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

The morphological discrepancy of neuromuscular junctions between bilateral paraspinal muscles in patients with adolescent idiopathic scoliosis: A quantitative immunofluorescence assay

Introduction

Prior studies suggested that neuromuscular factors might be involved in the pathogenesis of adolescent idiopathic scoliosis (AIS). The neuromuscular junction (NMJ) is the important pivot where the nervous system interacts with muscle fibers, but it has not been well characterized in the paraspinal muscles of AIS. This study aims to perform the quantitative morphological analysis of NMJs from paraspinal muscles of AIS.

Methods

AIS patients who received surgery in our center were prospectively enrolled. Meanwhile, age-matched congenital scoliosis (CS) and non-scoliosis patients were also included as controls. Fresh samples of paraspinal muscles were harvested intraoperatively. NMJs were immunolabeled using different antibodies to reveal pre-synaptic neuronal architecture and post-synaptic motor endplates. A confocal microscope was used to acquire z-stack projections of NMJs images. Then, NMJs images were analyzed on maximum intensity projections using ImageJ software. The morphology of NMJs was quantitatively measured by a standardized 'NMJ-morph' workflow. A total of 21 variables were measured and compared between different groups.

Results

A total of 15 AIS patients, 10 CS patients and 5 normal controls were enrolled initially. For AIS group, NMJs in the convex side of paraspinal muscles demonstrated obviously decreased overlap when compared with the concave side (34.27% ± 8.09% vs. 48.11% ± 10.31%, p = 0.0036). However, no variables showed statistical difference between both sides of paraspinal muscles in CS patients. In contrast with non-scoliosis controls, both sides of paraspinal muscles in AIS patients demonstrated significantly smaller muscle bundle diameters.

Conclusions

This study first elucidated the morphological features of NMJs from paraspinal muscles of AIS patients. The NMJs in the convex side showed smaller overlap for AIS patients, but no difference was found in CS. This proved further evidence that neuromuscular factors might contribute to the mechanisms of AIS and could be considered as a novel potential therapeutic target for the treatment of progressive AIS.

The Role of Neurophysiology in Managing Patients with Chiari Malformations

Chiari malformation type 1 (CM1) includes various congenital anomalies that share ectopia of the cerebellar tonsils lower than the foramen magnum, in some cases associated with syringomyelia or hydrocephalus. CM1 can cause dysfunction of the brainstem, spinal cord, and cranial nerves. This functional alteration of the nervous system can be detected by various modalities of neurophysiological tests, such as brainstem auditory evoked potentials, somatosensory evoked potentials, motor evoked potentials, electromyography and nerve conduction studies of the cranial nerves and spinal roots, as well as brainstem reflexes. The main goal of this study is to review the findings of multimodal neurophysiological examinations in published studies of patients with CM1 and their indication in the diagnosis, treatment, and follow-up of these patients, as well as their utility in intraoperative monitoring.

Scoliosis with Chiari I malformation without associated syringomyelia

PURPOSE

Many patients with presumed idiopathic scoliosis are found to have Chiari I malformation (CM-I) on MRI. The objective of this study is to report on scoliosis progression in CM-I with no syringomyelia.

METHODS

A retrospective review of patients with scoliosis and CM-I was conducted from 1997 to 2015. Patients with syringomyelia and/or non-idiopathic scoliosis were excluded. Clinical and radiographic characteristics were recorded at presentation and latest follow-up. CM-I was defined as the cerebellar tonsil extending 5 mm or more below the foramen magnum on MRI.

RESULTS

Thirty-two patients (72% female) with a mean age of 11 years (range 1-16) at scoliosis diagnosis were included. The average initial curve was 30.3° ± SD 16.3. The mean initial Chiari size was 9.6 mm SD ± 4.0. Fifteen (46.9%) experienced Chiari-related symptoms, and three (9%) patients underwent Posterior Fossa Decompression (PFD) to treat these symptoms. 10 (31%) patients went on to fusion, progressing on average 13.6° (95% CI 1.6-25.6°). No association was detected between decompression and either curve progression or fusion (p = 0.46, 0.60). For those who did not undergo fusion, curve magnitude progressed on average 1.0° (95% CI - 4.0 to 5.9°). There was no association between age, Chiari size, presence of symptoms, initial curve shape, or bracing treatment and fusion.

CONCLUSION

Patients with CM-I and scoliosis may not require surgical treatment, including PFD and fusion. Scoliosis curvature stabilized in the non-surgical population at an average progression of 1.0°. These results suggest that CM-I with no syringomyelia has minimal effect on scoliosis progression.

Distal Adding-on Phenomenon in Scoliosis Secondary to Chiari Malformation Type I: Incidence and Risk Factors

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to investigate the incidence and risk factors for distal adding-on (AO) phenomenon after posterior spinal fusion (PSF) in scoliosis secondary to Chiari malformation type I (CMS) patients with right major thoracic curve.

SUMMARY OF BACKGROUND DATA

Distal AO phenomenon is a common complication observed in adolescent idiopathic scoliosis (AIS), which is significantly associated with unsatisfactory outcomes. However, few studies specifically focused on the incidence and risk factors of distal AO in CMS.

METHODS

Seventy-eight CMS adolescents were included with a minimum of 2-year follow-up after PSF. patients with distal AO at the final follow-up were divided into AO group and those without were No-AO group. The coronal and sagittal parameters were evaluated preoperatively, immediately after surgery, and at the last follow-up. Clinical outcome was analyzed using the Chicago Chiari Outcome Scale (CCOS).

RESULTS

Distal AO was observed in 18 of 78 patients (23.1%). Compared with No-AO group, patients with distal AO had significantly lower Risser sign (P = 0.001), more flexibility of lumbar curve (P = 0.021), higher incidence of lowest instrumented vertebra-last substantially touched vertebra (LIV-LSTV) ≤0 (P = 0.001), smaller postoperative Cobb angle of lumbar curve (P < 0.001), and greater correction rate of lumbar curve (P = 0.001). Logistic regression analysis revealed that low Risser sign (Grade 1-2, odds ratio [OR] = 5.7, P = 0.029) and LIV-LSTV ≤0 (OR = 6.4, P = 0.019) were independent risk factors for distal AO. There was no significant difference of CCOS scores between two groups at the final follow-up (P > 0.05 for all).

CONCLUSION

The incidence of distal AO was 23.1% in CMS patients after PSF. Patients with low Risser sign and LIV-LSTV ≤0 were high risk factors for distal AO.Level of Evidence: 3.

Risk factors of unplanned neurosurgery for scoliotic patients with Chiari malformation type I and syringomyelia after spinal deformity correction

OBJECTIVES

It remains unclear which subgroups of scoliotic patients with CMI and syringomyelia are more likely to undergo unplanned neurosurgery after spinal deformity correction. The purpose of this study is to explore risk factors of unplanned neurosurgery for scoliotic patients with CMI and syringomyelia after spinal deformity correction.

PATIENTS AND METHODS

This cohort consisted of 62 scoliotic patients with CMI and syringomyelia who underwent spinal deformity surgery with a mean follow-up of 4.3 year. 14 of them underwent unplanned neurosurgery (the NN group), and the other 48 patient underwent single spinal correction surgery (the SS group). The radiological parameters were compared between the two groups, and multivariate logistic regression analysis and Kaplan-Meyer survival curves were used to identify potential risk factors of unplanned neurosurgery.

RESULTS

The incidence of unplanned neurosurgery after spinal deformity surgery was 22.28 % (14/62), and delayed headache was the most common reason for unplanned neurosurgery with five patients (36 %) and follow by neck pain with three patients (21 %). Significantly increased tonsil ectopia (9.7 ± 3.8 vs. 6.9 ± 2.9; P = 0.021), syrinx/cord width ratio (0.62±0.11 vs. 0.45±0.13; P＜0.001), and syrinx/cord area ratio (0.45 ± 0.11 vs. 0.26 ± 0.15; P＜0.001) were found in the NN group. While, there were no significant differents in pBC2 line, clivus canal angle, and syrinx length between the two groups. The logistic regression analysis indicated that tonsil ectopia≥10 mm (P = 0.019; OR=6.440; 95 %CI = 1.361 to 30.467) and syrinx/cord area ratio ≥ 0.4 (P = 0.006; OR=7.664; 95 %CI = 1.819 to 32.291) were independent risk factors of unplanned neurosurgery. Kaplan-Meyer survival curves showed cumulative unplanned neurosurgery for patients with tonsil ectopia ≥ 10 mm (P < 0.001) and syrinx/cord area ratio ≥ 0.4 (P = 0.001) after spinal deformity correction.

CONCLUSION

After spinal deformity correction, 78 % of the patients did not require later neurosurgery and those that needed it had a delay of more than nine months. Tonsil ectopia ≥ 10 mm and syrinx/cord area ratio ≥ 0.4 were independent risk factor of unplanned neurosurgery after spinal deformity correction. It is reasonable to perform spinal corrective surgery in patients with minimal symptoms and signs without the need for prior neurosurgical intervention.

Premature satellite cell activation before injury accelerates myogenesis and disrupts neuromuscular junction maturation in regenerating muscle

Satellite cell (SC) activation, mediated by nitric oxide (NO), is essential to myogenic repair, whereas myotube function requires innervation. Semaphorin (Sema) 3A, a neuro-chemorepellent, is thought to regulate axon guidance to neuromuscular junctions (NMJs) during myotube differentiation. We tested whether "premature" SC activation (SC activation before injury) by a NO donor (isosorbide dinitrate) would disrupt early myogenesis and/or NMJs. Adult muscle was examined during regeneration in two models of injury: myotoxic cardiotoxin (CTX) and traumatic crush (CR) (n = 4-5/group). Premature SC activation was confirmed by increased DNA synthesis by SCs immediately in pretreated mice after CTX injury. Myotubes grew faster after CTX than after CR; growth was accelerated by pretreatment. NMJ maturation, classified by silver histochemistry (neurites) and acetylcholinesterase (AchE), and α-bungarotoxin staining (Ach receptors, AchRs) were delayed by pretreatment, consistent with a day 6 rise in the denervation marker γ-AchR. With pretreatment, S100B from terminal Schwann cells (TSCs) increased 10- to 20-fold at days 0 and 10 after CTX and doubled 6 days after CR. Premature SC activation disrupted motoneuritogenesis 8-10 days post-CTX, as pretreatment reduced colocalization of pre- and postsynaptic NMJ features and increased Sema3A-65. Premature SC activation before injury both accelerated myogenic repair and disrupted NMJ remodeling and maturation, possibly by reducing Sema3A neuro-repulsion and altering S100B. This interpretation extends the model of Sema3A-mediated motoneuritogenesis during muscle regeneration. Manipulating the timing and type of Sema3A by brief NO effects on SCs suggests an important role for TSCs and Sema3A-65 processing in axon guidance and NMJ restoration during muscle repair.

Continuous Hypodynamic Change of Cerebrospinal Fluid Flow as A Potential Factor Working for Experimental Scoliotic Formation

Scoliosis is often associated with syringomyelia (SM). As an important role in SM formation, the influence from abnormal cerebrospinal fluid (CSF) flow is still unclear to scoliosis. The aim of this experimental work is to explore the connection between CSF flow and scoliosis through imaging and histological analysis on the basis of a kaolin-induced scoliotic rabbit model. For imaging observation, in 40 kaolin-induced rabbits by C7 spinal cord injection, through pre- and postoperative MRI and radiography, CSF flow and scoliosis formation were detected at consecutive phases. According to the final formation of scoliosis until postoperative week 12, the kaolin-induced rabbits were divided into 2 groups. Through comparing the 2 groups, the relationship between the changes of CSF flow velocity and scoliosis formation were reviewed and analyzed. For histological observation, another 20 kaolin-induced rabbits were used for consecutive histological observations of spinal cord at postoperative 3-day, 2-week, 4-week and 6-week. After kaolin-induction, abnormal spinal coronal curve was observed from postoperative week 6 in the 37 survived rabbits. At postoperative week 12, scoliosis formation was detected in 73.0% kaolin-induced rabbits and the mean Cobb angle was 27.4°. From the comparison between scoliotic and non-scoliotic groups, the difference of the velocities of CSF flow was more obviously from postoperative week 4 to 12, especially after week 6. In the scoliotic group, the peak velocity of CSF flow was diseased gradually following scoliosis formation after induction. Moreover, the decrease of the peak velocities of CSF flow from preoperation to postoperative 12 weeks (ΔVmax), including up-flow (ΔVUmax) and down-flow (ΔVDmax), were positively correlated to the final scoliotic Cobb angle (P < 0.01). Through histological observation at different phases, the distinctive pathological changes of the spinal cord included early inflammatory reaction, adhesion and blockage in the subarachnoid space and the central canal, perivascular space enlargement, central canal expansion, which suggested the CSF flow being blocked by multiple ways after kaolin-induction. In conclusion, experimental scoliosis can be successfully induced by intraspinal kaolin injection. In this model, continuous hypodynamic change of CSF flow was correlated to the formation of scoliosis, which could be an important factor of scoliotic pathogenesis being explored furtherly.

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.

Somatosensory and motor evoked potentials during correction surgery of scoliosis in neurologically asymptomatic Chiari malformation-associated scoliosis: A comparison with idiopathic scoliosis

OBJECTIVES

To analyze the somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) in neurologically asymptomatic Chiari malformation-associated scoliosis (CMS) patients with and without syringomyelia as compared with those in idiopathic scoliosis (IS) ones, and to identify whether the deformities have impacts on the neurophysiological monitoring.

PATIENTS AND METHODS

This study included neurologically asymptomatic CMS patients undergoing posterior correction surgery between January 2010 and January 2016. IS patients were involved as control group and a subgroup of age- and height-matched IS patients were selected. The age, standing height and Cobb angles of main curve were measured. The SEPs latency and amplitude, MEPs amplitude, and the rate of abnormal SEPs pathologic change were compared between CMS and IS patients using independent-sample t-test and Chi-square test.

RESULTS

Sixty CMS patients and 210 IS patients were included. There was no difference between CMS patients and IS or matched IS patients in SEPs latency and amplitude, MEPs amplitude or rate of abnormal SEPs (p > 0.05). Forty-eight CMS patients concurrent with syringomyelia were associated with higher Cobb angle of main curve and lower SEPs amplitude than those without syringomyelia (p < 0.05). No significant difference was found between CMS patients with and without syringomyelia in age, height, SEPs latency, MEPs amplitude or rate of abnormal SEPs (p > 0.05).

CONCLUSION

Neurologically asymptomatic CMS patients showed similar absolute values of neurophysiological monitoring with IS patients. The syringomyelia in CMS indicated more severe curvature and lower SEPs amplitude even after posterior fossa decompression.

The clinical efficacy study of treatment to Chiari malformation type I with syringomyelia under the minimally invasive surgery of resection of Submeningeal cerebellar Tonsillar Herniation and reconstruction of Cisterna magna

Purpose

Discuss the clinical efficacy of treatment to Chiari malformation type I with syringomyelia under the minimally invasive surgery of resection of Submeningeal Cerebellar Tonsillar Herniation and reconstruction of Cisterna magna.

Methods

130 Chiari malformation type I with syringomyelia patients, divided into treatment group, literature group and control group, were collected to be treated under the monitoring of ultrasound in the surgery.

Results

6 months after operation, the lesions were decreased or disappeared, the symptoms were relieved obviously. According to MRI and Mimics 17.0 software, the volumes of Cisterna magna increased distinctly (P < 0.001), the proportions of brain in foramen magnum region were decreased (P < 0.001). Assessed by CCOS scale and Tator methods, the improvement rates of treatment group were 97.7% and 94.6%, the literature group and control group were 82.2% and 77.8%, respectively.

Conclusion

The efficacy of Chiari malformation type I with syringomyelia under the minimally invasive surgery of resection of Submeningeal Cerebellar Tonsillar Herniation and reconstruction of Cisterna magna is remarkable, and the complications are fewer. This surgery emphasizes recovery of tonsil of cerebellum and reconstruction of Cisterna magna and the circulation path of cerebrospinal fluid, which is a safe and efficient treatment.

Surgical treatment for severe and rigid scoliosis: a case-matched study between idiopathic scoliosis and syringomyelia-associated scoliosis

BACKGROUND CONTEXT

Treatment guidelines for severe and rigid syringomyelia-associated scoliosis (SRSMS) are limited. Typically, surgeons apply practice guidelines for severe and rigid idiopathic scoliosis (SRIS) to treat SRSMS. No study has directly compared the results of surgical treatment between patients with SRSMS and those with SRIS.

PURPOSE

The present study was performed to compare the outcomes of surgical correction of SRSMS and SRIS from clinical and radiographic perspectives.

STUDY DESIGN

This is a retrospective, case-matched, single-center, institutional review board-approved study.

PATIENT SAMPLE

A total of 26 patients with SRSMS or SRIS treated by an anterior and posterior vertebral column resection approach or an internal distraction approach were enrolled.

OUTCOME MEASURES

The SRSMS and SRIS groups were compared on the following variables: fusion length, screw number, operation time, estimated blood loss, follow-up duration, different radiological parameters (including main thoracic curve, cranial compensatory curve, caudal compensatory curve, thoracic kyphosis, lumbar lordosis, thoracic apical vertebral translation, coronal balance, and sagittal vertical axis), Scoliosis Research Society (SRS)-22 scores, and complication rate.

METHODS

Thirteen patients with SRSMS were matched with patients with SRIS on curve magnitude, the flexibility of the main curve, surgical procedure, age, and gender. All patients had a minimum of 2 years of follow-up. The radiographic parameters and demographic data from patients were evaluated before surgery, immediately after surgery, and at the latest follow-up.

RESULTS

The case matches were relatively ideal except one pair with the main curve in the opposite direction. There was no significant difference in fusion length, screw number, operation time, estimated blood loss, or follow-up duration between the two groups. No significant differences were found between the two groups in the main curve or caudal compensatory curve before surgery, immediately after the operation, or at the final follow-up. The correction of thoracic apical vertebral translation in the SRIS group was better than that in the SRSMS group. The SRSMS group had a larger preoperative, postoperative, and final follow-up cranial compensatory curve and a lower correction rate than did the SRIS group. There was no significant difference in preoperative coronal balance between the two groups. After surgery, the coronal balance in the SRSMS and SRIS groups averaged 24.4±13.2 mm and 12.1±7.9 mm, respectively, which was significantly different (p=.04). At the most recent follow-up, the coronal balance in the SRSMS group improved to 14.8±12.6 mm, and it was 11.8±8.6 mm in the SRIS group. No significant difference was found between the two groups (p=.56). There was no significant difference in thoracic kyphosis, lumbar lordosis, or sagittal vertical axis before surgery, immediately after the operation, or at the final follow-up. Before surgery and at the final follow-up, the two groups had similar scores on function, pain, self-image, mental health, and satisfaction. There was no significant difference in complication rates between the two groups.

CONCLUSIONS

Typically, surgical correction outcomes are similar in patients with SRSMS and SRIS. Patients with SRIS tended to have a smaller cranial compensatory curve and better correction of the cranial compensatory curve and thoracic apical vertebral translation. Patients with SRSMS tended to have a higher proportion and greater amount of postoperative coronal imbalance, which may be improved during follow-up.

Posterior fossa decompression in Chiari I improves denervation of the paraspinal muscles

OBJECTIVE

To investigate whether posterior fossa decompression (PFD) could improve denervation of the paraspinal muscles in patients with Chiari I malformation (CMI).

BACKGROUND

Paraspinal muscle denervation is one of the essential elements in the pathophysiology of CMI/syringomyelia-related scoliosis. Although PFD has been widely used for managing CMI, whether denervation of the paraspinal muscles may benefit from this neurosurgical procedure remains ambiguous. Bax and Bcl-2 are two regulators of apoptosis that are closely related to the innervation status of skeletal muscles, and denervation is associated with upregulated Bax and downregulated Bcl-2.

METHODS

Thirty-seven patients who underwent PFD and subsequent deformity correction for CMI-associated scoliosis were enrolled. Biopsy specimens were obtained from bilateral erector spinae muscles during both procedures with an average interval of 6.5 months. The biopsy site was located within the spinal innervation region involved by the syrinx and near the level of upper instrumented vertebra. The expression levels of Bax and Bcl-2 as well as histological features of the muscle fibres were examined at the two time points.

RESULTS

After PFD, the mRNA level of antiapoptotic Bcl-2 was elevated by 178% and 260% in the convex and concave muscles, respectively, with a coincident decrease of 69% and 73% for proapoptotic Bax at the corresponding sites (p<0.001). Consistent with the mRNA data, the Bcl-2 protein in the paraspinal muscles was increased by 75% on the convex and by 169% on the concave side following PFD. For Bax protein, decreases of 45% and 52% were detected in the convex and concave muscles, respectively (p<0.001). On average, these changes led to a 60% decrease in the Bax/Bcl-2 ratio, suggesting reduced apoptotic signalling and improved innervation of the paraspinal muscles. Histologically, the specimens demonstrated improvements in denervation-associated changes of the muscle fibres following PFD, with the number of atrophic and necrotic/degenerated fibres decreasing significantly from 6.7 and 8.5 before surgery to 3.2 (p=0.012) and 4.2 (p<0.001) after surgery, respectively.

CONCLUSION

In patients with CMI, treatment with PFD led to a decrease in the Bax/Bcl-2 ratio at both the mRNA and protein levels, indicating an attenuated susceptibility to apoptotic cell death. These data, coupled with the observed improvements in histopathological features of the myofibres, suggest that PFD in Chiari I ameliorates denervation of the paraspinal muscles.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Atrophy, inducible satellite cell activation, and possible denervation of supraspinatus muscle in injured human rotator-cuff muscle

The high frequency of poor outcome and chronic pain after surgical repair of shoulder rotator-cuff injury (RCI) prompted this study to explore the potential to amplify muscle regeneration using nitric oxide (NO)-based treatment. After preoperative magnetic resonance imaging (MRI), biopsies of supraspinatus and ipsilateral deltoid (as a control) were collected during reparative surgery for RCI. Muscle fiber diameter, the pattern of neuromuscular junctions observed with alpha-bungarotoxin staining, and the γ:ε subunit ratio of acetylcholine receptors in Western blots were examined in tandem with experiments to determine the in vitro responsiveness of muscle satellite cells to activation (indicated by uptake of bromodeoxyuridine, BrdU) by the NO-donor drug, isosorbide dinitrate (ISDN). Consistent with MRI findings of supraspinatus atrophy (reduced occupation ratio and tangent sign), fiber diameter was lower in supraspinatus than in deltoid. ISDN induced a significant increase over baseline (up to 1.8-fold), in the proportion of BrdU+ (activated) Pax7+ satellite cells in supraspinatus, but not in deltoid, after 40 h in culture. The novel application of denervation indices revealed a trend for supraspinatus muscle to have a higher γ:ε subunit ratio than deltoid (P = 0.13); this ratio inversely with both occupancy ratio (P < 0.05) and the proportion of clusters at neuromuscular junctions (P = 0.05). Results implicate possible supraspinatus denervation in RCI and suggest NO-donor treatment has potential to promote growth in atrophic supraspinatus muscle after RCI and improve functional outcome.

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.

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.

Changes in CSF flow after one-stage posterior vertebral column resection in scoliosis patients with syringomyelia and Chiari malformation Type I

Object

Phase contrast–cine MRI (PC-cine MRI) studies in patients with syringomyelia and Chiari malformation Type I (CM-I) have demonstrated abnormal CSF flow across the foramen magnum, which can revert to normal after craniocervical decompression with syrinx shrinkage. In order to investigate the mechanisms leading to postoperative syringomyelia shrinkage, the authors studied the hydrodynamic changes of CSF flow in the craniocervical junction and spinal canal in patients with scoliosis associated with syringomyelia after one-stage deformity correction by posterior vertebral column resection.

Methods

Preoperative and postoperative CSF flow dynamics at the levels of the foramen magnum, C-7, T-7 (or apex), and L-1 were assessed by electrocardiogram-synchronized cardiac-gated PC-cine MRI in 8 adolescent patients suffering from severe scoliosis with syringomyelia and CM-I (scoliosis group) and undergoing posterior vertebral column resection. An additional 8 patients with syringomyelia and CM-I without spinal deformity (syrinx group) and 8 healthy volunteers (control group) were also enrolled. Mean values were obtained for the following parameters: the duration of a CSF cycle, the duration of caudad CSF flow (CSF downflow [DF]) and cephalad CSF flow (CSF upflow [UF]), the ratio of DF duration to CSF cycle duration (DF%), and the ratio of UF duration to CSF cycle duration (UF%). The ratio of the stationary phase (SP) duration to CSF cycle duration was calculated (SP%). The maximum downflow velocities (VDmax) and maximum upflow velocities (VUmax) were measured. SPSS (version 14.0) was used for all statistical analysis.

Results

Patients in the scoliosis group underwent one-stage posterior vertebral column resection for deformity correction without suboccipital decompression. The mean preoperative coronal Cobb angle was 102.4° (range 76°–138°). The mean postoperative Cobb angle was 41.7° (range 12°–75°), with an average correction rate of 59.3%. During the follow-up, 1 patient with hypermyotonia experienced a significant decrease of muscle tension and 1 patient with reduced anal sphincter tone manifested recovery. A total of 5 patients demonstrated a significant decrease (> 30%) in syrinx size. With respect to changes in CSF flow dynamics, the syrinx group was characterized by slower and shorter downflow than the control group, and the difference was more significant at the foramen magnum and C-7 levels. In patients with scoliosis, CSF downflow at the foramen magnum level was significantly restricted, and a prolonged stationary phase indicated increased obstruction of CSF flow. After posterior vertebral column resection, the peak velocity of CSF flow at the foramen magnum increased, and the downflow phase duration was markedly prolonged. The parameters showed a return to almost normal CSF dynamics at the craniocervical region, and this improvement was maintained for 6–12 months of follow-up.

Conclusions

There were distinct abnormalities of CSF flow at the craniocervical junction in patients with syringomyelia. Abnormal dynamics of downflow could be aggravated by associated severe spinal deformity and improved by correction via posterior vertebral column resection.

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.

Prediction of Curve Progression After Posterior Fossa Decompression in Pediatric Patients With Scoliosis Secondary to Chiari Malformation

OBJECTIVE

In this retrospective radiographic and clinical study, we analyzed the evolution of scoliosis after posterior fossa decompression (PFD) to determine the predictors of curve progression after PFD in patients with scoliosis secondary to Chiari malformation type I (CM-I) and syringomyelia (SM). Institutional Review Board approval was obtained to conduct the study. Previous studies have shown that PFD can improve the associated scoliosis in some patients with CM-I, and certain clinical factors can predict curve progression after PFD. However, the results were often contradictory.

METHODS

In our study, 54 patients with CM-I who underwent a standard PFD were divided into 2 groups according to the evolution of scoliosis after PFD. One group consisted of "progressors" with curve progression of more than 5° from before PFD to the final follow-up; the other group consisted of "nonprogressors" with curve stabilization or improvement. Clinical and radiographic data were compared between progressors and nonprogressors.

RESULTS

Twenty-five of the patients received brace treatment, and 11 patients underwent spinal fusion. Nineteen patients were identified as progressors, and 35 were nonprogressors. Age, curve type, curve magnitude, and bracing treatment were independent predictors for curve progression after PFD. Both an age ≥ 10.5 years and a Cobb angle ≥ 44.5° were strongly predictive factors for curve progression. Regarding those patients with an indication for bracing, a significant difference (p=.009) was noted in terms of the evolution of scoliosis between patients with and without bracing treatment.

CONCLUSION

PFD had an effect on the regression of scoliosis in 64.8% of the CM-I patients. An age ≥ 10.5 years, a Cobb angle ≥ 44.5°, and double curves were factors that could predict the progression of scoliosis in these patients. Additionally, we advocate that bracing treatment may be effective in some skeletally immature patients.

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.

Rib length asymmetry in thoracic adolescent idiopathic scoliosis: is it primary or secondary?

The development of scoliosis in animal models after inducing asymmetric rib growth suggests the possible role of asymmetric rib growth in the etiopathogenesis of adolescent idiopathic scoliosis (AIS). Asymmetric rib length is well recognized in idiopathic scoliosis; however, whether this rib asymmetry is primary or secondary has not been clearly documented. The objectives of this study were to investigate any rib length asymmetry in patients with AIS and compare those with scoliosis with syringomyelia (SS) with the intention of elucidating any relationship between rib growth and pathogenesis of AIS. Forty-eight AIS and 29 SS with apical vertebrae located between T7 and T9 were recruited. The average age was 13.5 ± 2.3 versus 12.5 ± 3.4 years, and the average Cobb angle of thoracic curve was 43.3° ± 16.4° versus 45.6° ± 22.6° in patients with AIS or SS, respectively. The length of all ribs was measured from the tip of costal head to the end of the same rib by built-in software on spiral computed tomography. At the levels of the apical vertebrae, the vertebrae above and below the apex, the mean discrepancy in rib length (concave minus convex rib) was 7, 4 and 7 mm, respectively, in AIS group (p < 0.01), and 6, 5 and 7 mm in SS group, respectively (p < 0.01). The rib length discrepancy between concave and convex sides was significantly correlated with the magnitude of the Cobb angle of thoracic curve in both AIS and SS groups (p < 0.01). Similar findings of the asymmetry of rib length in both AIS and SS patients pointed strongly to the fact that the rib length asymmetry in apical region is most likely secondary to the scoliosis deformity rather than playing a primary role in the etiopathogenesis.