~ Infantile Idiopathic Scoliosis ~
"We should no longer be content with the objective of only controlling the rate of progression of the deformity but aim instead at the ultimate objective of getting rid of the deformity. We need to be aware that growth can be an asset and a corrective force when it is properly exploited in the early treatment of scoliosis." ~ Min Mehta
~~~~ Infantile idiopathic scoliosis falls into two groups: the resolving and the progressive. The resolving cases just have to be observed over a period of time to ensure that they follow their natural course which usually takes anywhere from 18 to 24 months to complete. The rib vertebrae angle (RVAD) of such cases falls below 20 degrees. In a few cases, the RVAD is above twenty degrees but it will decrease within the next few months. These cases normally do not require any treatment other than periodic observation until the curve has resolved.
The progressive cases require immediate treatment. A doctor can determine at a very early stage a progressive curve by obtaining two A/P x-ray images within a two to three month interval. If the first x-ray shows an RVAD of 20 degrees or more (in a few cases, it starts out less than 20 degrees) and the second A/P x-ray image shows that the RVAD has not changed or has increased then it is a progressive curve.
Braces are generally NOT effective in holding down progressive curves ( except sometimes - not too often- for very small, flexible benign curves ). At best, braces will slow the progression of the curve. At some point during a child's rapid growth phase which usually occurs between the ages of 0 to 4, a child will grow at a rate which doubles the growth rate experienced during adolescence. To take advantage of this rapid growth, Dr. Mehta has treated numerous children with serial casts with incredible results. A cast is required to hold the curve in its newly corrected position for a period of three or four months. Once the child outgrows the cast, a new one is applied and the spine is further corrected. This process is continued until the the Rib Vertebrae Angle Difference falls to zero or thereabouts. Curves at the end of treatment having a Cobb angle less than 20 degrees, vertebral rotation less than 10, RVAD of 0 and no structural deformity of the vertebrae at the apex of the curve will usually evolve towards healing. The total length of time in a cast depends on the severity of the child's curve. If the child's curve is below 40 degrees, two or three cast changes may be all that's required. Curves above 40 degrees take longer to bring under control. Stiff, rigid curves referred to as "Malignant Progressive Scoliosis" can be brought under control with casting IF caught early - usually 25 degrees or less.
According to Dr. Mehta's article "Infantile Idiopathic Scoliosis", when the "RVA difference is zero, the ribs on either side of the spine are in symmetry, there may be a small residual curve which will disappear over time followed by vertebral derotation and a gradual disappearance of the rib hump ( always in that order )" She states that a brace should be worn for a period of time to maintain the RVAD at zero (perhaps for three to six months). If after that period of time, the RVAD is STILL zero, then the child can be freed of all external support. The child is then monitored to ensure that the RVAD remains at zero. Some residual curves can take up to 7 years to resolve, BUT if the RVAD remains at zero, then that child doesn't need to wear ANY kind of brace or cast !!! She then states "if the deformity (meaning the residual curve) has been corrected before the onset of the prepubertal growth spurt there will be no relapse at adolescence but if correction is incomplete a small relapse may occur".
Although, not all cases of progressive idiopathic scoliosis will resolve with casting, the majority will. Cases which will not generally resolve are:
i) malignant progressive: these cases are "rigid" curves which progress rapidly. Caught in the early stages, there is a chance that they can resolve.
ii) curves which have gone beyond a certain threshold of severity i.e., 70 or 80 degrees.
(The above comments are based on readings of Min Mehta's articles: "The Natural History of Infantile Idiopathic Scoliosis" "Infantile Idiopathic Scoliosis" and "The Conservative Management of Juvenile Idiopathic Scoliosis")
Further to the appearance of the above summary on the NSF in March of 2004, below is an excerpt of an
e-mail correspondence from Dr. Min Mehta:
...I have read your essay in the National Scoliosis Foundation Forum with interest. It is to a very large measure accurate and informative, but there are a few small errors which I think should be addressed - firstly in paragraph one the RVA should be RVAD. In paragraph three you are correct in saying the RVAD gradually falls with treatment to zero or thereabouts. In some children it never reaches zero but your sentence "Curves at the end of treatment having a Cobb angle less than 20 degrees, ............" does not always apply to every child and, the decision to discontinue treatment by plaster casts is individual to the child who has the scoliosis. In the radiographic assessment of a progressive infantile scoliosis, all parameters, namely Cobb angle, RVAD, and vertebral rotation, must be jointly evaluated. The RVAD as you have correctly stated in the first paragraph, is used in reaching an early differential diagnosis between the resolving and progressive forms of infantile scoliosis. You may be interested to read that original article published in the Journal of Bone and Joint Surgery British Volume 1972, 54-B, pages 230-43, titled - The rib-vertebra angle in the early diagnosis between resolving and progressive infantile scoliosis.
With best wishes.
Miss Min H Mehta, FRCS
Consultant Orthopaedic Surgeon
Correcting Scoliosis during the AIS
James O Sanders MD et. al., 2009:
Derotational Casting for Progressive Infantile Scoliosis
J.H. Ferreira and J.I.P. James:
Progressive and Resolving Infantile Idiopathic Scoliosis, The Differential Diagnosis
Growth as a Corrective Force in the Early Treatment of Progressive Infantile Scoliosis, Min Mehta, 2005: Growth as a Corrective Force.pdf
N. Ventura et. al., 1998: Infantile Idiopathic Scoliosis in the Newborn
Min H. Mehta and G. Morel, 1979 in: Zorab PA, Siegler D, eds.
Scoliosis. London: Academic Press, 1980: P 71-84:
The-Non Operative Treatment of Infantile Idiopathic Scoliosis
Min Mehta, 1984 In: Management of Spinal Deformities. Butterworth, London, Ed. Dickson R.A. and Bradford D.S. ( P 101 - 120):Infantile idiopathic scoliosis.pdf
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