Adult scoliosis in syringomyelia associated with Chiari I malformation

Correlation Among Syrinx Resolution, Cervical Sagittal Realignment, and Surgical Outcome After Posterior Reduction for Basilar Invagination, Atlantoaxial Dislocation, and Syringomyelia

BACKGROUND

The correlation among syrinx resolution, occipitoaxial sagittal alignment, and surgical outcome in long-term follow-up seems to have not been clarified.

OBJECTIVE

To further explore the relationship between the syrinx resolution and occipitoaxial realignment after posterior reduction and fixation in basilar invagination (BI)-atlantoaxial dislocation (AAD) patients with syringomyelia.

METHODS

A continuous series of 32 patients with BI-AAD and syringomyelia who received direct posterior reduction met the inclusion criteria of this study. Their clinical and imaging data were analyzed retrospectively. Before surgery and at the last follow-up, we used the Japanese Orthopedic Association (JOA) score and the Neck Disability Index (NDI) to assess the neurological status, respectively. The Pearson correlation coefficient and multiple stepwise regression analysis were used to explore the relevant factors that may affect surgical outcomes.

RESULTS

There were significant differences in atlantodental interval, clivus-axial angle, occiput-C2 angle (Oc-C2A), cervicomedullary angle (CMA), subarachnoid space (SAS) at the foramen magnum (FM), syrinx size, NDI, and JOA score after surgery compared with those before surgery. ΔCMA and the resolution rate of syrinx/cord as relevant factors were correlated with the recovery rate of JOA (R 2 = 0.578, P < .001) and NDI (R 2 = 0.369, P < .01). What's more, ΔSAS/FMD (SAS/FM diameter) and ΔOc-C2A were positively correlated with the resolution rate of syrinx/cord (R 2 = 0.643, P < .001).

CONCLUSION

With medulla decompression and occipital-cervical sagittal realignment after posterior reduction and fusion for BI-AAD patients with syringomyelia, the structural remodeling of the craniovertebral junction and occipitoaxial realignment could contribute to syringomyelia resolution.

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.

Spontaneous Reduction of Chiari Malformation and Syringomyelia After Posterior Spinal Fusion for Scoliosis: A Case Report

CASE

A 22-year-old skeletally mature man with scoliosis accompanied by syringomyelia associated with Chiari malformation type 1 was presented to our hospital. Because the maximal syrinx/cord ratio was small, and he had no neurological deficit, he underwent corrective surgery without the treatment of the syringomyelia.

CONCLUSION

The scoliosis was corrected without any neurological complications. Magnetic resonance imaging taken 8 days after the surgery showed the reduction of the size of the syringomyelia. The syringomyelia almost disappeared at the 8-year follow-up.

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.

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.

Ventrolateral Tonsillar Position Defines Novel Chiari 0.5 Classification

BACKGROUND

Cervicomedullary compression in young children has been described in the context of Chiari type 1 malformation, with symptoms associated with the extent of tonsillar herniation below McRae line. Historically, Chiari type 1 malformation has been defined by tonsillar herniation of at least 5 mm. However, in certain populations, including very young children, Chiari symptoms may be present without this finding. A new Chiari classification is thus necessary.

METHODS

Cases involving patients up to 5 years of age evaluated for possible posterior fossa decompression were retrospectively reviewed. Preoperative symptoms, magnetic resonance imaging findings, surgical management, and short- and long-term outcome and follow-up were recorded. Tonsillar descent and presence of ventral herniation (VH) were recorded. We define VH as the tonsils crossing a line that bisects the caudal medulla at the level of the foramen magnum, thus creating a novel entity, Chiari type 0.5 malformation. Patients with ventrally herniated tonsils were compared with patients exhibiting more typical Chiari morphology.

RESULTS

Of 41 cases retrospectively reviewed, 20 met criteria for VH. These differed from cases without VH because of the predominance of medullary symptoms. In the VH cohort, 11 patients underwent surgical decompression with symptom resolution; 9 were initially managed conservatively, but 3 subsequently required surgery.

CONCLUSIONS

We define a novel Chiari entity, Chiari type 0.5 malformation, characterized by ventral tonsillar wrapping around the medulla in young children in the absence of classic Chiari type 1 malformation imaging findings. These patients are more likely to present with medullary symptoms than patients without VH. They are also more likely to require surgical decompression and respond favorably to intervention.

Systematic review and meta-analysis of imaging characteristics in Chiari I malformation: does anything really matter?

PURPOSE

Previous studies have attempted to evaluate the utility of preoperative magnetic resonance imaging (MRI) parameters in predicting outcomes in Chiari I malformation. We performed a systematic review and meta-analysis to determine what preoperative imaging features (if any) predict (1) presence of preoperative symptoms or associated findings, (2) need for surgical decompression, or (3) improvement after surgical decompression.

METHODS

All publications through June 2018 on PubMed, Embase, and Cochrane Library databases were searched using the keywords "Chiari I malformation" AND "decompression" OR "imaging." One thousand two hundred ten publications were identified, and 20 were included for our systematic review; nine were included in the meta-analysis.

RESULTS

Tonsil position, clivus gradient, and scoliotic curve of > 20° were all associated with the presence of preoperative syrinx. Degree of scoliotic curve was associated with length of syrinx. Pre-operative findings of central syrinx morphology, shorter syrinx, and scoliotic curve < 20° were associated with post-operative stability/improvement. Post-operative symptomatic improvement was associated with preoperative pB-C2 line ≥ 3 mm, absence of scoliosis, and presence of syrinx. By meta-analysis, there was no significant difference in post-operative improvement between patients with and without syrinx (OR = 0.89; 95% CI 0.58-1.37). Meta-analysis showed no significant difference in post-operative improvement between patients with and without basilar invagination (OR = 1.31; 95% CI 0.72-2.36).

CONCLUSIONS

Multiple studies have attempted to identify preoperative imaging parameters to predict post-operative improvement, but no consistently reliable criteria have been defined. This review and meta-analysis highlight the importance of considering each patient's clinical history and physical exam within the context of associated radiographic abnormalities.

Comparison of Radiological Features and Clinical Characteristics in Scoliosis Patients With Chiari I Malformation and Idiopathic Syringomyelia: A Matched Study

STUDY DESIGN

Retrospective study.

OBJECTIVE

To compare syrinx characteristics, scoliotic parameters, and neurological deficits between Chiari I malformation (CIM) and idiopathic syringomyelia (IS) in the scoliotic population.

SUMMARY OF BACKGROUND DATA

CIM and IS are common in neuromuscular scoliosis patients; however, differences in syrinx characteristics, scoliotic parameters, and neurological deficits between CIM and IS are unclear.

METHODS

Thirty-six patients with scoliosis secondary to CIM were enrolled retrospectively and matched with 36 IS patients for sex, age, scoliosis classification, and Cobb angle. Information on radiographic features of scoliosis and syrinx and neurological deficits was systematically collected.

RESULTS

Sex, age, and coronal, and sagittal scoliosis parameters did not differ between the CIM and IS groups. The CIM group had a longer syrinx (12.9 ± 4.0 vertebral levels vs. 8.7 ± 5.5 vertebral levels, P < 0.001), a higher cranial extent (3.6 ± 2.2 vs. 5.2 ± 3.5, P = 0.027), and a lower caudal extent (15.6 ± 2.9 vs. 13.0 ± 4.6, P = 0.006) than the IS group, despite no differences in syrinx/cord (S/C) ratio or syrinx classification. No differences in neurological deficits were identified between the CIM and IS patients.

CONCLUSION

With demographic and scoliotic coronal parameters matched, the CIM patients had a longer syrinx, located at a higher cranial and lower caudal level, compared with the IS group. No significant differences in syrinx S/C ratio, sagittal features of scoliosis, or neurological deficits were detected between the two groups.

LEVEL OF EVIDENCE

3.

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.

A case report on result of posterior fossa decompression on syringomyelia in a case of chiary type I malformation

The prime objective in the surgical treatment of Chiari malformation (CM) and/or syringomyelia (SM) is based on the restoration of the normal cerebrospinal fluid (CSF) dynamics at the craniovertebral junction through the creation of a large artificial cisterna magna. In this case a patient came to our hospital with type 1 chiary malformation having large syrinx which underwent posterior fossa decompression by midline sub occipital craniectomy with subpial cerebellar tonsillar resection which after one year of follow up we have found significant resolution of syrinx radiologically.

Entire syringomyelia associated with Chiari II malformation and severe scoliosis and hydrocephalus

BACKGROUND

The syrinx can occur in any region of the spinal cord and is common in cervical and/or thoracic region, and distributing along spinal cord is unusual, especially association with Chiari II malformation and scoliosis.

OBJECTIVE

To report a first case of entire syringomyelia associated with Chiari II malformation and severe scoliosis and hydrocephalus.

CASE PRESENTATION

The patient began to experience symptoms of bilateral hand weakness in adulthood. In this patient, MR imaging of the brain and spine showed syrinx along entire spine and hydrocephalus, cerebellar tonsillar herniation, and expansion of the fourth ventricle and posterior cranial fossa. The patient underwent operative treatment to prevent the progression of her neurological deficit. At 12 months' follow-up, the patient's neurological deficit remains stable with the scoliosis left untreated.

CONCLUSIONS

Foramen magnum decompression, duraplasty and syrinx-shunting are effective methods even to CM II and entire syrinx.

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.

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.

Radiological Features of Scoliosis in Chiari I Malformation Without Syringomyelia

STUDY DESIGN

A retrospective radiographic analysis.

OBJECTIVE

The aim of this study was to investigate the scoliosis curve patterns/features and magnetic resonance imaging (MRI) tonsillar ectopia characteristics in Chiari I malformation without syringomyelia (CMI-only).

SUMMARY OF BACKGROUND DATA

The development of scoliosis associated with a CMI typically has been ascribed to the presence of syringomyelia. However, a subset of CMI patients with scoliosis may not have a concomitant syrinx. Scoliosis in these patients has been very poorly documented in the literature.

METHODS

A retrospective study was conducted on patients with a scoliosis secondary to CMI-only. The curve direction, curve pattern/features, and side of the dominant tonsillar ectopia were recorded and assessed quantitatively. On the basis of the measurement results, associations between the scoliosis curve patterns/features and MRI tonsillar ectopia characteristics were analyzed.

RESULTS

A total of 26 patients, consisting of seven males and 19 females with an average age of 15.4 years, were included in the current study. In 19 patients with asymmetrically displaced tonsils, the concordance between the dominant side of the asymmetrically displaced tonsils and curve direction was 78.9%. A statistically significant association was found between the dominant side of the tonsillar ectopia and the convex side of scoliosis according to Fisher exact test (P = 0.045). In addition, it was noted that there was a high incidence (52.9%) of atypical curve patterns in CMI-only patients. A significantly high incidence of atypical features with a superior shift of either the apical or the end vertebrae was found in 85.7% of thoracic curves and 40% of lumbar curves.

CONCLUSION

Scoliosis associated with CMI-only was found to have atypical curve patterns in all cases, and the direction of scoliosis was highly consistent with the dominant side of asymmetrically tonsillar herniation. These findings should be considered as an argument in favor of a nonidiopathic etiology and lead to more evidence that simple tonsillar impaction can provide enough impetus to produce or exaggerate scoliotic curvature.

LEVEL OF EVIDENCE

3.

Comparison of spinal deformity in children with Chiari I malformation with and without syringomyelia: matched cohort study

PURPOSE

To describe curve patterns in patients with Chiari malformation I (CIM) without syringomyelia, and compare to patients with Chiari malformation with syringomyelia (CIM + SM).

METHODS

Review of medical records from 2000 to 2013 at a single institution was performed to identify CIM patients with scoliosis. Patients with CIM were matched (1:1) by age and gender to CIM + SM. Radiographic curve patterns, MRI-based craniovertebral junction parameters, and associated neurological signs were compared between the two cohorts.

RESULTS

Eighteen patients with CIM-associated scoliosis in the absence of syringomyelia were identified; 14 (78 %) were female, with mean age of 11.5 ± 4.5 years. Mean tonsillar descent was 9.9 ± 4.1 mm in the CIM group and 9.1 ± 3.0 mm in the CIM + SM group (p = 0.57). Average syrinx diameter in the CIM + SM group was 9.0 ± 2.7 mm. CIM patients demonstrated less severe scoliotic curves (32.1° vs. 46.1°, p = 0.04), despite comparable thoracic kyphosis (43.7° vs. 49.6°, p = 0.85). Two (11 %) patients with CIM demonstrated thoracic apex left deformities compared to 9/18 (50 %) in the CIM + SM cohort (p = 0.01). Neurological abnormalities were only observed in the group with syringomyelia (6/18, or 33 %; p = 0.007).

CONCLUSION

In the largest series specifically evaluating CIM and scoliosis, we found that these patients appear to present with fewer atypical curve features, with less severe scoliotic curves, fewer apex left curves, and fewer related neurological abnormalities than CIM + SM. Notably, equivalent thoracic kyphosis was observed in both groups. Future studies are needed to better understand pathogenesis of spinal deformity in CIM with and without SM.

Long-Term Outcomes After Small-Bone-Window Posterior Fossa Decompression and Duraplasty in Adults with Chiari Malformation Type I

BACKGROUND

Small-bone-window posterior fossa decompression with duraplasty is one of the popular surgical options for Chiari malformation type I, but its efficacy is controversial and the risk factors of clinical outcome remain unclear.

METHODS

The study cohort included 152 patients with Chiari malformation type I who received small-bone-window posterior fossa decompression at Beijing Tiantan hospital from January 2008 to September 2009. All patients underwent combined surgical procedures: a small-bone-window suboccipital decompression (diameter, 2.5-3 cm) and a C1 laminectomy (1.5- to 2-cm wide) followed by a duraplasty with an autologous graft. Clinical manifestations, radiologic features, and follow-up data during a 6-year span were analyzed. Risk factors associated with outcome were investigated by the use of χ(2) analysis and logistic regression analysis.

RESULTS

The average follow-up duration was 74 months. Symptoms were improved in 126 patients (82.9%), remained stable in 21 patients (13.8%), and deteriorated in 5 patients (3.3%). There was no mortality. Postoperative magnetic resonance imaging scans were available for all patients. Preoperatively, 112 patients were associated with syringomyelia, and the follow-up magnetic resonance images showed obvious reduction of syringomyelia in 73 patients (65.2%) and no significant change in 39 patients (34.8%). In addition, enlargement of the cistern magna was observed in 92 patients (85.2%). Regression analysis indicates preoperative motor dysfunction, brainstem herniation and basilar invagination may influence the clinical outcome (P < 0.05).

CONCLUSIONS

Small-bone-window posterior fossa decompression with duraplasty is an effective and safe treatment option with a low complication rate. Motor dysfunction, brainstem herniation, and basilar invagination are predictors of poor clinical prognosis.

Pediatric and adult Chiari malformation Type I surgical series 1965-2013: a review of demographics, operative treatment, and outcomes

OBJECT

Chiari malformation Type I (CM-I) is a hindbrain disorder associated with elongation of the cerebellar tonsils, which descend below the foramen magnum into the spinal canal. It occurs in children and adults. Clinical symptoms mainly develop from alterations in CSF flow at the foramen magnum and the common subsequent development of syringomyelia.

METHODS

The authors reviewed English-language reports of pediatric, adult, and combined (adult and pediatric) surgical series of patients with CM-I published from 1965 through August 31, 2013, to investigate the following: 1) geographical distribution of reports; 2) demographics of patients; 3) follow-up lengths; 4) study durations; 5) spectrum and frequency of surgical techniques; 6) outcomes for neurological status, syrinx, and headache; 7) frequency and scope of complications; 8) mortality rates; and 9) differences between pediatric and adult populations. Research and inclusion criteria were defined, and all series that contained at least 4 cases and all publications with sufficient data for analysis were included.

RESULTS

The authors identified 145 operative series of patients with CM-I, primarily from the United States and Europe, and divided patient ages into 1 of 3 categories: adult (>18 years of age; 27% of the cases), pediatric (≤18 years of age; 30%), or unknown (43%). Most series (76%) were published in the previous 21 years. The median number of patients in the series was 31. The mean duration of the studies was 10 years, and the mean follow-up time was 43 months. The peak ages of presentation in the pediatric studies were 8 years, followed by 9 years, and in the adult series, 41 years, followed by 46 years. The incidence of syringomyelia was 65%. Most of the studies (99%) reported the use of posterior fossa/foramen magnum decompression. In 92%, the dura was opened, and in 65% of these cases, the arachnoid was opened and dissected; tonsillar resection was performed in 27% of these patients. Postoperatively, syringomyelia improved or resolved in 78% of the patients. Most series (80%) reported postoperative neurological outcomes as follows: 75% improved, 17% showed no change, and 9% experienced worsening. Postoperative headaches improved or resolved in 81% of the patients, with a statistical difference in favor of the pediatric series. Postoperative complications were reported for 41% of the series, most commonly with CSF leak, pseudomeningocele, aseptic meningitis, wound infection, meningitis, and neurological deficit, with a mean complication rate of 4.5%. Complications were reported for 37% of pediatric, 20% of adult, and 43% of combined series. Mortality was reported for 11% of the series. No difference in mortality rates was seen between the pediatric and adult series.

CONCLUSIONS

Before undergoing surgical treatment for CM-I, symptomatic patients and their families should be given clear information about the success of treatment and potential complications. Furthermore, surgeons may benefit from comparing published data with their own. In the future, operative CM-I reports should provide all details of each case for the purpose of comparison.

Tapering of the cervical spinal canal in patients with distended or nondistended syringes secondary to Chiari type I malformation

BACKGROUND AND PURPOSE

Steeper tapering of the cervical spinal canal as documented in recent studies is thought to have a role in the pathophysiology of Chiari malformation-associated syringomyelia. This study aimed to determine whether taper ratio of the cervical spinal canal differs between patients with distended and nondistended syringes.

MATERIALS AND METHODS

Seventy-seven adolescents (10-18 years) were divided into 2 groups: 44 with distended syrinx and 33 with nondistended syrinx. On T2-weighted MR images, anteroposterior diameter of the spinal canal was measured at each cervical level, and a linear trend line was fit by least squares regression to calculate the taper ratio. Taper ratios were compared between the 2 groups and further evaluated with respect to age and sex.

RESULTS

In the nondistended group ND, the taper ratios for C1-C7, C1-C4, and C4-C7 averaged -0.73 ± 0.57, -1.61 ± 0.98, and -0.04 ± 0.54, respectively, all of which were significantly steeper than those observed in the distended group (P = .001, .004, and .033, respectively). Regarding the average diameters plotted by cervical level, the narrowest region of the canal was found to occur at C4 in both groups. In addition, no significant differences in taper ratio were noted between males and females, or between older (>14 years) and younger patients (≤14 years).

CONCLUSIONS

Taper ratios of the cervical spinal canal were found to be different between patients with distended and nondistended syringes, indicating a reciprocal interaction between the syrinx and the cervical spine anatomy.

Asymmetry of tonsillar ectopia, syringomyelia and clinical manifestations in adult Chiari I malformation

BACKGROUND

The asymmetry of tonsillar ectopia, syringomyelia, and clinical manifestations, and their correlations in adult Chiari I malformation (CIM) are seldom discussed.

METHODS

Clinical and imaging data of 104 consecutive adult patients with CIM and syringomyelia were retrospectively reviewed. A method was devised to quantify tonsillar and syrinx asymmetry. Correlations between the asymmetrically displaced cerebellar tonsils, the side of the syrinx, clinical presentations, and the curve direction of scoliosis were investigated.

RESULTS

Tonsillar ectopia was left dominant in 46 patients (44.2 %), right dominant in 49 (47.1 %), and symmetrical in nine (8.7 %). The syrinx was left deviated in 44 patients (42.3 %), right deviated in 48 (46.2 %), and centrally located in 12 (11.5 %). A significant correlation was observed between the side of tonsillar herniation and the side of the syrinx (p < 0.001), and also between the descending ratio of tonsillar herniation and the deviation ratio of the syrinx (p < 0.001). The main side the of clinical presentations showed significant correlation with the dominant side of tonsillar herniation (p = 0.009) and the side of syrinx deviation (p = 0.012). In the 49 patients (47.1 %) with associated scoliosis, the curve direction was significantly related to not only the dominant side of tonsillar ectopia (p = 0.0,28) but also the deviated side of the syrinx (p = 0.044). Moreover, the curve magnitude was significantly correlated with the distance of the tonsillar herniation (p = 0.001).

CONCLUSIONS

In adult CIM, most tonsillar herniations are asymmetrical and most syringomyelia is eccentrical. We speculate that the dominant side of tonsillar herniation determines the side of syrinx deviation, which in turn determines the main side of clinical presentations and the convex side of scoliosis. Our results suggest that the more the descended tonsil tilts to one side, the more the syrinx tilts to the same side.

Relationship of syrinx size and tonsillar descent to spinal deformity in Chiari malformation Type I with associated syringomyelia

OBJECT

Chiari malformation Type I (CM-I) is a developmental abnormality often associated with a spinal syrinx. Patients with syringomyelia are known to have an increased risk of scoliosis, yet the influence of specific radiographically demonstrated features on the prevalence of scoliosis remains unclear. The primary objective of the present study was to investigate the relationship of maximum syrinx diameter and tonsillar descent to the presence of scoliosis in patients with CM-I-associated syringomyelia. A secondary objective was to explore the role of craniovertebral junction (CVJ) characteristics as additional risk factors for scoliosis.

METHODS

The authors conducted a retrospective review of pediatric patients evaluated for CM-I with syringomyelia at a single institution in the period from 2000 to 2012. Syrinx morphology and CVJ parameters were evaluated with MRI, whereas the presence of scoliosis was determined using standard radiographic criteria. Multiple logistic regression was used to analyze radiological features that were independently associated with scoliosis.

RESULTS

Ninety-two patients with CM-I and syringomyelia were identified. The mean age was 10.5 ± 5 years. Thirty-five (38%) of 92 patients had spine deformity; 23 (66%) of these 35 patients were referred primarily for deformity, and 12 (34%) were diagnosed with deformity during workup for other symptoms. Multiple regression analysis revealed maximum syrinx diameter > 6 mm (OR 12.1, 95% CI 3.63-40.57, p < 0.001) and moderate (5-12 mm) rather than severe (> 12 mm) tonsillar herniation (OR 7.64, 95% CI 2.3-25.31, p = 0.001) as significant predictors of spine deformity when controlling for age, sex, and syrinx location.

CONCLUSIONS

The current study further elucidates the association between CM-I and spinal deformity by defining specific radiographic characteristics associated with the presence of scoliosis. Specifically, patients presenting with larger maximum syrinx diameters (> 6 mm) have an increased risk of scoliosis.

Brace treatment versus observation alone for scoliosis associated with Chiari I malformation following posterior fossa decompression: a cohort study of 54 patients

PURPOSE

To be deemed effective in preventing curve progression, brace treatment should show alteration of the expected natural history. Most of the reported studies on the effect of bracing on the evolution of Chiari malformation-associated scoliosis (CMS) following posterior fossa decompression (PFD) were small series with inconclusive results. The goal of this study was to investigate whether post-PFD brace treatment for CMS produces better outcomes than observation alone.

METHODS

The clinical and radiographic data of 21 patients treated with observation alone (Ob group) and 33 patients receiving brace treatment (Br group) were retrospectively reviewed. Evolution of scoliosis was defined as progression of Cobb angle of the primary curve of >5°, as compared with that at brace initiation.

RESULTS

At the latest follow-up, curve progression occurred in 10 (30 %) of Br group and 13 (62 %) of Ob group (P = .022). Overall, 8 (24 %) patients in the Br group and 9 (43 %) in the Ob group underwent further scoliosis surgery (P = .151). When analyses were restricted to the 27 braced and 17 observed patients who had reached skeletal maturity or undergone spinal fusion surgery, decreased curve progression and surgical rates were also observed in the Br group though not reaching statistical significance. Results of the survival analysis, however, demonstrated a significantly increased survival proportion in the Br group (0.63 versus 0.35, P = .014).

CONCLUSIONS

Compared with observation alone, bracing treatment following PFD in patients with CMS was observed to reduce the rates of curve progression and scoliosis surgery. However, patients and their parents should be informed that almost a third of patients still go on to surgery.

[Scoliotic spine deformity in children and adolescents associated with the craniovertebral junction pathology]

This literature review is devoted to the clinical and pathogenic aspects of the relationship between Chiari type I malformation (CMT) and scoliosis. The view of the clinical presentation development in CMT associated with scoliosis is considered on the basis of both the CSF dynamics disturbances and vascular pathology of the craniovertebral junction. The role of the posterior atlanto-occipital membrane is evaluated. Case reports of the risk factors for scoliosis progression in patients with CMT are presented.

Is curve direction correlated with the dominant side of tonsillar ectopia and side of syrinx deviation in patients with single thoracic scoliosis secondary to Chiari malformation and syringomyelia?

STUDY DESIGN

A retrospective imaging study.

OBJECTIVE

To conduct an assessment of the correlation of the coronal asymmetries between tonsillar ectopia, syrinx, and scoliosis.

SUMMARY OF BACKGROUND DATA

A few reports have shown that the convex side of scoliosis was on the same side as the dominant tonsillar ectopia or syrinx deviation in a majority of patients. However, this issue remains controversial.

METHODS

A retrospective study was conducted on young patients with a single thoracic scoliosis secondary to Chiari malformation type I and syringomyelia. The curve direction, side of the dominant tonsillar ectopia and side of the syrinx deviation were recorded and assessed quantitatively. The correlations between the asymmetrically displaced tonsils, eccentrically located syrinx, and curve convexity were investigated.

RESULTS

A total of 39 patients were included. The concordance between the deviated side of the eccentrically located syrinx and dominant side of the asymmetrically displaced tonsils was 87.0%. In 88.5% of the patients with an asymmetrically displaced tonsil, the convex side of the scoliosis was concordant with the dominant side of the tonsillar ectopia, and in 86.2% of patients with an eccentrically located syrinx, the convex side of the scoliosis was on the same side as the deviated side of the syrinx. In addition, the dominant tonsillar ectopia, syrinx deviation, and curve direction were all on the same side in 82.6% patients with asymmetrically displaced tonsils and eccentrically located syrinx.

CONCLUSION

Asymmetrically displaced tonsils and eccentrically located syrinxes were common imaging features in these patients. The thoracic spine tended to be convex to not only the dominant side of the asymmetrically displaced tonsil, but also the deviated side of the eccentrically located syrinx. The effect of syrinx deviation on curve convexity is similar to that of dominant tonsillar ectopia in the majority of 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.

Syrinx resolution after posterior fossa decompression in patients with scoliosis secondary to Chiari malformation type I

INTRODUCTION

Description of syrinx resolution after posterior fossa decompression (PFD) in patients with scoliosis secondary to Chiari malformation type I (CMI) and syringomyelia (SM) has been rarely reported in the literature. This study was performed to investigate the outcome of PFD in patients with scoliosis secondary to CMI and to identify potential predictive factors for better outcome after PFD.

MATERIAL AND METHODS

Patients with scoliosis secondary to CMI and SM, who had undergone PFD during the period 2000 through 2009, were recruited. Inclusion criteria were (1) age ≤ 18 years, (2) diagnosis of SM associated with CMI, (3) scoliosis as the first complaint, (4) having undergone preoperative and follow-up magnetic resonance imaging (MRI). Patients with acquired CMI anomalies or who had received syringosubarachnoid shunting were excluded. The maximal S/C ratio and syrinx length were measured to evaluate syrinx resolution after PFD. A 20% decrease in S/C ratio or length at the latest follow-up was defined as a significant radiographic improvement and complete resolution was used to describe the syrinx disappearing after PFD.

RESULTS

44 patients were recruited. Follow-up MRI was conducted for all 44 patients at 6 ± 3 months postoperatively, for 37 patients at 2 years ± 3 months, for 26 patients at 4 years ± 3 months, and for 15 patients at 6 years ± 3 months. 97.7% (43 of 44) of patients showed significant radiographic improvement by MRI. The distance of tonsillar descent (mm) was correlated significantly with the surgical outcome (r = 0.116, P = 0.013). Significant improvement was observed within 6 months postoperatively, with continued slow improvement after that.

CONCLUSION

Syringes showed significant improvement after PFD in most patients with scoliosis secondary to CMI. Resolution generally occurred within 6 months follow-up and continued at a slow rate for several years. In addition, the severity of tonsillar descent is a potential predictor for better improvement after standard PFD.

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.

Long-term outcome after surgery for Chiari I malformation

OBJECTIVE

To examine the long-term effects of suboccipito-cervical decompression on an intention-to-treat basis in patients with Chiari I malformation (CMI).

PATIENTS AND METHODS

Twenty-four consecutive patients, 14 females and 10 males with a median age of 26 years, underwent decompressive surgery for CMI during 1998-2006. All patients were contacted by an independent examiner and asked to complete a questionnaire regarding headache, other neurological symptoms and negative impact of the disease on the daily life before and after surgery. The median follow-up time after surgery was 3.2 years (range 1.7-9.2 years). Twenty-three patients (96%) completed the questionnaire.

RESULTS

On an intention-to-treat basis there was an improvement in headache in 75%, decreased associated neurological symptoms in 88% and less negative impact on daily life in 75% of the 24-operated patients.

CONCLUSIONS

More than three-quarters of the patients still considered their situation improved at long-term follow-up after surgery. These results support surgical intervention in symptomatic Chiari I patients.

Factors contributing improvement of syringomyelia and surgical outcome in type I Chiari malformation

OBJECTIVE

The aim of our study was to compare pre- and postoperative radiologic data of posterior fossa and the improvement of syringomyelia after posterior fossa decompression (PFD) with and without tonsillar management in Chiari type capital I, Ukrainian malformation (CM-I).

MATERIAL AND METHODS

A retrospective analysis was made of all patients who underwent PFD between Oct 1991 and March 2007 for CM-I. Fifty-seven patients treated for CM-I at a single institution were included in the study. Patients were divided into two groups according to the procedures used during their PFD: PFD vs. PFD with tonsillar management. To determine whether the tonsillar management or changes of posterior fossa volume relate with surgical outcome, we measure posterior fossa size and syringomyelia pre- and postoperatively using magnetic resonance imaging.

RESULTS

Forty patients (70.2%) received PFD and 17 patients (29.8%) received PFD with tonsillar management. The length of syringomyelia affected improvement of syringomyelia (alteration rate, A-rate). Clinical symptoms, craniectomy size, syringomyelia type, and the surgeon's specialty did not affect A-rate. Tonsillar management has no significant effect on improvement of syringomyelia. Four patients need repeated surgery due to recurrence.

CONCLUSION

We have shown that tonsillar management do not lead to improve A-rate, and the radiologic changes of posterior fossa volume do not relate with radiologic improvement of syringomyelia. PFD without tonsillar management is sufficient to improve syringomyelia. The longer syrinx, the more A-rate improve in our study. However, a wider craniectomy is unrelated to A-rate. In cases of recurrent patients, we obtained good results with tonsillar management or syringosubarachnoid shunt.

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.

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.

Variations of the position of the cerebellar tonsil in idiopathic scoliotic adolescents with a cobb angle >40 degrees: a magnetic resonance imaging study

STUDY DESIGN

A retrospective study was performed through measurements on MRI images in adolescent idiopathic scoliosis (AIS) patients and age-matched adolescents.

OBJECTIVES

To investigate the position of the cerebellar tonsil in AIS patients with a Cobb angle >40 degrees in comparison with age-matched healthy adolescents and to determine the relationships of the tonsil position with age, sex, curve severity, and curve patterns.

SUMMARY OF BACKGROUND DATA

There have been increasing evidences implying that AIS patients may present with subtle or subclinical neurologic dysfunction and a higher incidence of tonsillar ectopia was documented in AIS patients. However, the tonsil position has not been clearly addressed in AIS patients with a severe curve.

METHODS

According to the method described by Aboulezz et al, measurements of the tonsil position relative to the magnum foramen on magnetic resonance images were performed in 203 AIS patients with a Cobb angle >40 degrees and 86 age-matched healthy adolescents. The inferior displacement of the cerebellar tonsil with an extent within 5 mm was defined as tonsillar ectopia when it located below the magnum foramen. On the basis of measurement results, the incidence of tonsillar ectopia was determined in both AIS and control groups. The associations of tonsillar ectopia with curve severity and curve patterns for AIS patients and the relationships of the tonsil positions with age and gender in all subjects were analyzed.

RESULTS

In AIS patients and healthy controls, the median position of the cerebellar tonsil was 0.8 and 2.9 mm above the magnum foramen, respectively. The incidence of tonsillar ectopia (0-4.8 mm below the magnum foramen) in AIS was found to be significantly higher than healthy adolescents (range 0-1.8 mm vs. 0-4.8 mm below the magnum foramen; ratio 34.5% vs. 5.8%; P < 0.01). No significant correlations were found between the position of the cerebellar tonsil with age or gender in AIS and control subjects. It was shown the position of the cerebellar tonsil was not significantly different among AIS patients with different curve severity. However, it was noted that there was a highest incidence (62.5%) of tonsillar ectopia in atypical scoliotic cases with a double thoracic curve. Additionally, a significantly higher incidence of tonsillar ectopia was found in patients with thoracic or thoracolumbar curves when compared with those with lumbar curves (37.4% vs. 21.6%, P = 0.049).

CONCLUSION

Tonsillar ectopia with the extent >2 mm in AIS patients should be regarded as abnormal. AIS patients had a lower tonsil position and a higher prevalence of tonsillar ectopia than controls, and tonsillar ectopia was found to be associated with curve patterns. It is suggested that a lower position of the cerebellar tonsil might be associated with the etiopathogenesis of AIS and might contribute to subclinical neurologic dysfunction in AIS patients.

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.

Surgical outcomes in adult patients with syringomyelia associated with Chiari malformation Type I: the relationship between scoliosis and neurological findings

Object

The clinical characteristics of pediatric scoliosis associated with syringomyelia have been reported in previous studies, but scoliosis associated with syringomyelia in adults is rarely treated, and there is a paucity of detailed studies. In the present study of adult syringomyelia associated with Chiari malformation Type I, the authors investigated the relationships among the syrinx, scoliosis, and neurological data.

Methods

The population was composed of 27 patients (≥ 20 years of age) who underwent foramen magnum decompression for the treatment of syringomyelia. The patients were divided into two groups: those with scoliosis of 10° or more (Group A) and those without scoliosis (Group B). The authors assessed the length of the syrinx, duration of morbidity, and clinical status before and after surgery based on the Japanese Orthopaedic Association (JOA) Scale.

There were 15 cases in Group A and 12 in Group B. The mean length of the syrinx was 12.8 vertebral bodies (VBs) in Group A and 7.2 VBs in Group B. The mean duration of morbidity was 14.2 years in Group A and 6.8 years in Group B. The mean preoperative JOA score was 10.1 in Group A and 14.4 in Group B, whereas the mean postoperative JOA scores were 11.9 and 15.8, respectively. There were significant differences between Groups A and B in length of the syrinx, duration of morbidity, and pre- and postoperative JOA scores.

Conclusions

In patients with syringomyelia and scoliosis the syringes spanned a greater number of VBs, the duration of morbidity was greater, neurological dysfunction was more severe, and surgical results were poorer. Scoliosis could be a predicting factor of the prognosis in patients with syringomyelia and Chiari malformation Type I.

Scoliosis in children with Chiari I-related syringomyelia

OBJECTIVE

To study the relationship between scoliosis and Chiari I malformation, with reference to the possible role of cranio-vertebral decompression in preventing the need for scoliosis correction.

MATERIAL AND METHODS

Out of a total of 36 patients with symptomatic Chiari I, who underwent primary cranio-vertebral decompression by a single paediatric neurosurgeon with an interest in Chiari malformation between 1998 and 2003, 13 had clinically detected scoliosis. Of these, ten had no other structural spine abnormality, which could influence the natural history of scoliosis and were included in this study.

RESULTS

In all but one patient, syringomyelia improved significantly after cranio-vertebral decompression. Of the ten patients, eight had levoscoliosis (left convexity), all single curves, and two had curves to the right (both double curves). Six patients did not require corrective scoliosis surgery after cranio-vertebral decompression. The mean Cobb angle for those not requiring scoliosis correction was 29 degrees in contrast to a mean of 76 degrees for those requiring correction [p=0.001, one-way analysis of variance (ANOVA)]. The mean age of patients requiring corrective surgery was 158 months against 125 months for those not requiring correction (p=0.084, one-way ANOVA). These findings were confirmed by multivariate analysis, which also confirmed that symptom duration, syrinx length and site were not significant in predicting the need for corrective surgery following cranio-vertebral decompression.

CONCLUSIONS

Cranio-vertebral decompression for Chiari I may prevent the need for corrective scoliosis surgery when performed before the age of ten and below a Cobb angle of 30 degrees.

Conservative treatment of a patient with syringomyelia using chiropractic biophysics protocols

OBJECTIVE

To present a case of a 41-year-old man with syringomyelia and intractable pain and the subsequent reduction of symptoms.

CLINICAL FEATURES

This patient acquired a traumatically induced syrinx in his upper cervical spinal cord after he fell approximately 9 feet and landed on his head, upper back, and neck 9 years before presenting for care. He was diagnosed with a spinal cord cyst (syrinx), located at approximately C2 through C4 after magnetic resonance imaging. In 1995, the patient underwent occipitoatlantal decompression surgery, which improved his symptoms for a short time.

INTERVENTION AND OUTCOMES

The patient was treated using Clinical Biomechanics of Posture protocol. The patient was seen 26 times over the course of 3 weeks. His scale for pain severity decreased 50% and other subjective complaints decreased. His posture improved based upon pretreatment and posttreatment lateral cervical radiographs, showing a change from a 10 degrees lordosis with midcervical kyphosis to a 30 degrees lordosis. One-year follow-up examination showed stable improvement in the cervical lordosis and pain intensity.

CONCLUSION

This case represents a change in subjective and objective measurements after conservative chiropractic care. This case provides an example that structural rehabilitation may have a positive effect on symptoms of a patient with syringomyelia.

Chiari in the family: inheritance of the Chiari I malformation

This report presents three families with Chiari malformation type I that became symptomatic during childhood: a mother and son; a set of monozygotic twins; and two half-siblings and their two maternal cousins. These children presented with various symptoms, including headache, stiff neck, and swallowing difficulty. A review of the relevant literature is presented, with an emphasis on familial examples and proposed inheritance. Less common presentations of Chiari malformation type I are discussed, as well as the possible pathogenesis of Chiari malformation type I and associated syringomyelia.

Evaluation and management of the Chiari malformation type 1 for the primary care pediatrician

Diagnosis and treatment of CMI is undergoing reexamination that includes redefinition of the anatomic Chiari malformation and refinement and redefinition of the clinical syndrome. Children with SMI present with head pain of some kind, a neurologic deficit, or with signs of spinal cord dysfunction from syrinx. Some will present with no clinical syndrome at all. Presence of anatomic Chiari malformation or compelling clinical Chiari syndrome should lead to evaluation by a neurologist or neurosurgeon experienced with the syndromes and their treatment. Treatment options are varied but usually result in resolution of symptoms. When symptoms persist after surgery, management is complex and not uniformly successful, even in the most experienced hands.

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.

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.