Syringomyelia and scoliosis: a review of twenty-five pediatric patients

Minimum 5-year follow-up outcomes for one-stage posterior instrumentation without neurosurgery intervention for correction of scoliosis associated with Chiari I malformation and syringomyelia

INTRODUCTION

Traditionally, the common belief has been that, all patients with Chiari I malformation (CM-1) and syringomyelia (SM) undergoing a neurosurgical procedure even if they are neurologically asymptomatic. As the pathology of CM-1 and SM has become better understood, the traditional concepts have been challenged. The objective of this study was to investigate the minimum 5-year follow-up clinical outcomes of surgical treatment of patients with scoliosis associated with CM-1 and SM and to evaluate the necessity of neurosurgical intervention before corrective surgery.

METHODS

This retrospective study was performed from May 2009 to September 2014. We enrolled 35 patients with scoliosis associated with CM-1 and SM who were undergoing spinal correction surgery without neurosurgical intervention. During the surgery, spinal cord monitor and wake-up test were used. Preoperative, postoperative, and final follow-up major curve coronary Cobb angle, correction rate, apical vertebral rotation (AVR), apical vertebral translation (AVT), thoracic kyphosis angle (T5-T12), lumbar lordosis angle (L1-S1) were analyzed on radiographs.

RESULTS

The mean follow-up period was 82.5 months. The preoperative and postoperative mean curve coronary Cobb angle was from 55.7 ± 7.5° to 20.1 ± 5.8°, correction rate was 63.9%, AVR from 2.8 ± 0.6° to 1.3 ± 0.5°, AVT from 5.1 ± 1.4 to 1.7 ± 0.7 cm, thoracic kyphosis angle from 18.7 ± 4.0° to 32.2 ± 2.7°, lumbar lordosis angle from 36.3 ± 4.1° to 43.8 ± 3.2°. No neurological deficits occurred during the operation and follow-up.

CONCLUSIONS

Our minimum 5-year follow-up outcomes showed that in a distinct patient population of neurologically asymptomatic individuals with CM-1, SM and progressive scoliosis, posterior instrumented spinal deformity surgery can be safely done without neurosurgical interverventions with the help of preoperative flexibility evaluation and intraoperative neuromonitoring.

Chiari 1: Is decompression always necessary previous to scoliosis surgery?

The association between Chiari 1 malformation and scoliosis is well known in the literature. Prevalence has increased after the advent of magnetic resonance imaging. In children with this association, prophylactic suboccipital decompression prior to scoliosis correction is a common surgical procedure although the rationale for this surgical management and whether not performing it may lead to spinal cord injury has not been clearly elucidated. We conducted a systematic review of the literature with the aim to obtain strong data to support the hypothesis that it is safe to proceed with scoliosis correction without prior prophylactic suboccipital decompression for Chiari 1 in an asymptomatic population. Using the Prisma methodology, we analyzed 3250 studies published between 1972 and 2018. Only four studies met the inclusion criteria. None of the studies had a level of evidence high enough to recommend prophylactic decompression previous to correction of the spinal deformity.

Brace treatment for scoliosis secondary to chiari malformation type 1 or syringomyelia without neurosurgical intervention: A matched comparison with idiopathic scoliosis

PURPOSE

To evaluate the effectiveness of brace treatment in patients with Chiari malformation type 1 (CM-1) or syringomyelia associated scoliosis without neurosurgical intervention.

METHODS

This was a retrospective case-control study. 34 CM-1 or syringomyelia (CMS) patients who received brace treatment without neurosurgical intervention were recruited. Another 68 matched patients with idiopathic scoliosis who received bracing served as the control group. The matching criteria included gender, age (± 1 years), Risser sign (± 1 grade), initial curve magnitude (± 5°), curve patterns and follow-up time (± 6 months). Patients who encountered curve progression and scoliosis surgery were compared between different groups.

RESULTS

Until the last visit, 16 (47%) patients in CMS group and 18 (26%) patients in IS group occurred curve progression; 9 (26%) patients and 15 (22%) patients underwent scoliosis surgery, respectively. Compared to idiopathic scoliosis, patients with CMS-associated scoliosis had a significantly higher rate of curve progression (P = 0.038). However, no significant difference was observed between two groups regarding to the rate of surgery (P = 0.867). Patients with combined CM-1 and syringomyelia had a higher rate of surgery than patients with isolated CM-1 or syringomyelia (P = 0.049). The double major curve pattern was identified as the risk factor for curve progression.

CONCLUSION

Brace treatment is effective for CMS-associated scoliosis without neurosurgical intervention. Compared to idiopathic scoliosis, brace can provide similar prevention for scoliosis surgery in CMS patients, but slight or moderate curve progression may occur. Specifically, patients with combined CM-1 and syringomyelia should be followed closely with a higher expectation of curve progression.

Surgical Treatment of Scoliosis-Associated with Syringomyelia: The Role of Syrinx Size

Background

The treatment of the syrinx prior to correction of the scoliosis in syringomyelia-associated scoliosis (SMS) patients remains controversial. The aim of this study is to evaluate the role of the syrinx size in the management of SMS patients.

Materials and Methods

This was a retrospective study of 36 SMS patients. They were divided into 2 groups: Group A (26 with a small syrinx, syrinx(S)/spinal cord(C) ratio ≤0.7) and Group B (10 with a large syrinx, S/C ratio >0.7). Patients with a large syrinx accepted prophylactic neurosurgery prior to scoliosis surgery. They were evaluated at baseline, 1-week and last follow-up after correction surgery for changes in curve correction, global coronal balance, thoracic kyphosis (TK), sagittal vertical axis (SVA), and Scoliosis Research Society (SRS)-22 scores.

Results

The syrinx size of patients in Group A was significantly smaller than that of in Group B. The syrinx size was significantly decreased after prophylactic neurosurgery in Group B. The radiographic parameters of scoliosis at baseline, 1-week and last follow-up after scoliosis surgery were comparable between two groups. No abnormal signal was detected during the process of neuromonitoring in both groups. Pre- and postoperative SRS-22 scores were similar between two groups.

Conclusions

Prophylactic neurosurgery may be beneficial for decreasing the risk of correction surgery in SMS patients with large syrinx (S/C ratio >0.7). After the intervention of syrinx prior to scoliosis correction, SMS patients with large syrinx could obtain similar clinical and radiographic outcomes of treatment with pedicle-screw-based spinal instrumentation and fusion compared to the patients with small syrinx.

The safety and efficacy of one-stage posterior surgery in the treatment of presumed adolescent idiopathic scoliosis associated with intraspinal abnormalities a minimum 3-year follow-up comparative study

PURPOSE

Adolescent idiopathic scoliosis (AIS) is a common type of idiopathic scoliosis. Previous studies reported that the incidence of intraspinal abnormalities among the presumed idiopathic scoliosis was 13-43%. Intraspinal abnormalities were also considered increasing the risks of progressing of scoliosis and neurological complications following scoliosis corrective surgery. The surgical strategy of presumed adolescent idiopathic scoliosis (PAIS) associated with intraspinal abnormalities remains controversial. The purpose of this study was to investigate whether one-stage posterior surgery safe and effective for the PAIS patients associated with intraspinal abnormalities.

MATERIALS AND METHODS

One hundred and thirteen consecutive patients who underwent one-stage posterior correction surgery were included. Thirty PAIS patients with intraspinal abnormalities without preoperative neurological symptoms were matched with eighty-three AIS patients for sex, age, blood loss, operating time, number of levels and location of instrumentation and curve magnitude. Radiographic and clinical parameters of the patients were evaluated before surgery, within 1 week after surgery, and more than 3 years at the last follow-up for complications and changes in main curve correction, global coronal balance, thoracic kyphosis, sagittal vertical axis, and ODI scores.

RESULTS

On average, the duration of follow-up was 51.5 months in the PAIS group compared to 52.5 months in the AIS group. The preoperative mean major coronal curve was 79.6° (ranged 56.2°-106.7°) and improved to 22.4° (ranged 6.4°-58.1°) at the last follow-up for a 71.9% of correction in the AIS group. The preoperative mean major coronal curve was 80.4° (ranged 63.4°-108.1°) and improved to 23.2° (ranged 4.8°-66.2°) at the last follow-up for a 71.1% of correction in PAIS group. The preoperative ODI score was 32.4 (10-42) in the PAIS group and improved to 11.4 (4-22) at last follow-up, 33.4 (12-42) in the AIS group and improved to 11.5 (5-22) at last follow-up. The global coronal balance, TK and SVA were all significantly improved after surgery and maintained to the last follow-up in the two groups. The neurological complications were observed in 3.3% of PAIS patients and 3.6% of AIS patients. No statistical difference in the parameters between the two groups was observed at the last follow-up.

CONCLUSION

One-stage posterior corrective surgery is safe and effective in PAIS patients associated with intraspinal abnormalities without preoperative neurological symptoms. Surgical guidelines of AIS are appropriate for the treatment of PAIS patients associated with intraspinal abnormalities.

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.

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.

Outcomes of patients with syringomyelia undergoing spine deformity surgery: do large syrinxes behave differently from small?

BACKGROUND CONTEXT

A paucity of data exists studying outcomes of patients with syringomyelia undergoing spinal deformity correction. The literature does not stratify patients by syrinx size, which is likely a major contributor to outcomes.

PURPOSE

The study aimed to compare differences in outcomes between patients with large (≥4 mm) and small syrinxes (<4 mm) undergoing spinal deformity correction.

DESIGN

This is a retrospective review.

PATIENT SAMPLE

The sample included 28 patients (11 with large syrinx [LS, >4 mm] and 17 with small syrinx [SS, <4 mm]).

OUTCOME MEASURES

The outcome measures were radiographic, operative, and neurophysiological measures.

METHODS

We retrospectively reviewed 28 patients with syringomyelia who underwent spine deformity surgery with 2-year follow-up. Demographic, surgical, and radiographic data were collected and compared preoperatively and at 2 years.

RESULTS

The LS group (11 patients) trended toward more left-sided thoracic curves (36% vs. 18%, p=.38) and was more likely to have had a Chiari decompression (45% vs. 12%, p=.08). The LS patients had larger preoperative major curves (LS=66° vs. SS=57°, p=.05), more thoracic kyphosis (LS=42°, SS=24°, p<.01), and greater rib prominences (LS=16°, SS=13°, p=.04). The LS patients had more levels fused (LS=12.2, SS=11.2, p=.05), higher estimated blood loss (EBL) (LS=1068 cc, SS=832 cc, p=.04), and a trend toward less percent correction of the major curve (LS=57%, SS=65%, p=.18). Four of 11 LS patients (36%) did not have somatosensory evoked potentials, and one of these also did not have motor evoked potentials. Neuromonitoring changes occurred in 3 of 11 (27%) LS patients and in none of the SS patients, with no postoperative deficits.

CONCLUSIONS

Outcomes of patients with syringomyelia undergoing spine deformity surgery are dependent on the size of the syrinx. Those with large syringomyelia are fused longer with more EBL and less correction. Spine surgeons should be aware that these patients are more likely to have less reliable neuromonitoring, with a higher chance of experiencing a change.

Long-term evaluation of intraoperative neurophysiological monitoring-assisted tethered cord surgery

PURPOSE

Patients with tethered spinal cord have been investigated for short-term effects after tethered spinal cord surgery in the past. However, little is known about the long-term effects in this patient group. In this retrospective, longitudinal, observational study, a patient sample of a previous report of 65 patients was reassessed to observe the long-term effects of intraoperative neurophysiological monitoring-assisted tethered cord surgery.

METHODS

With the use of patient charts and a survey, patients were scored on four domains: (1) neurological deficits, (2) urological deficits, (3) pain symptoms, and (4) orthopedic deficits. Measurements were performed at four moments in time: (1) preoperatively, (2) postoperatively, (3) follow-up 1 (4.6 years), and (4) follow-up 2 (11.2 years). Besides this, a subgroup analysis and a quality of life questionnaire were performed.

RESULTS

When observing the symptom domains in the long-term, the pain domain appeared to improve most postoperatively after which it remained stable over time. The neurological and urological domains showed a stable, slightly decreasing trend in the long-term follow-up. The orthopedic domain showed a significant increase of the number of patients with scoliosis during the long-term follow-up.

CONCLUSIONS

Lasting effects of stability in the neurological, urological, and pain domains were observed. Close monitoring during follow-up might contribute to early recognition of progressive scoliosis, in spite of detethering, in a risk group defined by females who underwent tethered cord surgery at or under the age of 12 years old with either lipomyelomeningocele, split cord malformation, or myelomeningocele. Detethering does not appear to protect these patients against progressive scoliosis.

Management of progressive late onset scoliosis with magnetic growth rod insertion leading to improvement of neural anomalies-a case report

BACKGROUND

To present the first known reported case of late onset idiopathic scoliosis with concomitant neural anomalies, treated with sequential distraction using magnetic growth rod, had significant improvement in both cranio-cervical and intraspinal anomaly.

METHODS

A caucasian, growing female child (at the age of ten) presented with moderately progressive late onset right thoracic scoliosis. She was found to have Chiari type I malformation and a cervicothoracic syrinx on routine pre-operative MRI scanning. We treated this child by inserting magnetic growing rod (MGR) system. After 48 months of follow up with serial distractions, the metalwork (MGR) was removed due to aseptic wound breakdown and granuloma formation. Subsequently due to the progression of deformity, a definitive posterior instrumented spinal fusion was done. A repeat MRI Scan of the Spine was done prior to this definitive procedure to assess for any residual neural anomalies.

RESULTS

The Chiari type I malformation appeared to have completely resolved, with no cerebellar tonsillar herniation seen, and a significant improvement in the size of the cervicothoracic syringomyelia effectively downgrading it to a prominent central canal.

CONCLUSIONS

This is a unique case of progressive late onset idiopathic scoliosis with associated Chiari malformation and syringomyelia, showing an improvement in these neural anomalies after gradual and protracted distractive lengthening of the spine with MGR.

Effectiveness of Selective Thoracic Fusion in the Surgical Treatment of Syringomyelia-associated Scoliosis: A Case-control Study With Long-term Follow-up

STUDY DESIGN

A retrospective case-control studyOBJECTIVE.: The aim of the study was to investigate the effectiveness of selective thoracic fusion in the surgical treatment of patients with syringomyelia-associated scoliosis.

SUMMARY OF BACKGROUND DATA

Selective thoracic fusion technique was introduced to treat idiopathic scoliosis patients with major thoracic curve. Theoretically, such therapeutic philosophy could be applied to syringomyelia patients. There is no previous study that specifically addresses the effectiveness of selective thoracic fusion in patients with syringomyelia-associated scoliosis.

METHODS

Two groups of scoliosis patients were enrolled, including 52 patients with syringomyelia-associated scoliosis and 52 patients with adolescent idiopathic scoliosis. Selective thoracic fusion was performed for both groups. Radiographic parameters including Cobb angle, apical vertebral translation, trunk shift, thoracic kyphosis (TK), lumbar lordosis, and sagittal vertical axis were measured on the standing posteroanterior and lateral radiographs before surgery, 1 week postoperatively and at the final follow-up, respectively. Inter- and intragroup comparisons were performed for each variable.

RESULTS

Patients of the two groups were matched in terms of age, sex, fusion levels, duration of follow-up, and all preoperative radiographic parameters except for TK. At the final follow-up, the coronal correction of the thoracic curve was comparable between the two groups (58.8 ± 10.2% vs. 61.3 ± 8.7%, P = 0.25). Moreover, the two groups were observed to have a similar improvement of lumbar curve (62.4 ± 7.3% vs. 64.9 ± 6.9%, P = 0.33). The mean correction loss of thoracic curve and lumbar curve in syringomyelia group were 3.6 ± 3.2% and 5.3 ± 1.8% respectively, showing no statistical difference when compared with those of adolescent idiopathic scoliosis group. The sagittal spinal alignments of the two groups, including TK and lumbar lordosis, were similarly maintained during the follow-up.

CONCLUSION

Syringomyelia-associated scoliosis can be successfully corrected through selective thoracic fusion surgery with a promising long-term surgical outcome.

LEVEL OF EVIDENCE

3.

Anatomical Origin of Abnormal Somatosensory-Evoked Potential (SEP) in Adolescent Idiopathic Scoliosis With Different Curve Severity and Correlation With Cerebellar Tonsillar Level Determined by MRI

STUDY DESIGN

A prospective cohort study.

OBJECTIVE

The aim of this study was to compare the somatosensory-evoked potential (SEP) findings of adolescent idiopathic scoliosis (AIS) subjects of different curve severity with age- and gender-matched controls and to evaluate any correlation between the site of the SEP abnormality with cerebellar tonsillar level measured by magnetic resonance imaging (MRI).

SUMMARY OF BACKGROUND DATA

Our previous studies showed that a higher percentage of SEP abnormality and cerebellar tonsillar ectopia was present in AIS patients than in normal controls. However, the relationship between the anatomical site of the neurophysiological abnormality and the severity in AIS patients has not been defined.

METHODS

SEP measurement was conducted on 91 Chinese AIS girls with major right thoracic curve of different curve severity (mild, moderate, severe) and 49 matched normal controls. Waveform characteristics (latency and amplitude) were compared among groups. Specific location of SEP abnormality was identified from tibial to cortical levels. Cerebellar tonsillar ectopia was defined by the previously established reference line between basion and opisthion on MRI.

RESULTS

Significant prolonged P37 latency was found on the right side between severe AIS patients and normal controls, while increased inter-side P37 latency difference was found between severe versus moderate, and severe versus normal controls. Cerebellar tonsillar ectopia was detected in 27.3% of severe group, 5.8% to 6.7% in mild and moderate group, but none in normal controls. Abnormal SEP occurred superior to C5 region in all surgical (severe) patients, of whom 58% had cerebellar tonsillar ectopia.

CONCLUSION

AIS patients showed significant prolonged latency and increased latency difference on the side of major curvature. The incidence of SEP abnormality increased with curve severity and occurred above the C5 level. The findings suggested that there was a subgroup of progressive AIS with subclinical neurophysiological dysfunction, associated with underlying neuromorphological abnormalities, which were only detectable by SEP and MRI.

LEVEL OF EVIDENCE

3.

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.

Risks and outcomes of spinal deformity surgery in Chiari malformation, Type 1, with syringomyelia versus adolescent idiopathic scoliosis

BACKGROUND CONTEXT

Chiari malformation, Type 1, with syringomyelia (CIM+SM) is often associated with spinal deformity. The safety of scoliosis surgery this population is controversial and has never been directly compared with adolescent idiopathic scoliosis (AIS).

PURPOSE

The purpose of this study was to compare the safety and subjective outcomes of spinal deformity surgery between patients with Chiari malformation Type 1-associated scoliosis and a matched AIS cohort.

STUDY DESIGN

This study is based on a retrospective matched cohort analysis.

PATIENT SAMPLE

Patients with CIM+SM and treated with spinal fusion for spinal deformity were identified in the surgical records of a single institution and were matched, 1:1, with AIS patients undergoing spinal fusion at the same institution.

OUTCOME MEASURES

The outcome measures were neurological monitoring data quality and integrity, radiographic parameters, and Scoliosis Research Society Questionnaire-22 (SRS-22) scores.

METHODS

A clinical database was reviewed for patients undergoing spinal reconstruction for CIM+SM-associated spinal deformity at our institution from 2000 to 2012. Thirty-six CIM+SM patients were identified and matched to an AIS cohort (1:1) based on age, gender, major curve magnitude, fusion length, and revision status. Demographics, deformity morphology, surgical details, neuromonitoring data, and preoperative and postoperative SRS-22 scores were recorded at a minimum of 2-year follow-up. Changes in SRS-22 scores were compared within and between groups. Complications and neurological monitoring data issues were compared between groups.

RESULTS

Mean age was 14.5±5 years (CIM+SM: 14.6±5; AIS: 14.4±5), and 42% of patients were male. Preoperative mean major coronal Cobb measured 58°±25° versus 57°±17° (p=.84) with mean kyphosis 52°±17° versus 41°±20° (p=.018). An average of 10.4±2.6 vertebral levels were fused (10.4±2.8 vs. 10.4±2.3, p=.928). No differences existed in surgical approach (p=.336), estimated blood loss (680±720 vs. 660±310 mL, p=.845), or duration of surgery (6.0±2.2 vs. 5.6±2 hours, p=.434). Complication rate was comparable between the two groups (33% vs. 14%, p=.052). Chiari malformation, Type 1, with syringomyelia experienced more neurological complications (11% vs. 0%, p=.04) and neuromonitoring difficulties (28% vs. 3%, p=.007) than the AIS cohort. Mean curve correction was comparable at 2 years (58% CIM+SM vs. 64% AIS, p=.2). At follow-up, both CIM+SM and AIS groups demonstrated improved cumulative SRS-22 outcome subscores (CIM+SM: +0.4, p=.027; AIS: +0.3, p<.001). No difference in outcome subscores existed between CIM+SM and AIS groups.

CONCLUSIONS

Although CIM+SM patients undergoing spine reconstruction can expect similar deformity corrections and outcome scores to AIS patients, they also experience higher rates of neuromonitoring difficulties and neurological complications related to surgery. Surgeons should be prepared for these difficulties, particularly in children with larger syrinx size.

Spinal Deformity Associated with Chiari Malformation

Despite the frequency of Chiari-associated spinal deformities, this disease process remains poorly understood. Syringomyelia is often present; however, this is not necessary and scoliosis has been described in the absence of a syrinx. Decompression of the hindbrain is often recommended. In young patients (<10 years old) and/or those with small coronal Cobb measurements (<40°), decompression of the hindbrain may lead to resolution of the spinal deformity. Spinal fusion is reserved for those curves that progress to deformities greater than 50°. Further research is needed to understand the underlying pathophysiology to improve prognostication and treatment of this patient population.

The impact of posterior temporary internal distraction on stepwise corrective surgery for extremely severe and rigid scoliosis greater than 130°

AIM

To investigate the efficacy and safety of temporary internal distraction corrective surgery for extremely severe scoliosis.

METHODS

Eleven scoliosis patients (3 males and 8 females) with curves ≥130° (mean 148.8°; range 130°-157°) who underwent a two-stage surgery, including a posterior temporary internal distraction correction and definitive posterior spinal correction with posterior pedicle screw instrumentation from 2008 to 2011 were retrospectively reviewed. Minimum follow-up was 2-years (mean 41.8 months; range 27.0-63.0 months). The analysis focused on the impact of temporary internal distraction on curve correction, pulmonary function tests (PFTs), complications and surgical outcomes. Neurosurveillance of sensory (somatosensory-evoked potentials) and motor (motor-evoked potentials) potential was performed in all cases. Posterior instrumentation was used in all patients.

RESULTS

After the use of internal distraction, the preoperative major curve (mean 148.8°; range 130°-157°) was corrected to a mean of 79° (range 63°-87°), the T5-T12 kyphosis Cobb angle (mean 79°; range 30°-97°) was corrected to a mean of 59° (range 20°-75°), the coronal imbalance (mean 0.8 cm; range -3.6 to 2.8 cm) was improved to a mean of 0.6 cm (range -1.5 to 2.0 cm), the forced vital capacity percentage (FVC%) was improved from 59.3 ± 11.6 to 68.7 ± 13.7, and the forced expiratory volume in 1 s (FEV1%) was improved from 61.4 ± 13.6 to 71.3 ± 9.3. The average increase in body height was 6.7 cm, and the dorsum razor was corrected to 3-5 cm. During definitive surgery, the final major curves were corrected to a mean of 55° (range 32°-72°), the T5-T12 kyphosis Cobb was corrected to 35° (range 15°-68°), the coronal imbalance was improved to 0.5 cm (range -1.2 to 1.8 cm), the FVC% was improved to 71.2 ± 8.3, the FEV1% was improved to 76.3 ± 16.7, the increase in body height was 3.1 cm, and the dorsum razor was corrected to 1-3 cm. The mean interval time between the two surgeries was 3.5 months. None of the patients exhibited postoperative neurologic deficits or infections. No instrument complications were found during the final follow-up.

CONCLUSIONS

Temporary internal distraction in a two-stage corrective surgery provided patients who had extremely severe and rigid scoliosis, an effective and safe solution for scoliosis without significant complications.

Evaluation of coronal shift as an indicator of neuroaxial abnormalities in adolescent idiopathic scoliosis: a prospective study

Background

In previous studies, many indicator factors have been proposed to select patients who need an MRI screening of the spinal canal. In current study, the clinical and radiologic factors including coronal parameters of the curve were evaluated to find out which indicator is more important.

Methods

A prospective study included 143 consecutive patients with the diagnosis of adolescent idiopathic scoliosis who were treated between 2010 and 2013 at our spinal clinics. Only patients with normal or subtle neurologic findings were included. All patients were evaluated by a total spine MRI protocol for examination of neuroaxial abnormalities. Known indicators and also coronal shift were analysed in all patients with or without abnormal MRI.

Results

The incidence of neuroaxial abnormalities was 11.9% (17 of 143); only 5 patients (3.5%) were operated to treat their neuroaxial problem. The significant indicators of the abnormalities in our patients were: younger age at onset, asymmetric superficial abdominal reflex and, coronal shift more than 15 mm (P = 0.03). Some previously known indicators like atypical curves, male gender, double curves and absence of thoracic lordosis were not different between two groups of the patients.

Conclusions

A total spine MRI is recommended at presentation in patients with younger age, abnormal neurologic findings and severe coronal shift.

A novel approach to gradual correction of severe spinal deformity in a pediatric patient using the magnetically-controlled growing rod

BACKGROUND CONTEXT

Acute correction of severe spinal deformities significantly increases the risk of neurologic complications. Previously used methods to safely correct these deformities include halo-traction devices and internal distraction rods.

PURPOSE

This report introduces a novel method for gradual correction of severe spinal deformity by using the magnetically controlled growing rod (MCGR).

STUDY DESIGN

This is a case report.

METHODS

A 12-year-old girl with severe kyphoscoliosis and concurrent syringomyelia and Arnold-Chiari Type I malformation underwent implantation of the MCGR. After implantation of the device, daily distractions of the implant were performed over the course of 2.5 months.

RESULTS

The patient underwent MCGR implantation without acute correction of her left-sided thoracic scoliosis (109° from T6 to T11) and upper thoracic kyphosis (72°). After 2.5 months of daily distractions in the ward, the scoliosis improved to 66° and the kyphosis to 62°. Final fusion was performed without problems, and her overall truncal balance was much improved.

CONCLUSIONS

This report is the first to note the safety and efficacy of the MCGR in treating young patients with severe spinal deformities. This technique allows correction of the deformity while the patient is awake so that neurology can be continuously monitored. The patient is also ambulatory throughout the distraction process and can be distracted on an outpatient basis. Repeated surgery can be avoided, and the MCGR has been shown to be safe and effective with this case illustration.

Scoliosis-Associated Cervical Spine Pathologies

STUDY DESIGN

A total of 126 scoliosis patients admitted to the hospital were screened for concomitant cervical pathologies.

OBJECTIVES

To investigate the prevalence of cervical spine pathologies and the clinical relevance of magnetic resonance imaging (MRI) in the evaluation of patients with neuromuscular, congenital, syndromic, and idiopathic scoliosis.

BACKGROUND SUMMARY

With the development of MRI, upper neural axis abnormalities such as syringomyelia and Chiari malformation are increasingly being found in patients with scoliosis, but no report in the literature describes other pathologies in the cervical area seen concomitant with different scoliosis types.

METHODS

A total of 126 consecutive patients who were classified as having neuromuscular, congenital, syndromic, and idiopathic scoliosis were retrospectively evaluated. Data regarding cervical neural axis abnormalities obtained from the MRI studies were analyzed and classified into each type of scoliosis group.

RESULTS

A total of 126 patients with scoliosis were evaluated for hindbrain and cervical spine anomalies. Patients were divided into 4 groups regarding the type of scoliosis. The cervical spine of all patients was evaluated with MRI and other radiologic methods when needed. The most frequently seen pathology was syringomyelia. Other pathologies found included congenital vertebral anomalies, Chiari malformation, arachnoid cyst, atlanto-axial dissociation, split cord, posterior vertebral fusion, vertebral hypoplasia, neurenteric cyst, myelomalacia, dermoid cyst, and decrease in craniovertebral angle. Cervical pathologies were most frequently seen in neuromuscular scoliosis, followed by congenital and syndromic groups.

CONCLUSIONS

Cervical spinal pathologies vary according to the type of scoliosis. The number of cervical spinal pathologies diagnosed in idiopathic scoliosis patients was least compared with neuromuscular and syndromic groups. The most common pathology was syringomyelia, followed by congenital vertebral anomalies and cerebral tonsillar hernia. Preoperative MRI scan provides vital information regarding cervical spinal pathologies encountered in scoliosis patients.

Effectiveness of brace treatment of Chiari malformation-associated scoliosis after posterior fossa decompression: a comparison with idiopathic scoliosis

STUDY DESIGN

Retrospective case-control study.

OBJECTIVE

To evaluate the effectiveness of bracing in patients with Chiari malformation-associated scoliosis (CMS) after posterior fossa decompression (PFD).

SUMMARY OF BACKGROUND DATA

The effectiveness of bracing has been poorly studied in patients with CMS who have undergone PFD.

METHODS

A retrospective study was conducted on 22 patients with CMS who received brace treatment of scoliosis after PFD. Forty-four age- and sex-matched patients with idiopathic scoliosis (IS) who were treated with bracing served as the control group. The bracing outcome was considered a failure if the curve worsened 6° or more; otherwise, the treatment was considered to be successful.

RESULTS

The age and Risser sign were similar between patients with CMS and IS at brace initiation. The initial curve magnitude of patients with CMS (mean, 32.9° ± 6.3°; range, 20°-45°) was marginally significantly larger than that of patients with IS (mean, 29.6° ± 6.4°; range, 20°-45°). Until the final follow-up, a 6° or more worsening of the major curve occurred in 8 patients with CMS (36%) and in 15 patients with IS (34%). Overall, 7 patients with CMS (32%) and 13 patients with IS (30%) underwent spinal fusion surgery. No significant differences were observed between the 2 groups in the surgery rates or the bracing success rates (P > 0.05). In patients with CMS, neither the performance of syringosubarachnoid shunting nor the extent of tonsillar descent correlated with the bracing outcomes, whereas a double major curve pattern was found to be predictive for the failure of bracing.

CONCLUSION

Brace treatment subsequent to PFD is effective in preventing curve progression for 64% of patients with CMS, which is comparable with the rate that is observed in patients with IS. Double major curve pattern may be a risk factor in predicting treatment failure in patients with CMS.

LEVEL OF EVIDENCE

3.

The use of routine preoperative magnetic resonance imaging in identifying intraspinal anomalies in patients with idiopathic scoliosis: a 10-year review

PURPOSE

This study sought to quantify the frequency of previously unidentified spinal cord anomalies identified by routine preoperative magnetic resonance imaging (MRI), in patients planned for surgical scoliosis correction.

METHODS

Our study group comprised 206 patients with idiopathic scoliosis who underwent deformity correction from 1998 to 2008. Clinical records of all the patients were retrospectively reviewed to ascertain the proportion having a neural abnormality on preoperative MRI scan.

RESULTS

Twenty of 206 patients (9.7 %) were diagnosed with an unexpected intraspinal anomaly on routine preoperative MRI. In all cases, a neurosurgical opinion was sought prior to further intervention. Of the 20 patients, 11 underwent a neurosurgical procedure (de-tethering of cord, decompression of Chiari, decompression of syrinx). There was no statistically significant difference between the group of patients who had intrinsic spinal cord anomalies on preoperative MRI and those did not have a cord abnormality with regard to age at presentation, gender, side of dominant curve and degree of curve (p < 0.05).

CONCLUSION

The high frequency of spinal cord abnormalities unidentified by preoperative neurological examination, and the frequent need for subsequent neurosurgical intervention, suggests that MRI assessment prior to deformity correction is important in the management of idiopathic scoliosis.

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.

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.

One-stage and posterior approach for correction of moderate to severe scoliosis in adolescents associated with Chiari I malformation: is a prior suboccipital decompression always necessary?

Priority of neurological decompression was regarded as necessary for scoliosis patients associated with Chiari I malformation in order to decrease the risk of spinal cord injury from scoliosis surgery. We report a retrospective series of scoliosis associated with Chiari I malformation in 13 adolescent patients and explore the effectiveness and safety of posterior scoliosis correction without suboccipital decompression. One-stage posterior approach total vertebral column resection was performed in seven patients with scoliosis or kyphosis curve >90° (average 100.1° scoliotic and 97.1° kyphotic curves) or presented with apparent neurological deficits, whereas the other six patients underwent posterior pedicle screw instrumentation for correction of spinal deformity alone (average 77.3° scoliotic and 44.0° kyphotic curves). The apex of the scoliosis curve was located at T7-T12. Mean operating time and intraoperative hemorrhage was 463 min and 5,190 ml in patients undergoing total vertebral column resection, with average correction rate of scoliosis and kyphosis being 63.3 and 71.1%, respectively. Mean operating time and intraoperative hemorrhage in patients undergoing instrumentation alone was 246 min and 1,450 ml, with the average correction rate of scoliosis and kyphosis being 60.8 and 53.4%, respectively. The mean follow-up duration was 32.2 months. No iatrogenic neurological deterioration had been encountered during the operation procedure and follow-up. After vertebral column resection, neurological dysfunctions such as relaxation of anal sphincter or hypermyotonia that occurred in three patients preoperatively improved gradually. In summary, suboccipital decompression prior to correction of spine deformity may not always be necessary for adolescent patients with scoliosis associated with Chiari I malformation. Particularly in patients with a severe and rigid curve or with significant neurological deficits, posterior approach total vertebral column resection is likely a good option, which could not only result in satisfactory correction of deformity, but also decrease the risk of neurological injury secondary to surgical intervention by shortening spine and reducing the tension of spinal cord.

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.

Intraspinal anomalies in scoliosis: An MRI analysis of 177 consecutive scoliosis patients

BACKGROUND

The association of intraspinal neural anomalies with scoliosis is known for more than six decades. However, there are no studies documenting the incidence of association of intraspinal anomalies in scoliotic patients in the Indian population. The guide lines to obtain an magnetic resonance imaging (MRI) scan to rule out neuro-axial abnormalities in presumed adolescent idiopathic scoliosis are also not clear. We conducted a prospective study (a) to document and analyze the incidence and types of intraspinal anomalies in different types of scoliosis in Indian patients. (b) to identify clinico-radiological 'indicators' that best predict the findings of neuro-axial abnormalities in patients with presumed adolescent idiopathic scoliosis, which will alert the physician to the possible presence of intraspinal anomalies and optimize the use of MRI in this sub group of patients.

MATERIALS AND METHODS

The data from 177 consecutive scoliotic patients aged less than 21 years were analyzed. Patients were categorized into three groups; Group A - congenital scoliosis (n=60), group B -presumed idiopathic scoliosis (n=94) and group C - scoliosis secondary to neurofibromatosis, neuromuscular and connective tissue disorders (n=23). The presence and type of anomaly in the MRI was correlated to patient symptoms, clinical signs and curve characteristics.

RESULTS

The incidence of intraspinal anomalies in congenital scoliosis was 35% (21/60), with tethered cord due to filum terminale being the commonest anomaly (10/21). Patients with multiple vertebral anomalies had the highest incidence (48%) of neural anomalies and isolated hemi vertebrae had none. In presumed 'idiopathic' scoliosis patients the incidence was higher (16%) than previously reported. Arnold Chiari-I malformation (AC-I) with syringomyelia was the most common neural anomaly (9/15) and the incidence was higher in the presence of neurological findings (100%), apical kyphosis (66.6%) and early onset scoliosis. Isolated lumbar curves had no anomalies. In group-C, incidence was 22% and most of the anomalies were in curves with connective tissue disorders.

CONCLUSION

The high incidence of intraspinal anomalies in presumed idiopathic scoliosis in our study group emphasizes the need for detailed examination for subtle neurological signs that accompany neuro-axial anomalies. Preoperative MRI screening is recommended in patients with presumed 'idiopathic' scoliosis who present at young age, with neurological findings and in curves with apical thoracic kyphosis.

Syringomyelia-associated scoliosis with and without the Chiari I malformation

Although there may be a hereditary component to true idiopathic scoliosis, the condition has no known cause and is not associated with dysraphism. However, scoliosis with an associated syrinx, with or without the Chiari I malformation, sometimes presents as an idiopathic-type curve. Physical examination findings and subtle clues on diagnostic imaging may help the orthopaedic surgeon diagnose scoliosis associated with syringomyelia. Examination findings include asymmetric reflexes and presentation at ages younger than those of patients who present with adolescent idiopathic curves (i.e., 10 to 14 years). Radiologic findings include kyphosis at the apex of the curve. Indications for surgical decompression include progressive neurologic deficits, weakness, pain, and progressive curves. Most orthopaedic surgeons agree that a syrinx should be evaluated neurosurgically before any planned spinal arthrodesis to decrease the risk of neurologic injury connected with surgical correction. The indications for arthrodesis in these patients compared with those with idiopathic curves are evolving.

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.

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.

Scoliosis associated with syringomyelia: analysis of MRI and curve progression

Little is known about the natural history of scoliosis found in patients with syringomyelia, including the factors affecting scoliosis curve progression and the effect of syrinx drainage treatment. Twenty patients having scoliosis with syringomyelia diagnosed by MRI were followed up for 6.6 (range 2.0-12.6) years on an average. Various factors potentially influencing curve pattern or progression in these patients were then retrospectively reviewed. The convex side of major curve of scoliosis tended to be on the same side as the syrinx and as the unilateral neurologic abnormality. No correlation was found between the location and the size of the syrinx and the location and size of the major curve of the scoliosis, or between the severity of neurologic deficit and the size of the major curve of the scoliosis. In patients under the age of ten at the time of diagnosis of scoliosis and with a flexible curve, decompression of the syrinx improved or stabilized scoliosis. In most patients over the age of ten, surgical treatment of the scoliosis was necessary because of the large initial size of the curve or progression of the curve even after syrinx drainage. Other factors including gender, location of the syrinx, type of the curve, and severity of neurologic deficits did not correlate with the progression of the curve. The results of this retrospective study suggest that early diagnosis and decompression of a syrinx in scoliosis patients especially under the age of ten is crucial and may decrease the curve size and limit scoliosis curve progression.

Spontaneous resolution of syringomyelia without Chiari malformation

A 30-year-old woman presented with a cervical syrinx manifesting as hemihypesthesia. Neuroimaging found no evidence of Chiari malformation or tight cisterna magna. Serial magnetic resonance imaging studies over a 6-year period demonstrated spontaneous and complete resolution of the syrinx accompanied by an asymptomatic clinical course. The natural history of syringomyelia is highly unpredictable. The outcome of surgical treatment for patients with syringomyelia is not always satisfactory, so the indications for surgery are controversial. Spontaneous resolution of syringomyelia unrelated with foramen magnum lesion has various causes. Close follow up of the patient is necessary to monitor for recurrence.

Thoracolumbar syrinx in association with Williams syndrome

Williams syndrome is a genetic condition caused by a deletion on chromosome 7. Clinically it consists of multiple cardiovascular and craniofacial structural abnormalities as well as developmental delay, specific cognitive difficulties, and a characteristic personality. Although scoliosis is a noted manifestation of the disorder, syrinx in association with Williams syndrome has not been reported previously in the literature. Here we present the case of a child with Williams syndrome, scoliosis, and a thoracolumbar syrinx that was successfully treated surgically. We recommend that children with Williams syndrome and scoliosis undergo preoperative evaluation of the spinal cord, as well as the spinal column, so that correctable lesions such as a syrinx are not overlooked. Although syrinxes are often associated with scoliosis, the association in this case of syrinx and Williams syndrome could imply the existence of a genetic contribution to syrinx formation on chromosome 7.

Chronic changes in cerebrospinal fluid pathways produced by subarachnoid kaolin injection and experimental spinal cord trauma in the rabbit: their relationship with the development of spinal deformity. An electron microscopic study and magnetic resonance imaging evaluation

Post-traumatic cystic changes in cerebrospinal fluid (CSF) pathways such as ventriculomegaly and/or hydrosyringomyelia are not uncommon, but their characteristics have not yet been fully clarified. This study was designed to investigate the alterations affecting the CSF pathways in rabbits at a late stage, and to clarify the relationship between these changes and the development of spinal deformity. In this study, a total of 60 New Zealand white rabbits were used and they were segregated into four different groups of 15 animals each: sham-operation group, kaolin group, and kaolin plus mild trauma group and kaolin plus severe trauma group. The animals were subjected to radiological investigation using direct X-ray study and magnetic resonance imaging (MRI) after 4 months. The thoracic spinal cords of the animals were dissected after intracardiac perfusion-fixation with 10% formalin for light microscopy and 2.5% glutaraldehyde for transmission electron microscopic study. Following the sectioning and staining procedures, the histological characteristics of the spinal cords were evaluated with light microscopy and transmission electron microscopy. A spinal deformity developed in 90% in rabbits in both kaolin injection group and spinal trauma groups. MRI revealed generalized dilatation of the ventricular system and the central canal of the spinal cord after the kaolin injection with/without trauma in this study. Gross morphologic examination showed some enlargement of entire CSF pathways in these groups. All animals with central canal dilatation had mild or severe scoliotic and kyphotic deformities. In a light microscopic study, a denuded ependymal line and multicyst formations in periependymal areas were found in both kaolin injection and spinal trauma groups. Ultrastructurally, an apical flattening of the ependyma, microcysts in the ependymal cells, axonal degeneration, demyelination, and loss of ependymal cells adjacent mild spongy were found in the spinal cords of animals in these groups. To the best of our knowledge, this is the first study to investigate the chronic effects of spinal cord injury (SCI) on the CSF pathways and their relationship with the development of spinal deformity in an experimental model of kaolin injection and trauma, using MRI as well as light and transmission electron microscopy. In the light of this study, the severity of spinal cord injury on the development of some degenerative findings in the spinal cord was clear, but further clinical and experimental studies using dynamic imaging techniques will be valuable.

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.

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.

Preoperative radiological and electrophysiological evaluation in 100 adolescent idiopathic scoliosis patients

This is a prospective study of spinal magnetic resonance imaging (MRI), electrophysiological recordings, and neurological examinations of 100 patients admitted for surgery for adolescent idiopathic scoliosis (AIS), which was conducted to assess the prevalence of structural and functional abnormalities within the spinal cord in patients with clinically normal neurologic condition. In all patients the clinical diagnosis and intact neurological condition was ascertained by a spinal orthopedic surgeon. Full-length spinal axis MRI studies (T1/T2 sequences) and somato-sensory evoked potentials of the tibial nerves (tSSEPs) were preoperatively assessed by independent evaluators blinded to the patients' medical histories. Structural spinal cord abnormalities were found in three of 100 AIS patients on MR imaging. In one patient a Chiari malformation type 1 with an accompanying syringomyelia was diagnosed, which required a suboccipital decompression. In the other two patients small thoracic syringomyelias were diagnosed. Abnormalities of spinal cord function were detected in 68% of the 100 patients: tSSEP latencies corrected for body height were increased in 56% of the patients; pathological differences between tSSEPs on the left and right sides were present in 17% (12% in combination with a prolongation of the latency). The findings of this study indicate that MRI and electrophysiological examinations are essential to assess spinal cord abnormalities that are clinically not detectable in AIS patients. Even in patients with intact neurologic condition and clinically typical right-curved thoracic scoliosis, the possibility of intraspinal pathologies should be ruled out by MRI. It is especially important to detect structural pathologies like syringomyelia and Chiari malformation before proceeding with scoliosis surgery, as these conditions are associated with a higher neurological risk during scoliosis surgery. The electrophysiological recordings made in the present study, with the high number of pathological tSSEPs, are indicative of functional abnormalities with a subclinical involvement of the recorded neuronal pathways. The relevance of the latter findings is not yet clear, but pre-operative tSSEP examinations offer the possibility of assessing alterations in spinal cord function that are undetectable by clinical examination.

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.