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

Surgical strategies in the management of atlantoaxial dislocation in Down syndrome

Aims

To study the clinicoradiological features and treatment outcomes of atlantoaxial dislocation (AAD) in Down syndrome.

Settings and Design

Retrospective case series.

Subjects and Methods

A retrospective chart and radiology review of 9 Down syndrome patients with AAD managed at our center from 2007 to 2018.

Statistical Analysis Used

Chi-squared/Fisher's exact test.

Results

There were 4 males and 5 females (n = 9). The median age was 14 years (interquartile range [IQR]: 7-15.5). 77.7% (7/9) of patients had severe spasticity (Nurick Grades 4 and 5). The median duration of symptoms was 9 months (IQR: 5-39). The AAD was reducible in all (n = 9) cases. Eight (88.8%) patients had os odontoideum. The mean atlantodental interval (ADI) was 8.5 mm (±2.9). T2W cord hyperintensity was seen in 66.6% (6/9). Posterior C1-2 transarticular fixation was done in 8 and occipitocervical fusion in 1 patient. Follow-up of more than 6 months (7-57 months) was available in 8/9 (88.9%) patients. There was a significant improvement in spasticity (n = 8, mean Nurick Grade 1.7 (±1.1), P = 0.003). Follow-up radiographs (n = 8) showed good reduction and fusion. A preoperative bedbound patient with poor respiratory reserve expired at 10 months following surgery. There were no other complications.

Conclusions

Posterior surgical approach for AAD in Down syndrome resulted in good alignment and fusion, with excellent clinical improvement. Patients with elevated PCO2 are poor surgical candidates and require home ventilation facility.

Neurophysiologic monitoring during cervical traction in a pediatric patient with severe cognitive disability and atlantoaxial instability

Background:

Surgical management of atlantoaxial instability (AAI) in pediatric patients with Down syndrome is associated with high neurological morbidity. Moreover, Down syndrome cognitive impairment coupled to AAI removes traditional verbal communication to relay evolving symptoms and aid in neurologic examination. It is not clear whether surgical adjuncts can alter clinical outcomes in this vulnerable population.

Case Description:

Herein, we report the case of a 6-year-old patient with significant developmental delay and severe AAI that was successfully managed by stabilization with guidance of neurophysiologic investigations in the perioperative phase.

Conclusion:

Perioperative neurophysiologic monitoring is safe, useful, and reliable in pediatric patients with trisomy 21 undergoing cervical traction and occipitocervical instrumented fusion for AAI.

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.

Perioperative care of adults with Down syndrome: a narrative review

Because of enhanced life expectancy due to medical and surgical therapeutic advances, it is estimated that there are more adults than children living with Down syndrome (DS), or trisomy 21, in the United States. Therefore, DS can no longer be considered a syndrome limited to the pediatric population. These patients are presenting for surgery and anesthesia in adult care settings, where anesthesiologists will encounter these patients more frequently. As these patients age, their commonly associated co-morbidities not only progress, but they also develop other cardiac, respiratory, gastrointestinal, and neurologic conditions. The manifestations and consequences of chronic disease can present new challenges for the anesthesiologist and require expertise and judgement to minimize patient risk. The purpose of this narrative review is to describe the common pediatric co-morbidities associated with DS and discuss the age-acquired manifestations. Additionally, considerations for anesthetic care of the adult with DS will be presented, including the preoperative assessment, intraoperative management, and postoperative care.

Evaluation of 2011 AAP cervical spine screening guidelines for children with Down Syndrome

PURPOSE

Atlantoaxial instability (AAI) has a higher incidence rate among individuals with Down syndrome (DS) than the non-DS population. In 2011, the American Academy of Pediatrics (AAP) updated its AAI screening guidelines for children with DS from radiographic screening to radiographs only if there are clinical symptoms suggestive of cervical spine pathology. An assessment of whether this alteration has been associated with an increase in AAI-associated spinal cord injury has not been undertaken.

METHODS

We provide the first neurosurgical review of a large experience implementing the 2011 AAP guidelines. We reviewed the courses of patients with DS seen at the Sie Center for Down Syndrome at Children's Hospital Colorado who were evaluated for cervical spine disease and determined whether screening radiographic imaging could have led to earlier diagnosis or prevented development of neurological deficits. We also report an illustrative case of a 5-year-old female with Down syndrome who presented with instability after normal screening radiographs per the pre-2011 guidelines.

RESULTS

The clinical experience of the Sie Center demonstrates that even when limiting imaging to patients who show signs or symptoms of spine pathology, the vast majority of x-rays are negative. Our exemplary patient presented to the emergency department for neck pain without a history of significant trauma. She was diagnosed and treated for atlantoaxial subluxation associated with os odontoideum.

CONCLUSION

Routine radiographic screening may not be sufficiently predictive of DS individuals at risk to develop AAI. This experience supports the appositeness of the de-escalation of care asserted by the guidelines.

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.

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.

Determination of mandibular morphology in a TURKISH population with Down syndrome using panoramic radiography

Background

Down syndrome (DS) is by far the most common known chromosomal disorder. Some characteristic features of DS are generalised growth deficiency, craniofacial abnormalities such as mandibular prognathism and underdevelopment of the midfacial region, dental abnormalities such as taurodontism and hypodontia. Individuals with DS have an increased prevalence of periodontal disease compared with age-matched control patients. The aim of the present study is to determine the morphologic features of the mandible among individuals with DS.

Methods

Thirty-four DS patients and thirty four age- and gender-matched control subjects underwent panoramic radiography, which included measurement of the mandibular canal (MC), the mandibular foramen (MF), the mandibular ramus (MR), the distance from the MC to the mandibular lower border (C-MLB), and the distance between the MC and the alveolar crest upper limit (C-AUL). Patients were separated into two groups based on age: < 15 (n = 15) and ≥ 15 (n = 19). In order to determine whether the MF, MR, MC, C-AUL, and C-MLB scores differed according to the groups (DS and control), one-way multivariate analysis of covariance (MANCOVA) was applied in which gender and age were taken as covariates.

Results

When the main effect according to the group was examined separately according to each measurement, the MF in the DS group was high with a moderate effect (F = 9207; p = 0.003). MR (F = 40,518; p < 0.001), MC (F = 23,747; p < 0.001), and C-AUL (F = 58,571; p < 0.001) in the DS group were lower with a larger effect. C-MLB did not significantly differ between the groups, and the effect size was quite low (p > 0.05).

Conclusions

Mandibular canal morphology may exhibit anatomical variations in DS. The alveolar bone level may differ from non-DS due to growth development retardation and/or periodontal diseases.

Iatrogenic neurological injury in children with trisomy 21

PURPOSE

Children with trisomy 21 are at a greater risk for craniocervical junction instability than the general population. These children frequently require administration of anesthesia due to surgical (including otolaryngological) interventions and are at risk for neurological injury. We reviewed the current literature describing iatrogenic neurological injury in children with trisomy 21 undergoing anesthesia in order to facilitate the development of safety recommendations.

METHODS

A systematic review of the literature was performed using Medline, Embase, Scopus, and Google Scholar, following the PRISMA statement. All cases of perioperative neurological injury in children with trisomy 21, aged 18 and under were identified. Clinical and radiographic data were extracted for each report. The data were synthesized to develop recommendations regarding perioperative management.

RESULTS

Of 348 articles screened, 16 cases of iatrogenic neurological injury (in children ages 0.7-18 years) were identified. Three injuries occurred during otolaryngological surgeries, nine during sedation for intubation for non-otolaryngological surgery, one during sedation for neuroimaging, one while restraining a child, and two were due to intraoperative head and neck positioning while anesthetized. Preoperative screening was reported in four cases. A diagnosis of atlantoaxial instability (AAI) or atlantooccipital instability (AOI) was made immediately following symptom presentation in three cases but was often delayed by a median (IQR) of 30(11.5-912.5) days. No cases resolved spontaneously, with 2 patients progressing to brain death and 12 requiring surgical stabilization. Of the latter, seven showed improvement, whereas one died 5 months later. No intraoperative precautions during the index procedure were reported in any of the 16 cases.

CONCLUSION

Iatrogenic neurological injury in children with trisomy 21 are rare but severe and likely under reported. Although the role of preoperative screening remains controversial, all children with trisomy 21 undergoing surgery should be considered at risk for neurological injury due to confirmed or undiagnosed AAI or AOI and should be transferred and positioned with appropriate caution. Children with instability should be referred for neurosurgical attention for preoperative stabilization to mitigate perioperative risk. It is imperative to consider the possibility of neurological injury secondary to medical procedures, as it is clear that neck manipulation of any sort places these children at risk.

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.

Preoperative evaluation and comprehensive risk assessment for children with Down syndrome

Down syndrome is a common chromosome disorder affecting all body systems. This creates unique physiologic concerns that can affect safety during anesthesia and surgery. Little consensus exists, however, on the best way to evaluate children with Down syndrome in preparation for surgery. We review a number of salient topics affecting these children in the perioperative period, including cervical spine instability, cardiovascular abnormalities, pulmonary hypertension, upper airway obstruction, hematologic disturbances, prematurity, low birth weight, and the use of supplements and alternative therapies. Recommendations include obtaining a complete blood count to detect an increased risk for bleeding or stroke, and cardiology evaluation to identify patients with pulmonary hypertension, as well as undiagnosed or residual heart disease. Pediatric cardiac anesthesiologists and intensivists should be involved as needed. The potential for cervical spine instability should be considered, and the anesthesiologist may wish to have several options available both for the medications and equipment used. The child's family should always be asked if he or she is on any nutritional supplements, as some products marketed to families may have secondary effects such as inhibition of platelet function. Using this evaluation in presurgical planning will allow physicians to better consider the individual circumstances for their patients with Down syndrome. Our goal was to optimize patient safety by choosing the most appropriate setting and perioperative personnel, and to mitigate those risk factors amenable to intervention.

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.

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.

[Anesthesiological considerations for patients with trisomy 21 (Down syndrome)]

The most common chromosomal abnormality is trisomy 21 which is also known as Down syndrome and occurs in approximately 1 in 800 births. The majority of the resulting disabling conditions cannot be cured and affect people of all ages, ethnicity and economic levels. Life expectancy has increased with advances in medical care in the same way as in the rest of the population. One of the major tasks for health care professionals is to help these differently abled children and their families function in the most effective way possible as they learn to accept the limitations imposed by a persistent disability. Signs and symptoms of trisomy 21 are very variable based on the trias of mental retardation to a variable degree, hand anomalies and cardiac complications. Other abnormalities are atlantoaxial instability (AAI), tracheal stenosis, a predisposition to respiratory complications, chronic hypothyroidism, microgenia and macroglossia. These conditions are relevant to anesthetic procedures and patients with Down syndrome and their families have specific expectations and attitudes towards medical and anesthetic treatment.

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.

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.

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.

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.

Down syndrome and sport participation

Individuals with Down syndrome (DS) derive measurable physiologic and psychologic benefits from participation in physical activities and sports. Physicians in the position of evaluating these individuals and providing guidance in regard to their competitive or recreational physical activities need to be aware of the physiologic and anatomic concerns specific to this population. Effective screening and evaluation by a physician, accompanied with clearly communicated guidelines for specific activities, can provide an individual with DS the opportunity to safely participate in sports and recreational physical activity.

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.

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.

Life-threatening neurological syndrome in Down's syndrome

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