Symptomatic atlantoaxial instability in an adolescent with trisomy 21 (Down's 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.

Otolaryngologic Disease in Down syndrome

As the most common human chromosomal abnormality, Trisomy 21 is a condition that many otolaryngologists and likely all pediatric otolaryngologists will encounter during their careers. There are several considerations regarding airway obstruction, otologic conditions, anesthetic implications, and endocrine disorders that will impact the treatment of these patients. Further, there is increasing literature supporting the use of early instrumental assessment of swallowing, drug-induced sleep endoscopy at the time of first surgical intervention for sleep apnea, consideration of concurrent upper and lower airway evaluation, and early otologic management including potential surgical hearing rehabilitation.

Cranial-Vertebral-Maxillary Morphological Integration in Down Syndrome

Background: Morphological integration refers to the tendency of anatomical structures to show correlated variations because they develop in response to shared developmental processes or function in concert with other structures. The objective of this study was to determine the relationships between the dimensions of different cranial-cervical-facial structures in patients with Down syndrome (DS). Methodology: The study group consisted of 41 individuals with DS who had undergone cone-beam computed tomography (CBCT) at the Dental Radiology Unit of the University of Santiago de Compostela (Spain). In the historical archive of this same unit, 41 CBCTs belonging to individuals with no known systemic disorders or severe malformations of the maxillofacial region were selected, forming an age and sex-matched control group. Twenty-nine measurements were performed on each participant’s CBCT images, which were grouped into three blocks: atlantoaxial dimensions, craniovertebral dimensions and cephalometric dimensions. To determine whether there were significant differences between the dimensions obtained in the DS and control groups, we applied multiple analysis of variance and linear discriminant analysis tests. The analysis of the association between blocks (in pairs) was performed with the canonical correlation analysis test. Results: The dimensions evaluated in the three blocks of variables of individuals with DS differ significantly from those of nonsyndromic controls (p < 0.001). The highest discriminative capacity to identify controls and patients with DS was obtained with the cephalometric dimensions (87.5%). With regard to the association between blocks (two-by-two measurements), we found no significant relationship in the DS group. However, we confirmed a statistically significant correlation between all pairs of blocks of variables in the controls, especially between the atlantoaxial and cephalometric dimensions (p < 0.001) and between the craniovertebral and cephalometric dimensions (p < 0.001). Conclusions: Our results confirm a very poor morphological integration of the cranial-cervical-maxillary complex in individuals with DS. This finding reinforces the proposal that gene overload enhances the channeling process.

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.

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.

Patient-Centered Strategies to Improve Radiographic Practice for Patients with Down Syndrome: A Systematic Review

BACKGROUND

Down syndrome is a common human genetic disorder caused by trisomy of chromosome 21. Individuals with Down syndrome can present with a range of health issues during their lives that may require imaging for diagnosis. Radiographers, therefore, play a significant role in the management and communication of Down syndrome patients' health.

PURPOSE

This review identified patient-centered strategies that radiographers should use to provide quality imaging services for Down syndrome patients, who may have limited verbal ability and behavioral issues.

METHOD

A systematic review using the established PRISMA guidelines was undertaken of current literature obtained through the Ovid and Scopus databases. A total of 189 articles were found, of which 41 were categorized and analyzed in detail.

FINDINGS

A high level of care for Down syndrome patients will require longer than usual procedures, and the patients will not respond well to being rushed or ignored. Down syndrome patients have difficulty verbalizing, yet they understand more than is often thought. Individuals may require increased imaging time to give them time to respond, especially to pain. Patients are at risk of injury with AAI or other pathologies, and caution should be taken with flexion and extension spine x-rays. Radiographs may reveal undisclosed physical abuse.

CONCLUSION

Specific strategies with verbal and nonverbal communication help to facilitate communication, reduce anxiety and fear, and improve compliance with Down syndrome patients. Patients may require an increased level of care; increased imaging time; and allowing support people to be present during the examination process.

Motor and somatosensory evoked potential spinal cord monitoring during intubation and neck extension for thyroidectomy in a Down syndrome boy with atlantoaxial instability

Intubation or neck extension can compress the spinal cord in patients with craniocervical instability. Protective motor evoked potential (MEP) and somatosensory evoked potential (SEP) monitoring of these maneuvers is an obvious consideration when these patients undergo already-monitored spinal surgery, but might be overlooked when they undergo other normally unmonitored procedures. Here we report monitoring intubation and neck extension for the unusual indication of thyroidectomy in a Down syndrome boy with atlantoaxial instability. Transcranial electric stimulation thenar MEPs and optimized median nerve SEPs were acquired about every minute throughout intubation and neck extension under propofol and remifentanil anesthesia without neuromuscular blockade. Potentials were stable and there was no neurologic deficit. This approach could protect craniocervical instability patients against cord compression when they undergo intubation and neck extension for surgical procedures that would not otherwise indicate spinal cord monitoring.

A cervical flexion-extension MRI study in Down syndrome

OBJECTIVE

To assess what kind of information MR examination in flexed and extended positions provides in Down syndrome subjects with suspected cranio-cervical instability.

METHODS

Between 2005 and 2008, 35 subjects with DS were recruited in the study. Ethics committee approval was granted and a signed informed consent was obtained from the parents. All the subjects were affected by hypotonic status and ligament laxity established by clinical evaluation, but were asymptomatic about focal neurological symptoms due to medullar damage caused by cranio-cervical instability. Each patient underwent lateral supine radiographs and MR imaging in the neutral, active flexed and extended positions. For evaluating the atlanto-axial and atlanto-occipital joint stability, multiple measurements were calculated.

RESULTS

A significant reduction of anterior subarachnoid space in flexed position was evident in DS subjects compared to healthy controls in neutral and flexed positions. Both, space available for cord and ligamentous thickness showed significant differences between DS subjects and healthy controls. In DS subjects with occipito-cervical instability, the anterior subarachnoidal space reduction was significantly reduced in flexed position.

CONCLUSIONS

In DS subjects with asymptomatic cranio-cervical instability, anterior subarachnoidal evaluation and ligamentous status could add new information about the risk of spinal cord damage.

Atlanto-Axial Instability in People with Down's Syndrome and its Impact on the Ability to Perform Sports Activities - A Review

Atlanto-axial instability (AAI) is a developmental anomaly often occurring in persons with Down’s syndrome (DS). According to various reports, AAI affects from 6.8 to 27% of the population with DS. The aim of this review was to illustrate the issue of AAI with regard to the progressively changing state of scientific knowledge. The extended distance between the rear surface of the frontal arcus of the C1 cervical vertebra and the anterior surface of C2 cervical vertebra dens (anterior atlanto-odontoid distance, AAOD) indicates the occurrence of AAI and is detectable through X-ray examination. Hypoplasia of the C2 dens, also detectable through X-ray examination, is another suggested risk factor for AAI. According to current data, the methodology of taking measurements is inconsistent, which leads to errors in interpretation. As research focusing on AAI was progressing, new data emerged from other studies on persons with DS, suggesting that neurological symptoms in persons with DS that indicated the occurrence of spinal cord compression were an important factor in medical imaging detection of AAI. One of the main arguments supporting this thesis is that in isolated cases spinal cord (SC) damage was noted during screening examinations conducted on a large population of subjects. Moreover, cases in which the neurological symptoms indicate spinal cord compression existed long before the occurrence of the actual damage also remain of significant importance. Therefore, it is necessary to promote neurological studies on persons with DS to enable early diagnosis of spinal cord compression and, at the same time, reduce the use of medical imaging in cases of neurological symptoms.

A review of the diagnosis and treatment of atlantoaxial dislocations

Study Design Literature review. Objective Atlantoaxial dislocation (AAD) is a rare and potentially fatal disturbance to the normal occipital-cervical anatomy that affects some populations disproportionately, which may cause permanent neurologic deficits or sagittal deformity if not treated in a timely and appropriate manner. Currently, there is a lack of consensus among surgeons on the best approach to diagnose, characterize, and treat this condition. The objective of this review is to provide a comprehensive review of the literature to identify timely and effective diagnostic techniques and treatment modalities of AAD. Methods This review examined all articles published concerning "atlantoaxial dislocation" or "atlantoaxial subluxation" on the PubMed database. We included 112 articles published between 1966 and 2014. Results Results of these studies are summarized primarily as defining AAD, the normal anatomy, etiology of dislocation, clinical presentation, diagnostic techniques, classification, and recommendations for timely treatment modalities. Conclusions The Wang Classification System provides a practical means to diagnose and treat AAD. However, future research is required to identify the most salient intervention component or combination of components that lead to the best outcomes.