Craniocervical junction fusions in patients with hindbrain herniation and syringohydromyelia

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.

Risk Factors of Postoperative Cerebrospinal Fluid Leak After Craniovertebral Junction Anomalies Surgery: A Case-Control Study

Objective: To identify potential risk factors for cerebrospinal fluid (CSF) leakage after craniovertebral junction (CVJ) anomaly surgery and to provide a reference for clinical practice.Methods: Sixty-six patients who underwent elective CVJ anomaly surgery during a 6-year period (April 2013 to September 2019) were retrospectively included. Research data were collected from the patients’ medical records and imaging systems. Patients were divided into CSF leak and no CSF leak groups. Univariate tests were performed to identify potential risk factors. For statistically significant variables in the univariate tests, a logistic regression test was used to identify independent risk factors for CSF leakage.Results: The overall prevalence of CSF leakage was 13.64%. Univariate tests showed that a basion-dental interval (BDI) > 10 mm and occipitalized atlas had significant intergroup differences (p < 0.05). Multivariate analysis indicated that a BDI > 10 mm was an independent risk factor for CSF leakage, and patients with CVJ anomalies with a BDI > 10 mm were more likely to have postoperative CSF leaks (odds ratio, 14.67; 95% confidence interval, 1.48–30.88; p = 0.004).Conclusion: It is necessary to maintain vigilance during CVJ anomaly surgery in patients with a preoperative BDI > 10 mm to avoid postoperative CSF leaks.

Cranio-cervical decompression associated with non-instrumented occipito-C2 fusion in children with mucopolysaccharidoses: Report of twenty-one cases

BACKGROUND

Mucopolysaccharidosis (MPS) is a multisystemic storage disorder of glycosaminoglycan deposits. Infiltration of the dura mater and supporting ligaments caused spinal cord compression and consecutive myelopathy, especially at the cranio-cervical junction (CCJ). Craniocervical instability and posterior decompression often raise the problem of fixation in children. The main purpose of this paper was to report the result of an original technique of occipito-cervical arthrodesis using a cranial halo-cast system in pediatric population.

METHODS

We recorded 21 patients with cervical myelopathy. All of them had spinal cord decompression by enlargement of the foramen magnum, C1 laminectomy, and occipito-C2 fusion using corticocancellous bone graft. Only one child has an extended laminectomy from C1 to C3. The occiput-C2 arthrodesis was stabilized by the cranial halo-cast system. This immobilization was performed preoperatively and kept for three months then switched to rigid cervical collar. Clinical assessment, including the Goel grade and mJOA, radiographs and magnetic resonance imaging were performed before surgery. The occipito-cervical arthrodesis was controlled by standard X-rays and CT scan.

RESULTS

According to the type of mucopolysaccharidosis, the patients were divided into MPS type I: n= 3, II: n=7, IV: n=11. The mean age of patients at surgery was 6.76 years. All mucopolysaccharidoses cases required a foramen magnum decompression by craniectomy, C1 laminectomy and occipito-C2 arthrodesis. As major complications, a child had immediate post-operative paraplegia due to spinal cord ischemia. The postoperative follow-up ranged from 1.5 to 4 years, with an average of 3.3 years. The average preoperative mJOA score was 8.9, and it improved to 14 points at the last follow-up.

CONCLUSIONS

Satisfactory fusion and good clinical results were obtained with the 2-stage approach to CCJ anomalies.

Relevance of C1/2 facet configurations and clivus-canal-angles for adult patients with Chiari I malformation with and without basilar invagination

OBJECTIVE

C1/2 facet configurations and clivus-canal angles (CXA) have been proposed as criteria for posterior fusion in Chiari I malformation (CMI).

METHODS

340 adults with CMI without basilar invagination (BI), 111 with CMI with BI and 100 age and sex matched controls were studied using sagittal T2-weighted MRI scans analyzing pre- and postoperative values with their impact on progression-free survival rates.

RESULTS

For CMI without BI, C1/2 facet configurations and CXA were similar to controls (142+11° and 144+10°, respectively) with low rates for posterior C1 displacements (7.1% and 10%, respectively). In CMI with BI, C1 facet displacements were common (54.9%) with lower CXA (120+15°). After foramen magnum decompression (FMD) in CMI without BI (n = 169), 1.8% developed posterior C1 facet displacements without CXA changes and a 97% progression-free survival rate for 10 years. In CMI with BI, patients without ventral compression or instability underwent FMD without fusion (n = 19). 5.3% developed a posterior C1 facet displacement without CXA changes and a 94% progression-free survival rate for 10 years. The remainder of CMI with BI underwent FMD with C1/2 fusion (n = 48). Among these, CXA values increased with 10 year progression-free survival rates of 74% and 93% with and without ventral compression, respectively.

CONCLUSION

For adult CMI without BI, C1/2 facet configurations and CXA are irrelevant. FMD alone provides excellent long-term outcomes. In CMI with BI, anterior C1 facet displacements indicate C1/2 instability. Posterior fusions can be reserved for patients with ventral compression or C1/2 instability.

Efficacy of a Lateral Mass Fusion Device Combined with a Three-Dimensional-Printed Model in the Treatment of Craniovertebral Junction Abnormalities

OBJECTIVE

To investigate the efficacy of a lateral mass fusion device combined with a three-dimensional-printed model in treatment of craniovertebral junction abnormalities.

METHODS

This retrospective study comprised 56 patients with irreducible atlantoaxial dislocation who underwent posterior fixation between January 2016 and December 2019. Patients were divided into 2 groups according to whether or not cages were used-cage group and autograft group. Visual analog scale score, Japanese Orthopaedic Association score, health-related quality of life, American Spinal Injury Association spinal cord injury grade, atlas-dens interval, space available for the cord, cervicomedullary angle, and fusion rate were compared between groups.

RESULTS

Medical follow-up was >1 year. There was no statistical difference between groups in preoperative visual analog scale score, Japanese Orthopaedic Association score, 12-Item Short Form Health Survey score, American Spinal Injury Association grade, atlas-dens interval, space available for the cord, and cervicomedullary angle, and these indexes significantly improved after surgery (P < 0.05). Visual analog scale score and atlas-dens interval were lower in the cage group than in the autograft group (P < 0.05). Japanese Orthopaedic Association score, 12-Item Short Form Health Survey score, space available for the cord, and cervicomedullary angle were significantly higher in the cage group than in the autograft group (P < 0.05). Fusion rate of the cage group 4-6 months after surgery was higher than that of the autograft group (P = 0.068). American Spinal Injury Association grade was significantly higher in the cage group than in the autograft group (P < 0.05).

CONCLUSIONS

During 1-year follow-up, neurological function improvement and atlantoaxial joint reduction were satisfactory. The lateral mass fusion device combined with a three-dimensional printed model may be a clinically useful technique.

Feasibility of occipital condyle screw placement in patients with Chiari malformation type I: a computed tomography-based morphometric study

BACKGROUND

The occipital condyle (OC) screw is an alternative technique for occipitocervical fixation that is especially suitable for revision surgery in patients with Chiari malformation type I (CMI). This study aimed to investigate the feasibility and safety of this technique in patients with CMI.

METHODS

The CT data of 73 CMI patients and 73 healthy controls were retrospectively analyzed. The dimensions of OCs, including length, width, height, sagittal angle, and screw length, were measured in the axial, sagittal, and coronal planes using CT images. The OC available height was measured in the reconstructed oblique parasagittal plane of the trajectory.

RESULTS

The mean length, width, and height of OCs in CMI patients were 17.79 ± 2.31 mm, 11.20 ± 1.28 mm, and 5.87 ± 1.29 mm, respectively. All OC dimensions were significantly smaller in CMI patients compared with healthy controls. The mean screw length and sagittal angle were 19.13 ± 1.97 mm and 33.94° ± 5.43°, respectively. The mean OC available height was 6.36 ± 1.59 mm. According to criteria based on OC available height and width, 52.1% (76/146) of OCs in CMI patients could safely accommodate a 3.5-mm-diameter screw.

CONCLUSIONS

The OC screw is feasible in approximately half of OCs in CMI patients. Careful morphometric analyses and personalized surgical plans are necessary for the success of this operation in CMI patients.

Occipital-Cervical Fusion and Ventral Decompression in the Surgical Management of Chiari-1 Malformation and Syringomyelia: Analysis of Data From the Park-Reeves Syringomyelia Research Consortium

BACKGROUND

Occipital-cervical fusion (OCF) and ventral decompression (VD) may be used in the treatment of pediatric Chiari-1 malformation (CM-1) with syringomyelia (SM) as adjuncts to posterior fossa decompression (PFD) for complex craniovertebral junction pathology.

OBJECTIVE

To examine factors influencing the use of OCF and OCF/VD in a multicenter cohort of pediatric CM-1 and SM subjects treated with PFD.

METHODS

The Park-Reeves Syringomyelia Research Consortium registry was used to examine 637 subjects with cerebellar tonsillar ectopia ≥ 5 mm, syrinx diameter ≥ 3 mm, and at least 1 yr of follow-up after their index PFD. Comparisons were made between subjects who received PFD alone and those with PFD + OCF or PFD + OCF/VD.

RESULTS

All 637 patients underwent PFD, 505 (79.2%) with and 132 (20.8%) without duraplasty. A total of 12 subjects went on to have OCF at some point in their management (PFD + OCF), whereas 4 had OCF and VD (PFD + OCF/VD). Of those with complete data, a history of platybasia (3/10, P = .011), Klippel-Feil (2/10, P = .015), and basilar invagination (3/12, P < .001) were increased within the OCF group, whereas only basilar invagination (1/4, P < .001) was increased in the OCF/VD group. Clivo-axial angle (CXA) was significantly lower for both OCF (128.8 ± 15.3°, P = .008) and OCF/VD (115.0 ± 11.6°, P = .025) groups when compared to PFD-only group (145.3 ± 12.7°). pB-C2 did not differ among groups.

CONCLUSION

Although PFD alone is adequate for treating the vast majority of CM-1/SM patients, OCF or OCF/VD may be occasionally utilized. Cranial base and spine pathologies and CXA may provide insight into the need for OCF and/or OCF/VD.

Prognostic significance of C1-C2 facet malalignment after surgical decompression in adult Chiari malformation type I: a pilot study based on the Chicago Chiari Outcome Scale

OBJECTIVE

The authors assessed the prognostic significance of various clinical and radiographic characteristics, including C1-C2 facet malalignment, in terms of surgical outcomes after foramen magnum decompression of adult Chiari malformation type I.

METHODS

The electronic medical records of 273 symptomatic patients with Chiari malformation type I who were treated with foramen magnum decompression, C1 laminectomy, and duraplasty at Mayo Clinic were retrospectively reviewed. Preoperative and postoperative Neurological Scoring System scores were compared using the Friedman test. Bivariate analysis was conducted to identify the preoperative variables that correlated with the patient Chicago Chiari Outcome Scale (CCOS) scores. Multiple linear regression analysis was subsequently performed using the variables with p < 0.05 on the bivariate analysis to check for independent associations with the outcome measures. Statistical software SPSS version 25.0 was used for the data analysis. Significance was defined as p < 0.05 for all analyses.

RESULTS

Fifty-two adult patients with preoperative clinical and radiological data and a minimum follow-up of 12 months were included. Motor deficits, syrinx, and C1-C2 facet malalignment were found to have significant negative associations with the CCOS score at the 1- to 3-month follow-up (p < 0.05), while at the 9- to 12-month follow-up only swallowing function and C1-C2 facet malalignment were significantly associated with the CCOS score (p < 0.05). Multivariate analysis showed that syrinx presence and C1-C2 facet malalignment were independently associated with the CCOS score at the 1- to 3-month follow-up. Swallowing function and C1-C2 facet malalignment were found to be independently associated with the CCOS score at the 9- to 12-month follow-up.

CONCLUSIONS

The observed results in this pilot study suggest a significant negative correlation between C1-C2 facet malalignment and clinical outcomes evaluated by the CCOS score at 1-3 months and 9-12 months postoperatively. Prospective studies are needed to further validate the prognostic value of C1-C2 facet malalignment and the potential role of atlantoaxial fixation as part of the treatment.

Posterior atlantoaxial facet joint reduction, fixation and fusion as revision surgery for failed suboccipital decompression in patients with basilar invagination and atlantoaxial dislocation: Operative nuances, challenges and outcomes

OBJECTIVE

To report the technical nuances and clinical outcomes of posterior atlantoaxial facet joint reduction, fixation and fusion (AFRF) technique as a revision procedure for BI and AAD patients with failed suboccipital decompression and large occipital bone defect.

PATIENTS AND METHODS

We reviewed 32 patients with BI and AAD who were misdiagnosed as a simple Chiari malformation and received a suboccipital decompression surgery before admission. All patients underwent AFRF as a revision surgery. The separating, fusing, opacifying and false-coloring-volume rendering (SFOF-VR) technique was used to identify the course of the VA. Clinical and radiological outcomes were assessed after revision surgeries.

RESULTS

Clinical symptoms improved in all patients. The postoperative atlantodens interval, Wackenheim line and clivus-canal angle significantly improved (all P < 0.01). Intraoperative dural tear and cerebrospinal fluid leakage occurred in 3 patients and were managed by suture repair and lumbar drain. Abnormal VA was identified in 7 patients and no VA injury occurred with the aid of SFOF-VR technique. The average follow-up was 19.1 months and atlantoaxial bone fusion was confirmed in 31 patients.

CONCLUSION

For BI and AAD patients with failed suboccipital decompression, revision surgery is challenging. Occipitocervical fixation and posterior midline bone grafting are rather difficult due to the large occipital bone defect. The current study demonstrated that the posterior AFRF is a simple, safe and highly effective technique in revision surgery for such cases. For VA variations, the SFOF-VR technique is an effective tool to delineate the course VA.

Chiari malformation type I and basilar invagination originating from atlantoaxial instability: a literature review and critical analysis

Introduction

Recently, a novel hypothesis has been proposed concerning the origin of craniovertebral junction (CVJ) abnormalities. Commonly found in patients with these entities, atlantoaxial instability has been suspected to cause both Chiari malformation type I and basilar invagination, which renders the tried and tested surgical decompression strategy ineffective. In turn, C1-2 fusion is proposed as a single solution for all CVJ abnormalities, and a revised definition of atlantoaxial instability sees patients both with and without radiographic evidence of instability undergo fusion, instead relying on the intraoperative assessment of the atlantoaxial joints to confirm instability.

Methods

The authors conducted a comprehensive narrative review of literature and evidence covering this recently emerged hypothesis. The proposed pathomechanisms are discussed and contextualized with published literature.

Conclusion

The existing evidence is evaluated for supporting or opposing sole posterior C1-2 fusion in patients with CVJ abnormalities and compared with reported outcomes for conventional surgical strategies such as posterior fossa decompression, occipitocervical fusion, and anterior decompression. At present, there is insufficient evidence supporting the hypothesis of atlantoaxial instability being the common progenitor for CVJ abnormalities. Abolishing tried and tested surgical procedures in favor of a single universal approach would thus be unwarranted.

Chiari 1 Formation Redefined-Clinical and Radiographic Observations in 388 Surgically Treated Patients

OBJECTIVE

The subject of Chiari formation is revisited and redefined. Results of surgical treatment of patients with Chiari formation by atlantoaxial fixation are presented.

METHODS

Results were analyzed of 388 patients with Chiari formation surgically treated during 2010 to June 2019.

RESULTS

Two hundred and sixty-six patients had syringomyelia. Two hundred and three patients had no craniovertebral bone abnormality and 74 patients had group A and 111 patients had group B basilar invagination. Twenty-nine patients had been earlier treated by foramen magnum decompression surgery with or without duroplasty. Clinical parameters, analysis of video recordings both before and after surgery, and patient self-assessment were included in the analysis of outcome. Immediate postoperative and sustained clinical improvement was observed in 385 patients (99.4%).

CONCLUSIONS

Satisfactory clinical outcome in most patients after atlantoaxial fixation and without any manipulation of neural structures, dura, or bone in the region of foramen magnum consolidates the viewpoint that atlantoaxial instability is the nodal point of pathogenesis of Chiari 1 formation. The study suggests that Chiari 1 formation may be a secondary natural neural alteration in the face of atlantoaxial instability. The role of foramen magnum decompression surgery needs to be reassessed.

A Novel Instrumentation Approach in a Pediatric Patient with Atlanto-Occipital Dislocation and Cervical Fracture: Case Report

BACKGROUND

Although instrumented stabilization of pediatric atlanto-occipital dislocation (AOD) has been described in the literature, there is little evidence regarding instrumentation techniques in pediatric patients presenting with both AOD and a cervical fracture. We present a case of a 2-year-old male involved in a motor vehicle collision with an unstable C2 fracture and AOD, treated with an occiput-C4 posterior arthrodesis using a rod, crosslink, and cable construct.

CASE DESCRIPTION

This patient suffered a type III C2 fracture and AOD with 4 mm craniocaudal and 3 mm anterior displacement. In the operating room, 2 cobalt chrome connecting rods (3.5 mm) were connected to 1 another with crosslinks at C2 and C4. These were affixed with suboccipital and sublaminar cables at C1, C2, and C4. At 14 months postoperatively, his spine is clinically and radiographically stable. He has spontaneous movement in all 4 extremities, and remains in a persistent vegetative state because of his underlying central nervous system injury.

CONCLUSIONS

Although there is a breadth of literature investigating instrumentation approaches to pediatric AOD, there is minimal evidence on outcomes of patients presenting with both AOD and cervical fracture. The technique we describe has proven safe and effective for this patient.

Chiari malformation and syringomyelia

Chiari malformation was first described over a century ago, and consists of posterior fossa anomalies that generally share the feature of cerebellar tonsillar descent through the foramen magnum. Our understanding of this disorder was initially based on autopsy studies, and has been greatly enhanced by the advent of MRI. The surgical management of Chiari anomalies has also evolved in a parallel fashion. Although the exact surgical technique varies among individual surgeons, the goals of surgery remain constant and consist of relieving brainstem compression and cranial nerve distortion, restoring the normal flow of CSF across the foramen magnum, and reducing the size of any associated syrinx cavity. Syrinx cavities are most commonly associated with Chiari anomalies, yet primary spinal syringomyelia (PSS) can be caused by traumatic, infectious, degenerative, and other etiologies that cause at least a partial CSF flow obstruction in the spinal subarachnoid space. As with syringomyelia associated with Chiari anomalies, the main goal of PSS surgery is to reestablish CSF flow across the area of obstruction. In addition to MRI, myelography with CT can be very helpful in the evaluation and management of these patients by identifying focal regions of CSF obstruction that may be amenable to surgical intervention. Future directions for the treatment of Chiari anomalies and syringomyelia include the application of advanced imaging techniques, more widespread use of genetic evaluation, large-scale outcome studies, and the further refinement of surgical technique.

Chiari malformation and atlantoaxial instability: problems of co-existence

BACKGROUND

Association of Chiari malformation and atlantoaxial subluxation varies. There is a complex relationship between the two, bony and soft tissue pathologies.

METHODS

This is a review of various articles available from the literature on the management of Chiari and its association with atlantoaxial instability.

RESULTS

We have an experience of operating on 86 cases of paediatric atlantoaxial subluxation, of which 12 had Chiari malformation diagnosed preoperatively (13.95%). Of the 76 children with Chiari malformations operated on by us, 11 had associated atlantoaxial subluxation diagnosed on imaging (14.47%).

CONCLUSIONS

Re-alignment and reduction with fixation may be effective in achieving decompression in cases where reduction is possible from posterior approach. In these cases, posterior fixation is all that is required. If reduction is not possible from posterior and there is "fixed" ventral compression, anterior decompression needs to be combined with posterior fixation. In most cases, direct posterior decompression is warranted.

Craniometric Analysis of Skullbase With Magnetic Resonance Imaging in Patients With Chiari Malformation

Basilar invagination, Platibasi, increased tentorium angle, and posterior fossa hypoplasia are the anomalies associated with Chiari malformation. When Chiari is symptomatic; tonsillary ectopenia appears to be a definitive criterion for diagnosis and treatment, the detection of additional anomaly may alter the surgical outcome. The aim of this study is to investigate the relationship between tonsillar ectopia and other anomalies.The authors retrospectively reviewed 31 cases which had Chiari Malformation at our Hospital. There were 8 men (25.8%) and 23 female (74.2%). Average age of the samples is 37.93 ± 12.93 years. Seventeen patients (54.8%) had tonsillar ectopia 0 to 5 mm, 14 patients had tonsillar ectopia over 5 mm. Seven patients had syrinx (22.6%), 2 patients had mild hydrocephalus (6.5%). Six patients had surgery for the treatment. The mean length of the clivus was 39.3 mm, supraoksiput length was 40.4 mm, cerebellar hemisphere length was 61.08 mm, Mc Rae line was 33.14 mm, Twinning Line was 79.4mm, and Tentorium-Twinning line angle was 40.35°. There was no significant difference between Tonsillar ectopia, syrinks, and hydrocephalus. Basilar invagination had relationship between platibasi (6 patients had platibasi according to 2 mm criteria, 2 patients had platibasi according to 5 mm criteria (P < 0.05). Patients with syrinx had relationship between Chamberlain line (P < 0.05).In the authors' study, although there was no statistically significant difference between the tonsillary ectopia and the criteria of these anomalies, the relationship between basilar invagination and platibasi was significant.

Secondary sacral tethered cord syndrome after treatment of secondary cervical syringomyelia

A female patient operated at the age of 11 on a pilocytic astrocytoma in the posterior fossa, was re-operated for a recurrence 9 years later. A Torkildsen drain was placed in the 4th ventricle and she remained asymptomatic for 15 years before presenting again with acute hydrocephalus, tonsillar herniation, and a massive cervicothoracic syrinx. The symptoms retreated following craniocervical untethering and decompression. Two weeks later, however, she suffered from debilitating radiculopathy provoked by tethering of the cauda equina. Again, symptoms retreated completely after microsurgical intervention. This combination of a secondary Chiari-like malformation with cervical syringomyelia and tethering of the cauda equina in a single patient as a delayed complication of posterior fossa surgery has not been reported before. Diagnosis and treatment of lower tethered cord syndrome may be obscured and delayed in complex clinical situations. In particular, awareness to symptoms that are not related to syringomyelia is important in patients with a known syrinx and a history of posterior fossa surgery.

Chiari I Malformation and Basilar Invagination in Fibrous Dysplasia: Prevalence, Mechanisms, and Clinical Implications

Fibrous dysplasia (FD) is a mosaic disorder of benign fibro-osseous lesions, which may be associated with extraskeletal features as part of McCune-Albright syndrome (MAS). Cranial base abnormalities, including Chiari I malformation (CM1), in which the cerebellum extends below the foramen magnum, and secondary basilar invagination (BI), in which the odontoid prolapses into the posterior cranial fossa, are potentially serious complications of metabolic bone disorders. The purpose of this study was to determine the prevalence, natural history, and risk factors for CM1 and BI in patients with FD/MAS, and to determine mechanisms of cranial base deformities. Clinical and radiographic data from subjects in an FD/MAS natural history study were evaluated and compared to normal controls. In 158 patients with craniofacial FD, 10 (6.3%) cases of CM1 and 12 (7.6%) cases of BI were diagnosed. No cranial base abnormalities were identified in 10 control subjects. Craniomorphometric and volumetric analyses identified cranial constriction and cranial settling as the primary mechanisms of cranial base abnormalities, whereas intracranial hypertension was a contributing factor in a minority of subjects. Longitudinal analyses found progression of odontoid position with age, but no progression of tonsillar position. No endocrinopathies were associated with CM1. MAS endocrinopathies associated with BI included hyperthyroidism (odds ratio [OR] 12.0; 95% confidence interval [CI], 2.9 to 55.6; p < 0.01), precocious puberty (OR 5.6; 95% CI, 1.2 to 26.0; p < 0.05), and hypophosphatemia (OR 7.7; 95% CI, 1.9 to 27.0; p < 0.01). Scoliosis was associated with both CM1 (OR 4.8; 95% CI, 1.1 to 22.8; p < 0.05) and BI (OR = infinity; 95% CI, 4.7 to infinity; p < 0.01). This study successfully characterized cranial base abnormalities in FD/MAS and the pathophysiological connection between them. These findings support routine screening for cranial base abnormalities in patients with craniofacial FD, as well as aggressive management of contributory risk factors. © 2018 American Society for Bone and Mineral Research.

Evaluation of Soft Tissue Hypertrophy at the Retro-Odontoid Space in Patients with Chiari Malformation Type I on Magnetic Resonance Imaging

INTRODUCTION

Chiari malformation type I (CM-I) is a well-known hindbrain disorder in which the cerebellar tonsils protrude through the foramen magnum. The soft tissues, including the transverse ligament and the tectorial membrane at the retro-odontoid space, can compress the cervicomedullary junction if they become hypertrophic.

METHODS

Twenty-two symptomatic patients with CM-I (aged 5-19 years) were treated between 2007 and 2017 at our institute. The retro-odontoid soft tissue was evaluated using T2-weighted magnetic resonance imaging. Anteroposterior (AP) distances and craniocaudal distances of the soft tissue were measured in patients with CM-I and 48 normal control children. Modified clivoaxial angles were also evaluated as the index of ventral compression of the cervicomedullary junction.

RESULTS

Of the 18 patients treated with foramen magnum decompression, 16 patients improved postoperatively, whereas the condition of 2 remained unchanged. The AP distances in the CM-I group (6.0 mm) were significantly larger than those in the control group (3.5 mm), whereas there were no apparent differences in the craniocaudal distances. Modified clivoaxial angles were obviously smaller in the CM-I group (131.5°) than in the control group (146.9°). Moreover, the AP distances were significantly reduced postoperatively (5.5 mm), although the other parameters did not change significantly.

CONCLUSIONS

The retro-odontoid soft tissue in symptomatic patients with CM-I can be hypertrophic enough to compress the cervicomedullary junction ventrally even if there are no combined osseous anomalies. Foramen magnum decompression works to reduce the hypertrophic changes significantly, suggesting that downward tonsil movement might participate in hypertrophic soft tissue formation at the retro-odontoid space.

Role of dynamic computed tomography scans in patients with congenital craniovertebral junction malformations

AIM

To evaluate the role of dynamic computed tomography (CT) scan imaging in diagnosing craniovertebral junction (CVJ) instability in patients with congenital CVJ malformations.

METHODS

Patients with symptomatic congenital CVJ malformations who underwent posterior fossa decompression and had a preoperative dynamic CT scan in flexion and extended position were included in this study. Measurements of the following craniometrical parameters were taken in flexed and extended neck position: Atlanto-dental interval (ADI), distance of the odontoid tip to the Chamberlain’s line, and the clivus-canal angle (CCA). Assessment of the facet joints congruence was also performed in both positions. Comparison of the values obtained in flexion and extension were compared using a paired Student’s t-test.

RESULTS

A total of ten patients with a mean age of 37.9 years were included. In flexion imaging, the mean ADI was 1.76 mm, the mean CCA was 125.4° and the mean distance of the odontoid tip to the Chamberlain’s line was + 9.62 mm. In extension, the mean ADI was 1.46 mm (P = 0.29), the mean CCA was 142.2° (P < 0.01) and the mean distance of the odontoid tip to the Chamberlain’s line was + 7.11 mm (P < 0.05). Four patients (40%) had facetary subluxation demonstrated in dynamic imaging, two of them with mobile subluxation (both underwent CVJ fixation). The other two patients with a fixed subluxation were not initially fixed. One patient with atlantoaxial assimilation and C23 fusion without initial facet subluxation developed a latter CVJ instability diagnosed with a dynamic CT scan. Patients with basilar invagination had a lower CCA variation compared to the whole group.

CONCLUSION

Craniometrical parameters, as well as the visualization of the facets location, may change significantly according to the neck position. Dynamic imaging can provide additional useful information to the diagnosis of CVJ instability. Future studies addressing the relationship between craniometrical changes and neck position are necessary.

Trends in surgical treatment of Chiari malformation Type I in the United States

OBJECTIVE The goal of this analysis was to define temporal and geographic trends in the surgical treatment of Chiari malformation Type I (CM-I) in a large, privately insured health care network. METHODS The authors examined de-identified insurance claims data from a large, privately insured health care network of over 58 million beneficiaries throughout the United States for the period between 2001 and 2014 for all patients undergoing surgical treatment of CM-I. Using a combination of International Classification of Diseases (ICD) diagnosis codes and Current Procedural Terminology (CPT) codes, the authors identified CM-I and associated diagnoses and procedures over a 14-year period, highlighting temporal and geographic trends in the performance of CM-I decompression (CMD) surgery as well as commonly associated procedures. RESULTS There were 2434 surgical procedures performed for CMD among the beneficiaries during the 14-year interval; 34% were performed in patients younger than 20 years of age. The rate of CMD increased 51% from the first half to the second half of the study period among younger patients (p < 0.001) and increased 28% among adult patients between 20 and 65 years of age (p < 0.001). A large sex difference was noted among adult patients; 78% of adult patients undergoing CMD were female compared with only 53% of the children. Pediatric patients undergoing CMD were more likely to be white with a higher household net worth. Regional variability was identified among rates of CMD as well. The average annual rate of surgery ranged from 0.8 surgeries per 100,000 insured person-years in the Pacific census division to 2.0 surgeries per 100,000 insured person-years in the East South Central census division. CONCLUSIONS Analysis of a large nationwide health care network showed recently increasing rates of CMD in children and adults over the past 14 years.

Occipitocervical Fixation

BACKGROUND

Occipitocervical junction instability can lead to serious neurological injury or death. Open surgical fixation is often necessary to provide definitive stabilization. However, long-term results are limited to small case series.

OBJECTIVE

To review the causes of occipitocervical instability, discuss the indications for surgical intervention, and evaluate long-term surgical outcomes after occipitocervical fixation.

METHODS

The charts of all patients undergoing posterior surgical fixation of the occipitocervical junction by the senior author were retrospectively reviewed. A total of 120 consecutive patients were identified for analysis. Patient demographic characteristics, occipitocervical junction pathology, surgical indications, and clinical and radiographic outcomes are reported.

RESULTS

The study population consisted of 64 male and 56 female patients with a mean age of 39.9 years (range, 7 months to 88 years). Trauma was the most common cause of instability, occurring in 56 patients (47%). Ninety patients (75%) were treated with screw/rod constructs; wiring was used in 30 patients (25%). The median number of fixated segments was 5 (O-C4). Structural bone grafts were implanted in all patients (100%). Preoperative neurological deficits were present in 83 patients (69%); 91% of those patients improved with surgery. Mean follow-up was 35.1 ± 27.4 months (range, 0-123 months). Two patients died, and 10 were lost to follow-up before the end of the 6-month follow-up period. Fusion was confirmed in 107 patients (89.1%). The overall complication rate was 10%, including 3 patients with vertebral artery injuries and 2 patients who required revision surgery.

CONCLUSION

Occipitocervical fixation is a durable treatment option with acceptable morbidity for patients with occipitocervical instability.

Meta-generalis: A novel method for structuring information from radiology reports

BACKGROUND

A structured report for imaging exams aims at increasing the precision in information retrieval and communication between physicians. However, it is more concise than free text and may limit specialists' descriptions of important findings not covered by pre-defined structures. A computational ontological structure derived from free texts designed by specialists may be a solution for this problem. Therefore, the goal of our study was to develop a methodology for structuring information in radiology reports covering specifications required for the Brazilian Portuguese language, including the terminology to be used.

METHODS

We gathered 1,701 radiological reports of magnetic resonance imaging (MRI) studies of the lumbosacral spine from three different institutions. Techniques of text mining and ontological conceptualization of lexical units extracted were used to structure information. Ten radiologists, specialists in lumbosacral MRI, evaluated the textual superstructure and terminology extracted using an electronic questionnaire.

RESULTS

The established methodology consists of six steps: 1) collection of radiology reports of a specific MRI examination; 2) textual decomposition; 3) normalization of lexical units; 4) identification of textual superstructures; 5) conceptualization of candidate-terms; and 6) evaluation of superstructures and extracted terminology by experts using an electronic questionnaire. Three different textual superstructures were identified, with terminological variations in the names of their textual categories. The number of candidate-terms conceptualized was 4,183, yielding 727 concepts. There were a total of 13,963 relationships between candidate-terms and concepts and 789 relationships among concepts.

CONCLUSIONS

The proposed methodology allowed structuring information in a more intuitive and practical way. Indications of three textual superstructures, extraction of lexicon units and the normalization and ontologically conceptualization were achieved while maintaining references to their respective categories and free text radiology reports.

Clinical significance of changes in pB-C2 distance in patients with Chiari Type I malformations following posterior fossa decompression: a single-institution experience

OBJECT The coexistence of Chiari malformation Type I (CM-I) and ventral brainstem compression (VBSC) has been well documented, but the change in VBSC after posterior fossa decompression (PFD) has undergone little investigation. In this study the authors evaluated VBSC in patients with CM-I and determined the change in VBSC after PFD, correlating changes in VBSC with clinical status and the need for further intervention. METHODS Patients who underwent PFD for CM-I by the senior author from November 2005 to January 2013 with complete radiological records were included in the analysis. The following data were obtained: objective measure of VBSC (pB-C2 distance); relationship of odontoid to Chamberlain's, McGregor's, McRae's, and Wackenheim's lines; clival length; foramen magnum diameter; and basal angle. Statistical analyses were performed using paired t-tests and a mixed-effects ANOVA model. RESULTS Thirty-one patients were included in the analysis. The mean age of the cohort was 10.0 years. There was a small but statistically significant increase in pB-C2 postoperatively (0.5 mm, p < 0.0001, mixed-effects ANOVA). Eleven patients had postoperative pB-C2 values greater than 9 mm. The mean distance from the odontoid tip to Wackenheim's line did not change after PFD, signifying postoperative occipitocervical stability. No patients underwent transoral odontoidectomy or occipitocervical fusion. No patients experienced clinical deterioration after PFD. CONCLUSIONS The increase in pB-C2 in patients undergoing PFD may occur as a result of releasing the posterior vector on the ventral dura, allowing it to relax posteriorly. This increase appears to be well-tolerated, and a postoperative pB-C2 measurement of more than 9 mm in light of stable craniocervical metrics and a nonworsened clinical examination does not warrant further intervention.

Allograft versus autograft for pediatric posterior cervical and occipito-cervical fusion: a systematic review of factors affecting fusion rates

OBJECT Fusion rates are high for children undergoing posterior cervical fusion (PCF) and occipito-cervical fusion (OCF). Autologous bone has been widely used as the graft material of choice, despite the risk of donor-site morbidity associated with harvesting the bone, possibly because very low fusion rates were reported with posterior allograft cervical fusions in children several decades ago. Higher overall fusion rates using allograft in adults, associated with improvements in internal fixation techniques and the availability of osteoinductive substances such as bone morphogenetic protein (BMP), have led to heightened enthusiasm for the use of bank bone during pediatric PCF. A systematic review was performed to study factors associated with successful bone fusion, including the type of bone graft used. METHODS The authors performed a comprehensive PubMed search of English-language articles pertaining to PCF and OCF in patients less than 18 years old. Of the 561 abstracts selected, 148 articles were reviewed, resulting in 60 articles that had sufficient detail to be included in the analysis. A meta-regression analysis was performed to determine if and how age, fusion technique, levels fused, fusion substrate, BMP use, postoperative bracing, and radiographic fusion criteria were related to the pooled prevalence estimates. A systematic review of the literature was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. RESULTS A total of 604 patients met the specific inclusion and exclusion criteria. The overall fusion rate was 93%, with a mean age of 9.3 years and mean follow-up of 38.7 months. A total of 539 patients had fusion with autograft (94% fusion rate) and 65 patients with allograft (80% fusion rate). Multivariate meta-regression analysis showed that higher fusion rates were associated with OCF compared with fusions that excluded the occiput (p < 0.001), with the use of autograft instead of allograft (p < 0.001), and with the use of CT to define fusion instead of plain radiography alone. The type of internal fixation, the use of BMP, patient age, and the duration of follow-up were not found to be associated with fusion rates in the multivariate analysis. CONCLUSIONS Fusion rates for PCF are high, with higher rates of fusion seen when autograft is used as the bone substrate and when the occiput is included in the fusion construct. Further study of the use of allograft as a viable alternative to autograft bone fusion is warranted because limited data are available regarding the use of allograft in combination with more rigid internal fixation techniques and osteoinductive substances, both of which may enhance fusion rates with allograft.

Distraction, Compression, Extension, and Reduction Combined With Joint Remodeling and Extra-articular Distraction: Description of 2 New Modifications for Its Application in Basilar Invagination and Atlantoaxial Dislocation: Prospective Study in 79 Cases

BACKGROUND

Recent strategies for treatment of basilar invagination (BI) and atlantoaxial dislocation (AAD) are based on simultaneous posterior reduction and fixation.

OBJECTIVE

To describe new modifications of the procedure distraction, compression, extension, and reduction (DCER), ie, joint remodeling (JRM) and extra-articular distraction (EAD) in patients with "vertical" joints, and to quantify the improvement in joint indices, ie, sagittal inclination (SI), craniocervical tilt (CCT), and coronal inclination.

METHODS

Prospective study (May 2010 to September 2014). Joint indices measured included (normal values): SI (87.15 ± 5.65°), CCT (60.2 ± 9.2°), and coronal inclination (110.3 ± 4.23°). Surgical procedures included DCER alone (performed in SI <100°, group I) or JRM with DCER (in SI: 100-160°, group II), or EAD with DCER in severe BI with almost vertical joints (SI >160°, group III).

RESULTS

Seventy-nine patients were selected (mean, 22.5 years of age). All conventional indices improved significantly (P < .001). CCT improved in all groups (P < .01); group I (n = 32): 54 ± 8.7° (preoperative 80.71 ± 12.72°); group II (n = 40): 58 ± 7.0° (preoperative 86.5 ± 14°); group III (n = 7): 62 ± 10.0° (preoperative 104 ± 11.2°). SI improved in both group I and II, P < .01 (cannot be measured in group III). At long-term follow-up (n = 64, 29 ± 8 months, range 12-39 months), the Nurick grade improved to 1.5 ± 0.52 (preoperative: 3.4 ± 0.65; P < .001).

CONCLUSION

DCER seems to be an effective technique in reducing both BI and AAD. JRM and EAD with DCER are useful in moderate to severe BI and AAD (with SI >100°). Joint indices provide useful information for surgical strategy and planning.

Complex Chiari Malformations in Children: Diagnosis and Management

This article describes the diagnosis and management of patients with complex Chiari malformations. This group of patients cannot be categorized as a Chiari 1 or 1.5 because the pathology and progression of their disease is unique. The authors discuss how to diagnose and treat patients with complex Chiari malformations, particularly with regard to discerning which patients would benefit from a simple Chiari decompression versus Chiari decompression with occipitocervical fusion.

Craniovertebral Junction Instability in the Setting of Chiari I Malformation

This article addresses the key features, clinical presentation, and radiographic findings associated with craniovertebral junction instability in the setting of Chiari I malformation. It further discusses surgical technique for treating patients with Chiari I malformation with concomitant craniovertebral junction instability, focusing on modern posterior rigid instrumentation and fusion techniques.

Is atlantoaxial instability the cause of Chiari malformation? Outcome analysis of 65 patients treated by atlantoaxial fixation

OBJECT

Understanding that atlantoaxial instability is the cause of Chiari malformation (CM), the author treated 65 patients using atlantoaxial stabilization. The results are analyzed.

METHODS

Cases of CM treated using atlantoaxial fixation during the period from January 2010 to November 2013 were reviewed and analyzed. Surgery was aimed at segmental arthrodesis.

RESULTS

The author treated 65 patients with CM in the defined study period. Fifty-five patients had associated syringomyelia. Forty-six patients had associated basilar invagination. Thirty-seven patients had both basilar invagination and syringomyelia. Three patients had been treated earlier using foramen magnum decompression and duraplasty. According to the extent of their functional capabilities, patients were divided into 5 clinical grades. On the basis of the type of facetal alignment and atlantoaxial instability, the patients were divided into 3 groups. Type I dislocation (17 patients) was anterior atlantoaxial instability wherein the facet of the atlas was dislocated anterior to the facet of the axis. Type II dislocation (31 patients) was posterior atlantoaxial instability wherein the facet of the atlas was dislocated posterior to the facet of the axis. Type III dislocation (17 patients) was the absence of demonstrable facetal malalignment and was labeled as "central" atlantoaxial dislocation. In 18 patients, dynamic images showed vertical, mobile and at-least partially reducible atlantoaxial dislocation. All patients were treated with atlantoaxial plate and screw fixation using techniques described in 1994 and 2004. Foramen magnum decompression or syrinx manipulation was not performed in any patient. Occipital bone and subaxial spinal elements were not included in the fixation construct. One patient died, and death occurred in the immediate postoperative phase and was related to a vertebral artery injury incurred during the operation. One patient had persistent symptoms. In the rest of the patients there was gratifying clinical improvement. More remarkably, in 7 patients, the symptoms of lower cranial nerve paresis improved. No patient worsened in their neurological function after surgery. Reductions in the size of the syrinx and regression of the CM were observed in 6 of 11 cases in which postoperative MRI was possible. During the follow-up period, there was no delayed worsening of neurological function or symptoms in any patient. Sixty-three patients improved after surgery, and the improvement was sustained during the average follow-up period of 18 months.

CONCLUSIONS

On the basis of outcomes in this study, it appears that the pathogenesis of CM with or without associated basilar invagination and/or syringomyelia is primarily related to atlantoaxial instability. The data suggest that the surgical treatment in these cases should be directed toward atlantoaxial stabilization and segmental arthrodesis. Except in cases in which there is assimilation of the atlas, inclusion of the occipital bone is neither indicated nor provides optimum stability. Foramen magnum decompression is not necessary and may be counter-effective in the long run.

Incidence of basilar invagination in patients with tonsillar herniation ? a case control craniometrical study

A retrospective case-control study based on craniometrical evaluation was performed to evaluate the incidence of basilar invagination (BI). Patients with symptomatic tonsillar herniation treated surgically had craniometrical parameters evaluated based on CT scan reconstructions before surgery. BI was diagnosed when the tip of the odontoid trespassed the Chamberlain’s line in three different thresholds found in the literature: 2, 5 or 6.6 mm. In the surgical group (SU), the mean distance of the tip of the odontoid process above the Chamberlain’s line was 12 mm versus 1.2 mm in the control (CO) group (p<0.0001). The number of patients with BI according to the threshold used (2, 5 or 6.6 mm) in the SU group was respectively 19 (95%), 16 (80%) and 15 (75%) and in the CO group it was 15 (37%), 4 (10%) and 2 (5%).

Plasmonic photothermal therapy for atheroregression below Glagov threshold

The advent of nanomedicine allowed for the development and design of tools that enhance detailed diagnosis and target treatment of atherosclerosis. Given the rapid progress in nanoagent synthesis and utility, clinical application of these technologies can be anticipated in the near future. This review article focuses on the development of these technologies in interventional cardiology, with the main goal of achieving atheroregression below a Glagov threshold of 40%. Special attention is given to plasmonic photothermal therapy. Vascular remodeling maintains the lumen dimension as long as the external elastic membrane can accommodate an increase in plaque burden that does not surpass a certain threshold. We propose that this threshold becomes the target for the development of strategies that reverse atherosclerosis, especially for the generation of devices and tools of nanomedicine.

Percutaneous anterior occiput-to-axis screw fixation: technique aspects and case series

BACKGROUND CONTEXT

Posterior occipitocervical fusion techniques have been previously described; however, traditional open anterior approaches are plagued by exposure difficulty. A minimally invasive percutaneous anterior occipitocervical fixation approach avoids this difficult exposure procedure.

PURPOSE

This article describes a novel technique of percutaneous anterior occiput-to-axis screw fixation and its clinical outcomes.

STUDY DESIGN

Technique report.

METHODS

Anteroposterior, lateral and open-mouth views, and computed tomography scans are preoperatively obtained to appraise the feasibility of surgery. We extend our experience of using percutaneous anterior transarticular screw fixation to occiput-to-axis screw fixation. This procedure was performed on six patients.

RESULTS

The operation was successfully performed on all patients without technical difficulties, and no vertebral artery, nerve injury or soft tissue (such as esophageal) complications occurred. All six patients followed up 10 to 39 months (averaged 20.5 months). Bone union was achieved in five patients, and the one patient lacking bone union was stable at final follow-up. The syringomyelia of four patients is almost complete reduction. No screw loosening or breakage has occurred.

CONCLUSIONS

With the correct puncture point, angle of insertion, and use of the appropriate tools, we suggest that percutaneous anterior occiput-to-axis fixation technique is a feasible, safe, and minimally invasive procedure.

Acquired Chiari malformation secondary to atlantoaxial vertical subluxation in a patient with rheumatoid arthritis combined with atlanto-occipital assimilation

A 65-year-old woman with a history of rheumatoid arthritis presented with a rare case of acquired Chiari malformation secondary to atlantoaxial vertical subluxation, associated with congenital atlanto-occipital assimilation. Syringomyelia and tetraparesis improved immediately after posterior fossa decompression and simultaneous occipito-cervical junction fusion. The progression of acquired Chiari malformation is not well known. We concluded that coexisting assimilation accelerated crowded foramen magnum following atlantoaxial vertical subluxation and induced acquired Chiari malformation over the course of a few years.

Distraction, Compression, and Extension Reduction of Basilar Invagination and Atlantoaxial Dislocation

BACKGROUND:

The management of basilar invagination (BI) and atlantoaxial dislocation (AAD) is a challenge.

OBJECTIVE:

To describe a new innovative method to reduce BI and AAD through a single-stage posterior approach.

METHODS:

Thirty-five patients had irreducible BI and AAD (May 2010 to April 2012). In all patients, reduction of AAD and BI was achieved by using an innovative method of distraction and spacer placement, followed by compression and extension. A C1 lateral mass/C2 translaminar screw was performed in cases where the C1 arch was not assimilated, and occipito-C2 translaminar screw fixation was performed in cases where the C1 arch was assimilated.

RESULTS:

Thirty-two of 35 (94%) patients improved clinically and 2 patients had stable symptoms (mean Nurick postoperative score = 1.4; preoperative score = 3.7). AAD reduced completely in 33/35 patients and &gt;50% in 2. BI improved significantly in all patients. Solid bone fusion was demonstrated in 24 patients with at least 1-year follow-up (range, 12-39 months; mean, 19.75 + 7.09 months). The duration of surgery was 80 to 190 minutes, and blood loss was 90 to 500 mL (mean, 170 ± 35 mL). There was 1 death because of cardiac etiology and 1 morbidity (wound infection).

CONCLUSION:

Distractive compressive extension and reduction of BI and AAD seems to be an effective and safe method of treatment. It is different from the earlier described techniques, because it is the first procedure that uses a spacer not, only for distraction, but also as a pivot to perform extension to reduce the AAD.

Occipitocervical fusion using a contoured rod and wire construct in children: a reappraisal of a vintage technique

OBJECT

Many methods to stabilize and fuse the craniocervical junction have been described. One of the early designs was a contoured (Luque) rod fixated with wires, the so-called Hartshill-Ransford loop. In this study, the authors report their 20-year experience with this surgical technique in children.

METHODS

The authors reviewed the medical records of patients 18 years of age or younger who underwent dorsal occipitocervical fusion procedures between March 1992 and March 2012 at Le Bonheur Children's Hospital using a contoured rod and wire construct. Data on basic patient characteristics, causes of instability, neurological function at presentation and at last follow-up, details of surgery, complications, and radiographic outcome were collected.

RESULTS

Twenty patients (11 male) were identified, with a mean age of 5.5 years (range 1-18 years) and a median follow-up of 43.5 months. Fourteen patients had atlantooccipital dislocation, 2 patients had atlantoaxial fracture-dissociations, 2 had Down syndrome with occipitocervical and atlantoaxial instability, 1 had an epithelioid sarcoma from the clivus to C-2, and 1 had an anomalous atlas with resultant occipitocervical instability. Surgical stabilization extended from the occiput to C-1 in 3 patients, C-2 in 6, C-3 in 8, and to C-4 in 3. Bone morphogenetic protein was used in 2 patients. Two patients were placed in a halo orthosis; the rest were kept in a hard collar for 6-8 weeks. All patients were neurologically stable after surgery. One patient with a dural tear experienced wound dehiscence with CSF leakage and required reoperation. Eighteen patients went on to achieve fusion within 6 months of surgery; 1 patient was initially lost to follow-up, but recent imaging demonstrated a solid fusion. There were no early hardware or bone failures requiring hardware removal, but radiographs obtained 8 years after surgery showed that 1 patient had an asymptomatic fractured rod. There were no instances of symptomatic junctional degeneration, and no patient was found to have increasing lordosis over the fused segments. Five (31%) of the 16 trauma patients required a shunt for hydrocephalus.

CONCLUSIONS

Despite the proliferation of screw-fixation techniques for craniocervical instability in children, the contoured rod-wire construct remains an effective, less expensive, and technically easier alternative that has been in use for almost 30 years. It confers immediate stability, and therefore most patients will not need to be placed in a halo device postoperatively. A secondary observation in our series was the high (30%) rate of hydrocephalus requiring a shunt in patients with traumatic instability.

Plasmonic photothermic and stem cell therapy of atherosclerotic plaque as a novel nanotool for angioplasty and artery remodeling

BACKGROUND

Some modern angioplasty techniques drastically affect the geometry of the plaque and the lumen, but have some inherent clinical and technical limitations.

METHODS

A total of 101 Yucatan miniature swine were allocated to the three following groups (34 pigs into 60/15- to 70/40-nm silica-gold nanoparticles (NPs), 34 swine into ferromagnetic group with iron-bearing NPs and delivery in hand of magnetic fields, and 33 in a sirolimus stenting control). Animals in the nanogroup were subdivided further into four subsets according to the delivery approach: (1) Intracoronary infused circulating stem progenitor cells (SPCs), including SP(+) (side population) cells, (2) intracoronary infused, ultrasound-mediated, albumin-coated, gas-filled microbubbles, (3) CD73(+)105(+) SPCs in the composition of a bioengineered on-artery patch (cardiac surgery), (4) CD73(+)CD105(+) SPCs engrafted by manual subadventitial injection (cardiac surgery). NPs were detonated with a microwatt near-infrared (NIR) laser (821 nm, 35-44 W/cm(2) for 7 min of exposure).

RESULTS

Changes of the total atheroma volume (TAV; mm(3)) immediately after the laser irradiation at month 6 in the nanoshell, ferromagnetic, and control groups were -7.54%/-22.92%, -9.7%/-16.84%, and -10.5%/-7.06% (p<0.01), respectively, and in the subsets reached -2.79%/-21.92%, -6.26%/-15.24%, -4.6%/-31.21%, -16.5%/-23.3% (p<0.05), respectively. Some cases of atherothrombosis and distal embolism (23.5%) were documented only in the microbubbles subset. The impact of the therapy on the nonorganic part of the plaque-antiinflammative and antiapoptotic effects, signs of neovascularization, and restoration of artery function-were predominant in the observed subsets with SPCs (p<0.01).

CONCLUSION

Nanoburning, especially in combination with stem cell technologies, is a very challenging technique for altering advanced plaque and holds the promise of revolutionizing state-of-the-art interventional cardiology, assuring destruction of plaque and functional restoration of the vessel wall. It could potentially become the current mechanical and pharmacological treatment.

Complex Chiari malformations in children: an analysis of preoperative risk factors for occipitocervical fusion

OBJECT

Chiari malformation Type I (CM-I) is a congenital anomaly often treated by decompressive surgery. Patients who fail to respond to standard surgical management often have complex anomalies of the craniovertebral junction and brainstem compression, requiring reduction and occipitocervical fusion. The authors hypothesized that a subgroup of "complex" patients defined by specific radiographic risk factors may have a higher rate of requiring occipitocervical fusion.

METHODS

A retrospective review was conducted of clinical and radiographic data in pediatric patients undergoing surgery for CM-I between 1995 and 2010. The following radiographic criteria were identified: scoliosis, syringomyelia, CM Type 1.5, medullary kinking, basilar invagination, tonsillar descent, craniocervical angulation (clivoaxial angle [CXA] < 125°), and ventral brainstem compression (pB-C2 ≥ 9 mm). A multivariate Cox regression analysis was used to determine the independent association between occipitocervical fusion and each variable.

RESULTS

Of the 206 patients who underwent CM decompression with or without occipitocervical fusion during the study period, 101 had preoperative imaging available for review and formed the study population. Mean age at surgery was 9.1 years, and mean follow-up was 2.3 years. Eighty-two patients underwent suboccipital decompression alone (mean age 8.7 years). Nineteen patients underwent occipitocervical fusion (mean age 11.1 years), either as part of the initial surgical procedure or in a delayed fashion. Factors demonstrating a significantly increased risk of requiring fusion were basilar invagination (HR 9.8, 95% CI 2.2-44.2), CM 1.5 (HR 14.7, 95% CI 1.8-122.5), and CXA < 125° (HR 3.9, 95% CI 1.2-12.6).

CONCLUSIONS

Patients presenting with basilar invagination, CM 1.5, and CXA < 125° are at increased risk of requiring an occipitocervical fusion procedure either as an adjunct to initial surgical decompression or in a delayed fashion. Patients and their families should be counseled in regard to these findings as part of a preoperative CM evaluation.

Craniocervical fusions in children

The surgical management of craniovertebral junction (CVJ) instability in pediatric patients presents unique challenges. As compared with the adult patient, the anatomical variations of the CVJ in the pediatric patient are significant, complicate the approach, and limit the use of internal fixation. Diminutive osseous and ligamentous structures and syndromic craniovertebral abnormalities complicate the issue. Advances in imaging analysis and instrumentation have improved the armamentarium for managing the pediatric patient who requires craniocervical stabilization. In this paper, the author's experience of performing more than 850 pediatric CVJ fusions is reviewed. This work includes the indications for atlantoaxial arthrodesis and occipitocervical fusion. Early atlantoaxial fusions were performed using interlaminar rib graft fusion, and more recently using either transarticular screw fixation in the older patient, or lateral mass screws at C-1 and rod fixation with either C-2 pars interarticular screw fixation or pedicle screw fixation. A C-2 translaminar screw fixation is also described. Occipitocervical fusions are performed with rib grafts in patients younger than 6 years of age. Subsequently, above that age, contoured loop fixation was performed, and in the past 8-10 years, screw and rod fixation was used. Abnormal spine growth was not observed in children who underwent craniocervical stabilization below the age of 5 years (clearly the bone grew with the patient). However, no deleterious effects were noted in the children treated with rigid instrumentation. The success rate for bone fusion alone was 98%. The author's success rate with rigid instrumentation is nearly 100%. A detailed review of the technique of fusion is presented, as well as the indications and means of avoidance of complications, their prevention, and management.

Craniovertebral junction abnormalities with hindbrain herniation and syringomyelia: regression of syringomyelia after removal of ventral craniovertebral junction compression

Object

Hindbrain herniation syndrome, or Chiari malformation Type I (CM-I), occurs frequently with craniovertebral junction (CVJ) abnormalities when there is reduction in the posterior fossa volume. Syringomyelia is often present. Posterior fossa dorsal decompression (PFDD) is typically performed but has adverse results when ventral bone abnormality exists. This paper presents the results of a prospective study on CVJ abnormalities in patients with CM-I and syringomyelia.

Methods

Between 1984 and 2008 (the MR imaging era), 298 patients with CVJ abnormalities and CM-I underwent ventral cervicomedullary decompression. Eighty-four patients had associated syringomyelia (15 with secondary invagination and 69 with primary basilar invagination, os odontoideum, or malunion of fractures). Of these 84 patients with CVJ abnormalities, CM-I, and syringomyelia, 46 had previously undergone PFDD, and 28 had previously undergone PFDD combined with fusion procedures or shunt placements. Of the 84 patients, a cervicothoracic syrinx was observed in 57, thoracic syrinx in 14, and holocord syrinx in 13. Studies included CT, MR imaging, and cine flow studies. All 298 patients who underwent ventral CVJ decompression had irreducible or partially reducible pathology. All 84 with syringomyelia showed brainstem dysfunction, lower cranial nerve symptoms, or myelopathy.

Results

Brainstem signs improved in 66 of the 84 patients, myelopathy improved in 58, and syringomyelia regressed in 64.

Conclusions

Neurological improvement and syringomyelia resolution can occur using only ventral cervicomedullary junction decompression in patients with basilar invagination and basilar impression. This is likely due to the relief of neural encroachment and reestablishment of CSF pathways.

Analysis of the treatment of 576 patients with congenital craniovertebral junction malformations

We aim to report our experience treating craniovertebral junction malformations (CVJM) and to investigate the management of this uncommon condition. Between 2000 and 2009, 629 patients with CVJM underwent surgery in our department. Fifty-three patients were lost to follow-up; therefore 576 patients completed follow-up, for an average period of 3 years and 2 months. All patients were diagnosed on the basis of clinical presentation and imaging features, and we found that anomalies of the occipitocervical junction manifested as four major types. Different microsurgical treatments were carried out in these patients according to disease type, and the effectiveness of individualised treatments was analysed. Categorizing patients with CVJM into these four types to simplify this somewhat unclear area could provide insight into the pathogenesis of the anomaly and a basis for rational surgical treatment.