Scoliosis associated with syringomyelia

Treatment of Chiari Malformation and Concomitant Paediatric Scoliosis Long-Term Follow-Up in One Major Referral Centre in the UK

OBJECTIVE

Paediatric scoliosis (PS) and Chiari malformation type 1 (CM-1) have been reported to be associated with each other. Scoliosis curvature is a common finding among patients operated for CM-1, and curve development has been related to it. We report a cohort of PS and CM-1 patients managed with posterior fossa and upper cervical decompression (PFUCD) by a single surgeon, with an average of two years of follow-up.

METHODS

We present a retrospective cohort in a single referral centre for patients with CM-1 and PS.

RESULTS

From 2011 to 2018, we identified fifteen patients with CM-1 and PS; eleven underwent PFUCD, ten had symptomatic CM-1, and one had asymptomatic CM-1 but showed curve progression. The remaining four CM-1 patients were asymptomatic and were hence treated conservatively. The average follow-up post-PFUCD was 26.2 months. Scoliosis surgery was performed in seven cases; six patients underwent PFUCD prior to the scoliosis correction. One scoliosis case underwent surgery in the presence of mild CM-1 treated conservatively. The remaining four cases were scheduled for scoliosis correction surgery, while three were managed conservatively, with one case lost to follow-up. The average time between PFUCD and scoliosis surgery was 11 months. None of the cases had intraoperative neuromonitoring alerts or perioperative neurological complications.

CONCLUSION

CM-1 with concomitant scoliosis can be found. Symptomatic CM-1 might require surgery, but as we discovered, PFUCD had negligible effect on curve progression and the future need for scoliosis surgery.

Magnetic resonance imaging effectiveness in adolescent idiopathic scoliosis

OBJECTIVE

To assess the effectiveness of preoperative magnetic resonance imaging (MRI) in adolescent idiopathic scoliosis (AIS) patients with unremarkable history and physical examination.

METHODS

The imaging data of consecutive patients with presumed AIS treated with a posterior spinal fusion between 2010 and 2016 were reviewed. The presence of traditional risk factors, atypical curve patterns, and its association with relevant abnormalities on MRI were investigated. The number needed to diagnose (NND) and the number needed to misdiagnose (NNM) were calculated to measure MRI effectiveness.

RESULTS

A total of 198 consecutive patients were identified and divided according to the presence of MRI findings. Both groups predominantly consisted of females, with a mean age of 15 years and right thoracic curvature. Neural axis abnormalities were detected in 25 patients, and the groups had a similar proportion of atypical findings, as curve magnitude, thoracic kyphosis, curve direction, and sex. The NND was 7.9 patients and NNM was 66 patients, meaning that the management was changed before the spine fusion in 12% of patients with neural axis abnormalities. None of the traditional risk factors could predict a higher incidence of neural axis abnormalities in asymptomatic AIS patients.

CONCLUSION

Traditional risk factors may not be predictive of patients with a higher risk of changes in MRI. Both NND and NNM are representations easily understood by clinicians. Using these indexes to define if a patient should be submitted for additional imaging tests may facilitate the decision of using MRI as a preoperative screening tool in AIS patients.

LEVEL OF EVIDENCE

Level II.

Selective thoracolumbar/lumbar fusion for Syringomyelia-associated scoliosis: a case-control study with Lenke 5C adolescent idiopathic scoliosis

Background

Selective thoracolumbar/lumbar fusion technique was introduced to treat adolescent idiopathic scoliosis (AIS) patients with major thoracolumbar/lumbar curves. Theoretically, this surgical strategy could also be applied to syringomyelia patients. No previous study has specifically addressed the effectiveness of selective thoracolumbar/lumbar fusion for patients with syringomyelia-associated scoliosis. The aim of the study was to investigate the effectiveness of selective thoracolumbar/lumbar fusion for the surgical treatment of patients with syringomyelia-associated scoliosis.

Methods

From February 2010 to September 2016, 14 syringomyelia-associated patients with major thoracolumbar/lumbar curves were retrospectively reviewed. Besides, 30 Lenke 5C AIS patients were enrolled as a control group. Posterior selective thoracolumbar/lumbar fusion was performed for both groups. Patients’ demographic, operative, radiological, and quality of life data were reviewed with follow-up. Intragroup comparisons were performed for each parameter.

Results

The two groups were matched by age, gender, curve characteristics, duration of follow-up, and all preoperative radiographic parameters except for thoracic kyphosis. After surgery, the average correction rate of the major thoracolumbar/lumbar curve was 82.2 ± 7.8% in the syringomyelia group, which was not significantly different from that of AIS group (82.5 ± 10.6%, P = 0.47). A similar improvement of unfused thoracic curve was observed between the two groups (50.1 ± 16.5% vs. 48.5 ± 26.9%, P = 0.29). During the follow-up, the correction effect of scoliosis was well maintained, without aggravation of the original neural symptoms or fresh permanent neurological deficits. Of note, the number of fusion levels was significantly larger in syringomyelia group than that in AIS group (7.6 ± 1.4 vs. 6.5 ± 1.2, P < 0.01). The average follow up was 47.6 months (36–81 months).

Conclusion

Similar to AIS cases, syringomyelia-associated scoliosis can be effectively and safely corrected by selective thoracolumbar/lumbar fusion with satisfactory surgical outcomes. However, the syringomyelia group, on average, required an additional fused segment for treatment as compared to the AIS group (7.6 versus 6.5 in the AIS group).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03779-0.

Chiari I malformations with syringomyelia: long-term results of neurosurgical decompression

STUDY DESIGN

Retrospective case series.

OBJECTIVES

The objective was to assess the long-term outcomes on scoliosis following Chiari-I (CM-I) decompression in patients with CM-I and syringomyelia (SM). A secondary objective was to identify risk factors of scoliosis progression.

BACKGROUND

The association between CM-I with SM and scoliosis is recognized, but it remains unclear if CM-I decompression alters the long-term evolution of scoliosis in patients with associated syringomyelia.

METHODS

A retrospective review of children with scoliosis, CM-I, and SM during 1997-2015 was performed. Congenital, syndromic, and neuromuscular scoliosis were excluded. Clinical and radiographic characteristics were recorded at presentation, pre-decompression, after 1-year, and latest follow-up. A scale to measure syringomyelia area on MRI was used to evaluate SM changes post-decompression.

RESULTS

65 children with CM-I, SM, and scoliosis and a mean age of 8.9 years (range 0.7-15.8) were identified. Mean follow-up was 6.9 years (range 2.0-20.4). Atypical curves were present in 28 (43%) children. Thirty-eight patients (58%) underwent decompression before 10 years. Syringomyelia size reduced a mean of 70% after decompression (p < 0.001). Scoliosis improved in 26 (40%), stabilized in 17 (26%), and progressed in 22 (34%) cases. Early spinal fusion was required in 7 (11%) patients after a mean of 0.5 ± 0.37 years and delayed fusion in 16 (25%) patients after 6.0 ± 3.24 years. The remaining 42 (65%) patients were followed for a median of 6.1 years (range 2.0-12.3) without spine instrumentation or fusion. Fusion patients experienced less improvement in curve magnitude 1-year post-decompression (p < 0.001) and had larger curves at presentation (43° vs. 34°; p = 0.004).

CONCLUSIONS

Syringomyelia size decreased by 70% after CM-I decompression and scoliosis stabilized or improved in two-thirds of patients. Greater curve improvement within the first year post-decompression and smaller curves at presentation decreased the risk of spinal fusion. Neurosurgical decompression is recommended in children with CM-I, SM, and scoliosis with the potential to treat all three conditions.

LEVEL OF EVIDENCE

Level IV.

A three-dimensional analysis of scoliosis progression in non-idiopathic scoliosis: is it similar to adolescent idiopathic scoliosis?

PURPOSE

To evaluate the three-dimensional (3D) characteristics of spine deformity in patients with non-idiopathic scoliosis compared with those observed in patients with adolescent idiopathic scoliosis (AIS).

METHODS

A retrospective chart review was conducted to identify patients with non-idiopathic scoliosis. Twenty-eight patients with neural axis (NA) abnormalities (Chiari 1, syrinx) and 20 patients with connective tissue disorder (CTD) (Marfan's, Beal's, Ehlers-Danlos syndrome, mixed) were identified. The 3D parameters of the coronal, sagittal, and axial plane were compared with 284 AIS patients with a similar range of coronal deformity.

RESULTS

The average coronal curve was similar between all three groups (AIS 48 ± 15°, CTD 43 ± 22°, and NA 49 ± 18°; p = 0.4). The NA patients had significantly greater 3D thoracic kyphosis (20 ± 18° vs 10 ± 15°, p = 0.001) and less thoracic apical vertebral rotation (- 5 ± 18° vs - 12 ± 10°, p = 0.003) when compared with AIS. The CTD group's 3D thoracic kyphosis (p = 0.7) and apical vertebral rotation (p = 0.09) did not significantly differ from AIS. Significant negative correlations were found in all three groups between thoracic kyphosis and coronal curve magnitude (AIS r = - 0.49, CTD r = - 0.772, NA r = -0.677, all p < 0.001).

CONCLUSIONS

Scoliotic patients with NA abnormalities have a more kyphotic, less-rotated 3D profile than patients with AIS, while scoliosis patients with CTD have 3D features similar to AIS. Irrespective of the underlying diagnosis, however, greater scoliotic curves were associated with a greater loss of intersegmental kyphosis, suggesting a similar biomechanical pathophysiology for curve progression.

Anterior Spinal Overgrowth of the Thoracic Spine May Not Be Involved in the Initiation of Adolescent Idiopathic Scoliosis

OBJECTIVE

To compare vertebral morphology among patients with adolescent idiopathic scoliosis (AIS), patients with Chiari I malformation (CMS)-associated scoliosis, and normal control subjects, with the goal of determining the role of anterior column overgrowth in the development of AIS.

METHODS

One hundred and forty adolescent girls were enrolled (50 with AIS, 40 with CMS, and 50 control subjects). Thoracic computed tomography images were obtained for all subjects. Anterior height of the vertebral body (VBHa), posterior height of the vertebral body (VBHp), and height of the pedicle (PH) were measured for each level. Finally, the ratios of VBHa and VBHp to PH were calculated and compared among the 3 groups.

RESULTS

Compared with the control group, both the AIS and CMS groups exhibited consistently longer VBHa and VBHp for most thoracic vertebral bodies, whereas the PH of most vertebral bodies was shorter in both AIS and CMS groups. Moreover, the ratios for differential growth between the anterior and posterior elements of each thoracic vertebra in both the AIS and CMS groups were significantly larger than the ratios in the control group. However, for all mentioned parameters, there were no significant differences between the AIS and CMS groups.

CONCLUSIONS

Faster growth of the anterior spinal column was confirmed by longer vertebral bodies and shorter pedicles in both patient groups. Relative anterior spinal overgrowth of the thoracic spine is not involved in the initiation of AIS, and the abnormal growth pattern of the vertebral body in AIS might be a secondary change to the spinal curve.

The Role of Vitamin D in the Pathogenesis of Adolescent Idiopathic Scoliosis

Several theories have been proposed to explain the etiology of adolescent idiopathic scoliosis (AIS) until present. However, limited data are available regarding the impact of vitamin D insufficiency or deficiency on scoliosis. Previous studies have shown that vitamin D deficiency and insufficiency are prevalent in adolescents, including AIS patients. A series of studies conducted in Hong Kong have shown that as many as 30% of these patients have osteopenia. The 25-hydroxyvitamin D3 level has been found to positively correlate with bone mineral density (BMD) in healthy adolescents and negatively with Cobb angle in AIS patients; therefore, vitamin D deficiency is believed to play a role in AIS pathogenesis. This study attempts to review the relevant literature on AIS etiology to examine the association of vitamin D and various current theories. Our review suggested that vitamin D deficiency is associated with several current etiological theories of AIS. We postulate that vitamin D deficiency and/or insufficiency affects AIS development by its effect on the regulation of fibrosis, postural control, and BMD. Subclinical deficiency of vitamin K2, a fat-soluble vitamin, is also prevalent in adolescents; therefore, it is possible that the high prevalence of vitamin D deficiency is related to decreased fat intake. Further studies are required to elucidate the possible role of vitamin D in the pathogenesis and clinical management of AIS.

Intraspinal Pathology Associated With Pediatric Scoliosis: A Ten-year Review Analyzing the Effect of Neurosurgery on Scoliosis Curve Progression

STUDY DESIGN

This was a retrospective study of patients with Chiari I (CM I) and Chiari II (CM II) malformations, tethered cord syndrome, and syringomyelia examining the effect of neurosurgery on scoliosis.

OBJECTIVE

The aim of this study was to determine the factors affecting spinal deformity progression in patients with diseases of the neural axis following neurosurgical management.

SUMMARY OF BACKGROUND DATA

There have been attempts to explain which factors influence the spinal deformity in diseases of the neural axis with varying results. Debate still exists as to the effectiveness of neurosurgery in curve stabilization.

METHODS

The medical records for patients treated over the past 10 years were reviewed. The spinal deformity surgical group consisted of patients who received surgery or progressed to surgical range (50°) and the nonsurgical group those who did not undergo fusion.

RESULTS

Fifteen patients (eight females and seven males) with scoliosis who underwent neurosurgical intervention were identified. Ten had tethered cord, six CM II, four CM I, and 11 syrinx. Average age at the time of neurosurgery was 7 ± 4 years (range 0.7-14 yrs). Following neurosurgery, no patients experienced improvement in their curves (defined as >10° decrease in Cobb angle), eight patients experienced stabilization (<10° decrease), and seven experienced worsening (>10° increase). The group that went on to spinal deformity surgery possessed larger curves before neurosurgery (mean 42°, range 20°-63°) than the nonsurgical group (19°, range 15°-26°; P = 0.004). CM II patients had the greatest magnitude of curve progression, mean of 49°, compared with patients with CM I (6°) or tether cord without CM I or II (11°, P = 0.01).

CONCLUSION

Neurosurgical intervention may prevent curve progression in patients with scoliosis and Cobb angles < 30° if they do not have a complex CM II malformation. Patients with CM II are at a higher risk of curve progression and undergoing spinal fusion than patients with CM I, tethered cord syndrome, or syringomyelia.

LEVEL OF EVIDENCE

4.

Understanding the role of the immune system in adolescent idiopathic scoliosis: Immunometabolic CONnections to Scoliosis (ICONS) study protocol

INTRODUCTION

Adolescent idiopathic scoliosis (AIS) affects up to 3% of children around the world. There is limited knowledge of AIS aetiopathogenesis, and this evidence is needed to develop new management strategies. Paraspinal muscle in AIS demonstrates evidence of differential fibrosis based on curve sidedness. Fibrosis is the hallmark of macrophage-driven inflammation and tissue remodelling, yet the mechanisms of fibrosis in paraspinal muscle in AIS are poorly understood.

OBJECTIVES

The primary objective of this study is to determine the influence of curve sidedness on paraspinal muscle inflammation. Secondary objectives include defining the mechanisms of macrophage homing to muscle, and determining muscle-macrophage crosstalk in muscle fibrosis in AIS.

METHODS AND ANALYSIS

This is a cross-sectional study conducted in a tertiary paediatric centre in Hamilton, Ontario, Canada. We will recruit boys and girls, 10-17 years of age, who are having surgery to correct AIS. We will exclude children who have an active infection or are on immunosuppressive therapies within 2 weeks of surgery, smokers and pregnant girls. Paraspinal muscle biopsies will be obtained at the start of surgery. Also, blood and urine samples will be collected from participants, who will fill questionnaires about their lifestyle. Anthropometric measures will also be collected including height, weight, waist and hip circumferences.

ETHICS AND DISSEMINATION

This study has received ethics authorisation by the institutional review board. This work will be published in peer-reviewed journals and will be presented in oral and poster formats at scientific meetings.

DISCUSSION

This study will explore the mechanisms of paraspinal muscle inflammation, remodelling and fibrosis in AIS. This will help identify pathways and molecules as potential therapeutic targets to treat and prevent AIS. It may also yield markers that predict scoliosis progression and response to treatment in these children.

The prevalence of intraspinal anomalies in infantile and juvenile patients with "presumed idiopathic" scoliosis: a MRI-based analysis of 504 patients

Background

Though several studies have reported the incidence of intraspinal neural axis abnormalities in infantile and juvenile “presumed idiopathic” scoliosis, there has been a varying prevalence ranging from 11.1 to 26.0 % based on a limited sample size. Therefore, such inconclusive findings have resulted in some questions on the MRI-associated role in the management of these patients. We aimed to investigate the prevalence and distribution of intraspinal anomalies in the infantile and juvenile patients with “presumed idiopathic” scoliosis and to explore the radiographic and clinical indicators with large sample size.

Methods

A total of 504 infantile and juvenile patients diagnosed with “presumed idiopathic” scoliosis were examined for potentially-existing neural axis abnormalities by MRI. Patients were grouped into two cohorts according to the presence of neural axis abnormalities. Radiographic parameters including curve magnitude, curve pattern, location of apex, degree of thoracic kyphosis, and span of curve were recorded and compared between the two groups. The prevalence of the neural abnormalities between the infantile-age group and juvenile-age group was also compared. The student t test was used to evaluate the differences of continuous variables and the chi-square test was used to evaluate the difference of categorical variables. Fisher exact test was applied to detect the difference of the rate of intraspinal anomalies between the “infantile idiopathic scoliosis” and “juvenile idiopathic scoliosis” group.

Results

Involving the spinal cord, 94 patients (18.7 %) were found to have a neural abnormality: Arnold-Chiari malformation alone in 43 patients, Arnold-Chiari malformation combined with syringomyelia in 18 patients, isolated syringomyelia in 13 patients, diastematomyelia in six patients, tethered cord combined with diastematomyelia in six patients, tethered cord alone in four patients, and other uncommon intraspinal abnormalities in the remaining four patients. Totally Arnold-Chiari malformation with or without syringomyelia accounted for 64.8 % (61/94) among all these abnormalities. Male gender, left thoracic curve and right lumbar curve were found to be significantly associated with the presence of neural axis abnormalities on MRI.

Conclusions

The incidence of neural axis abnormalities in the presumed IIS and JIS was 18.7 %. Thus a routine MRI evaluation appears warranted for those “presumed idiopathic” scoliosis patients if aged less than 10 years, being male or having left thoracic or right lumbar curve.

Does Surgical Correction of Right Thoracic Scoliosis in Syringomyelia Produce Outcomes Similar to Those in Adolescent Idiopathic Scoliosis?

BACKGROUND

Practice guidelines for deformity correction in patients with syringomyelia-associated scoliosis (SMS) remain ill defined. Although surgeons experienced in treating adolescent idiopathic scoliosis (AIS) are commonly called on to treat SMS, no study has directly compared the results of surgical treatment between patients with SMS and those with AIS. The present study was performed to compare the radiographic and clinical outcomes of posterior spinal fusion between patients with right-thoracic SMS and those with right-thoracic AIS.

METHODS

Sixty-nine adolescents with SMS were matched with patients with AIS for sex, age, and curve magnitude. Patients were evaluated before surgery, immediately after surgery, and at the latest follow-up examination for changes in curve correction, global coronal balance, and scores on the Scoliosis Research Society (SRS)-22 questionnaire.

RESULTS

The preoperative primary curve magnitude was similar between the two groups, but a trend toward less flexibility was observed in the SMS group. The amount of correction of the thoracic Cobb angles obtained surgically (68% compared with 71%) and the ratio of percent correction to flexibility (1.80 compared with 1.76) were similar in the SMS and AIS groups. At the latest evaluation, eight patients with SMS and five with AIS had lost >10° of thoracic spine correction (p = 0.382). The postoperative coronal decompensation averaged 13% and 6%, respectively, in the SMS and AIS groups (p = 0.243). No intergroup differences were noted with respect to the sagittal vertical axis or proximal junctional change, with preservation of global sagittal balance in both groups during follow-up. There were no neurologic or other major complications related to surgery in either group.

CONCLUSIONS

Despite the differences in preoperative status, adolescents with idiopathic right thoracic scoliosis and those with syringomyelia-associated right thoracic scoliosis had comparable clinical and radiographic outcomes of pedicle-screw-based posterior spinal fusion, without neurologic complications.

Comparison of clinical and radiological manifestations and surgical outcomes of pediatric Chiari I malformations in different age groups

PURPOSE

The aim of this study was to elucidate the differences in clinical and radiological manifestations and treatment outcomes of pediatric Chiari I malformation patients according to age.

METHODS

We retrospectively reviewed the patients who received surgery in our institution for symptomatic Chiari I malformations between January 1991 and December 2012. Fifty-four patients were identified, and their medical records were reviewed for clinical presentation, radiological findings, surgical treatment, and outcomes including complications. We divided the patients into 3 groups: Group I (n = 4) younger than 3 years old; Group II (n = 9) between 3 and 5 years old; and Group III (n = 41) older than 5 years old. Surveyed data were compared among the groups. The mean follow-up period was 82.8 months.

RESULTS

All of Group I patients presented with stem compression signs. Ventriculomegaly was common (3/4, 75%), but no syrinx or scoliosis was observed. In Group II, scoliosis was the most common presentation (5/9, 56%), and these patients rarely complained any other symptoms. Pain, such as headache (18/41, 44%), was the predominant presentation in Group III. The incidences of syrinx and scoliosis were similar in Groups II and III. There were no differences in the treatment outcomes among the groups. The spinal curve did not improve in 4 of 5 Group II patients despite their early FMD surgeries. The incidence of complications related to cerebrospinal fluid leakage was higher in the young age group.

CONCLUSIONS

The clinical and radiological manifestations of pediatric Chiari I malformation appeared to be different according to age.

Surgical outcome of Chiari I malformation in children: clinico-radiological factors and technical aspects

PURPOSE

The optimal treatment for Chiari I malformation in children is still under debate. The aim of this study was to evaluate the surgical outcome of the pediatric Chiari I malformation,focusing on clinico-radiological factors and technical aspects.

METHODS

Fifty-six patients with Chiari I malformation who received surgery at Seoul National University Children’s Hospital were included. The mean age was 7.9 years. The patients were divided into three groups: group I (n =8) with hydrocephalus, group II (n =11) without syrinx, and group III (n =37) with syrinx. Group I received shunting operation initially,and others received foramen magnum decompression (FMD). Group III was further subdivided: group IIIa (n =9), minimal intradural manipulation, and group IIIb (n =27), active intradural manipulation. The outcomes were compared between the groups. The mean follow-up period was 75.9 months.

RESULTS

In group I, symptoms were resolved or had improved in most patients, with only one patient received additional FMD. Symptoms resolved or improved in 10 (91 %) and 25 cases (84 %) in groups II and III, respectively. Syrinx was markedly decreased in 31 cases (86 %) in group III. FMD was less effective for scoliosis (improved or stabilized in 57 %).The persistence of syrinx was related with an aggravation of scoliosis. The outcomes between group IIIa and IIIb showed no significant difference.

CONCLUSIONS

In most pediatric Chiari I patients with hydrocephalus,a shunting operation was sufficient. FMD showed high efficacy in treating patients without hydrocephalus. The extent of the intradural procedure did not have a significant effect on the clinical outcome.

Are intraspinal anomalies in early onset idiopathic scoliosis as common as once thought? A two centre United Kingdom study

PURPOSE

Rates of neural axis abnormalities in infantile and juvenile idiopathic scoliosis may be as high as 50 %. We aimed to determine the rates of neural axis abnormalities in early onset idiopathic scoliosis patients in a British population.

METHODS

This retrospective study at two British spinal deformity clinics identified 72 patients satisfying the inclusion criteria of: (1) age at diagnosis of 7 years and younger, (2) idiopathic scoliosis and (3) magnetic resonance imaging of the neuraxis.

RESULTS

The mean age at diagnosis was 3.6 years and the mean Cobb angle was 47° with a near equal distribution of left (32) and right (36) sided curves. Eight (11.1 %) neural axis abnormalities consisting of two syrinxes, one Arnold-chiari Type I malformation and five combined (Arnold-chiari malformation Type I and syrinx) anomalies were identified.

CONCLUSIONS

This multi-centre study on the largest number of British subjects to date helps to establish the rates of neural axis abnormalities.

Outcomes of Chiari I-associated scoliosis after intervention: a meta-analysis of the pediatric literature

PURPOSE

Various series have reported successful management of scoliosis after surgical treatment of the associated Chiari malformation, syrinx, or bracing. Multiple factors have been associated with curve progression, but interpretation of outcomes is confounded by the wide range of reported results and size of individual series. We attempted to evaluate the outcomes of Chiari I-associated scoliosis by performing a meta-analysis of currently published data.

METHODS

We conducted a systematic review of published articles using Medline, PubMed (from 1950 to January 2010), and reference lists of identified articles for Chiari malformation and scoliosis.

RESULTS

One hundred and twenty patients were identified in 12 studies, of them, 37 % were male. The mean age at the time of surgery was 9.7 ± 4.1 years. The mean curve magnitude at presentation was 34.4 ± 13.0° and progressed to a mean value of 38.9 ± 20.2°, with an average follow-up of 48.3 ± 48.2 months. After surgical intervention, curve magnitude improved in 37 % of patients (n = 42); there was no change in 18 % (n = 20), and curves progressed in 45 % (n = 51). Age (p = 0.0097) and presence of surgical intervention (foramen magnum decompression [p = 0.0099] and syrinx shunting/drainage [p = 0.0039]) were statistically associated with improvement of the scoliotic curve. Surgical decompression of the foramen magnum had the greatest impact on the scoliotic curves.

CONCLUSIONS

Data accrued from our analysis suggest that curve magnitude will improve after surgical treatment of the Chiari malformation in one third of patients, and curve progression will stabilize or improve in one half.

The correlation between coronal balance and neuroaxial abnormalities detected on MRI in adolescent idiopathic scoliosis

INTRODUCTION

The indications for magnetic resonance imaging in presumed adolescent idiopathic scoliosis (AIS) have not been established, with some studies suggesting that rates of spinal cord abnormalities are low and question the use of the routine MRI in AIS.

OBJECTIVE

Given the restraints on MRI resources the authors performed a retrospective audit to see if the presence of coronal or sagittal misbalance-balance could be used as a surrogate marker for the presence of spinal cord abnormalities in this patient group and hence reduce the need for unnecessary MRI scans.

METHODS

We performed a retrospective review of imaging of patients with AIS at our centre over a 2-year-period. All MRI scans were reported by the senior author and the presence of spinal cord abnormalities noted. All plain films were assessed by a senior SpR and ST2 orthopaedic surgeons for Cobb angle, coronal balance, sagittal balance and Lenke classification.

RESULTS

A total of 171 patients were identified with AIS. Of these, a total of 15 patients (9%) were found to have neural axis anomalies on MRI including syringomyelia, Chiari malformations and dural ectasia. The average Cobb angle was 44.9° with coronal balance varying from 67.2 mm left to 40.2 mm right. Sagittal balance varied from 125 mm negative to 83 mm positive. No correlation was found between coronal/sagittal misbalance and the presence of neural axis anomalies.

CONCLUSIONS

Our audit demonstrates that neither coronal nor sagittal misbalance should be used as an indicator of neural axis abnormalities.

Asynchronous neuro-osseous growth in adolescent idiopathic scoliosis--MRI-based research

Adolescent idiopathic scoliosis (AIS) is a common worldwide problem and has been treated for many decades; however, there still remain uncertain areas about this disorder. Its involvement and impact on different parts of the human body remain underestimated due to lack of technology in imaging for objective assessment in the past. The advances in imaging technique and image analysis technology have provided a novel approach for the understanding of the phenotypic presentation of neuro-osseous changes in AIS patients as compared with normal controls. This review is the summary of morphological assessment of the skeletal and nervous systems in girls with AIS based on MRI. Girls with AIS are found to have morphological differences in multiple areas including the vertebral column, spinal cord, skull and brain when compared with age- and sex-matched normal controls. Taken together, the abnormalities in the skeletal system and nervous system of AIS are likely to be inter-related and reflect a systemic process of asynchronous neuro-osseous growth. The current knowledge about the anatomical changes in AIS has important implications with respect to the understanding of fundamental pathomechanical processes involved in the evolution of the scoliotic deformity.

Magnetic resonance imaging evaluation of patients with idiopathic scoliosis: a prospective study of four hundred seventy-two outpatients

STUDY DESIGN

A prospective study of magnetic resonance imaging findings in outpatients with idiopathic scoliosis.

OBJECTIVE

The purpose of this study was to determine the prevalence of neural axis abnormalities in outpatients with scoliosis and to analyze the characteristics of patients who had such abnormalities.

SUMMARY OF BACKGROUND DATA

In previous studies, neural axis abnormalities were found in 2.9% to 37% of patients with idiopathic scoliosis. The current guidelines for MRI screening in scoliosis are valuable, and the proposed indications for performing MRI in the literature include early onset, atypical curvature, double thoracic curve (King type-5), rapid progression, male gender, and abnormal neurologic findings.

METHODS

A total of 472 outpatients with a primary diagnosis of idiopathic scoliosis were examined for neural axis abnormalities by magnetic resonance imaging. Logistic regression was used to determine significant predictors of neural axis abnormalities on MRI.

RESULTS

The incidence of neural axis abnormalities on MRI was 3.8% (18 of 472 patients). Among the 18 patients, 6 had a Chiari I malformation alone, 10 had a Chiari I malformation combined with syringomyelia, and 2 had a syringomyelia without Chiari I malformation. Male gender, patients younger than 11 years old, and abnormal superficial abdominal reflexes were significantly associated with the detection of neural axis abnormalities on MRI.

CONCLUSION

We recommend routine use of MRI in male patients, younger than 11 years old, and abnormal superficial abdominal reflexes. Even if a patient has no specific indications for MRI, we recommend its routine use in preoperative planning.

The utility of superficial abdominal reflex in the initial diagnosis of scoliosis: a retrospective review of clinical characteristics of scoliosis with syringomyelia

Background

With increasing use of magnetic resonance imaging (MRI), underlying syringomyelia is increasingly found in patients with presumed idiopathic scoliosis. To determine the indications for MRI in the differential diagnosis of scoliosis, several clinical characteristics of syringomyelia have been reported. Neurological signs, particularly abnormal superficial abdominal reflex (SAR), are important in establishing the initial diagnosis of scoliosis. However, the prevalence of abnormal SAR in patients with scoliosis and the sensitivity of this sign in predicting syringomyelia are not well known. We aimed to determine the diagnostic utility of SAR and other characteristics of syringomyelia in patients with scoliosis.

Methods

We reviewed the medical records of 93 patients with scoliosis, 90 of whom underwent corrective surgery. All patients underwent MRI to determine the presence of syringomyelia. Mean age at surgery was 12.5 years. Abnormal SAR was defined as unilateral or bilateral absence or hyporeflexia of SAR. We calculated indices of diagnostic utility of abnormal SAR for non-idiopathic scoliosis and for syringomyelia. Abnormal SAR, left thoracic curve pattern, gender, and curve flexibility were compared between scoliosis with syringomyelia and idiopathic scoliosis. Logistic regression analysis was performed with the existence of syringomyelia as the dependent variable and curve flexibility as the independent variable.

Results

Abnormal SAR was observed in 20 patients (prevalence 22%). All 6 patients with myopathic scoliosis displayed bilateral absence of SAR. The sensitivity of abnormal SAR for non-idiopathic scoliosis was 38%, with 96% specificity, 90% PPV (positive predictive value), and 60% NPV (negative predictive value). Syringomyelia was identified in 9 of the 93 patients (9.7%); 8 of these had abnormal SAR. The sensitivity of abnormal SAR for syringomyelia in presumed idiopathic scoliosis was 89%, with 95% specificity, 80% PPV, and 98% NPV. Gender, abnormal neurological findings, and curve flexibility differed significantly between patients with syringomyelia and those with idiopathic scoliosis (P < 0.05). In the logistic regression model, the area under the receiver operating characteristic (ROC) curve was 0.79 and the cut-off value of curve flexibility for syringomyelia was 50% (P = 0.08).

Conclusion

Abnormal SAR was a useful indicator not only for syringomyelia, but also for myogenic scoliosis.

Chiari malformation Type I in children younger than age 6 years: presentation and surgical outcome

OBJECT

The authors conducted a study to evaluate the unique presenting signs and symptoms of Chiari malformation Type I (CM-I) in children younger than 6 years of age and highlight the benefits of early surgical treatment in this patient population.

METHODS

The authors reviewed the medical records of patients who presented to the neurosurgery department before their 6th birthday and subsequently underwent surgery for CM-I. They identified 39 patients who had been evaluated between 1984 and 2007 and examined the medical records for presentation, surgical intervention, and outcome.

RESULTS

Children aged 0-2 years commonly presented with oropharyngeal dysfunction (77.8%). Children aged 3-5 years more frequently presented with syringomyelia (85.7%), scoliosis (38.1%), and/or headache (57.1%). All patients underwent posterior fossa craniectomy. Additionally, in many patients cervical laminectomy and/or duraplasty was performed. A few patients required transoral decompression and occipitocervical fusion. In most cases, surgery led to resolution or dramatic improvement of initial symptoms.

CONCLUSIONS

Early recognition and surgical treatment of CM-I in young children leads to good outcomes in the majority of patients. Additional therapies for oropharyngeal dysfunction, syringomyelia, and scoliosis can frequently be avoided.

Curve length, curve form, and location of lower-end vertebra as a means of identifying the type of scoliosis

PURPOSE

To determine if the curve length, curve form, and location of the lower-end vertebra can identify the type of scoliosis.

METHODS

Standing posteroanterior and lateral radiographs of 78 women and 27 men with scoliosis aged 8 to 32 years were retrospectively analysed. Parameters measured were (1) the curve length (the number of vertebrae in the main curve), (2) the curve form (C-form, inverted C-form, or S-form), (3) the curve apex (the vertebral body at the apex of each curve), (4) the site of the scoliosis (thoracic, thoracolumbar, or lumbar), and (5) the location of the lower-end vertebra.

RESULTS

Only 3 (4%) of 77 patients with idiopathic scoliosis had a curve length of >8 vertebrae, compared with 19 (90%) of 21 patients with neuromuscular/neuropathic scoliosis (p<0.001, Fisher's exact test). 14 (18%) of the patients with idiopathic scoliosis had an S-form curve, compared with none in those with neuromuscular/neuropathic or congenital/osteogenic scoliosis (p=0.035, Fisher's exact test). No patient with idiopathic scoliosis had the lower- end vertebra located at L5, compared with 8 (38%) patients with neuromuscular scoliosis (p<0.001, Fisher's exact test). The criteria for neuromuscular/neuropathic scoliosis (a curve length of >8 vertebrae, a C-form or inverted C-form curve, and a lower-end vertebra located at L4 or L5) had 81% specificity, 76% sensitivity, 100% positive and 93% negative predictive values.

CONCLUSION

These criteria may help identify patients with neuromuscular/neuropathic scoliosis for further investigation by magnetic resonance imaging or computed tomography before they undergo corrective surgery.

The left thoracic curve pattern: a strong predictor for neural axis abnormalities in patients with "idiopathic" scoliosis

STUDY DESIGN

A prospective trial of MRI study in patients with "idiopathic" left thoracic scoliosis.

OBJECTIVE

To investigate the prevalence of neural axis abnormalities in asymptomatic patients with "idiopathic" left thoracic scoliosis.

SUMMARY OF BACKGROUND DATA

Some patients with neural axis abnormalities have scoliosis as the only presenting sign, and they might be given a diagnosis of "idiopathic" scoliosis. These neural axis abnormalities are risk factors for neurologic injury during spine correction. With the development of MRI, neural axis abnormalities are increasingly being found in patients with "idiopathic" scoliosis. However, there are few reports on the prevalence of neural axis abnormalities in asymptomatic patients with "idiopathic" left thoracic scoliosis.

METHODS

A total of 68 patients with presumed "idiopathic" left thoracic scoliosis were examined for neural axis abnormalities, using MRI.

RESULTS

Neural axis abnormalities were detected in 37 (54%) patients, including Chiari 1 malformation in 15 patients, Chiari 1 malformation with syringomyelia in 10, Chiari 1 malformation with syringomyelia and tethered cord in 1, Chiari 1 malformation with syringomyelia and diastematomyelia in 1, syringomyelia in 8, syringomyelia with tethered cord in 1, and arachnoidal cyst in cerebellomedullary cistern in 1 patient. There were statistically significant differences between patients with and without neural axis abnormalities regarding gender and curve severity (P < 0.05).

CONCLUSION

When a left thoracic curve pattern is present in patients with "idiopathic" scoliosis, especially in male patients or patients with severe curve, strong consideration should be given to the possibility of the presence of neural axis abnormalities, and acquisition of an MRI scan considered.

The role of routine magnetic resonance imaging in the preoperative evaluation of adolescent idiopathic scoliosis

The routine use of magnetic resonance imaging (MRI) in adolescent idiopathic scoliosis remains controversial, and current indications for MRI in idiopathic scoliosis vary from study to study. The purpose of this study was to demonstrate the prevalence of neural axis malformations and the clinical relevance of routine MRI studies in the evaluation of patients with adolescent idiopathic scoliosis undergoing surgical intervention without any neurological findings. A total of 249 patients with a diagnosis of idiopathic scoliosis were treated surgically between the years 2002 and 2007. A routine whole spine MRI analysis was performed in all patients. On the preoperative clinical examination, all patients were neurologically intact. There were 20 (8%) patients (3 males and 17 females) who had neural axis abnormalities on MRI. Three of those 20 patients needed additional neurosurgical procedures before corrective surgery; the remaining underwent corrective spinal surgery without any neurosurgical operations. Magnetic resonance imaging may be beneficial for patients with presumed idiopathic scoliosis even in the absence of neurological findings and it is ideally performed from the level of the brainstem to the sacrum.

MRI Findings in Spinal MRI of 306 Children with Scoliosis

The aim of this study was to analyze the MRI findings and assess the prevalence of different associated structural abnormalities in children with scoliosis and to determine if the age of onset is a possible indicator of intraspinal pathology. This is a retrospective analysis of 663 consecutive MR examinations (319 patients). Thirteen patients with known intraspinal tumors were excluded and a total of 306 patients aged 2–18 years with scoliosis were subjected for analysis. The scoliosis was regarded as idiopathic in 62% of patients. Among the remaining 38% the most commonly seen abnormality was syrinx and Chiari malformations. There was no statistically significant difference in the occurrence of syrinx only or syrinx associated with Chiari I malformation in patients younger than ten years and those older than ten years. MRI examination is an essential part of the work up of scoliosis in the pediatric population especially before any corrective surgery. This study and a review of the current literature suggest there is no clinical marker that would definitely serve as an indicator of the presence of intraspinal pathology in these patients.

Relative shortening and functional tethering of spinal cord in adolescent scoliosis - Result of asynchronous neuro-osseous growth, summary of an electronic focus group debate of the IBSE

There is no generally accepted scientific theory for the causes of adolescent idiopathic scoliosis (AIS). As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The Statement for this debate was written by Dr WCW Chu and colleagues who examine the spinal cord to vertebral growth interaction during adolescence in scoliosis. Using the multi-planar reconstruction technique of magnetic resonance imaging they investigated the relative length of spinal cord to vertebral column including ratios in 28 girls with AIS (mainly thoracic or double major curves) and 14 age-matched normal girls. Also evaluated were cerebellar tonsillar position, somatosensory evoked potentials (SSEPs), and clinical neurological examination. In severe AIS compared with normal controls, the vertebral column is significantly longer without detectable spinal cord lengthening. They speculate that anterior spinal column overgrowth relative to a normal length spinal cord exerts a stretching tethering force between the two ends, cranially and caudally leading to the initiation and progression of thoracic AIS. They support and develop the Roth-Porter concept of uncoupled neuro-osseous growth in the pathogenesis of AIS which now they prefer to term 'asynchronous neuro-osseous growth'. Morphological evidence about the curve apex suggests that the spinal cord is also affected, and a 'double pathology' is suggested. AIS is viewed as a disorder with a wide spectrum and a common neuroanatomical abnormality namely, a spinal cord of normal length but short relative to an abnormally lengthened anterior vertebral column. Neuroanatomical changes and/or abnormal neural function may be expressed only in severe cases. This asynchronous neuro-osseous growth concept is regarded as one component of a larger concept. The other component relates to the brain and cranium of AIS subjects because abnormalities have been found in brain (infratentorial and supratentorial) and skull (vault and base). The possible relevance of systemic melatonin-signaling pathway dysfunction, platelet calmodulin levels and putative vertebral vascular biology to the asynchronous neuro-osseous growth concept is discussed. A biomechanical model to test the spinal component of the concept is in hand. There is no published research on the biomechanical properties of the spinal cord for scoliosis specimens. Such research on normal spinal cords includes movements (kinematics), stress-strain responses to uniaxial loading, and anterior forces created by the stretched cord in forward flexion that may alter sagittal spinal shape during adolescent growth. The asynchronous neuro-osseous growth concept for the spine evokes controversy. Dr Chu and colleagues respond to five other concepts of pathogenesis for AIS and suggest that relative anterior spinal overgrowth and biomechanical growth modulation may also contribute to AIS pathogenesis.

Morphological and functional electrophysiological evidence of relative spinal cord tethering in adolescent idiopathic scoliosis

STUDY DESIGN

Magnetic resonance (MR) imaging and multiplanar reconstruction was used to evaluate the morphology and relative position of the spinal cord in adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To determine the longitudinal and cross-sectional morphology of spinal cord in AIS subjects versus normal controls and their correlation with relative position of cerebellar tonsils and somatosensory cortical evoked potentials (SSEP).

SUMMARY OF BACKGROUND DATA

Our previous studies revealed significantly reduced spinal cord to vertebral column length ratios in AIS patients with severe scoliotic curves suggesting the presence of disproportional growth between the neural and skeletal system. A possible neural origin of etiopathogenesis of AIS is suggested.

METHODS

MR multiplanar reconstruction was performed in 97 adolescent girls (35 moderate, 26 severe AIS with right-sided thoracic/thoracolumbar curve, and 36 age-matched controls). Measurements of the ratio of anteroposterior (AP) and transverse (TS) diameter of the cord, the concave and convex lateral cord space (LCS) were obtained at the apical level in AIS subjects. Same parameters were obtained in normal controls at matched vertebral levels. Correlations were made with cord to vertebral column length ratio, cerebellar tonsil position and SSEP findings.

RESULTS

AP/TS cord ratio and LCS ratio were increased in AIS subjects in the presence of reduced spinal cord to vertebral length ratio when compared with normal controls (P < 0.05). The above ratios were exaggerated in AIS subjects with abnormal SSEP findings. The AP/TS cord ratio and LCS ratio were negatively correlated with the cord to vertebral column length ratio (rho = -0.410 and -0.313, P < 0.01) and cerebellar tonsillar level (rho = -0.309 and -0.432, P < 0.01).

CONCLUSION

Our study suggests presence of tethering and increased tension along the longitudinal axis of spinal cord with associated morphologic changes of cross-sectional shape and relative position of the cord.

Radiological presentations in relation to curve severity in scoliosis associated with syringomyelia

BACKGROUND

Few radiographic guidelines are available to assist clinicians in deciding when to order magnetic resonance imaging in patients with a normal history and physical examination. Most of the recent reports on the radiographic characteristics of scoliosis are limited by a small number of patients and a shortage of large curves. The association between radiological features and the severity of scoliosis has little been elaborated. The purpose of this study is to further explore the radiological presentations in relation to curve severity in scoliosis associated with Chiari malformation and syringomyelia.

METHODS

A total of 87 children and adolescents were divided into 3 groups: group 1 (10 degrees < or = Cobb angle < or = 30 degrees), group 2 (30 degrees < Cobb angle < or = 60 degrees), and group 3 (Cobb angle > 60 degrees). Curves were classified into typical and atypical patterns in the coronal plane, and the sagittal profile was measured. Cerebellar tonsillar descent or syrinx patterns in relation to curve severity and the frequency of atypical curves were also investigated.

RESULTS

The frequency of atypical curve patterns from groups 1 to 3 was 46.2%, 45.2%, and 40.7%, respectively. A total of 65.3% of patients with typical curve patterns had atypical features in all of the 3 groups. There was a significant difference of kyphotic angle among the 3 groups showing that the larger curves tended to have greater thoracic kyphosis. Both the degree of cerebellar tonsillar descent and syrinx patterns had no correlation with the curve severity or the frequency of atypical curves.

CONCLUSIONS

These results show that radiographic presentations including atypical curve patterns, atypical features in typical curve patterns, and a normal to hyperkyphotic thoracic spine may suggest the need for a preoperative magnetic resonance imaging. Kyphosis may be indicative of progressive scoliosis. There is no evidence to suggest that the degree of cerebellar tonsillar descent and syrinx patterns have an effect on the progress of scoliosis and the frequency of atypical curves.

Cervical spinal motion before and after surgery in patients with Chiari malformation type I associated with syringomyelia

OBJECT

There have been few reports about the cervical spinal motion in patients with Chiari malformation Type I (CM-I) associated with syringomyelia. To investigate this phenomenon, the relationship between the preoperative cervical range of motion (ROM) and the stage of cerebellar tonsillar descent as well as the cervical ROM before and after foramen magnum decompression (FMD) were evaluated.

METHODS

Thirty patients who had CM-I associated with syringomyelia and who underwent FMD participated in the study. The ROM and lordosis angle of the cervical spine were measured on x-ray films. In addition, the relationship between preoperative degree of cerebellar tonsillar descent and the ROM between the levels of the occiput (Oc) and C2 was investigated.

RESULTS

The mean flexion-extension ROM at Oc-C2 was 15.5 degrees before and 14.1 degrees after surgery, and the mean flexion-extension ROM of C2-7 was 55.1 degrees before and 52.8 degrees after surgery. The mean pre- and postoperative lordosis angles at C2-7 were 16.8 and 19.1 degrees, respectively. There was no significant difference between the values measured before and after surgery. There was no correlation between the degree of cerebellar tonsillar descent and the ROM at Oc-C2. CONCLUSIONS. Foramen magnum decompression is an excellent surgical technique that has no effect on the postoperative cervical ROM and cervical alignment.

Abnormal spreading and subunit expression of junctional acetylcholine receptors of paraspinal muscles in scoliosis associated with syringomyelia

STUDY DESIGN

A comparative study was performed among 2 groups of patients: Group A with scoliosis and syringomyelia and Group B with idiopathic scoliosis.

OBJECTIVE

To investigate the denervation of paraspinal muscles and analyze its association with scoliosis in patients with syringomyelia.

SUMMARY OF BACKGROUND DATA

The mechanism by which scoliosis develops secondary to syringomyelia remains unclear. Some authors hypothesize that scoliosis may be caused by an alteration in the innervation of the trunk musculature. Few studies, however, have been reported to testify the presence of denervation of the paraspinal muscles in scoliotic patients with syringomyelia.

METHODS

Forty-one children were enrolled in the study and were divided into 2 groups. Group A consisted of 25 patients with scoliosis associated with syringomyelia. Group B included 16 adolescents with idiopathic scoliosis. Bilateral biopsy of paraspinal muscles was performed during scheduled spinal surgery. Distribution of acetylcholine receptors (AChRs) and acetylcholinesterase was investigated by immunofluorescence staining. RT-PCR was performed to determine the AChRs subunit mRNA expression.

RESULTS

Immunostaining showed that 56% patients in Group A were scored positive for the loss of localization of AChRs to neuromuscular junction, while all Group B patients were negative. gamma-AChR subunit expression was detected in 65% patients in Group A while absent in all samples in Group B. There was no statistical significance of both the positive rate of abnormal spreading and that of gamma subunit expression of AChRs between the convex and concave side in Group A.

CONCLUSION

The denervation of paraspinal muscles is present in some patients with scoliosis associated with syringomyelia. The size of the syrinx and the degree of cerebellar tonsillar descent might seem to have no relation to the denervation of paraspinal muscles.

The outcomes of scoliosis surgery in patients with syringomyelia

STUDY DESIGN

A retrospective review of a consecutive case series.

OBJECTIVE

To describe patient demographics, syrinx morphology, and deformity characteristics, as well as postsurgical correction, progression, and complications.

SUMMARY OF BACKGROUND DATA

Conflicting data are available on the natural and postsurgical history of patients with spinal deformity associated with syringomyelia. This is the largest series in the literature on the surgical outcomes of these patients.

METHODS

All patients treated for spinal deformity at our institution with an associated syrinx were reviewed. Demographics, deformity morphology, treatment methods, and postoperative outcomes were measured and recorded.

RESULTS

Thirteen patients met inclusion criteria. All were Lenke thoracic modifier normal or positive. Ten patients underwent neurosurgical decompression. All curves either progressed or remained unchanged following neurosurgical treatment. The average thoracic kyphosis measured 46 degrees (29 degrees-69 degrees). Thoracic kyphosis was significantly increased compared with a population of adolescent idiopathic patients (P = 0.00002). The average curve before scoliosis surgery was 71 degrees (31 degrees-119 degrees) in the coronal plane and 46 degrees (29 degrees-68 degrees) in the sagittal plane. The average correction from the initial scoliosis surgery was 48% (6%-83%). All patients had spinal cord monitoring or wake-up tests during surgery. There were no instances of spinal cord injury from surgery. Three patients progressed significantly following anterior fusion, 2 of whom required further corrective surgery. Following arthrodesis, 4 patients progressed >10 degrees during follow-up.

CONCLUSION

The lack of thoracic hypokyphosis seen in idiopathic-like curves is a strong indicator of a possible underlying syrinx. Neurosurgical treatment of the syrinx did not improve the scoliosis. Caution should be exercised when choosing fusion levels, and arthrodesis should be planned with the underlying pathology in mind. Scoliosis surgery has proven to be safe in patients with treated syrinx when spinal cord monitoring or wake-up tests are used.

A detailed morphologic and functional magnetic resonance imaging study of the craniocervical junction in adolescent idiopathic scoliosis

STUDY DESIGN

Conventional and phase-contrast magnetic resonance (MR) imaging were used to evaluate the morphology and cerebrospinal fluid (CSF) flow dynamics at craniocervical junction in adolescent idiopathic scoliosis (AIS).

OBJECTIVES

To determine the morphology of cerebellar tonsil, foramen magnum, and dynamic flow of CSF at the craniocervical junction in AIS patients versus normal controls and their correlation with somatosensory cortical evoked potentials (SSEP).

SUMMARY OF BACKGROUND DATA

Previous studies have documented obstructed CSF flow in patients with Chiari I malformation. Low-lying cerebellar tonsils and syringomyelia are also observed in AIS patients. We sought to investigate whether disturbed CSF flow is also evident in AIS subjects at the foramen magnum level and its association with level of cerebellar tonsils and dimensions of foramen magnum.

METHODS

Conventional and phase-contrast MR were performed in 105 adolescent girls (69 AIS subjects and 36 age-matched controls). Measurements of cerebellar tonsillar level related to the basion-opsithion (BO) line, anteroposterior (AP), transverse (TS) diameter, and area of foramen magnum, and peak velocity of CSF flow in both the anterior and posterior subarachnoid space through foramen magnum were obtained. Correlations were made among different parameters and SSEP findings.

RESULTS

A total of 42% of subjects in the AIS group had the cerebellar tonsillar tip positioned 1 mm below the BO line. The cerebellar tonsillar level in AIS subjects was significantly lower than the median tonsillar level in normal controls (P < 0.01). The AP diameter and area of foramen magnum were significantly larger in AIS subjects when compared with normal controls (P < 0.05), but the peak CSF velocities through foramen magnum showed no significant difference (P > 0.05).

CONCLUSION

Peak CSF velocities through foramen magnum were not significantly different in AIS subjects despite the presence of low-lying cerebellar tonsils. This might be explained by the compensatory effect of larger foramen magnum in AIS subjects.

Recent advances in the aetiology of adolescent idiopathic scoliosis

The aetiology of adolescent idiopathic scoliosis (AIS) is still unknown despite many years of research effort. Theories on AIS's aetiology have included mechanical, hormonal, metabolic, neuromuscular, growth, and genetic abnormalities. Amongst these, some factors may be epiphenomena rather than the cause itself. Other factors may even contribute to curve progression, rather than curve initiation. Current views maintain that AIS is a multifactorial disease with genetic predisposing factors [Lowe et al. in J Bone Joint Surg [Am] 82:1157-1168, 2000]. With improvements in diagnostic methods, imaging and genomics, there has been considerable recent work on aetiology. This review aims to bring readers up-to-date with the latest developments in scoliosis research.

The position of the aorta relative to the spine in patients with left thoracic scoliosis: a comparison with normal patients

STUDY DESIGN

Analysis axial magnetic resonance images (MRIs) identifying the position of the aorta in left thoracic scoliosis and normal patients.

OBJECTIVES

To determine the position of the aorta in patients with left thoracic scoliosis and to compare these findings with those seen in normal patients.

SUMMARY OF BACKGROUND DATA

Screws placed during an anterior spinal fusion and instrumentation for right thoracic scoliosis are in proximity to the aorta, which is primarily due to the position of the aorta on the posterolateral left aspect of the vertebra. There are no studies that have evaluated the aorta in left thoracic scoliosis.

METHODS

A retrospective review of all patients with an MRI with left thoracic scoliosis (Group LTS) was performed and compared with patients with a normal straight spine (Group N). Axial MRI images from T4 to L3 in both groups were analyzed to include the aorta-vertebral angle (AVA), where 0 degrees = aorta directly lateral to the left and 180 degrees = directly lateral to the right.

RESULTS

There were 20 patients in Group LTS and 43 patients in Group N. There were no differences in age (13.1 vs. 14.0 years) or gender (52% vs. 62% females) between the LTS and N groups. The aorta was positioned more anterior (larger AVA) to the vertebral body at levels T4 thru T11 (average, 70.1 degrees vs. 40.6 degrees) and L3 (77.1 degrees vs. 70.9 degrees) in Group LTS compared with group N (P < 0.05). With increasing thoracic coronal Cobb angle, the aorta was positioned more laterally to the right (larger AVA) at T8 and T10 (P < 0.05). In the LTS group, curves greater than 40 degrees had a larger AVA (91.4 degrees vs. 57.7 degrees) at apical levels (T7-T10) than for curves < or =40 degrees (P < 0.05).

CONCLUSIONS

In left thoracic LTS, the aorta is positioned more anteriorly and to the right (toward the concavity) compared with patients with a straight spine. This position will allow full access to the convexity of the left curve to perform an anterior fusion/release as well as instrumentation and is not in the trajectory of a well-placed anterior screw. This relative safety was not seen at the apex of larger curves (>40 degrees).

Scoliosis in a child with Chiari I malformation and the absence of syringomyelia: case report and a review of the literature

BACKGROUND

Scoliosis is a common finding in children with Chiari I malformation and syringomyelia. The development of scoliosis associated with a Chiari malformation typically has been ascribed to the presence of syringomyelia. Decompression of the hindbrain hernia will often alleviate the syringomyelia and, in many cases, stabilize or reverse the scoliosis.

CASE REPORT

We report a child with Chiari I malformation and scoliosis who presented with Valsalva-induced headache/neck pain. MRI revealed no syringomyelia or hydrocephalus. Radiographs revealed that her scoliotic curvature was approximately 13 degrees and was a single levoscoliotic curve. This patient underwent a posterior fossa decompression with duraplasty for her Valsalva-induced pain. Postoperatively, she had resolution of her pain and there has been no progression of her scoliosis at 3 years follow-up.

PROGNOSIS

Intriguingly, and scattered throughout the medical literature, many have noted cases of scoliosis in patients with only a Chiari I malformation and no syringomyelia. Moreover, experimental studies have induced scoliosis in animals after compression of the dorsal columns. After a review of the medical literature regarding a potential cause and effect of herniated hindbrain-induced scoliosis in the absence of syringomyelia, this association although rare, does seem plausible.

Relative shortening and functional tethering of spinal cord in adolescent idiopathic scoliosis?: study with multiplanar reformat magnetic resonance imaging and somatosensory evoked potential

STUDY DESIGN

MR imaging and multiplanar reconstruction were used to evaluate relative length of the spinal cord to the vertebral column in adolescent idiopathic scoliosis (AIS).

OBJECTIVES

Ratio of spinal cord length to vertebral column length and position of the cerebellar tonsils were evaluated and correlated with somatosensory cortical evoked potentials (SSEP).

SUMMARY OF BACKGROUND DATA

Tonsillar herniation, abnormal anthropometric growth, relative spinal overgrowth, and abnormal somatosensory function have been reported in AIS. All these observations suggest a possible neural origin of the etiopathogenesis of AIS, which can be linked to a disproportional growth between spinal column and cord.

METHODS

Two-dimensional sagittal MRI of the spine was performed in 28 AIS patients (14 mild curve; 14 severe curve) and 14 age-matched controls. Measurements of spinal cord, vertebral column length, and tonsillar position were made on reformat images and correlated with SSEP studies.

RESULTS

No significant differences in the absolute spinal cord length were found. However, there was significant relative segmental lengthening of the spinal column at the thoracic level in AIS patients with severe curve; hence, ratios of cord to vertebral column length were significantly reduced (P < 0.01). There was high interobserver reliability (0.9); 28% (8 of 28) scoliosis patients had low-lying cerebellar tonsils and abnormal SSEP, respectively.

CONCLUSION

There was significantly reduced spinal cord to vertebral column ratios in the AIS patients with severe curve, suggesting a disproportional growth between the skeletal and the neural systems. The relative shortening and functional tethering of spinal cord may play an important role in the etiopathogenesis of AIS.

Prevalence and clinical significance of superficial abdominal reflex abnormalities in idiopathic scoliosis

To determine prevalence and significance of abnormal superficial abdominal reflexes (SARs) in idiopathic scoliosis. Study of 73 patients with presumed idiopathic scoliosis referred for magnetic resonance imaging (MRI), either as a routine pre-operative assessment (n=42) or because of abnormal symptoms or neurological signs (n=31). All patients were examined prior to magnetic resonance imaging (MRI), and the presence of abnormal SARs was noted. All patients then underwent MRI of the whole spine from the foramen magnum to the sacrum. The presence of Chiari 1 malformation and syrinx was recorded. The study group consisted of 11 males and 62 females with a mean age at time of MRI of 18 years (range 5-51 years) and a mean Cobb angle of 48 degrees (range 10-104 degrees). Abnormality of the SARs was recorded in eight cases (prevalence 11%). An abnormal MRI study was recorded in nine cases (12.3%), all patients having a syrinx and four having in addition, a Chiari 1 malformation. Of the patients with abnormal SARs, only 2 (25%) had an abnormal MRI study; 1 had unilateral absence of the reflexes whereas the other had complete absence of SARs. Of patients referred for MRI as a routine pre-operative assessment, 5 (11.6%) had an abnormal MRI study. In patients with idiopathic scoliosis, abnormality of the SARs was recorded in 11% of cases. Unilateral absence was present in one case only and was associated with the presence of syrinx. Other patterns of abnormality were not a useful indicator of underlying cord abnormality.

Preoperative MRI analysis of patients with idiopathic scoliosis: a prospective study

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.

Anaesthesia for caesarean section in a patient with syringomyelia and Arnold-Chiari type I malformation

A 37-year-old primiparous woman with syringomyelia and Arnold-Chiari type I malformation was scheduled to undergo elective caesarean section for a fetus in the breech presentation. Caesarean section was performed under general anaesthesia without complications; all we observed was an exaggerated response to atracurium. The patient was discharged home 7 days after the operation without neurological deterioration. General anaesthesia was chosen in this patient to avoid any spinal manipulation that could increase intracranial pressure or reduce intraspinal pressure and cause deterioration of neurological symptoms. Syringomyelia is a progressive myelopathy characterised by cystic degeneration within the spinal cord, which causes severe neurological deficits. The anaesthetic management is discussed.

Indications for magnetic resonance imaging in presumed adolescent idiopathic scoliosis

BACKGROUND

The use of magnetic resonance imaging has led to the diagnosis of abnormalities of the central nervous system associated with apparent idiopathic scoliosis. The indications for magnetic resonance imaging for presumed adolescent idiopathic scoliosis have not been established.

METHODS

One thousand, two hundred and eighty children with presumed adolescent idiopathic scoliosis were evaluated over a ten-year period. Magnetic resonance imaging of the central nervous system (brainstem and spinal cord) was performed for specific patients, on the basis of the presence of selected indicators determined from the clinical history, physical examination, and plain radiographic examination of the spine. The medical records were reviewed to determine the specific indicators, the results of the imaging studies, and the subsequent treatment.

RESULTS

Magnetic resonance imaging was ordered for 274 (21%) of the 1280 children who were evaluated. Abnormal findings were seen in twenty-seven (10%) of the 274 patients who underwent imaging, or 2% of the entire cohort. The most valuable single indicator of an abnormal finding on magnetic resonance imaging was absence of thoracic apical segment lordosis: eight of thirty-nine patients with that indicator had an abnormal finding on magnetic resonance imaging. The optimal diagnostic yield for a single category of indicators occurred when an atypical curve pattern was the only indicator: six of fifty-eight patients in whom this was the case had an abnormal finding on magnetic resonance imaging. None of the twenty children in whom pain was the only indicator category had an abnormal imaging study. The optimal diagnostic yield occurred when both an atypical curve pattern and neurological indicators were present: thirteen (25%) of fifty-three patients in whom this was the case had an abnormal finding on magnetic resonance imaging. Thirteen of the twenty-seven patients received surgical treatment for the abnormality of the central nervous system revealed by the imaging.

CONCLUSIONS

The correct use of diagnostic tests is an important component of effective medical practice. An abnormality of the central nervous system is present in approximately 10% of patients with presumed adolescent idiopathic scoliosis in whom only subtle abnormalities are identified on the basis of the clinical history, physical examination, or radiographic examination. Knowledge of the diagnostic value of the specific clinical indicators, considered individually and in combination, can help the clinician to determine more effectively when advanced imaging of the central nervous system should be performed.

Predictors of progression of scoliosis after decompression of an Arnold Chiari I malformation

STUDY DESIGN

Retrospective study of patients with scoliosis and an Arnold Chiari I malformation requiring operative management.

OBJECTIVES

Determine the factors that could predict whether a particular spinal deformity might progress despite neurosurgical management of Arnold Chiari I malformation.

SUMMARY OF BACKGROUND DATA

Few studies have documented the relationship between diagnosis and treatment of Arnold Chiari I malformation and associated spinal deformities. Most studies mix neural axis abnormalities and contain limited information about the spinal deformity.

METHODS

Medical records, radiographs, and magnetic resonance images of patients were evaluated focusing on age and findings at presentation, characteristics of presenting and follow-up spinal deformities, and the specifics of neurosurgical and orthopedic management. Patients were divided into two groups: those whose curves progressed >10 degrees or to surgical range (largest curve >45 degrees ) after neurosurgical intervention (progressors) and those whose curves stabilized or decreased (nonprogressors).

RESULTS

Eight progressors presented at an average age of 11.4 years (range 2-19) and were followed for 6.3 years (range 2-15). Seven nonprogressors presented at 6.5 years of age (range 5-10) and were followed for 6.6 years (range 3.5-14). Neurosurgical procedures were equivalent in both groups; however, surgical revisions were required in 3 out of 8 progressors and 1 out of 7 nonprogressors. All progressors had a double scoliosis curve; but only one nonprogressor had a double curve. Six out of 8 progressors and 0 out of 7 nonprogressors had a rotation >or=2+ and 50% of progressors had a thoracic kyphosis >50 degrees compared to 1 out of 7 nonprogressors.

CONCLUSIONS

In this series, progression of spinal deformity after neurosurgical management of Arnold Chiari I malformation was associated with later age at neurosurgical decompressions and initial neurologic symptoms, double scoliosis curve patterns, kyphosis, rotation, and larger curve at presentation.

A prognostic model for the presence of neurogenic lesions in atypical idiopathic scoliosis

STUDY DESIGN

Consecutive series of patients with idiopathic scoliosis with atypical features.

OBJECTIVES

The purpose of this study is to define a specific yet sensitive set of signs and symptoms to indicate the use of MRI in patients with atypical idiopathic scoliosis. Specifically, this study empirically defines a new diagnostic test for the presence of neurogenic lesions based on clinical and radiologic data and then reports the properties of this test in relation to MRI as the gold standard.

SUMMARY OF BACKGROUND DATA

The reported prevalence of brain stem and spinal cord abnormalities in patients with idiopathic scoliosis associated with atypical features varies from 0% to 60%. This wide range most likely results from the fact that the samples studied are either not well defined or are heterogeneous across studies. Because of these issues, the likelihood of neurogenic lesions in atypical idiopathic scoliosis is not known; consequently, the decision to order an MRI is controversial.METHODS A total of 1,206 patients coded as having idiopathic scoliosis were identified from our institutional database. Of these, 72 patients had one or more atypical features: early-onset scoliosis, atypical curve, severe curve despite immaturity (>45 degrees ), rapidly progressive curve (>1 degrees per month), back pain, headache, or neurologic abnormalities on clinical examination. All 72 patients underwent brain and spinal cord MRI. Logistic regression was used to determine significant predictors of positive MRI and to define the prognostic model.

RESULTS

Eleven patients (15%) had abnormal findings on MRI. Eight had an Arnold-Chiari type I malformation associated with a syrinx; 1 had an Arnold-Chiari type I malformation; 1 a syrinx; and 1 a cervical syrinx with a conus lipoma. MRI was positive in 5 of 9 patients (55%) with severe curves despite immaturity. Twenty patients had one or more abnormal neurologic signs. Of these, 8 (40%) had a positive MRI, while only 3 of the 52 patients (6%) with a normal neurologic examination (but other atypical features) had a positive MRI. The most predictive model included the variables neurologic abnormalities (yes or no) and severe curve despite immaturity (yes or no). Using this model, patients with atypical characteristics other than severe curvatures or abnormal neurologic abnormalities(s) had a 3% probability (95% confidence interval [CI], 1-12%) of having a positive MRI; patients with abnormal neurologic change(s), but a nonsevere curve, had a 29% probability of a positive MRI (95% CI, 12-53%) and patients with severe curves and no neurologic change(s) had a 32% probability of positive MRI (95% CI, 8-71%). Patients with both a severe curve and abnormal neurologic change(s) had an 86% probability of positive MRI (95% CI, 46-98%). Agreement between this test and the MRI was 75%, with a sensitivity of 82% (95% CI, 48-97%) and a specificity of 74% (95% CI, 61-83%).

CONCLUSIONS

The model derived in this study indicates that the probability of neurogenic lesions is extremely low in most patients with idiopathic scoliosis with atypical features. However, patients with severe curves despite skeletal immaturity and an abnormal neurologic examination have a significant probability of neurogenic lesions. Therefore, clinical efficiency will be enhanced by narrowing the indications for MRI to those patients with these risk factors.

Sagittal plane deformity in the thoracic spine: a clue to the presence of syringomyelia as a cause of scoliosis

STUDY DESIGN

A retrospective review of scoliosis radiographs of 93 patients with either idiopathic scoliosis or syringomyelia-associated scoliosis were assessed, defining their sagittal alignment.

OBJECTIVE

To validate an observation regarding the absence of Dickson's sagittal deformity of the thoracic spine in patients with syringomyelia-associated scoliosis.

SUMMARY OF BACKGROUND DATA

Patients with adolescent idiopathic scoliosis have a classic sagittal deformity. Dickson described that patients with adolescent idiopathic scoliosis (AIS) have an associated lordotic deformity at the apex of their coronal deformity.

MATERIALS AND METHODS

Retrospective reviews of standard scoliosis series radiographs of 93 patients with idiopathic or syringomyelia-associated scoliosis from two institutions were compared. Particular attention was given to the lateral radiograph of the spine assessing presence or absence of Dickson's apical lordosis. Nine patients had to be excluded because of inadequate imaging. The study group consisted of 30 patients with scoliosis from TSRH with documented syringomyelia identified between 1985 and 1997. The demographic and radiographic features of this group were compared with those of a control group consisting of a consecutive series of 54 patients from HSS with adolescent idiopathic and normal MRI. The groups were comparable for age (mean age: control 13 y; syrinx 12 y) and curve pattern but differed in curve magnitude (mean Cobb: control 50 degrees; syrinx 40 degrees ).

RESULTS

Apical lordosis was present in 97% of patient with AIS and a normal MRI but was absent in 75% of patients with syringomyelia-associated scoliosis (P < 0.0001). The results also confirmed that male patients with scoliosis and left-side curves have a predisposition to having a syringomyelia (P < 0.0001).

CONCLUSIONS

Sagittal plane deformity in scoliosis can be an indicator of the presence of a syringomyelia. Our results reinforce the necessity of assessing sagittal plane deformity when treating scoliosis. If apical lordotic deformity is absent, a diagnosis of idiopathic scoliosis should be made with caution.

Scoliotic curve patterns in patients with Chiari I malformation and/or syringomyelia

STUDY DESIGN

A retrospective radiographic review was performed on 41 patients with scoliosis associated with a Chiari I malformation and/or syringomyelia.

OBJECTIVES

To characterize curve patterns and curve features in this population and possibly refine the radiographic indications for magnetic resonance imaging in patients with a normal history and physical examination.

SUMMARY OF BACKGROUND DATA

A subset of patients with "idiopathic" scoliosis may have an underlying neurologic abnormality. The radiographic indications for magnetic resonance imaging in asymptomatic patients with a normal clinical examination are not well defined.

METHODS

Data were collected from standing posteroanterior and lateral radiographs. The curve pattern and specific curve features were recorded and compared with historic controls. Thoracic kyphosis and total lumbar lordosis were also measured.

RESULTS

Fifty-one percent of patients were male. Ten curve patterns were identified, and, based on our criteria, approximately 50% of patients had an "atypical" pattern (left thoracic, double thoracic, triple, long right thoracic). A subset of those with "typical" patterns (right thoracic, right thoracic/left lumbar) had atypical features including a superior or inferior shift of the apex and/or the upper or lower end vertebrae. The mean kyphosis (T3-T12) was 41.8 degrees.

CONCLUSIONS

Although the decision to obtain magnetic resonance imaging in a patient with scoliosis should be based on both clinical and radiographic criteria, we suggest that a heightened index of suspicion is warranted with certain curve patterns (left thoracic, double thoracic, triple, and a long right thoracic curve with end vertebra caudal to T12), and with a high or low apex and/or end vertebra, especially in males and patients with a normal to hyperkyphotic thoracic spine.

Scoliosis associated with syringomyelia: clinical and radiologic correlation

STUDY DESIGN

A retrospective review with statistical correlations of 112 patients having both scoliosis and syringomyelia was performed.

OBJECTIVE

To determine whether there were significant correlations between the type of scoliosis, location of the syrinx, size of the syrinx, clinical manifestation of the syrinx, and associated lesions such as cord tethering and Chiari malformation (Chiari I or Arnold-Chiari II).

SUMMARY OF BACKGROUND DATA

The coexistence of scoliosis and syringomyelia has been described previously, but these detailed correlations have had minimal attention.

METHODS

All patients at the center with scoliosis of any type plus a syrinx had a detailed chart and radiologic review coupled with detailed statistical analysis.

RESULTS

Scoliosis and syringomyelia were seen in four diagnoses: myelomeningocele, myelomeningocele with congenital scoliosis, congenital scoliosis, and scoliosis with neither congenital anomalies nor myelomeningocele. Chiari malformation and cord tethering appear to have a major relation to scoliosis with syringomyelia.

CONCLUSIONS

Anomalies of the spinal cord or spinal column coexisting with lesions of the central nervous system have significant effects on the syrinx and scoliosis. There is a significant relation between the most caudal level of the syrinx and the locations of the scoliosis.