrome. Duane's syndrome is often a congenital disorder and patients are born with
double vision. The exact mechanism of how this eye disorder is brought on is still unknown. There have been a number of
chromosomal abnormalities that have been found in association with Duane's syndrome. The most notible being on
chromsosme 22. There maybe changes that occur during pregnancy that influence the development of the eye movement
systems. In your particular instance the fact that you are a dizygotic (fraternal) twin makes you genetically quite different. Even
in monozgotic twins who share the same gentic make up, one twin make have the syndroem wheras the other maybe normal.
The explanation for this is thought to be due to the fact that one twin who was affected had experienced some problems during
pregancy (prehaps in the 4th or 8th week) to have caused the syndrome. In
one instance a communication between the two umblical cords was found and thought to have contributed to the development
of this syndrome in that particular case. The management of Duane's syndrome is controversial. Most of the patients who have
is disorder develop an abnormal head posture in order to prevent double vision. Corrective eye surgery is done then when this
head posture becomes problematic or if symptoms progress as they can in some instances. To find out more about your
specific case you may want to contact an Opthalmologist who specializes in strabismus sugery. Some institutions in addition to
our own which have some experience in this regard are listed below:
Storm Eye Institute, Charleston, SC
Jules Stein Eye Institute, Los Angeles
Opthalmology Department at University of Medicine & Dentistry of New Jersy
I hope you find this information useful.
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