Clinical predictors and radiological reliability in atlantoaxial subluxation in Down's syndrome

The Change of Asymptomatic Atlantoaxial Instability With Down Syndrome From Infant to Adolescent in Japanese Population: Minimum 10 Years Follow-Up

BACKGROUND

Although 10% to 60% of patients with Down syndrome (DS) develop atlantoaxial instability (AAI), clarifying the course of asymptomatic AAI may prevent unnecessary clinical interactions and investigations. This study investigates the radiographic changes observed in asymptomatic AAI associated with DS in Japanese children as they grow from infancy to adolescence over a minimum of 10 years.

METHODS

A retrospective analysis of cervical radiographs acquired from asymptomatic patients with DS in both infancy and adolescence was carried out. Radiographic evaluation included measuring the atlantodental interval (ADI) and the space available for the cord (SAC). In neutral lateral cervical radiographs, AAI was defined as ADI >6 mm and SAC <14 mm.

RESULTS

Two hundred thirty-nine patients were included. The mean follow-up was 12.8 years. ADI was 2.3 mm at initial evaluation and 2.7 mm at final evaluation (P<0.01) in a neutral position, 3.1 and 3.3 mm in flexion (P=0.18), and 1.7 and 2.1 mm in extension (P<0.01), respectively. SAC was 15.8 mm at initial evaluation and 20.9 mm at final evaluation (P<0.01) in neutral position, 15.6 and 20.7 mm in flexion (P<0.01), and 16.8 and 21.0 mm in extension (P<0.01), respectively. Forty-five patients (18.8%) showed evidence of AAI at the initial evaluation with 4 patients meeting the threshold for AAI at the final evaluation, one of which had os odontoideum. In contrast, of the 194 patients who did not have AAI at the initial evaluation, 3 (1.3%) developed AAI at the final evaluation. One of these with a normal den developed AAI at 13 years.

CONCLUSIONS

As 1 patient with a normal dens developed AAI at 13 years, we recommend screening for AAI with X-ray in infancy and adolescence regardless of the presence or absence of an os odontoideum.

EVIDENCE LEVEL

Level IV.

Successful recovery from cardiac arrest due to atlantoaxial subluxation in Down syndrome: a case report

INTRODUCTION

Down syndrome is the most common chromosomal abnormality associated with intellectual impairments. Unexpected deaths are common with this disease. There are certain difficulties in clarifying the cause of death because the manifestations may be quite diverse and involve many organ systems. Atlantoaxial subluxation is a dangerous complication of Down syndrome, as it may lead to cervical cord-medullary compression.

CASE PRESENTATION

Herein, we present a case of Down syndrome in a patient who completely recovered from cardiac arrest due to atlantoaxial subluxation. The neck was immobilized during post-cardiac arrest care, and the patient underwent surgery after 14 days. The patient could walk independently and was discharged 3 months later. At the last follow-up 5 years after surgery, the patient's general condition was good.

DISCUSSION

Physicians should be aware that atlantoaxial instability can cause cardiac arrest in patients with genetic syndromes.

Repeat Pediatric Trisomy 21 Radiographic Exam: Does Atlantoaxial Instability Develop Over Time?

BACKGROUND

Atlantoaxial instability (AAI) is common in pediatric patients with Trisomy 21 and can lead to spinal cord injury during sports, trauma, or anesthetized neck manipulation. Children with Trisomy 21 therefore commonly undergo radiographic cervical spine screening, but recommendations on age and timing vary. The purpose of this study was to determine if instability develops over time.

METHODS

We performed a retrospective review for all pediatric Trisomy 21 patients receiving at least 2 cervical spine radiographic series between 2008 and 2020 at our institution. Atlantodens interval (ADI) and space available for the cord at C1 (SAC) were measured; bony abnormalities such as os odontoidium, and age and time between radiographs were noted. AAI was determined by ADI ≥6 mm or SAC ≤14 mm based on our groups' prior study. Those who developed instability were compared with those who did not.

RESULTS

A total of 437 cervical spine radiographic series from 192 patients were evaluated, with 160 included. Mean age at first radiograph was 7.4±4.4 years, average ADI was 3.1 mm (±1.2), and SAC was 18.1 mm (±2.6). The average time between first and last radiographs was 4.3 years (±1.8), with average final ADI 3.2 mm (±1.4) and SAC 18.9 mm (±2.9). Seven patients (4%) had instability: 4 were unstable on their initial studies and 3 (1.6%) on subsequent imaging. Os odontoideum was found in 5 (71%) unstable spines and 3 (2%) stable spines (P<0.0001); only 1 patient that became unstable on subsequent radiograph did not have an os. There was no specific age cut-off or surveillance time period after which one could be determined no longer at risk.

CONCLUSIONS

Trisomy 21 patients have a 4.4% overall rate of AAI in our series with a 1.6% rate of progression to instability over ∼4 years. Given this nearly 1 in 23 risk of instability, we recommend initial surveillance radiograph for all children over 3 years with Trisomy 21; repeat asymptomatic surveillance should continue in those with os odontoideum given their high instability risk.

LEVEL OF EVIDENCE

Level II-diagnostic study.

Sport Preparticipation Screening for Asymptomatic Atlantoaxial Instability in Patients With Down Syndrome

Down syndrome (DS) is a clinical syndrome comprising typical facial features and various physical and intellectual disabilities due to extra genetic material on chromosome 21, with one in every 1000 babies born in the United Kingdom affected. Patients with Down syndrome are at risk of atlantoaxial instability (AAI). Although AAI can occur in other conditions, such as rheumatoid arthritis, this position statement deals specifically with patients with DS and asymptomatic AAI. Atlantoaxial instability, also referred to as atlantoaxial subluxation, is defined as increased movement between the first (atlas) and second (axial) cervical vertebra joint articulation, the atlantoaxial joint. Atlantoaxial instability is reported to occur in 6.8% to 27% of the DS population, although this varies depending on the age of the patients whom you are screening. Less than 1% to 2% of these patients are then thought to later develop symptomatic AAI, although the natural history and progression of AAI is not well understood. The risks associated with AAI are neurological injury from excessive movement of the cervical vertebra impinging on and then damaging the spinal cord, although the risk of this during sporting activities is extremely rare. Clearly, physical activity and sports participation for patients with DS has many biological, psychological, and social benefits, and the Faculty of Sport and Exercise Medicine (FSEM), United Kingdom, wishes to promote safe physical activity and sport for all. The FSEM, United Kingdom, has therefore produced a statement regarding sport preparticipation screening for asymptomatic AAI in patients with DS.

Assessment of craniocervical motion in Down syndrome: a pilot study of two measurement techniques

OBJECTIVE

Hypermobility of the craniocervical junction (CCJ) in patients with Down syndrome (DS) is common. Whereas atlantoaxial (C1-2) hypermobility is well characterized, occipitoatlantal (Oc-C1) laxity is recognized but poorly defined. A clear understanding of the risks associated with DS-related hypermobility is lacking. Research efforts to address the topic of axial cervical spine instability in the patient with DS require a reliable and reproducible means of assessing CCJ mobility. The authors conducted a pilot study comparing two methods of quantifying motion of the CCJ on dynamic (flexion/extension) plain radiographs: the delta-condyle-axial interval (ΔCAI) and the delta-basion-axial interval (ΔBAI) methods.

METHODS

Dynamic radiographs from a cohort of 10 patients with DS were evaluated according to prescribed standards. Independent movement of Oc-C1, C1-2, and Oc-C2 was calculated. Interrater and intrarater reliability for CCJ mobility was then calculated for both techniques.

RESULTS

Measurement using the ΔCAI technique had excellent fidelity with intraclass correlation coefficients (ICCs) of 0.77, 0.71, and 0.80 for Oc-C1, C1-2, and Oc-C2, respectively. The ΔBAI technique had lower fidelity, yielding respective ICCs of 0.61, 0.65, and 0.50.

CONCLUSIONS

This pilot study suggests that ΔCAI is a superior measurement technique compared to ΔBAI and may provide reliable assessment of the mobility of the CCJ on dynamic radiographs in the pediatric patient with DS. The use of reliable and reproducible measurement techniques strengthens the validity of research derived from pooled database efforts.

An Updated Algorithm for Radiographic Screening of Upper Cervical Instability in Patients With Down Syndrome

STUDY DESIGN

Retrospective evaluation of cervical spine images from 2006-2012 for the purposes of "screening" children with Down syndrome for instability.

OBJECTIVE

To determine whether a full series of cervical spine images including flexion/extension lateral (FEL) radiographs was needed to avoid missing upper cervical instability.

SUMMARY OF BACKGROUND DATA

The best algorithm, measurements, and criteria for screening children with Down syndrome for upper cervical instability are controversial. Many authors have recommended obtaining flexion and extension views. We noted that patients who require surgical stabilization due to myelopathy or cord compression typically have grossly abnormal radiographic measurements on the neutral upright lateral (NUL) cervical spine radiograph.

METHODS

The atlanto-dental interval, space available for cord, and basion axial interval were measured on all films. The Weisel-Rothman measurement was made in the FEL series. Clinical outcome of those with abnormal measurements were reviewed. Sensitivity, specificity, and positive and negative predictive values of NUL and FEL radiographs for identifying clinically significant cervical spine instability were calculated.

RESULTS

A total of 240 cervical spine series in 213 patients with Down syndrome between the ages of 4 months and 25 years were reviewed. One hundred seventy-two children had an NUL view, and 88 of these patients also had FEL views. Only one of 88 patients was found to have an abnormal atlanto-dental interval (≥6 mm), space available for cord at C1 (≤14 mm), or basion axial interval (>12 mm) on an FEL series that did not have an abnormal measurement on the NUL radiograph. This patient had no evidence of cord compression or myelopathy.

CONCLUSIONS

Obtaining a single NUL radiograph is an efficient method for radiographic screening of cervical spine instability. Further evaluation may be required if abnormal measurements are identified on the NUL radiograph. We also propose new "normal" values for the common radiographic measurements used in assessing risk of cervical spine instability in patients with Down syndrome.

LEVEL OF EVIDENCE

Level IV.

Systematic review of the diagnostic accuracy, reliability, and safety of the sharp-purser test

Introduction: The Sharp-Purser Test (SPT) is used to assess for atlantoaxial instability (AI) in patients with rheumatoid arthritis (RA). The test is commonly used by clinicians; however, many experts argue it lacks reliability and validity along with concerns of safety. The primary purpose of this review is to determine the diagnostic accuracy of the SPT to detect AI.Methods: A search of five databases was performed from inception to 19 December 2018 using search terms related to the SPT. Studies were eligible for inclusion if the SPT was used on a patient/participant. Methodological quality assessment of diagnostic studies was performed with the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) for studies that reported data to calculate sensitivity (SN), specificity (SP), positive likelihood ratio (+LR), and negative likelihood ratio (-LR).Results: The search yielded 1009 articles, and 32 studies met the inclusion criteria for analysis. Meta-analysis on diagnostic accuracy studies assessing the SPT was not possible due to statistical heterogeneity. Six diagnostic accuracy studies assessed the SN of the SPT ranging from 0.19 to 1.00. Four of the studies assessed SP of the SPT ranging from 0.71 to 0.98. The +LR was identified in 4 studies was 0.655, 1.73, 22, and 17.25. The -LR was 1.14, 0.799, 0.571, and 0.323. Seven RCTs utilized the SPT to screen for AI, and the SPT was used in 18 case reports.Conclusion: The SPT may be inappropriate to use due to inconsistent validity, poor inter-rater reliability, and potential to cause harm.Level of evidence: 1.

Musculoskeletal anomalies in children with Down syndrome: an observational study

BACKGROUND

Musculoskeletal complications of Down syndrome (DS) are common but infrequently reported. The combination of ligamentous laxity and low muscle tone contributes to increased risk of a number of musculoskeletal disorders and a delay in acquisition of motor milestones. The primary aim of this study was to describe musculoskeletal anomalies reported in a national cohort of children with DS.

METHODS

This was an observational study. Children with DS, aged 0-21 years, were invited to attend a musculoskeletal assessment clinic conducted by a paediatric physician. Relevant musculoskeletal history and clinical findings were documented.

RESULTS

Over an 18-month period, 503 children with DS were examined (56% male). The median age was 8.1 years (0.6-19.2). Pes planus was almost universal, occurring in 91% of the cohort. A range of other musculoskeletal anomalies were observed, with inflammatory arthritis (7%) and scoliosis (4.8%) occurring most frequently after pes planus. Delay in ambulation was common; the median age to walk was 28 months (12-84).

CONCLUSION

Children with DS are at increased risk of a number of potentially debilitating musculoskeletal problems. These conditions can present in variable manners or be completely asymptomatic. Pes planus is common; therefore, early consideration of orthotics and lifelong appropriate supportive footwear should be considered. Delayed ambulation is frequently noted. A significant proportion of children with DS have arthritis; however, despite a high prevalence, it is often missed, leading to delayed diagnosis. An annual musculoskeletal assessment for all children with DS could potentially enable early detection of problems, allowing for timely multidisciplinary team intervention and better clinical outcomes.

Dynamic MRI in the Evaluation of Atlantoaxial Stability in Pediatric Down Syndrome Patients

BACKGROUND/AIMS

Down syndrome is the most common inherited disorder. Some patients develop atlantoaxial instability. Existing screening guidelines were developed prior to availability of MRI. We present predictors for deficit using dynamic MRI of the craniocervical junction.

METHODS

A retrospective review of Down syndrome patients from 2001 to 2015 was carried out. Patients were considered symptomatic if they had clinical deficits or signal change on MRI. Measurements were taken at the atlantoaxial junction and structural abnormalities noted. Analysis was performed with SPSS.

RESULTS

A total of 36 patients were included. Patients averaged 93 months of age with a follow-up of 57 months. No asymptomatic patients developed myelopathy during follow-up. During dynamic imaging, symptomatic patients had greater changes in space available for the cord (SAC) (5.2 vs. 2.7 mm; p < 0.001) and atlantodental interval (ADI) (2.8 vs. 1.3 mm; p = 0.04). These patients were also more likely to have a bony anomaly (50 vs. 13%; p = 0.03).

CONCLUSION

This study characterizes the range of motion seen on dynamic MRI and provides parameters that can be used to distinguish patients at risk for neurologic injury. Changes greater than 3 mm in ADI or 5 mm in SAC during dynamic MRI or any bony abnormality warrants further investigation. Patients without these features may be able to avoid an unnecessary intervention.

A review of canine atlantoaxial joint subluxation

Atlantoaxial subluxation was first reported in dogs nearly fifty years ago. Since that time a better understanding of the aetiologies pre-disposing to joint laxity and instability has been achieved. Surgeons however are still trying to address the problems associated with stabilizing this joint which by nature is often required in small juvenile dogs. This review describes the various techniques used, discussing the associated benefits and complications thereby allowing the clinician to make an informed decision on the best treatment for the individual patient.

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.

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.

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.

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.

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

Atlantoaxial instability (AAI) occurs in 15% of children with Trisomy 21. Health supervision guidelines were revised by the American Academy of Pediatrics in 2011 to reflect advances in care for children with special health care needs (CSHCN). Previous guidelines recommended cervical spine radiological screenings in preschool years to evaluate for atlantoaxial instability. For patients with negative screening, re-screening was recommended if they wished to compete in the Special Olympics, or became symptomatic. We present the case of an adolescent who developed a symptomatic atlantoaxial dislocation despite previous negative radiological screening at the age three (under the 2001 guidelines). This case report highlights the revisions in the 2011 guidelines for health supervision and anticipatory guidance. It underlines the need for a high index of suspicion if symptoms develop. It also addresses the need for a medical home for CSHCN, with health care providers who know the child's baseline health status.

Health supervision for children with Down syndrome

These guidelines are designed to assist the pediatrician in caring for the child in whom a diagnosis of Down syndrome has been confirmed by chromosome analysis. Although a pediatrician's initial contact with the child is usually during infancy, occasionally the pregnant woman who has been given a prenatal diagnosis of Down syndrome will be referred for review of the condition and the genetic counseling provided. Therefore, this report offers guidance for this situation as well.

Imaging the craniocervical junction

INTRODUCTION

The craniovertebral junction (CVJ) comprises the occiput, atlas, and axis. Radiographic evaluation of this region involves knowledge of only a few anatomical landmarks, as well as basic normal measurements and relationships to perform CVJ craniometry. Occipital bone anomalies and atlanto-occipital non-segmentation typically produce basilar invagination. Atlas anomalies predominantly involve the posterior arch, while the os odontoideum accounts for the majority of axis anomalies.

RESULTS AND DISCUSSION

A number of syndromes are associated with CVJ pathology, the most notable being Klippel-Feil and Down syndromes, achondroplasia, the mucopolysaccharidoses, and osteogenesis imperfecta. Skull-base softening associated with some of these syndromes results in acquired basilar invagination or basilar impression. In this article, we present a detailed review of essential anatomy and craniometry needed for radiographic assessment of the CVJ and illustrate various congenital anomalies of the occiput, atlas, and axis. The common syndromes affecting this region are also discussed and illustrated.

Pediatric cervical spine instability

Cervical spine instability in children is rare but not exceptional and may be due to many factors. Although it mostly occurs at the upper cervical spine, all vertebrae from the occiput to T1 may be involved. It may be acute or chronic, occurring secondary to trauma or due to congenital anomaly, skeletal or metabolic dystrophy or rheumatoid arthritis. It can be isolated or associated with other musculoskeletal or visceral anomalies. A thorough knowledge of embryology, anatomy, physiology and physiopathology of the cervical spine in children is essential to avoid pitfalls, recognize normal variants and identify children at risk of developing cervical spine instability and undertake the appropriate treatment.

Cervical spine abnormalities associated with Down syndrome

Atlantoaxial instability (AAI) affects 10-20% of individuals with Down syndrome (DS). The condition is mostly asymptomatic and diagnosed on radiography by an enlarged anterior atlanto-odontoid distance. Symptomatic AAI, which affects 1-2% of individuals with DS, manifests with spinal cord compression. Cervical spondylosis, which is common in DS, also has the potential for cord damage but it has received less attention because paediatric populations were mostly studied. Forty-four Kuwaiti subjects with DS, whose ages were > or = 15 years, were evaluated clinically and radiographically. Lateral neck radiographs were taken in the neutral and flexion positions. Asymptomatic AAI was diagnosed in eight subjects (18%) and congenital anomalies of C1-2 were found in five (12%). Five patients had AAI in flexion only while three patients had it in both views. Three patients with AAI had odontoid anomalies contributing to the condition. When assessing AAI, the posterior atlanto-odontoid distance has to be considered because it indicates the space available for the cord. Cervical spondylosis was noted in 16 (36%) subjects. Degenerative changes increased with age, occurred earlier than in the normal population, and affected mostly the lower cervical levels. Half the patients with AAI had cervical spondylosis, a comorbidity that puts the cord at increased risk.

Intra- and inter-rater reliability of the anterior atlantodental interval measurement from conventional lateral view flexion/extension radiographs

An investigation of intra- and inter-rater reliability anterior atlantodental interval (AADI) measurements was conducted using flexion/extension plain radiographs. Flexion and extension lateral radiographs of individuals investigated for atlantoaxial instability were measured for AADI on three occasions. Intra-rater intraclass correlation coefficients (ICC) were calculated for both flexion (0.99) and extension (0.96). Inter-rater ICCs were 0.93 and 0.84 for flexion and extension, respectively. The AADI measurement proved to be reproducible with a minimal standard of error, between and within raters.

Longitudinal study of thyroid function in Down's syndrome in the first two decades

AIMS AND METHODS

Thyroid function tests were initially carried out on 122 children with Down's syndrome aged 6-14 years and then repeated four to six years later in 103 adolescents (85% of the group of 122) when they were aged 10-20 years (median 14.4 years). At the second test two were hypothyroid and two with isolated raised thyroid stimulating hormone (IR-TSH) were receiving thyroxine.

RESULTS

At the first test there were 98 (80%) euthyroid children: 83 were retested and four (5%) had IR-TSH. At the first test 24 had IR-TSH: 20 were retested and 14 (70%) had become normal. Seventeen with IR-TSH on initial testing had a thyrotrophin releasing hormone test within three months; TSH had become normal in eight (47%) of these children. There was no association between reported clinical symptoms and IR-TSH, but there were clear symptoms in one of the two with definite hypothyroidism.

CONCLUSIONS

The likelihood ratio for a positive result on second testing when raised TSH and positive antibody status on first testing are combined is 20. This suggests initial testing results could be used as a basis to select a subgroup for further testing at say five yearly intervals unless new symptoms emerge in the interim. It also suggests that yearly screening (as recommended by the American Academy of Pediatrics, 2001) is probably not justified in the first 20 years of life.

Sports participation of children with Down syndrome

Patients with Down syndrome, by virtue of ligamentous laxity, are prone to a number of orthopedic problems with potentially serious sequelae. These disorders need to be evaluated throughout childhood and, when detected, appropriately managed. Given such management, the child with Down syndrome should be able to participate actively in and derive benefits from sports activities.

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.

Musculoskeletal rehabilitation and sports medicine. 4. Miscellaneous sports medicine topics

This self-directed learning module highlights new advances in this topic area. It is part of the chapter on musculoskeletal rehabilitation and sports medicine in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. This article discusses physiatric duties as a team physician, preparticipation physical examinations, ergogenic aids, heat-related illness, pediatric sports injuries, female sports injuries, and sports medicine topics pertinent to geriatric and physically or mentally challenged athletes. New advances covered in this section include use of creatine, guidelines for the preparticipation examination, sudden cardiac athletic death, pediatric and female anterior cruciate ligament injuries, the female athlete triad, spine screening in Down syndrome athletes, and "boosting" in athletes with spinal cord injury.

Indications and trends in use in cervical spinal fusions

Anterior cervical decompression and arthrodesis has evolved over the last 40 years and has become the preferred procedure for managing many cervical spine disorders. The first half of this article discusses the indications for cervical fusion in the management of traumatic, degenerative, neoplastic, infectious, and congenital conditions of the cervical spine. The second half of this article discusses the recent trends in use of cervical spine fusions that demonstrate the increasing frequency of this procedure in the United States over the last 10 years.

Congenital syndromes in paediatric anaesthesia: what is important to know

The purpose of this review is to re-evaluate our approach to the perioperative management of children with congenital syndromes, as a result of recent advances in the understanding of the role of genetic factors in the aetiology of specific syndrome complexes, and in accordance with current paediatric anaesthetic practice. Recent information elucidating the genetic basis of these syndromes will be examined and made relevant to paediatric anaesthetists in their emerging roles as perioperative physicians. Diagnostic testing and family counseling, as well as alterations in reactions to drugs will be considered. Finally, the current year of clinical practice at this hospital will be reviewed to determine the frequency that congenital syndromes are encountered, the most common clinical challenges they present, and to provide examples of the management of anaesthesia in selected cases. The review aims to facilitate the anaesthetist's preoperative assessment of a child with a congenital syndrome, suggest approaches to clinical anaesthetic management, and be a basis for further study of the influence of genetics in anaesthesia.

Atlantoaxial dislocation related to instilling eyedrops in a patient with Down's syndrome

PURPOSE

To alert ophthalmologists of the risk of hyperextending the neck of patients with Down's syndrome while holding them to instill eyedrops.

METHOD

We describe a case of atlantoaxial dislocation related to instilling eyedrops in a 6-year-old girl with Down's syndrome.

RESULT

Early recognition of the problem allowed prompt treatment and partial recovery of the patient.

CONCLUSION

Examination and clinical maneuvers in a child with Down's syndrome require gentleness and avoidance of hyperextension of the neck to prevent spinal cord injury.

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

STUDY DESIGN

A retrospective review of 15 patients with Down syndrome who had undergone arthrodesis of the upper cervical spine for instability.

OBJECTIVES

To determine the complication rate and long-term outcome after posterior cervical arthrodesis for upper cervical instability in patients with Down syndrome.

SUMMARY OF BACKGROUND DATA

Atlantoaxial instability is common in patients with Down syndrome, and fusion of the upper cervical spine has been recommended for patients who have instability, with or without myelopathy. Unfortunately, the results of posterior cervical arthrodesis are not well reported, and the natural history of this condition is unknown.

METHODS

Fifteen patients with an average follow-up period of 74.6 months (range, 24-142 months) were reviewed after posterior arthrodesis of the upper cervical spine. Twelve patients were reexamined by the investigators specifically for the purpose of this study, and three patients had long-term follow-up results available from chart review.

RESULTS

Eleven of 15 patients (73%) sustained 23 major complications including nonunion, loss of reduction, neurologic deterioration, late subaxial instability, infection, and wound dehiscence. Six patients (40%) required seven reoperations to address a complication. Ultimately, 12 patients (80%) obtained osseous union, but a definite clinical improvement was identifiable in only three patients, whereas two others had worsened neurologically at latest follow-up evaluation.

CONCLUSIONS

A high complication rate should be anticipated after posterior arthrodesis of the upper cervical spine in patients with Down syndrome. A cautious approach to asymptomatic instability in this condition is advocated.

Neck flexion and extension in children with Down syndrome: a somatosensory study

The cervical spine in Down syndrome patients is often lax, at least at radiographic imaging, and the risk of spinal cord embarrassment is increased. This study was performed to obtain information that would help identify patients at risk for this problem and reduce the risk of endotracheal intubation and other surgical procedures in patients with Down syndrome. Somatosensory evoked potential studies were performed in 15 consecutive children who were undergoing elective otolaryngic surgery. None had neurologic symptoms or the physical examination finding of cervical spinal cord embarrassment, and their cervical spines were considered normal by plain radiographs obtained in the neutral, flexed, and extended positions. No significant change in latency (P = .16) or amplitude (P = .19) was found when the anesthetized children had their necks placed in either full flexion or full extension. With more than 90% certainty, the authors believe that children with Down syndrome who have "normal" plain cervical spine radiographs are exposed to no extra risks from neck flexion or extension during surgery.

Atlantoaxial instability in Down's syndrome: a five year follow up study

In 1986 all 90 children aged 4-19 years with Down's syndrome attending school in the area served by the Southern Derbyshire Health Authority underwent radiography to identify atlantoaxial instability (AAI). This study details repeat observations five years later. Full results were available on 67 (74%), information on health status was available on the remaining 19 (21%); four (4%) were untraced. There was an overall significant reduction in the atlanto-axial gap over five years. No one developed AAI on repeat testing who had not had it earlier. One child who had previously had normal neck radiography developed acute symptomatic AAI after ear, nose, and throat surgery. Radiographs were done on three occasions on the same day in 49 individuals, ensuring full flexion of the upper neck. There were no significant differences between the radiographs, even in five subjects with AAI. Management of AAI in Down's syndrome is discussed in the light of these findings. Radiography can reliably detect children with chronic AAI who may be at risk of gradually developing symptoms; this may justify a screening programme. This must be distinguished from those who develop symptoms after acute trauma or anaesthesia, for which specific precautions are needed, and previous screening radiographs are unhelpful.

Preoperative evaluation of the cervical spine in children with trisomy-21: results of a questionnaire study

Atlantoaxial subluxation (AAS) is a form of cervical spine instability predominantly found in persons with Trisomy-21. Several case reports describe the occurrence of acute AAS in the perioperative period. Some authors have recommended cervical spine radiographs prior to elective surgery in all children with Trisomy-21. The objective of this study was to determine practice patterns of North American members of the Society of Pediatric Anesthesia with regard to the perioperative evaluation and management of potential cervical spine instability in patients with Trisomy-21. Of 171 respondents, a minority of respondents (18%) obtain preoperative radiographs and/or subspecialty consultation (9%) in asymptomatic children with Trisomy-21. For symptomatic children the majority of respondents would obtain radiographs (64%) and/or preoperative consultation (74%). Approximately half of the respondents would attempt to maintain the head and neck in a neutral position for either asymptomatic (42%) or symptomatic (55%) patients. We conclude that the majority of respondents base their preoperative evaluation of the cervical spine on the signs and symptoms of the patient. This is supported by the literature reviewed, but is contrary to the recommendations made in some case reports.

Radiological assessment of the atlantoaxial distance in Down's syndrome

People with Down's syndrome are pre-disposed to atlantoaxial instability. As part of a study to determine whether those with Down's syndrome should be screened for atlantoaxial instability before they participate in sport, a series of 279 children, aged 6 to 17 years was investigated radiologically. Lateral radiographs of the cervical spine were taken in neutral position and in flexion. The magnification factor was assessed by means of a marker attached to the nape of the neck. After correction for magnification 15% of the patients were found to have an atlantoaxial distance greater than 4 mm on the flexion film, especially boys under 11 years of age. However, sex and age together explained at most 9% of the variation in atlantoaxial distance. The maximum distance found was 6.5 mm. The disagreement between the means of first and second measurements by the same (test-retest) and by another (inter-) observer was more for those taken in the neutral position than in flexion. On a group level the results for reliability were satisfactory.