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Study design Familial cases of "idiopathic" scoliosis associated with neurologic abnormalities are reported with a review of the literature. Objective To investigate the prevalence of neurologic abnormalities such as syringomyelia, Chiari 1 malformation, and tonsillar ectopia in patients with genetically determined "idiopathic" scoliosis. Summary of background data Idiopathic scoliosis is widely considered to be a genetic disorder of unknown etiology. Magnetic resonance imaging (MRI) studies have shown that several cases of "idiopathic" scoliosis show neurologic abnormalities including syringomyelia and Chiari 1 malformation. Recently, several familial cases of either syringomyelia or Chiari malformation were reported, and it is suspected that genetic factors may influence the development of the craniovertebral malformation. It was hypothesized that some cases of "idiopathic" scoliosis include a craniovertebral malformation that is genetically determined. Methods This study, using clinical examinations and MRI, investigated 71 patients with scoliosis and a family history of "idiopathic" scoliosis in third-degree relatives for the presence of neurologic abnormalities. If neurologic abnormalities were confirmed with MRI, the relatives affected with scoliosis were also examined. Results Nine (13%) patients showed neurologic abnormalities on MRI. Magnetic resonance imaging showed syringomyelia with Chiari 1 malformation in four patients, Chiari 1 malformation in three patients, and tonsillar ectopia in two patients. Among the relatives of these patients, 4 of 15 individuals affected with scoliosis also showed neurologic abnormalities on MRI. Conclusions It is suggested that familial neurologic abnormalities may have a wide range of expression, and that some patients with "idiopathic" scoliosis present with genetically determined craniovertebral malformations such as syringomyelia, Chiari 1 malformation, and tonsillar ectopia.

Study Design. Analysis of the estrogen receptor gene of girls with idiopathic scoliosis. Objectives. To determine whether estrogen receptor gene polymorphisms correlate with curve severity of adolescent idiopathic scoliosis. of Background Data. Studies suggest that idiopathic scollosis is a familial condition and that curve progression is related to genetically determined factors, such as skeletal and sexual growth. Methods. A total of 304 girls with idiopathic scoliosis were followed until growth maturation. Height, arm span, menarcheal age, and age at growth maturation were recorded, and curve severity was measured using Cobb's method. The estrogen receptor gene, which contains polymorphic Pvull and Xbal sites, was amplified from lymphocyte deoxyribonucleic acid by polymerase chain reaction. Results. The mean maximum Cobb measurements for patients with genotypes XX and Xx were greater than for those with genotype xx (P = 0.002). The risk of curve progression, defined as progression of >5° from initial evaluation, was higher with genotype Xx than with xx (P = 0.03). Patients with genotypes XX and Xx had a significantly higher risk for operative treatment than those with genotype xx (21,4%, 24.7% vs. 7.6%, P < 0.001). Growth examination around the time of the growth spurt revealed that the Xbal site polymorphism was also related to the age of growth maturation. The frequency of patients with growth maturation at ≥16 years was higher for genotypes XX and Xx than for genotype xx (33.3%, 29.9% vs. 16.8%, P = 0.013). Conclusion. Our results suggest that the Xbal site polymorphism is associated with curve severity. DNA analysis may predict curve progression.

Progressive scoliosis in young children has been treated with "spinal instrumentation without fusion" to avoid interference with spinal growth. Patients have to undergo a series of operations to have instruments exchanged for maintaining the correction. We have developed a newly designed remote-controlled growing-rod spinal instrumentation system proposed for the treatment of progressive scoliosis in young children. It can be used to stretch and correct the spinal deformities repeatedly and non-surgically, by means of a remote controller, after the first instrumentation operation. The purpose of this study is to describe the possible clinical application of this system for the treatment of progressive scoliosis in young children. To this end, we used the system in five beagle dogs with induced scoliotic deformities. The maximum distraction force of the instrument was 194 N. Correction of 1 cm was performed non-surgically in awake animals 3 weeks after the instrumentation operation, and then correction of 1 cm was carried out again 6, 9, and 12 weeks after the operation. The average initial Cobb's angle of the induced scoliotic deformities was 25 degrees; this was corrected to 20 degrees, 15 degrees, 8 degrees, and 3 degrees, after the distractions at 3, 6, 9, and 12 weeks, respectively, postoperatively. All corrections were performed non-surgically without apparent complications. By repetitive distractions with the use of our new system, we may be able to reduce the number of operations required in young scoliotic children.

We investigated 21 pairs of twins for zygosity and idiopathic scoliosis. DNA fingerprinting confirmed that 13 pairs were monozygotic and eight were dizygotic. There was concordance for idiopathic scoliosis in 92.3% of monozygotic and 62.5% of dizygotic twins. Of the 12 pairs of monozygotic twins concordant for idiopathic scoliosis, six showed discordant curve patterns but eight had differences in Cobb angle of less than 10°. Seven of the ten pairs of monozygotic twins had similar back shapes. Our findings suggest that there is a genetic factor in the aetiology of idiopathic scoliosis; they also indicate that there is a genetic factor in both the severity of the curve and the general shape of the back.

Study design A prospective trial of preoperative MRI study in patients with "idiopathic" scoliosis. Objectives To investigate the prevalence of neural axis malformations and the clinical relevance of MRI in the evaluation of patients with idiopathic scoliosis undergoing surgical intervention. Summary of background data With the development of MRI, neural axis abnormalities such as syringomyelia or Chiari malformations are increasingly being found in patients with "idiopathic" scoliosis. The risk of neurologic complications during correction of scoliosis without prior decompression surgery for syringomyelia has been documented; however, there have been no prospective studies for identifying the risk of neurologic complications as a result of scoliosis surgery in patients with asymptomatic neural axis malformations. Methods A total of 250 patients who were classified as having "idiopathic" scoliosis at first presentation and admitted for spinal surgery were evaluated. All patients were examined for neural axis abnormalities using MRI. The presence of neurologic symptoms and abnormal neurologic signs was also examined before and after surgical intervention. Neurologic complications during scoliosis surgery were reviewed in patients with neural axis abnormalities. Results There were 44 (18%) patients (13 males and 31 females) who had neural axis abnormalities on MRI, including syringomyelia with Chiari malformations in 22 patients, syringomyelia with tonsillar ectopia in 2, Chiari malformations in 13, tonsillar ectopia in 6, and low conus medullaris in 1. On clinical examination, 44 (18%) patients had abnormal neurologic signs and 26 (7%) patients complained of headache or back pain. There were significant differences between patients with and without neural axis abnormalities regarding the age at first visit, gender, curve pattern, sagittal profile of thoracic spine, presence of neurologic deficit, and complaint of pain. Only 12 of 44 patients needed neurosurgical treatment for foramen magnum decompression before correction of scoliosis. Neurologic status temporarily worsened in 3 patients, including 2 patients with neurosurgical treatment and 1 patient without neurosurgical treatment; however, there were no permanent neurologic complications as a result of scoliosis surgery. All patients without neurologic deficits or complaints of pain did not receive neurosurgical treatment, while they had no permanent neurologic complications. Conclusions Foramen magnum decompression for neural axis malformations could prevent permanent neurologic complications during scoliosis surgery. There is little risk of neurologic complications in patients with "idiopathic" scoliosis whose neurologic status is normal, even if these patients have a neural axis malformation on MRI.

Three hundred and four girls with adolescent idiopathic scoliosis were investigated to determine if DNA polymorphisms in the vitamin D receptor (VDR), estrogen receptor (BR), and CYP17 gene were related to curve progression of idiopathic scoliosis. The results suggested that XbaJ site polymorphism in the ER gene was associated with curve progression. The Cobb's curve angle with genotype XX and Xx was statistically greater than that with genotype xx. The curve progression risk (approximately 5 degrees) was higher for genotype XX and Xx than for genotype xx. Furthermore, patients with genotype XX and Xx had a higher risk of receiving operative treatment than those with genotype xx. In conclusion, DNA analysis may predict curve progression, although other polymorphisms were not associated with curve severity.

We undertook a radiographic analysis with pre-operative computed tomographic myelography in 78 patients with idiopathic scoliosis in order to analyse rotation of the spinal cord and to investigate its clinical significance. The angle of rotation of the cord had a statistically significant relationship to both that of the apical vertebra and the size of the primary curve. The relationship between the rotation of the cord and that of the apical vertebra was divided into three types. The cord rotated in the same direction as the apical vertebra in 55 patients and rotated in the opposite direction in the remaining 23 patients. In the first group, the angle of rotation of the cord was more than that of the vertebra in six patients, but less than it in 49 patients. These results suggest that the neuraxis in idiopathic scoliosis may be under tension in the axial dimension.