Friday, December 23, 2016

What organ systems are affected by Early-Onset Scoliosis (EOS)?

Scoliosis, at any age, causes distortion of the body from the neck to the waistline.  Though on the x-rays (or radiographs) that are obtained to evaluate for scoliosis the spine only appears to curve in a lateral direction, however it actually has become deformed in three dimensions (front, side and axial).  The front view is shown below in the first x-ray or radiograph.  It is easy to see the severe curve, causing the right shoulder to be higher than the left, but also it is easy to appreciate the shift of the body to the right relative to the pelvis and hips.

As the spine starts to curve to the side it also twists on itself, and it is this twisting which causes the ribs to be differently oriented between the left and right sides of the body.  In the x-ray below one can also appreciate the difference in the ribs, both in their position, shape and spacing.  The ribs on the left side are more horizontal, while those on the right are more vertical, especially at the middle of this severe curve.  Also the ribs on the left are very close together, and those on the right more spaced apart.  This is because the spine on the concave side of the deformity is relatively shorter than the convex side, so the ribs are more close together.  Also as the spine curves to the side the distance of the spine, from the neck to the hips, shortens which can cause the body to look uneven, with the leg looking longer than they should be.

In Early-onset scoliosis (<10 years of age at detection) the main organ system of concern in the lungs.  The two main issues impacting the child’s lungs are the shortening of the spine (neck to pelvis) and the twisting of the spine.  In general as the spine shortens the abdominal contents (liver, spleen, stomach, intestines, etc…) relatively move upward into the chest.  Since the lungs are very compliant or soft, compared to the abdominal contents, this effectively creates less room for the lungs.  In other words the lungs become squished. 


3-d Computed Tomography (CT) scan of the lungs in a patient with EOS



The graph above is from a study by Emery and Mithal in 1960 which is looking at the alveoli in the young child’s lung.  The alveoli are the air sacs which permit us to get oxygen into our blood stream and get rid of carbon dioxide.  It is important that the development of the lungs is optimized early in life as the alveoli multiply in number up to approximately 8-10 years of age.  Thereafter it is mainly the alveoli mainly increase in size, not in numbers.  So it is important to maximize the growth, or length of the spine, during the first 10 years of life as this impacts how well the lungs develop.

The other organ systems (heart, gastrointestinal) are impacted to a lesser degree.  These two systems are impacted only in severe (>100 degrees) of scoliosis.  However, unlike the lungs, the impact of scoliosis on theses two systems is much more reversible.  When the scoliosis is treated these systems will return close to normal status. 

Pediatric spine deformity surgeons focus much of their attention on maximizing the development of the lungs in children unde 10 years of age.  This is why performing definitive, long spine fusions in this age group is rarely performed.  A long, multi-level spine fuison will permanently shorten the spine, and secondarily decrease the volume of the lungs.  To treat spine deformity in children <10 year pediatric spine deformity surgeons use “growth-friendly” techniques, which corrects/manages the scoliosis but permits growth of the spine.  Bracing and casting are nonsurgical techniques which are “growth-friendly” have already been posted on this blog earlier.  In subsequent blogs surgical techniques which are “growth-friendly” will be explained. 

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