Complications and long-term outcome of upper cervical spine arthrodesis in patients with Down syndrome

Treatment of Atlantoaxial Dislocation in Children with Down Syndrome Using Posterior Atlantoaxial Screw Fixation

Background

To investigate the effect of posterior atlantoaxial screw fixation for the treatment of atlantoaxial dislocation in children with Down syndrome (DS).

Methods

Children diagnosed with DS who underwent posterior atlantoaxial screw fixation or occipitocervical fusion from January 2017 to January 2020 in Hebei Children’s Hospital were retrospectively included. Preoperative CT and MRI were performed to check the os odontoideum (OsO) and spinal cord compression, signal changes and spinal cord injury grade (ASIA grade).

Results

All 5 children have atlantoaxial dislocation and OsO. Among which 60% (3/5) of children had changes in spinal cord signals and 40% (2/5) had dural sac compression. Every child underwent posterior atlantoaxial screw fixation (3.5-mm diameter), and the average fusion level was 1.8 (1–2). All 5 cases wore the head-neck-chest brace for 3–6 months after the operation. 1 case had dural tear and recovered well after timely suturing. 1 case had internal fixation breakage of the prosthetic joint and underwent revision surgery. At the last follow-up, all cases were fused and the neurological function were all ASIA grade E.

Conclusion

After posterior atlantoaxial screw fixation, fusion and nerve recovery were achieved in all children with atlantoaxial dislocation and OsO. Postoperative head-neck-chest braces are necessary for children, especially those with occipitocervical fusion.

Complications of Posterior Fusion for Atlantoaxial Instability in Children With Down Syndrome

Objective

To clarify the complications of posterior fusion for atlantoaxial instability (AAI) in children with Down syndrome and to discuss the significance of surgical intervention.

Methods

Twenty pediatric patients with Down syndrome underwent posterior fusion for AAI between February 2000 and September 2018 (age, 6.1±1.9 years). C1–2 or C1–3 fusion and occipitocervical fusion were performed in 14 and 6 patients, respectively. The past medical history, operation time, estimated blood loss (EBL), duration of Halo vest immobilization, postoperative follow-up period, and intra- and perioperative complications were examined.

Results

The operation time was 257.9±55.6 minutes, and the EBL was 101.6±77.9 mL. Complications related to the operation occurred in 6 patients (30.0%). They included 1 major complication (5.0%): hydrocephalus at 3 months postoperatively, possibly related to an intraoperative dural tear. Other surgery-related complications included 3 cases of superficial infections, 1 case of bone graft donor site deep infection, 1 case of C2 pedicle fracture, 1 case of Halo ring dislocation, 1 case of pseudoarthrosis that required revision surgery, and 1 case of temporary neurological deficit after Halo removal at 2 months postoperatively. Complications unrelated to the operation included 2 cases of respiratory infections and 1 case of implant loosening due to a fall at 9 months postoperatively.

Conclusion

The complication rate of upper cervical fusion in patients with Down syndrome remained high; however, major complications decreased substantially. Improved intra- and perioperative management facilitates successful surgical intervention for upper cervical instability in pediatric patients with Down syndrome.

Trisomy 21 impairs PGE2 production in dermal fibroblasts

The triplication of human chromosome 21 results in Down syndrome (DS), the most common genetic form of intellectual disability. This aneuploid condition also results in an enhanced risk of a spectrum of comorbid conditions, such as leukemia, early onset Alzheimer's disease, and diabetes. Individuals with DS also display an increased incidence of wound healing complications and resistance to solid tumor development. Due to this unique phenotype and the involvement of eicosanoids in key comorbidities like poor healing and tumor development, we hypothesized that cells from DS individuals would display altered eicosanoid production. Using age- and sex-matched dermal fibroblasts we interrogated this hypothesis. Briefly, assessment of over 90 metabolites derived from cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome p450 systems revealed a possible deficiency in the COX system. Basal gene expression and Western blotting experiments showed significantly decreased gene expression of COX1 and 2, and COX2 protein abundance in DS fibroblasts compared to euploid controls. Further, using two different stressors, scratch wound or LPS, we found that DS fibroblasts could not upregulate COX2 abundance and prostaglandin E2 production. Together, these findings show that dermal fibroblasts from DS individuals have a deficient COX2 response, which may contribute to wound healing complications and tumor resistance in DS.

Use of recombinant human bone morphogenetic protein for revision cervical spine fusion in children with Down syndrome: a case series

OBJECTIVE

Patients with trisomy 21 (Down syndrome; DS) often have atlantoaxial instability (AAI), which, if severe, causes myelopathy and neurological deterioration. Children with DS and AAI who undergo cervical spine fusion have a high rate of nonunion requiring revision surgery. Recombinant human bone morphogenetic protein-2 (rhBMP-2) is a TGF-β growth factor that is used to induce bone formation in spine fusion. Although previous studies in the adult population have reported no reduction in pseudarthrosis rates with the use of rhBMP-2, there is a lack of literature in the pediatric DS population. This study describes the use of rhBMP-2 in children with DS and AAI during revision to treat nonunion.

METHODS

A retrospective review of a cervical spine fusion database (n = 175) was conducted. This database included all cervical spine fusions using modern instrumentation at the authors' institution from 2002 to 2019. Patients with DS who underwent a revision utilizing rhBMP-2 were included in the study. The number of prior fusions, use of rhBMP-2 in fusions, length of stay, halo use, and surgical data were collected. Postoperative complications and length of follow-up were also recorded.

RESULTS

Eight patients (75% female) met the inclusion criteria. The average age at revision with rhBMP-2 was 11 years (range 3-19 years). All patients were diagnosed with nonunion after an initial cervical fusion. All revisions were posterior fusions of C1-2 (n = 2) or occiput to cervical (n = 6). All revisions included implant revisions, iliac crest bone grafting, and rhBMP-2 use. One patient required irrigation and debridement of an rhBMP-induced seroma. Another patient required return to the operating room to repair a dural tear. There were no neurological, infectious, airway, or implant-related complications. Revision utilizing rhBMP-2 achieved fusion in 100% (n = 8) of patients. The average length of follow-up was 42.6 months. All patients demonstrated solid fusion mass on the last radiograph.

CONCLUSIONS

This is the first case series reporting the successful use of rhBMP-2 to facilitate cervical spine fusion in patients with DS after previous nonunion. In addition, few rhBMP-2-related postoperative complications occurred.

Atlantoaxial dislocation due to os odontoideum in patients with Down's syndrome: literature review and case reports

PURPOSE

To clarify etiology, clinical features, and diagnostic and treatment options of atlantoaxial dislocation (AAD) due to os odontoideum (OsO) in patients with Down's syndrome (DS).

METHODS

We described and analyzed three clinical cases of AAD due to OsO in DS patients and reviewed descriptions of similar cases in the scientific sources.

RESULTS

According to literature review, more than 80% of DS patients with odontoid ossicles had atlantoaxial instability (AAI). AAI in DS patients with OsO is more often manifested in childhood and adolescence, rarely in adults when ligament relaxation is reduced. Some patients had acute clinical manifestation after a minor trauma without any precursors; in some of the cases, neurological deterioration increased during several years. We found that the earlier surgical treatment of AAD due to OsO in DS patients carries the higher recovery potential.

CONCLUSIONS

Most patients with DS and OsO had AAI. The method of appropriate treatment in such cases is a posterior screw fixation. Preoperative halo traction and posterior fusion have proved to be a very useful tool in the treatment of AAD due to OsO in DS patients. Even if irreducibility of the AAD established preoperatively, it should not be an absolute indication for anterior decompression. In such cases, an attempt to reduce the AAD should be made under general anesthesia during posterior fixation.

Surgical Fixation Using Screw-Rod Construct Instrumentation for Upper Cervical Instability in Pediatric Down Syndrome Patients

STUDY DESIGN

Retrospective case series.

OBJECTIVES

To describe the indications and outcomes of cervical fixation using modern instrumentation in a case series of pediatric Down syndrome (DS) patients.

SUMMARY OF BACKGROUND DATA

Cervical instability is the major cervical spine concern in children with DS. Although fixation techniques have advanced over the past quarter-century, the outcome of fixation with modern instrumentation for upper cervical instability in DS patients has not been thoroughly investigated.

METHODS

We searched the orthopedic database at our institution for patients with a diagnosis of DS who had undergone a cervical spine fusion between 2006 and 2017. Patient demographics, diagnoses, surgical indications, surgical details, and complications were recorded. Preoperative imaging was reviewed to determine atlanto-dens intervals and spinal cord signal changes. Postoperative radiographs or CT scans were reviewed to determine union.

RESULTS

Twelve DS patients met our inclusion criteria. The mean age at surgery was 9.3 years (range 3.8-18.8 years). Patients with secondary causes of instability included 7 patients with os odontoideum and 1 patient with a pars fracture. Three patients (25%) were identified on asymptomatic screening, with none of these having cord signal changes on magnetic resonance imaging (MRI). Modern implants (screws, plates, cages) were used in every patient in our series. The mean number of levels fused was 1.9 (range 1-5). The overall complication rate was 41.7% (5/12). Four patients required repeat surgery for nonunion. All patients with adequate radiographic follow-up demonstrated union (11/11, 100%). One patient was lost to follow-up.

CONCLUSIONS

Fixation for cervical instability is a critical component of the management of DS. A minority of patients receiving surgery were identified through asymptomatic screening. There was a high complication risk associated with surgery in our study; however, the addition of rigid fixation has lessened the complication rate compared with previous studies.

LEVEL OF EVIDENCE

Level IV.

Autogenic Rib Graft for Atlantoaxial and Occipitocervical Fixation in Pediatric Patients

Study Design

Retrospective case series.

Purpose

To evaluate surgical outcomes and effectiveness of an autogenic rib graft for upper cervical fixation in pediatric patients.

Overview of Literature

Autogenic bone grafts have long been considered the ‘gold standard’ bone source for posterior cervical fusion in pediatric patients. However, there are some unsolved problems associated with donor-site morbidity and amount of bone grafting.

Methods

We studied five consecutive pediatric patients who underwent atlantoaxial fixation or occipitocervical fixation (OCF) using an autogenic rib graft with at least 2 years of follow-up (mean age, 9.8 years; mean follow-up period, 73.0 months). Two patients underwent OCF without screw-rod constructs and three patients with screw-rod constructs. Autogenic rib grafts were used in all patients. We evaluated the surgical outcomes including radiographic parameter, bony union, and perioperative complications.

Results

The atlantoaxial interval (ADI) was corrected from 11.6 to 6.0 mm, and the C1–2 angle was corrected −14.8° to 7.8°. The C2–7 angle was reduced from 31° to 9° spontaneously. Two patients with OCF required revision surgery due to loss of correction. Patients did not experience any complication associated with the donor sites (rib bone grafts). Six months postoperation X-rays clearly showed regeneration of the rib at the donor sites. Bony fusion was achieved in all patients; however, bony fusion occurred more slowly in patients without screw-rod constructs compared with patients with screw-rod constructs. Bone regeneration of the rib was observed in all patients with no complications at the donor site.

Conclusions

Autogenic rib grafts have advantages of potential bone regeneration, high fusion rate, and low donor-site morbidity. In addition, a screw-rod construct provides better bony fusion in pediatric patients with OCF and atlantoaxial fixation.

Outcomes of Surgical Correction of Atlantoaxial Instability in Patients with Down Syndrome: Systematic Review and Meta-Analysis

BACKGROUND

Atlantoaxial instability (AAI) is a common cause of neurologic dysfunction and pain in patients with Down syndrome (DS), frequently requiring instrumented fusion of the upper cervical spine. Despite this, optimal treatment strategy is controversial.

METHODS

A systematic review of the literature was performed according to the Preferred Reporting Items for Systemic Reviews and Meta-Analysis statement to identify patients with AAI and DS were treated with upper cervical spine fusion. Patient demographics, preoperative symptoms, fixation type, and outcome measures including complications, neurologic outcomes, and bony fusion status were gathered for patients in the included publications. Meta-analysis was performed to compare outcomes of different types of fixation constructs.

RESULTS

Of the 1191 publications retrieved, 51 met inclusion criteria, yielding 137 patients. Six fixation strategies were identified: noninstrumented (n = 6), wiring (n = 77), wiring with rods (n = 14), screw fixation (n = 33), hook and rod fixation (n = 2), and screw and wire fixation (n = 5). Constructs with screws and rods had greater bony union (P = 0.003) and a lower rate of revision surgery (P = 0.047), loss of reduction or pseudoarthrosis (P = 0.009), halo utilization (P < 0.001), and early neurologic decline (P = 0.004) compared with wiring alone. Constructs with wires and rods had greater bony union (P = 0.036) than wiring alone.

CONCLUSIONS

Numerous fixation strategies exist for AAI in patients with DS. Using a combination of screws, rods, and wiring in appropriately selected patients may help reduce the high rate of surgical complications in these patients.

Morphologic variations of the second cervical vertebra in Down syndrome compared with age-matched peers

OBJECTIVEAtlantoaxial instability is an important cause of pain and neurological dysfunction in patients with Down syndrome (DS), frequently requiring instrumented fusion of the upper cervical spine. This study provides a quantitative analysis of C2 morphology in DS patients compared with their peers without DS to identify differences that must be considered for the safe placement of instrumentation.METHODSA retrospective chart review identified age-matched patients with and without DS with a CT scan of the cervical spine. Three-dimensional reconstructions of these scans were made with images along the axis of, and perpendicular to, the pars, lamina, facet, and transverse foramen of C2 bilaterally. Two of the authors performed independent measurements of anatomical structures using these images, and the average of the 2 raters' measurements was recorded. Pedicle height and width; pars axis length (the distance from the facet to the anterior vertebral body through the pars); pars rostrocaudal angle (angle of the pars axis length to the endplate of C2); pars axial angle (angle of the pars axis length to the median coronal plane); lamina height, length, and width; lamina angle (angle of the lamina length to the median coronal plane); and transverse foramen posterior distance (the distance from the posterior wall of the transverse foramen to the tangent of the posterior vertebral body) were measured bilaterally. Patients with and without DS were compared using a mixed-effects model accounting for patient height.RESULTSA total of 18 patients with and 20 patients without DS were included in the analysis. The groups were matched based on age and sex. The median height was 147 cm (IQR 142-160 cm) in the DS group and 165 cm (IQR 161-172 cm) in the non-DS group (p < 0.001). After accounting for variations in height, the mean pars rostrocaudal angle was greater (50.86° vs 45.54°, p = 0.004), the mean transverse foramen posterior distance was less (-1.5 mm vs +1.3 mm, p = 0.001), and the mean lamina width was less (6.2 mm vs 7.7 mm, p = 0.038) in patients with DS.CONCLUSIONSPatients with DS had a steeper rostrocaudal trajectory of the pars, a more posteriorly positioned transverse foramen posterior wall, and a narrower lamina compared with age- and sex-matched peers. These variations should be considered during surgical planning, as they may have implications to safe placement of instrumentation.

The Outcomes of Posterior Arthrodesis for Atlantoaxial Subluxation in Down Syndrome Patients: A Meta-Analysis

STUDY DESIGN

This is a meta-analysis.

OBJECTIVE

To establish rates of (1) neurological complications, (2) bony-related complications, (3) complications delaying recovery, (4) reoperation, and (5) fatalities following posterior cervical arthrodesis in Down syndrome (DS) patients with atlantoaxial subluxation. To determine if presenting symptoms had any relationship to postoperative complications.

SUMMARY OF BACKGROUND DATA

Posterior arthrodesis is commonly utilized to correct cervical instability secondary to atlantoaxial instability in DS patients. However, there has never been a global evaluation of postoperative complications associated with posterior cervical spinal arthrodesis in DS patients.

METHODS

A comprehensive search of Medline/PubMed, EMBASE, and Ovid databases between January 1980 and July 2017 was utilized to identify DS patients with atlantoaxial subluxation who underwent posterior cervical arthrodesis. Data were sorted by neurological complications, complications delaying recovery, bony-related complications, reoperations, and fatalities. Patients were sorted into 2 groups based on presentation with or without neurological deficits.

RESULTS

Twelve studies met inclusion criteria, including 128 DS patients. Mean age was 13.8 years (range: 6.7-32.7 y; 47.8% male). Mean follow-up was 31.7 months (range: 14.9-77 mo). All patients underwent primary posterior cervical arthrodesis with an average of 2.5 vertebrae fused. A total of 39.6% of patients had bony-related complications [95% confidence interval (CI), 31.4%-48.5%], 23.3% had neurological deficits (95% CI, 16.6%-31.6%), and 26.4% experienced complications delaying recovery (95% CI, 19.4%-34.9%). The reoperation rate was 34.9% (95% CI, 25.5%-45.6%). The mortality rate was 3.9% (95% CI, 1.5%-9.7%). Neurological complications were 4-fold (P<0.05) and reoperation was 5.5-fold (P<0.05) more likely in patients presenting with neurological deficits compared with those without.

CONCLUSIONS

This study detailed global complication rates of posterior arthrodesis for DS patients, identifying bony-related complications and reoperations among the most common. Patients presenting with neurological symptoms and cervical instability have increased postoperative rates of neurological complications and reoperations than patients with instability alone. Further investigation into how postoperative complications effect patient independence is warranted.

Radiographic Outcomes of Upper Cervical Fusion for Pediatric Patients Younger Than 10 Years

Purpose: This study aimed to investigate radiographic outcomes after posterior spinal fusion (PSF) for pediatric patients younger than 10 years with upper cervical disorders. Methods: Thirteen patients (mean age at surgery, 5.9 years; range, 1 to 9 years) who underwent PSF with a minimum of 2 years of follow-up (mean, 5.8 years) were included. Diagnoses were atlanto-axial instability due to congenital disorders for 11 patients and atlanto-axial rotatory fixation for 2 patients. The fusion area was occipito-cervical for 7 patients and C1/2 for 6 patients. PSF was performed using rigid screw-rod constructs for 6 patients and conventional techniques for 7 patients. Ten patients required halo immobilization after surgery. Fusion status, perioperative complications, radiographic alignment, and range of motion (ROM) from C2 to C7 were evaluated. Results: Twelve patients successfully achieved bony fusion (fusion rate, 92%), but complications occurred in 5 patients. Regarding radiographic measures (preoperative/postoperative/final follow-up), the mean atlanto-dental interval was significantly reduced (8.0 mm/2.7 mm/3.5 mm) and the C2-7 ROM was increased (from 49.4 degrees to 66.0 degrees) at the final follow-up (both comparisons, p<0.05). Sagittal alignment was unchanged. Conclusion: Use of rigid screw-rod instrumentation in the upper cervical spine with careful radiological evaluation is amenable for pediatric patients younger than 10 years. However, conventional procedures such as wiring fixation with rigid external immobilization are still alternative options for preventing serious neurological and vascular complications.

Co-occurring medical conditions in adults with Down syndrome: A systematic review toward the development of health care guidelines

Adults with Down syndrome (DS) represent a unique population who are in need of clinical guidelines to address their medical care. The United States Preventive Service Task Force (USPSTF) has developed criteria for prioritizing conditions of public health importance with the potential for providing screening recommendations to improve clinical care. The quality of existing evidence needed to inform clinical guidelines has not been previously reviewed. Using the National Library of Medicine (NLM) database PubMed, we first identified 18 peer reviewed articles that addressed co-occurring medical conditions in adults with DS. Those conditions discussed in over half of the articles were prioritized for further review. Second, we performed detailed literature searches on these specific conditions. To inform the search strategy and review process a series of key questions were formulated a priori. The quality of available evidence was then graded and knowledge gaps were identified. The number of participating adults and the design of clinical studies varied by condition and were often inadequate for answering all of our key questions. We provide data on thyroid disease, cervical spine disease, hearing impairment, overweight-obesity, sleep apnea, congenital heart disease, and osteopenia-osteoporosis. Minimal evidence demonstrates massive gaps in our clinical knowledge that compromises clinical decision-making and management of these medically complex individuals. The development of evidence-based clinical guidance will require an expanded clinical knowledge-base in order to move forward.

Efficacy of Intraoperative Neurophysiologic Monitoring for Pediatric Cervical Spine Surgery

STUDY DESIGN

Clinical case series.

OBJECTIVE

To investigate the efficacy of intraoperative neuromonitoring in pediatric cervical spine surgery.

SUMMARY OF BACKGROUND DATA

Intraoperative neuromonitoring (IONM) consisting of somatosensory-evoked potentials (SSEP) and transcranial motor-evoked potentials (tcMEP) has been shown to effectively prevent permaneny neurologic injury in deformity surgery. The role of IONM during pediatric cervical spine surgery is not well documented. Advances in cervical spine instrumentation have expanded the surgical options in pediatric populations. The goal of this study is to report the ability of IONM to detect neurologic injury during pediatric cervical spine instrumentation.

METHODS

A single institution database was queried for pediatric-aged patients who underwent cervical spine instrumentation and fusion between 2011 and 2014. Age, diagnosis, surgical indication, number of instrumented levels, and a complete IONM were extracted. Sensitivity and specificity for the detection of neurologic deficits were calculated with exact 95% confidence intervals. Positive and negative predictive values were calculated with estimated 95% confidence intervals.

RESULTS

Sixty-seven patients who underwent cervical spine instrumentation were identified with a mean age of 11.6 years (range 1-18). Diagnoses included instability (27), congenital (11), kyphosis (8), fracture (7), tumor (7), arthritis (4), and basilar invagination (3). Mean number of vertebral levels fused was 4 (range 2-7). All patients underwent cervical instrumentation with SSEP and tcMEP monitoring. A significant change in tcMEP monitoring was observed in 7 subjects (10%). There were no corresponding SSEP changes in these patients. The sensitivity of combined IONM was 75% [95% CI = 24.9, 98.7] and the specificity was 98.5% [92.7, 99.9].

CONCLUSION

tcMEP is a more sensitive indicator to spinal cord injury than SSEP, which is consistent with previous studies. IONM changes in 10% of a patient population are significant enough to warrant intraoperative determination if true SCI has occurred or is underway and intervene accordingly.

LEVEL OF EVIDENCE

4.

Aida, Kurosawa K, Saito T. New radiological parameters for the assessment of atlantoaxial instability in children with Down syndrome

Aims

To determine the normal values and usefulness of the C1/4 space available for spinal cord (SAC) ratio and C1 inclination angle, which are new radiological parameters for assessing atlantoaxial instability in children with Down syndrome.

Patients and Methods

We recruited 272 children with Down syndrome (including 14 who underwent surgical treatment), and 141 children in the control group. All were aged between two and 11 years. The C1/4 SAC ratio, C1 inclination angle, atlas-dens interval (ADI), and SAC were measured in those with Down syndrome, and the C1/4 SAC ratio and C1 inclination angle were measured in the control group.

Results

The mean C1/4 SAC ratio in those requiring surgery with Down syndrome, those with Down syndrome not requiring surgery and controls were 0.63 (standard deviation (sd) 0.1), 1.15 (sd 0.13) and 1.29 (sd 0.14), respectively, and the mean C1 inclination angles were -3.1° (sd 10.7°), 15.8° (sd 7.3) and 17.2° (sd 7.3), in these three groups, respectively. The mean ADI and SAC in those with Down syndrome requiring surgery and those with Down syndrome not requiring surgery were 9.8 mm (sd 2.8) and 4.3 mm (sd 1.0), and 11.1 mm (sd 2.6) and 18.5 mm (sd 2.4), respectively.

Conclusion

The normal values of the C1/4 SAC ratio and the C1 inclination angle were found to be about 1.2° and 15º, respectively. Cite this article: Bone Joint J 2016;98-B:1704–10.

Down syndrome-A narrative review with a focus on anatomical features

Down syndrome (DS) is the most common aneuploidy of chromosome 21, characterized by the presence of an extra copy of that chromosome (trisomy 21). Children with DS present with an abnormal phenotype, which is attributed to a loss of genetic balance or an excess dose of chromosome 21 genes. In recent years, advances in prenatal screening and diagnostic tests have aided in the early diagnosis and appropriate management of fetuses with DS. A myriad of clinical symptoms resulting from cognitive, physical, and physiological impairments caused by aberrations in various systems of the body occur in DS. However, despite these impairments, which range from trivial to fatal manifestations, the survival rate of individuals with DS has increased dramatically from less than 50% during the mid-1990s to 95% in the early 2000s, with a median life expectancy of 60 years reported recently. The aim of this narrative review is to review and summarize the etiopathology, prenatal screening and diagnostic tests, prognosis, clinical manifestations in various body systems, and comorbidities associated with DS. Clin. Anat. 29:568-577, 2016. © 2015 Wiley Periodicals, Inc.

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.

Computed tomography morphometric analysis for C-1 posterior arch crossing screw placement in the pediatric cervical spine

OBJECT

The goal of this study was to evaluate the feasibility of the C-1 posterior arch crossing screw fixation technique in the pediatric age group.

METHODS

One hundred twenty-three pediatric patients were divided into 6 age groups. Computed tomography morphometric analysis of the C-1 posterior arch was performed. Measurements included height, width, and length. Statistical analysis was performed using the Student t-test and linear regression analysis.

RESULTS

The mean measurement of the posterior arch was height (6.35 ± 1.80 mm), width (Width 1: 4.48 ± 1.25 mm; Width 2: 4.42 ± 0.68 mm; Width 3: 4.42 ± 0.50 mm), and length (14.48 ± 1.67 mm). Seven (6.93%) of the 101 children in Groups 1-4 and 13 (59.1%) of the 22 children in Groups 5 and 6 could safely accommodate placement of C-1 posterior arch crossing screws.

CONCLUSIONS

This investigation found that a C-1 posterior arch crossing screw was feasible in this group of Chinese pediatric patients, particularly in those 13 years and older. Preoperative thin-cut CT is essential for identifying children in whom this technique is applicable and for planning screw placement.

Novel 2 radiographical measurements for atlantoaxial instability in children with Down syndrome

STUDY DESIGN

A retrospective case-control study.

OBJECTIVE

To assess the usefulness and reproducibility of 2 novel safe and simple radiographical measurements for atlantoaxial instability in children with Down syndrome.

SUMMARY OF BACKGROUND DATA

In pediatric atlantoaxial instability, early diagnosis is important for improved outcomes because of poor postoperative recovery in progressed neurological symptoms. Conventional dynamic radiography of the cervical spine is associated with a potential risk of worsening neurological symptoms.

METHODS

We retrospectively reviewed the medical records of 50 patients (24 boys and 26 girls) with atlantoaxial instability associated with Down syndrome. Of the 50 children, 11 had undergone and 4 had been scheduled for surgery (surgical group). In this investigation, in addition to the atlas-dens interval (ADI) and space available for spinal cord (SAC), we measured C1 inclination angle and C1/4 SAC ratio on lateral radiographs of the cervical spine in the neutral position. To assess the diagnostic abilities of these indices to determine indication for surgery, receiver operating characteristic analysis of each index was performed, and their diagnostic abilities were compared using the area under the receiver operating characteristic curve. Moreover, we assessed reproducibility of our 2 proposed indices.

RESULTS

The discriminatory abilities of C1/4 SAC ratio (area under the receiver operating characteristic curve, 1.00) and C1 inclination angle (0.91) were comparable with those of ADI (0.98) and SAC (0.95). For the interobserver and intraobserver reliability of the novel indices, the correlation coefficients were in the range from 0.88 to 0.99. Correlation was observed between the ADI and C1/4 SAC ratio (r = 0.507, P < 0.01) and between the ADI and C1 inclination angle (r = 0.407, P < 0.01).

CONCLUSION

The diagnostic abilities of the 2 novel radiographical measurements were comparable with those of ADI and SAC. Moreover, these novel measurements can be obtained safely on lateral radiographs of the cervical spine in the neutral position.

LEVEL OF EVIDENCE

4.

Imaging of the craniovertebral junction anomalies in children

The craniovertebral junction (CVJ) is interposed between the unsegmented skull and the segmented spine; it is functionally unique as it allows the complex motion of the head. Because of its unique anatomy, numerous craniometric indices have been devised. Because of its complex embryology, different from that of the adjacent skull and spine, it is commonly the seat of malformations. Because of the mobility of the head, and its relative weight, the craniovertebral junction is vulnerable to trauma. Like the rest of the axial skeleton, it may be affected by many varieties of dysplasia. In addition, the bony craniovertebral junction contains the neural craniovertebral junction and its surrounding CSF: any bony instability or loss of the normal anatomic relationships may therefore compromise the neural axis. In addition, the obstruction of the meningeal spaces at this level can compromise the normal dynamics of the CSF and result in hydrocephalus and/or syringohydromyelia. To image the CVJ, plain X-rays are essentially useless. MR is optimal in depicting the soft tissues (including the neural axis) and the joints, as well as the bone itself. CT still may be important to better demonstrate the bony abnormalities.

A review of the neurological and neurosurgical implications of Down syndrome in children

Down syndrome is the most commonly encountered chromosomal translation and has been associated with significant congenital abnormalities in various organ systems. Along with classic facial findings, it may involve the gastroenterologic, cardiac, ophthalmologic, endocrine, immunologic, orthopedic, or neurologic systems. With respect to the neurological system, a higher incidence of moyamoya, seizure disorders, strokes, and spinal ligamentous laxity has been described in these children. We have summarized the current available literature with respect to children who have Down syndrome and the varying neurological pathologic entities associated to help health care providers better understand these patients.

Successful cranio-cervical fusion in a patient with Down syndrome

We present a patient with Down syndrome with neck pain and severe cervical myelopathy. Imaging revealed occipito-atlantal and atlanto-axial instability with severe spinal cord compression. There are no standardized radiological or clinical guidelines to aid in managing this unique subset of patients. We demonstrate a successful occiput-C3 internal fixation and fusion without complication. Due to the largely unknown natural history and ongoing management difficulties in this population, we demonstrate a case that may aid future decision making for this specialized field. We also discuss an approach to reduce this deformity, which, to our knowledge, has not been published before.

Posterior occipito-axial fixation applied C2 laminar screws for pediatric atlantoaxial instability caused by Down syndrome: Report of 2 cases

Background

Upper cervical spine instability is one of the most critical orthopedic problems in patients with Down syndrome. However, arthrodesis of the upper cervical spine in these patients can be very difficult to achieve and has a high complication rate because of mental retardation and accompanying various medical conditions of the vital organs. Even now, surgeries in such patients, especially pediatric cases, are challenging and the optimal operative procedure remains unsettled. The purpose of this study was to report 2 cases of pediatric atlantoaxial instability due to Down syndrome in which posterior occipito-axial fixation with C2 laminar screws was performed.

Methods

Case 1 was a girl aged 6 years 10 months who had atlantoaxial rotatory fixation with os odontoideum. Atlantoaxial rotatory fixation was incompletely reduced by halo traction, and it was not maintained without halo-ring and -vest fixation. Posterior occipito-axial fixation with bilateral C2 laminar screws was then performed. Case 2 was a boy aged 10 years 7 months who had atlantoaxial subluxation with os odontoideum. He also had incomplete quadriplegia, so he could neither walk nor have a meal by himself. Posterior occipito-axial fixation with right C2 pedicle and left C2 laminar screws was then carried out.

Results

In case 1 bone union was obtained at 3 months after surgery and the patient's symptoms were resolved. In case 2 bone union was obtained at 3 months after surgery and the paralysis was improved.

Conclusions/level of evidence

In cases of atlantoaxial instability due to Down syndrome, symptomatic patients often present between ages 5 and 15 years and mental retardation interferes with postoperative cervical immobilization. C2 laminar screws can be safely applied for the pediatric axis and biomechanically accomplished rigid fixation. The C2 laminar screw is one of the most useful options to achieve stability of the pediatric atlantoaxial complex without the risk of vertebral artery injuries (level IV case series).

Review of cervical spine anomalies in genetic syndromes

STUDY DESIGN

Focused review of the literature.

OBJECTIVE

Assist spine specialists in diagnosis and treatment of cervical spine anomalies found in selected genetic syndromes.

SUMMARY OF BACKGROUND DATA

Cervical spine instability and/or stenosis are potentially debilitating problems in many genetic syndromes. These problems can be overlooked among the other systemic issues more familiar to clinicians and radiologists evaluating these syndromes. It is imperative that spine specialists understand the relevant issues associated with these particular syndromes.

METHODS

The literature was reviewed for cervical spine issues in 10 specific syndromes. The information is presented in the following order: First, the identification and treatment of midcervical kyphosis in Larsen syndrome and diastrophic dysplasia (DD). Next, the upper cervical abnormalities seen in Down syndrome, 22q11.2 Deletion syndrome, pseudoachondroplasia, Morquio syndrome, Goldenhar syndrome, spondyloepiphyseal dysplasia congenita, and Kniest dysplasia. Finally, the chin-on-chest deformity of fibrodysplasia ossificans progressiva.

RESULTS

Midcervical kyphosis in patients with Larsen syndrome and DD needs to be evaluated and imaged often to track deformity progression. Upper cervical spine instability in Down syndrome is most commonly caused by ligamentous laxity at C1 to C2 and occiput-C1 levels. Nearly 100% of patients with 22q11.2 deletion syndrome have cervical spine abnormalities, but few are symptomatic. Patients with pseudoachondroplasia and Morquio syndrome have C1 to C2 instability related to odontoid dysplasia (hypoplasia and os odontoideum). Morquio patients also have soft tissue glycosaminoglycan deposits, which cause stenosis and lead to myelopathy. Severely affected patients with spondyloepiphyseal dysplasia congenita are at high risk of myelopathy because of atlantoaxial instability in addition to underlying stenosis. Kniest syndrome is associated with atlantoaxial instability. Cervical spine anomalies in Goldenhar syndrome are varied and can be severe. Fibrodysplasia ossificans progressiva features severe, deforming heterotopic ossification that can become life-threatening.

CONCLUSION

It is important to be vigilant in the diagnosis and treatment of cervical spine anomalies in patients with genetic syndromes.

Complications and outcomes of posterior fusion in children with atlantoaxial instability

INTRODUCTION

Atlantoaxial instability (AAI) is an uncommon disease in children. Surgical treatment of pediatric patients with AAI poses a challenge to spine surgeons because of the patients' immature bone quality, extensive anatomical variability, and smaller osseous structures. In this study, the authors report complications and outcomes after posterior fusion in children with AAI.

METHODS

The authors reviewed medical records of patients 13 years old and younger with AAI who underwent posterior fusion in the Nagoya Spine Group hospitals, a multicenter cooperative study group, from January 1995 to December 2007. We identified 11 patients who underwent posterior fusion, and analyzed their clinical outcomes and complications. To determine if vertical growth within the construct continued after posterior fusion, in three patients at 5 or more years following occipito-cervical (O-C) fusion, intervertebral disc heights and vertebral heights between the fused and non-fused levels were compared on the final follow-up.

RESULTS

The initial surgeries were C1-C2 fusions in six patients and O-C fusion in five patients. Successful fusion ultimately occurred in all patients, however, the complication rate related to the operations was high (64%). Complications included neurologic deterioration, pedicle fracture with pedicle screw insertion, C1 posterior arch fracture with lateral mass screw insertion, perforation of the skull with a head pin placement, and fusion extension to adjacent vertebrae. Two patients required reoperation. The mean fixed and non-fixed intervertebral disc heights on the final follow-up were 2.6 and 5.3 mm, respectively, showing that the disc height of the fixed level was less than the non-fused level. Each vertebra lengthened similarly between fused and non-fused levels except for C2 which had a lower growth rate than the other vertebrae.

CONCLUSIONS

A high complication rate should be anticipated after posterior fusion in children with AAI. Careful consideration should be paid to pediatric patients with AAI treated by screw and/or rod systems. After posterior fusion in pediatric patients, each vertebra continued to grow, in contrast the disc height decreased between fused levels.

Use of occipital bone graft in pediatric posterior cervical fusion: an alternative paramedian technique and review of the literature

An alternative method of bone grafting for pediatric posterior cervical and occipitocervical fixation is presented in detail. Full-thickness autografts from small craniectomies of the occipital bone are used to augment posterior segmental fusion in pediatric patients. Twelve patients have been treated successfully without bone graft donor site complications. The technical differences from previously reported uses of calvarial autograft in spine fusion are reviewed.

Craniovertebral Junction Abnormalities in Down Syndrome

CHILDREN WITH DOWN syndrome may have occipitocervical and atlantoaxial instability. To prevent neurologic injury during athletic competitions, such as the Special Olympics, radiographic cervical spine screening was established in 1983 as a prerequisite for participation in some events. This review discusses the biomechanics underlying upper cervical instability in children with Down syndrome, the evolution of cervical spine screening protocols, and current opinion regarding management for children with Down syndrome and upper cervical instability.

Variable morphology of the axis vertebrae in 100 specimens: implications for clinical palpation and diagnostic imaging

OBJECTIVE

The purpose of this study was to investigate and measure the variable morphologies of axis vertebrae and explore the clinical significance of variations as it may pertain to clinical palpation and diagnostic imaging.

METHODS

The common variable morphologies in 100 specimens of intact dry adult axis vertebrae (Chinese) were investigated and measured. The frequencies in deviation of odontoid processes, deviation of spinous processes, and presence of bifid spinous processes were observed. The distances between the apices of transverse processes and inferior articular facets were also measured.

RESULTS

Variable morphologies of C2 that we observed were deviation of odontoid processes (14 cases, 14.0%), deviation of spinous processes (3 cases, 3.0%), and bifid spinous processes (95 cases, 95.0%). Of the bifid spinous processes, 56 had a process on the left side equal to the right side, 21 were longer on the left, and 18 were longer on the right. The distances between apices of transverse processes and inferior articular facets in the left side of C2 were 17.67 +/- 2.47 mm, and that of the right side were 17.81 +/- 2.55 mm.

CONCLUSIONS

Because variable morphology of the axis is common, congenital deviation of the odontoid process, deviation of the spinous process, and asymmetrical bifid spinous processes should be taken into account during clinical palpation and diagnostic imaging.

Single stage reduction and stabilization of basilar invagination after failed prior fusion surgery in children with Down's syndrome

STUDY DESIGN

We describe an innovative single-stage reduction and stabilization technique using modern cervical instrumentation.

OBJECTIVE

We hypothesis modern instrumentation has made more aggressive surgical corrections possible and has reduced the need for transoral resection of the odontoid and traction reduction in children with basilar invagination.

SUMMARY OF BACKGROUND DATA

Craniocervical junction abnormalities, including atlantoaxial instability and progressive basilar invagination, are relatively common phenomenon in Down's syndrome patients, and can lead to chronic progressive neurologic deficits, catastrophic injury, and death. This patient population also can be a difficult one in which to perform successful stabilization and fusion.

METHODS

We reviewed the records and films on 2 children with Down's syndrome and atlantoaxial instability who had undergone prior occipital-cervical fusion and then presented with symptomatic progressive basilar invagination due to atlantoaxial displacement. In both cases, the children had progressive symptoms of spinal cord and brain stem compression. Multiple approaches for surgical correction, including preoperative traction and transoral odontoid resection, were considered, but ultimately it was elected to perform a single stage posterior operation. In both patients, we performed fusion takedown, intraoperative realignment with reduction of the basilar invagination, and stabilization using modern occipito-cervical instrumentation.

RESULTS

In both children, excellent cranio-cervical realignment was achieved; along with successful fusion and improvement in clinical symptoms.

CONCLUSION

In this article we will discuss the clinical cases and review the background of craniocervical junction abnormalities in Down's syndrome patients. We hypothesis modern instrumentation has made more aggressive surgical corrections possible and has reduced the need for transoral resection of the odontoid and traction reduction in children with basilar invagination.

Specific entities affecting the craniocervical region: Down's syndrome

INTRODUCTION

The ligamentous laxities and bony abnormalities associated with Down's syndrome, os odontoideum, achondroplasia, osteogenesis imperfecta, and basilar invagination have been discussed with the imaging of the craniocervical junction. These are significant and require suspicion when dealing with children with the previously mentioned entities.

CONCLUSION

Previous adverse surgical results in managing these patients reflect the lack of understanding of the underlying pathology and the appropriate surgical treatment.

Down syndrome: orthopedic issues

PURPOSE OF REVIEW

The purpose of this review is to update the role of the orthopedic surgeon in the management of Down syndrome as these patients are living longer and participating in sporting activities.

RECENT FINDINGS

Approximately 20% of all patients with Down syndrome experience orthopedic problems. Upper cervical spine instability has the most potential for morbidity and, consequently, requires close monitoring. Other conditions such as scoliosis, hip instability, patellar instability and foot problems can cause disability if left untreated. In some of these conditions, early diagnosis can prevent severe disability.

SUMMARY

Surgical intervention in children with Down syndrome has a high risk of complications, particularly infection and wound healing problems. Careful anesthetic airway management is needed because of the associated risk of cervical spine instability.

Spinal disorders associated with skeletal dysplasias and syndromes

Skeletal dysplasias are a heterogeneous group of disorders in which there is abnormal cartilage and bone formation, growth, and remodeling. There are more than 200 described skeletal dysplasias. Skeletal dysplasias can affect the spine in various ways, with attendant neurosurgical implications for diagnosis and treatment. Craniocervical junction abnormalities, atlantoaxial subluxation, and kyphoscoliotic deformity are among the common spinal problems that are found in certain skeletal dysplasias.

Bone morphogenetic protein for salvage fusion in an infant with Down syndrome and craniovertebral instability. Case report

The authors describe the use of bone morphogenetic protein (BMP) to promote bone fusion in an infant with craniovertebral instability after two attempts at arthrodesis had failed. To their knowledge, this is the first such report. Management of craniovertebral instability remains challenging in infants with Down syndrome. Surgical treatment may result in nonunion in this patient population. The authors report on a 4-month-old boy with Down syndrome who suffered a high cervical spinal cord injury secondary to craniovertebral instability. Two attempts to fuse and stabilize the craniovertebral junction resulted in nonunion. Finally, the use of BMP led to a stable fusion construct within 6 months without encroachment on the spinal canal. At 4 years of follow up, the patient has a solid fusion mass. The case suggests a role for the use of BMP to promote fusion in this patient population.

Down syndrome in children: the role of the orthopaedic surgeon

Down syndrome, the result of trisomy of chromosome 21, is one of the most common chromosomal abnormalities. Patients have a characteristic facial appearance, variable levels of intelligence and self-care skills, and a variety of associated medical conditions. Orthopaedic manifestations occur frequently; most are related to hypotonia, joint hypermobility, and ligamentous laxity. Atlanto-occipital and atlantoaxial hypermobility, as well as bony anomalies of the cervical spine, can produce atlanto-occipital and cervical instability. Methods of screening for this instability, particularly with regard to participation in sports, are a subject of controversy. Scoliosis, hip instability, slipped capital femoral epiphysis, patellar instability, and foot deformities are other musculoskeletal conditions found in patients with Down syndrome that can be challenging for the orthopaedic surgeon to treat.

Down syndrome and scoliosis: a review of a 50-year experience at one institution

STUDY DESIGN

Retrospective review case series.

OBJECTIVE

To evaluate the incidence, patterns, and treatment of scoliosis in a Down syndrome population.

SUMMARY OF BACKGROUND DATA

Despite a preponderance of literature concerning cervical abnormalities in Down syndrome, there is little information concerning scoliosis in this patient group. We examined the 50-year history of treating scoliosis at our institution in patients with Down syndrome.

METHODS

Following institutional review board approval, chart review identified patients with Down syndrome with scoliosis. We performed a radiographic review of curve pattern, and determined results of brace and operative treatment.

RESULTS

A total of 379 patients were identified as having Down syndrome. There were 33 patients diagnosed with scoliosis, for an incidence of 8.7%. Mean follow-up was 4.15 years (range 0-12). The double major curve predominated with 18 (55%). Of 33 patients, 16 (49.5%) had previously undergone thoracotomy for congenital heart defects. There were 8 (24%) patients who were braced for an average of 26.5 months (range 12-63), with an average progression in brace of 10 degrees (range 0 degrees-44 degrees), 3 of whom went on to spinal fusion. There were 7 (21.2%) patients who underwent spinal fusion, including 6 posterior spinal fusions and 1 anterior spinal fusion. Four patients had complications, including 3 pseudarthroses, 4 implant failures, 3 superior junctional kyphosis, and 1 infection, for a 57% complication rate.

CONCLUSIONS

Scoliosis developed in 8.7% of patients with Down syndrome. There was a high rate of cardiac surgery within this population. Bracing was ineffective for the majority of the patients treated. Although surgery has a high rate of complications, there was only one patient who underwent reoperation.

Implantable direct current stimulation in para-axial cervical arthrodesis

This retrospective, case-controlled pilot study was designed to examine the efficacy and safety of an implantable direct current bone growth stimulator (IDCBGS) as an adjunct to cervical arthrodesis in patients at high risk for nonunion after undergoing cervical fusion in region from the occiput to C3. Twenty patients underwent para-axial cervical arthrodesis (involving posterior spine fusion and instrumentation using standard surgical techniques) for the correction of instability. All were at high risk for nonunion due to advanced age, rheumatoid arthritis, prior failed fusion attempts, infection, or immunosuppressive drug use. An IDCBGS was used to augment the surgical procedure. The mean follow-up period was 19 months, and 16 patients were available for follow-up. Radiographic evidence of fusion was demonstrated in 15 of 16 patients (94%). After surgery, all patients demonstrated clinical stabilization, a resolution of symptoms in combination with an improvement in neurologic status, or both. The mean elapsed time before fusion occurred was 4.6 months. No neurologic complications related to cathode or generator placement were observed. The use of the stimulator as an adjunct to instrument- or non-instrument-assisted surgical fusion of the para-axial region in these high-risk patients appeared both safe and efficacious. Further investigation is warranted to define the possible role and clinical utility of the IDCBGS in selected patients requiring cervical fusion, particularly those at high risk for nonunion.

Cervical myelopathy in an adult due to atlantoaxial subluxation associated with Down syndrome: a case study

Atlantoaxial subluxation resulting in cervical myelopathy in patients with Down syndrome has been well documented. The risk of cervical myelopathy is reported to decrease with age, and reports of adult-onset cases are limited. We report an adult patient with Down syndrome who developed cervical myelopathy and was successfully treated by surgery. Because there is little information on this condition with adult onset, we report the features of the radiographic findings. Particular care over the long term should be taken in those who have atlantoaxial subluxation combined with odontoid hypoplasia or accessory ossicles, as they are at particular risk of cervical myelopathy even during adulthood.

Down's syndrome

The sequencing of chromosome 21 and the use of models of Down's syndrome in mice have allowed us to relate genes and sets of genes to the neuropathogenesis of this syndrome, and to better understand its phenotype. Research in prenatal screening and diagnosis aims to find methods to identify fetuses with Down's syndrome, and reduce or eliminate the need for amniocentesis. Other areas of active research and clinical interest include the association of Down's syndrome with coeliac disease and Alzheimer's disease, and improved median age of death. Medical management of the syndrome requires an organised approach of assessment, monitoring, prevention, and vigilance. Improvements in quality of life of individuals with Down's syndrome have resulted from improvements in medical care, identification and treatment of psychiatric disorders (such as depression, disruptive behaviour disorders, and autism), and early educational interventions with support in typical educational settings. Approaches and outcomes differ throughout the world.

C1-C2 posterior fusion in growing patients: long-term follow-up

STUDY DESIGN

A retrospective review of patients undergoing C1-C2 posterior fusion during childhood was undertaken.

OBJECTIVES

The aim of this study was to investigate the change in the sagittal curvature of the cervical spine in children after C1-C2 posterior fusion.

SUMMARY OF BACKGROUND DATA

There have been only a few reports on postoperative changes in the sagittal curvature of the cervical spine after C1-C2 posterior fusion in children. However, they have all described the onset of sagittal postoperative cervical deformities.

METHODS

Between January 1977 and December 1992, a total of 12 children underwent C1-C2 posterior fusion for atlantoaxial instability resulting from congenital malformation in eight, juvenile rheumatoid arthritis in one, and rotatory subluxation in three. The average age at the time of surgery was 10.9 years (range 7-12 years). All children underwent a similar treatment program with gradual preoperative reduction in halo cast, followed by C1-C2 posterior fusion with Mersilene loops in two cases, wiring in eight (Gallie's or Brooks' techniques), and interlaminar clamps in the remaining two. The halo cast made it possible to avoid a hyperextended or hyperflexed C1-C2 position while performing the atlantoaxial fusion, thus ensuring a more anatomic position during C1-C2 fusion. In the postoperative period, the halo cast was maintained for 7 to 9 weeks. RESULTS Follow-up ranged from 7 years to 13 years. Preoperative alignment of the cervical spine was classified into two groups: lordosis (eight patients) and straight (four patients). Postoperative subaxial malalignment (kyphosis) occurred in four cases (33%): these patients showed evidence of spontaneous and gradual sagittal improvement and presented either a straight (two cases) or a lordotic (two cases) cervical spine at follow-up. Immediately after surgery, the cervical spine was normally aligned in the remaining eight patients (lordosis and straight alignment in six and two cases, respectively) and was unchanged at follow-up. At follow-up, none of the 12 patients had a cervical deformity on sagittal plane.

CONCLUSION

In children, a spontaneous realignment of the subaxial kyphosis observed after C1-C2 posterior fusion can be noted at follow-up, when a postoperative deformity occurs (33% in the present series). According to the present findings, it is not always mandatory to perform occipitocervical fusion in children with atlantoaxial instability just to prevent subaxial deformity in the cervical spine.

Down syndrome: progress in research

This review discusses the research published in the last five years on the behavioral, genetic, medical, and neuroscience aspects of Down syndrome. The subject areas that have experienced the most active research include Alzheimer disease, language development, leukemia, and pregnancy screening and diagnosis. These and other areas are reviewed.

Treatment of Down syndrome-associated craniovertebral junction abnormalities

OBJECT

Operative intervention for craniovertebral junction (CVJ) instability in patients with Down syndrome has become controversial, with reports of a low incidence of associated neurological dysfunction and high surgical morbidity rates. The authors analyzed their experience in light of these poor results and attempted to evaluate differences in management.

METHODS

Medical and radiographic records of 36 consecutive patients with Down syndrome and CVJ abnormalities were reviewed. The most common clinical complaints included neck pain (15 patients) and torticollis (12 patients). Cervicomedullary compression was associated with ataxia and progressive weakness. Hyperreflexia was documented in a majority of patients (24 cases), and 13 patients suffered from varying degrees of quadriparesis. Upper respiratory tract infection precipitated the presentation in five patients. Four patients suffered acute neurological insults after a minor fall and two after receiving a general anesthetic agent. Atlantoaxial instability was the most common radiographically observed abnormality (23 patients), with a rotary component present in 14 patients. Occipitoatlantal instability was also frequently observed (16 patients) and was coexistent with atlantoaxial dislocation in 15 patients. Twenty individuals had bone anomalies, the most frequent of which was os odontoideum (12 patients) followed by atlantal arch hypoplasia and bifid anterior or posterior arches (eight patients). Twenty-seven patients underwent surgical procedures without subsequent neurological deterioration, and a 96% fusion rate was observed. In five of 11 patients basilar invagination was irreducible and required transoral decompression. Overall, 24 patients enjoyed good or excellent outcomes.

CONCLUSIONS

The results of this series highlight the clinicopathological characteristics of CVJ instability in patients with Down syndrome and suggest that satisfactory outcomes can be achieved with low surgical morbidity rates.

Instability of the craniovertebral junction and treatment outcomes in patients with Down's syndrome

Operative intervention for the treatment of instability at the craniovertebral junction in patients with Down's syndrome has become somewhat controversial because some authors have reported high surgery-related complication rates and suggested that the incidence of neurological abnormality associated with this abnormal motion may be low. In this report, the authors describe the clinical and radiographic findings in 33 patients treated at their institution. Common presenting symptoms included neck pain (14 patients), torticollis (12 patients), and myelopathy manifested as hyperreflexia (21 patients), or varying degrees of quadriparesis (11 patients). Four patients suffered acute neurological insults, two after receiving routine general anesthetics for minor surgical procedures and two other patients following minor falls. Atlantoaxial instability was the most common abnormality documented on radiography (22 patients). Atlantooccipital instability (15 patients) was also frequently observed and was coexistent with the presence of atlantoaxial luxations in 14 patients. A rotary component of the atlantoaxial luxation was present in 13 cases. In 17 patients bony anomalies were present, the most frequent of which was os odontoideum (10 patients). Twenty-four patients underwent operative intervention, and successful fusion was achieved in 23. In six of nine patients with basilar invagination, reduction was achieved with preoperative traction and thus avoided the need for ventral decompressive procedures. There were no cases of postoperative deterioration, and 22 patients made excellent or good recoveries. The results of this series highlight the clinicopathological phenomena of craniovertebral instability in patients with Down's syndrome and suggest that satisfactory outcomes can be achieved with a low rate of surgical morbidity.

Closed treatment of hip dislocation in Down syndrome

Two young children (three hips) with Down syndrome and dislocation of the hip were successfully treated by nonoperative methods by using the principle of prolonged immobilization or bracing. A 5-year, 6-month-old patient with bilateral habitual dislocation used an ambulatory abduction orthosis full-time for 6 months and then part-time for 4 months. Complete dislocation of the right hip in a 4-year, 6-month-old patient was managed by closed reduction, spica cast immobilization for 4 months, and then an ambulatory abduction orthosis for 8 months. Both patients developed stable, well-contained hips. Nonoperative management of hip dislocation in Down syndrome can be successful and avoids the complications associated with operations previously recommended for these patients.