Adolescent Idiopathic Scoliosis comprises about
80% of the cases of scoliosis that we see in our usual practice of
pediatric orthopaedic surgery. Although the cause of this type of
curvature of the spine is not completely understood, it is clear
that the tendency to develop this problem is inherited. The
scoliosis is more likely to be seen in the females in any one
family, and usually begins to be noticeable on physical exam
around age ten. In virtually all cases, the curves are concave to
the right side of the chest ( that is the spine deviates toward
the right side of the patients body.) From early in my residency
in orthopaedic surgery, I was taught to be especially wary of left
sided thoracic curves. At the time, we did not have M.R.I. as an
imaging tool. Syringomyelia was a very poorly understood condition
that was almost never diagnosed in a child. Usually the diagnosis
was made only in adult patients following years of vague
progressive and non-specific complaints. Patients required a
pneumoencephalogram to properly make the diagnosis. For those who
may be unfamiliar with this outdated test, let me assure you that
you would not want to go through one, and I do not remember ever
ordering one on a child. Thus we recognized that the left sided
thoracic curve behaved in a strange way ( did not respond very
well to brace treatment) but we did not appreciate why. I suspect
that many of these children had the Arnold-Chiari malformation and
syringomyelia that went undiagnosed.
Now that we are aware of the association between
syringomyelia and unusual scoliosis patterns, we order M.R.I.
testing to look for syringomyelia. At our children's hospital, we
find several cases of syringomyelia every year, and few of the
patients have any findings on neurologic exam, and almost none of
these children have any complaints. We are left with many
unresolved questions concerning the treatment that should be
recommended for the management of these children.
I try to inform the parents that there is very
much that we do not know about the natural history of
syringomyelia and its associated scoliosis (natural history = what
will happen to the patient if nothing at all is done.) We do not
know the way in which syringomyelia produces the scoliosis, since
many patients with syringomyelia do not have any scoliosis and
most patients with scoliosis do not have syringomyelia. In the
absence of strong scientific proof, treatment is guided by general
principles that are used for Idiopathic Scoliosis. My colleagues
and I generally attempt to control scoliosis with braces if the
curve exceeds 25 degrees in a growing child. If an Arnold-Chiari
malformation is identified in association with syringomyelia and
scoliosis, we recommend decompression before bracing, as many of
our patients have shown either reduction or stabilization of the
curve after this procedure. Most often the decompression will also
produce a significant reduction in the size of the syringomyelia.
If the scoliosis continues to be progressive, we institute brace
management. The success of brace management is not as high for
these patients as it is for patients with idiopathic Scoliosis.
There are those who feel that braces are not indicated for the
treatment of scoliosis associated with syringomyelia. I would say
that although the success rate is lower, until a large series of
patients is studied closely and the long term results are
published, it is still probably a wise conservative approach to
use a brace in an attempt to arrest the progression of the
curvature. Regardless of whether bracing is used, the patient
should be followed closely (X-Rays approximately every four
months) for progression. If the child is still growing and the
curvature exceeds 45 degrees, we would recommend spinal fusion
with instrumentation. This presents the surgeon and the family
with yet another dilemma. Instrumentation dramatically increases
the healing rates for this surgery, and can produce dramatic
improvements in the cosmetic appearance of the spine, especially
in the young, flexible patient. Contrary to some very early
published reports, we have found no increased risk of neurologic
damage associated with the use of internal fixation devices in
patients with syringomyelia. The usual fixation devices are made
of stainless steel, and therefore are not ideal for use in
patients who would likely be in need of M.R.I. testing to follow
the course of their syringomyelia. Titanium versions of most
standard instrumentation are available, and with these in place,
M.R.I. testing can safely be performed, however, even though the
testing can be done, the quality of the images will be inferior
due to artifact produced by the metal implants.
In conclusion, since the number of cases of
patients with scoliosis associated with syringomyelia is small, no
hard evidence exists to completely support any recommendations
concerning management. I believe that bracing should be attempted
in curves that are progressing, although braces are probably less
effective in these patients than in patients with adolescent
idiopathic scoliosis. I have seen enough of my patients benefit
from decompression of their Arnold-Chiari malformations (decreased
curvatures, shrinking of the size of their syringomyelia) that I
have recommended that procedure to others. I am less certain about
whether decompression of a stable syringomyelia in an asymptomatic
patient is indicated. It is clear that this disease is rare enough
that definitive recommendations cannot be made until multi-center
studies are used to accumulate enough data to produce reliable
statistics concerning the benefit of various treatments. Until
then, each patient and their physicians will continue to make
their decisions based on careful counseling in light of the scant
information available.
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