Hypoplastic posterior arch of C-1 in children with Down syndrome: a double jeopardy

Symptomatic Atlas Hypoplasia in a Latin-American Patient: Case Report and Literature Review

Background:

Atlas hypoplasia is an infrequent cause of upper cervical stenosis. Only 24 cases in nonsyndromic adult population have been published. We are not aware of previous reports describing isolated fully formed atlas hypoplasia in a Latin-American patient. The purpose of this work was to report a case of an 80-year-old Argentinian woman with cervical myelopathy because of atlas hypoplasia and a literature review about this subject.

Methods:

A clinical case and an extended review of the literature are presented. We assessed from each case: age, sex, posterior atlanto-dens interval, surgical treatment, outcomes, and follow-up period.

Results:

Neurologic symptoms markedly improved after posterior decompression from severe to moderate in the Japanese Orthopaedic Association Scoring System and from four to three on the Nurick scale. Twenty-five patients were analyzed (mean 58.4 years, 32% female). The mean posterior atlanto-dens interval was 8.8 mm. Twenty-three patients underwent decompression alone, and two needed posterior fusion. All patients reported clinical improvement at an average follow-up of 13 months.

Conclusion:

Cervical myelopathy caused by fully formed atlas hypoplasia is not an exclusive pathology of far east population, and it may present in nonsyndromic patients. Surgical treatment by C1 laminectomy improved neurologic impairment.

Study Design:

Case report and literature review.

Incidental findings of posterior arch defects of the atlas in orthodontic patients: A case series

INTRODUCTION

Congenital defects of the posterior arch of atlas are uncommon anomalies that may go unnoticed. Radiographs and cone-beam computed tomography scans made for orthodontic purposes often show the atlas; therefore, these rare defects might first be noted as incidental findings on orthodontic records.

METHODS

A series of 7 cases of posterior arch defects of atlas (C1) that were detected during routine radiographic examination are presented here.

RESULTS

The distribution of the defects was as follows: type A, 2; type B, 1; type C, none; type D, 1; and type E, 3.

CONCLUSION

As the potential complications associated with these defects may be quite concerning, a thorough analysis of the radiographs for these defects is imperative.

C1 Stenosis - An Easily Missed Cause for Cervical Myelopathy

C1 stenosis is often an easily missed cause for cervical myelopathy. The vast majority of cervical myelopathy occurs in the subaxial cervical spine. The cervical canal is generally largest at C1/2, explaining the relatively rare incidence of neurological deficits in patients with odontoid fractures. However, some subjects have anatomical anomalies of the atlas, which may cause stenosis and result in clinical symptoms similar to subaxial cord compression. Isolated pure atlas hypoplasia leading to stenosis is quite rare and may be associated with other anomalies, such as atlas clefts or transverse ligament calcification. It may also be more commonly associated with syndromic conditions such as Down or Turner syndrome. Although the diagnosis can be easily made with a cervical magnetic resonance imaging, the C3/2 spinolaminar test using a lateral cervical plain radiograph is a useful and sensitive tool for screening. Surgical treatment with a C1 laminectomy is generally necessary and any atlantoaxial or occipito-atlanto instability must be treated with spinal stabilization and fusion.

Occipitocervical or C1-C2 fusion using allograft bone in pediatric patients with Down syndrome 8 years of age or younger

Sufficient internal fixation for occipitocervical (OC) or C1-C2 instability in pediatric patients with Down syndrome is difficult owing to small osseous structures, congenital deformities, and immature ossification. The purpose of this study was to evaluate the clinical outcomes of patients aged 8 years or younger with Down syndrome who underwent OC or C1-C2 fusion using freeze-dried allograft as bone graft substitute. The participants included seven consecutive patients aged 8 years or younger with Down syndrome who were treated for upper cervical disorders with posterior OC or C1-C2 fusion using freeze-dried allografts at our hospital between 2007 and 2016 and had a minimum follow-up of 1 year. Postoperative flexion/extension cervical radiography and computed tomography were repeated at 3 months after surgery before removal of the collar. The modified McCormick scale was used to grade functional status. The seven patients had an age range of 5-8 years (mean: 5.9 years). The mean follow-up period was 36 months (12-120 months). Six patients had os odontoideum and one had basilar invagination. Three patients underwent C1-C2 fusion, and in all cases, bilateral C1 lateral mass screws and bilateral C2 pedicle screws were used. Four patients underwent OC fusion, and in three of these cases, occipital and bilateral pedicle screws were used. One patient underwent reoperation because of occipital screw back-out with autograft; therefore, C2 lamina screws were added to pedicle screws. Solid bony fusion was achieved, and stable constructs were maintained on radiography in all patients, without infection or implant failure. In this study, we used freeze-dried allograft as a bone graft substitute, and we were able to detect bony trabeculae at the graft-recipient interface on lateral cervical radiographs and on reconstructed sagittal computed tomographic images in all patients. These results suggest that use of allograft is effective for treatment of upper cervical spine abnormalities in pediatric patients with Down syndrome.

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.

Posterior fusion of the occipital axis in children with upper cervical disorder using both C2 pedicle and laminar screws (C2 hybrid screws)

Introduction

An occipital-cervical surgery for children is challenging for surgeons because of the immature bone quality, extensive anatomical variability, and small osseous structures. Furthermore, occipital-C2 fusion in children results in great stress on the C2 screws. We report a technique that uses both C2 pedicle and bilateral lateral mass screws (C2 hybrid screws) in children with an upper cervical disorder to preserve motion segment and secure strength in those who require occipital-cervical fusion.

Case Report

Case 1 was that of a 5-year-old girl with Down syndrome who had atlantoaxial dislocation and os odontoideum. Owing to the C1 hypoplasia, the posterior arch was fractured by the C1 lateral mass screw. Therefore, O-C2 fusion was performed. C2 bilateral lamina screws were added along with the C2 bilateral pedicle screws for reinforcement. Case 2 was that of an 8-year-old boy who presented with torticollis and neck pain. The patient was diagnosed as having atlantoaxial rotatory fixation. The right vertebral artery was obstructed, and the left vertebral artery was dominant. The C1 posterior arch was bifid and assimilated with the occipital bone. C2 bilateral lamina screws were added with the right C2 pedicle screw for reinforcement. Both cases attained bone union after O-C2 fusion surgery using hybrid screws.

Conclusions

The use of C2 hybrid screws with both C2 pedicle and bilateral lateral mass screws can preserve mobile segments in the fusion area in young children who require occipital-cervical fixation.

Screw fixation for atlantoaxial dislocation related to Down syndrome in children younger than 5 years

The aim of this study was to present cases of upper cervical fixation in Down syndrome patients younger than 5 years. In two cases, C1 lateral mass screws were installed. However, owing to the irreducible atlantoaxial dislocation, the screw backed out and fractured. Therefore, O-C2 fusion was performed. Furthermore, C2 bilateral lamina screws were added to the C2 pedicle screw for reinforcement. C1-C2 fusion is an option for Down syndrome patients younger than 5 years with atlantoaxial dislocation, when the dislocation is reducible. If the dislocation is irreducible, or the implant cannot be firmly secured, the fixation range should be expanded to O-C2 or below.

What the mind does not know, the eyes do not see: a rare congenital fusion of the odontoid process to the atlantal hemiarch

Congenital spinal fusion of an odontoid process to an atlantal hemiarch is very rare. The unfamiliarity of the medical fraternity with this congenital malformation can easily be mistaken for an acute fracture, chronic infection or inflammatory disease. We present our experience of managing an adult who presented with neck pain after a motor vehicle accident. Radiological investigation revealed congenital fusion of the odontoid process to the atlantal hemiarch. The prevalence, embryology and clinical significance of this anomaly are discussed. As the natural progression of this anomaly is not well documented, we suggest periodic follow-up to monitor the progression of degenerative changes and instability of the occipitoatlantal junction.

Possible Further Evidence of Low Genetic Diversity in the El Sidrón (Asturias, Spain) Neandertal Group: Congenital Clefts of the Atlas

We present here the first cases in Neandertals of congenital clefts of the arch of the atlas. Two atlases from El Sidrón, northern Spain, present respectively a defect of the posterior (frequency in extant modern human populations ranging from 0.73% to 3.84%), and anterior (frequency in extant modern human populations ranging from 0.087% to 0.1%) arch, a condition in most cases not associated with any clinical manifestation. The fact that two out of three observable atlases present a low frequency congenital condition, together with previously reported evidence of retained deciduous mandibular canine in two out of ten dentitions from El Sidrón, supports the previous observation based on genetic evidence that these Neandertals constituted a group with close genetic relations. Some have proposed for humans and other species that the presence of skeletal congenital conditions, although without clinical significance, could be used as a signal of endogamy or inbreeding. In the present case this interpretation would fit the general scenario of high incidence of rare conditions among Pleistocene humans and the specific scenariothat emerges from Neandertal paleogenetics, which points to long-term small and decreasing population size with reduced and isolated groups. Adverse environmental factors affecting early pregnancies would constitute an alternative, non-exclusive, explanation for a high incidence of congenital conditions. Further support or rejection of these interpretations will come from new genetic and skeletal evidence from Neandertal remains.

"Dynamic" Rotational Canal Stenosis Caused by Osteoma of the Atlas: A Case Report and Review of Literature

The upper cervical canal stenosis is relatively rare compared to other cervical regions. We report a rare case of upper cervical canal stenosis caused by osteoma of C1 lamina related to dynamic factor of cervical rotation. A 43-year-old woman had a 2-year history of numbness and pain in the right hand. Because of aggravation of the numbness and loss of the fine movement and strength in the right hand, she visited our outpatient clinic. Computed tomographic (CT) scan revealed an ovoid bony lesion at the right side of the C1 lamina. And magnetic resonance (MR) imagings of the cervical spine showed intramedullary high intensity signals in T₂-weighted imaging at a site slightly distant from the bony lesion. Rotational dynamic myelo-CT scan was performed because aggravation of the radiating pain was observed with neck rotation to the right. Dynamic CT scan of the craniocervical junction with neck rotation to the right revealed that the bony lesion was moved to the dorsal side and posteriorly compressed the spinal cord. The symptoms were relieved following surgical removal of this bony lesion. The histopathological examination was compatible for osteoma. The dynamic rotational factor for cervical canal stenosis should be taken in consideration, especially in dealing with upper cervical lesions.

Hypertrophy of the anterior arch of the atlas associated with congenital nonunion of the posterior arch: a retrospective case-control study

BACKGROUND CONTEXT

Nonunion of the posterior arch of the atlas is an uncommon but normal developmental variant. It is usually asymptomatic in the patient but may be associated with greater incidence of fracture because of increased stress on the anterior arch.

PURPOSE

We sought to determine whether anterior arch hypertrophy is present in cases of congenital nonunion of the posterior arch of the atlas.

STUDY DESIGN/SETTING

A retrospective analysis of 1 year (February 2005-January 2006) of computed tomography cervical spine studies requested by the University of California San Diego Medical Center Trauma Department was undertaken.

PATIENT SAMPLE

All patients matching the search criteria (see Study design) were included.

OUTCOME MEASURES

Area density product, defined as the midline cross-sectional area of the anterior arch on sagittal reformat multiplied by the average areal radiodensity in Hounsfield units (HU) as measured by two raters, was calculated for cases and controls.

METHODS

Cases of posterior arch nonunion were identified and matched to controls. The significance of differences in area density product between cases and controls were established by the Student t test. Interrater correlation was calculated.

RESULTS

Posterior arch nonunion was identified in 26 individuals (3.1% of 839 studies reviewed). Compared with age- and sex-matched controls, a 21% increase in area density product of the midline anterior arch was observed in posterior arch nonunion cases (773 HU-cm2 in cases vs. 637 HU-cm2 in controls; p<.001). This increase was attributable to a 21% increase in cross-sectional area (1.05 cm2 in cases vs. 0.87 cm2 in controls; p<.002). In contrast, there was no significant difference with regard to increased average radiodensity.

CONCLUSIONS

It has long been subjectively recognized but not objectively quantified, until the present study, that the anterior arch of the atlas is hypertrophied in cases of posterior arch nonunion. Anterior arch hypertrophy may represent an adaptive response to chronically elevated mechanical stress and loss of hoop strength in cases of posterior nonunion.

Congenital bipartite atlas with hypodactyly in a dog: clinical, radiographic and CT findings

A three-year-old Border collie was diagnosed with a bipartite atlas and bilateral forelimb hypodactyly. The dog showed signs of acute, non-progressive neck pain, general stiffness and right thoracic limb non-weight-bearing lameness. Computed tomography imaging revealed a bipartite atlas with abaxial vertical bone proliferation, which was the cause of the clinical signs. In addition, bilateral hypodactyly of the second and fifth digits was incidentally found. This report suggests that hypodactyly may be associated with atlas malformations.

Isolated cervical spinal canal stenosis at C-1 in the pediatric population and in Williams syndrome

OBJECT

Isolated cervical canal stenosis at the level of the atlas (C-1) is a rare cause of cervical myelopathy in the pediatric population. It has been associated with several genetic disorders including spondyloepiphysial dysplasia congenita, Down syndrome, and Klippel-Feil syndrome. The purpose of this study is to highlight the authors' experience with 4 additional pediatric cases, review the literature, and report a new association of this disease with Williams syndrome.

METHODS

The medical records and radiological imaging studies of 4 patients treated at Texas Children's Hospital for symptomatic hypoplasia of the atlas were retrospectively reviewed. Pertinent patient demographic data, clinical presentation, imaging findings, and outcomes after surgery were recorded. A thorough literature review was performed, allowing the authors to compare and contrast their 4 cases to surgical cases already published in the literature.

RESULTS

There were 11 boys and 1 girl in the aggregate series. The average age of the patients was 7 years (range 13 months-14 years), and the duration of symptoms prior to presentation was 6 months (range 0-36 months). The mean sagittal diameter of the spinal canal at the level of the atlas measured from the posterior aspect of the dens to the anterior aspect of the arch of C-1 was 11.9 mm (range 8.3-16 mm) in the aggregate series. In 2 new pediatric patients with hypoplasia of the atlas the disease was associated with Williams syndrome, which has not been previously described. Patients in the aggregate series were followed for an average of 18 months (range 3-50 months). Laminectomy of C-1 provided neurological improvement in all patients who presented.

CONCLUSIONS

Isolated cervical spinal canal stenosis at the level of the atlas is a rare cause of cervical myelopathy. The authors hope that this report will prompt clinicians to consider it when searching for the origin of signs and symptoms of cervical myelopathy, especially in children.

Atlas hypoplasia and ossification of the transverse atlantal ligament: a rare cause of cervical myelopathy

Myelopathy at the level of the atlas is rarely encountered by the practicing spine surgeon. Due to the region's unique anatomy, compression of the cord at this level is either caused by a large compressing lesion or an abnormally stenotic canal. We describe a rare instance of a congenitally stenotic canal due to a hypoplastic intact posterior arch of atlas, coexisting with an extremely rare ossified transverse ligament of the atlas. The coexistence of these two lesions has only been documented thrice before. We describe the clinical presentation, imaging findings, and favorable response to surgery.

[Spinal stenosis at the level of atlas in a boy with Down syndrome. A case report and literature review]

INTRODUCTION

The appearance of congenital anomalies at the level of atlas is frequent in patients with neural alterations, as well as in the Down syndrome. The presence of clinical stenosis for alteration in the posterior arch of C1 without a previous atlantoaxial subluxation hasn't been described in the literature thus far.

CASE REPORT

We report an exceptional case of myelopathy due to compression at the level of the atlas in a 5-year-old boy with Down syndrome provoked by a developmental anomaly of the posterior arch of C1. A posterior laminectomy was achieved at that level with improvement of the previous symptoms.

CONCLUSIONS

We have to pay special attention in children with syndromes associated with chondrogenesis alterations, as in the case of those with Down syndrome, to benefit from early treatment, since in most of the time they are diagnosed when symptoms are very severe.

Bipartite atlas in a collegiate football player - Not necessarily a contraindication for return-to-play: A case report and review of the literature

Background:

Congenital malformations of the posterior arch of the atlas are rare, occurring in 4% of the population. Anterior arch aplasia is extremely rare and often only coexists with posterior arch anomalies, resulting in a split or bipartite atlas. This congenital anomaly is believed to be present in only 0.1% of the population.

Case Description:

A 19-year-old male collegiate football player presented with neck pain and upper extremity paresthesias after sustaining a tackle that forced neck hyperextension. Computed tomography revealed significant congenital bony anomalies of the cervical spine, with incomplete fusion of the anterior and posterior arches of the atlas; however, there was no evidence for of any acute traumatic injury or fracture. Magnetic resonance imaging revealed increased edema in pre-vertebral soft tissues around C1–C2, with a possible increase in signal within the fibrous ring of the anterior C1 ring. Flexion and extension imaging confirmed reduced range of motion and no instability. Patient was treated non-operatively, and was able to resume normal activity and training regimens, and continued to do well clinically.

Conclusion:

We describe a rare case of split or bipartite atlas in collegiate football athlete who sustained a neck injury during a tackle. The patient had no atlanto-axial instability or other clinical contraindications and was managed non-operatively, resuming full participation shortly thereafter with a full resolution of symptoms.

Recurrent attacks of headache and neck pain caused by congenital aplasia of the posterior arch of atlas in an adult

A 47-year-old Chinese woman, with a history of recurrent attacks of vertigo and vomiting for the past 5 years, presented with intermittent radicular pain in the left upper limb for the past 2 years. She also reported recurrent attacks of severe headache and neck pain for more than 10 years. The pain might be aggravated by coughing or sneezing and relieved after sleeping in the decubitus position. The MRI depicted Chiari malformation. A multidetector CT scan and three-dimensional CT reconstruction revealed partial aplasia of the left posterior arch of atlas of a small gap. The patient underwent plastic surgeries in Beijing. The disappearance of the recurrent pain syndrome was confirmed by follow-up after surgery.

Anteroposterior spondyloschisis of atlas with incurving of the posterior arch causing compressive myelopathy

STUDY DESIGN

A case report of a patient with a combined anterior and posterior arch anomaly of atlas leading to compressive myelopathy.

OBJECTIVE

To describe a rare presentation of cervical stenosis at the atlas where congenital defects of the posterior arch with an incurving portion exists. This report includes a feasible hypothesis for the development of this anomaly on the basis of previous hypotheses and surgical findings.

SUMMARY OF BACKGROUND DATA

Congenital defects of the posterior arch of atlas are uncommon and congenital symptomatic cervical stenosis is very rarely seen at this level. The congenital midline cleft of the posterior arch of an atlas has been described in patients with progressive motor symptoms and sensory deficit in extremities.

METHODS

An 11-year-old boy suffered from right side weakness for 1 year. His mother witnessed his awkward walking and clumsiness in using chopsticks and writing. His medical history was unremarkable, and there was no history of significant trauma. Right upper limb weakness of Grade IV/V and difficulty in hopping on right leg was checked on neurologic examination. The magnetic resonance image showed cervical canal stenosis at atlas level and high signal intensity change in the spinal cord. The computed tomography demonstrated partial defect at anterior and posterior arch of the atlas with incurving at defect site leading to cord compression. Suspecting one of craniovertebral junction anomalies, we performed a surgical resection of the posterior arch of the atlas (decompressive laminectomy).

RESULTS

The laminectomy was done. The defect site of the posterior arch was substituted with a cartilage and there was no dural adhesion. After surgery, right lower limb weakness was improved and no instability has been observed during 1-year follow-up.

CONCLUSION

We describe the association between compressive myelopathy and combined anteroposterior spondyloschisis of an atlas with incurving of the arch at defect site. Both computed tomography and magnetic resonance image were required to demonstrate the bony configuration and cord compression. And decompressive laminectomy of atlas was effective as a treatment for this compressive myelopathy caused by midline defect in the posterior atlantal arch with bony incurving.

The incidence and clinical implications of congenital defects of atlantal arch

OBJECTIVE

Atlantal arch defects are rare. Few cadaveric and imaging studies have been reported on the variations of such anomalies. Our goal in this study was to examine the incidence and review the clinical implications of this anomaly.

METHODS

A retrospective review of 1,153 neck or cervical spine computed tomography (CT) scans was performed to identify patients with atlantal arch defects. Neck CT scans were performed in 650 patients and cervical spine CT scans were performed in 503 patients. Posterior arch defects of the atlas were grouped in accordance with the classification of Currarino et al. In patients exhibiting this anomaly, special attention was given to defining associated anomalies and neurological findings.

RESULTS

Atlantal arch defects were found in 11 (11/1153, 0.95%) of the 1,153 patients. The type A posterior arch defect was found in nine patients and the type B posterior arch defect was found in two patients. No type C, D, or E defects were observed. One patient with a type A posterior arch defect had an anterior atlantal-arch midline cleft (1/1153, 0.087%). Associated cervical spine anomalies observed included one C(6-7) fusion and two atlantal assimilations. None of the reviewed patients had neurological deficits because of atlantal arch anomalies.

CONCLUSION

Most congenital anomalies of the atlantal arch are found incidentally during investigation of neck mass, neck pain, radiculopathy, and after trauma.

Cervical myelopathy associated with congenital C2/3 canal stenosis and deficiencies of the posterior arch of the atlas and laminae of the axis: case report and review of the literature

STUDY DESIGN

A case report of a young male suffering progressive neurologic dysfunction associated with a previously unreported combination of structural bony abnormalities. A review of the literature is also presented.

OBJECTIVE

To describe a unique presentation of cervical myelopathy related to posterior deficiencies of the atlas and axis, and to report on the successful management of this case.

SUMMARY OF BACKGROUND DATA

Cervical myelopathy from congenital canal stenosis is an uncommon presentation in the adolescent age group, especially affecting the C2/3 level. Aplasia of the atlas is a rare, although well-reported phenomena. Defects of the posterior elements of the axis are similarly uncommon. A combination of the 2 defects in the 1 patient has not previously been recorded.

METHODS

A 14-year-old Caucasian male with no history of trauma or neck pain presented with progressive cervical myelopathy over a 2-year period. Plain radiograph and computed tomography revealed congenital aplasia of the posterior arch of the atlas and bilateral cleft defects of the laminae of the axis resulting in a free floating C2 spinous process. Magnetic resonance imaging showed T1 and T2 signal abnormality at the C2-C3 level, with C2/3 congenital canal stenosis and mild disc protrusion.

RESULTS

The patient underwent a posterior decompression and lateral mass fixation at the C2/3 articulation to preserve maximal motion segments. At 12-month follow-up, the patient's cervical myelopathy had improved in terms of gait dysfunction and hemiparesis. Fusion was evident across the posterior lateral mass on radiologic investigation.

CONCLUSION

Posterior deficiencies of the atlas and axis are rare occurrences in isolation, let alone in the 1 patient. This report broadens the radiographic differential diagnosis of patients presenting with cervical myelopathy, which has been associated with congenital posterior C2 anomalies in only a handful of patients. Surgery is an appropriate option for these patients faced with progressive neurologic dysfunction.

Cervical myelopathy accompanied with hypoplasia of the posterior arch of the atlas: case report

STUDY DESIGN

Case reports of 2 patients having cervical myelopathy accompanied with idiopathic hypoplasia of the posterior arch of the atlas.

OBJECTIVE

A standard for the sagittal inside diameter (SID) of the vertebral foramen of the atlas was determined for use in the diagnosis of hypoplasia. From the point of view of short SID, the etiologies of myelopathy in patients with this disease were analyzed.

SUMMARY OF BACKGROUND DATA

There is no established definition of hypoplasia of the atlantal vertebral foramen. The mechanism underlying the occurrence of this myelopathy in adulthood is unknown.

METHODS

Lateral x-ray views of the cervical vertebrae of 150 Japanese men and 150 Japanese women were investigated, and the standard values of the SID were obtained. The features of myelopathy associated with this disease were analyzed in 2 cases managed at our facility and in the literature.

RESULTS

The mean standard value was 34.4 mm in women and 37.1 mm in men, showing a significant sex difference (P<0.0001). When a case with a value -2 SD below the standard was regarded as having hypoplasia, case 1 (female) showed 25 mm, that is, -3.9 SD, and case 2 (male) showed 30 mm, that is, -2.7 SD. The space available for the spinal cord of the atlas was 8.0 mm in case 1 and 9.5 mm in case 2. Both patients showed atlantoaxial subluxation on images, but atlantodental interval on flexion in cases 1 and 2 was 3.8 and 4.5 mm, respectively, showing the degree to be mild.

CONCLUSIONS

In the presence of congenital hypoplasia of the posterior arch of the atlas, the spinal cord is highly susceptible to injury because congenital spinal canal stenosis is present. Therefore, the presence of even a mild mechanical compressive lesion leads to myelopathy. Acquired mild atlantoaxial subluxation was associated with this hypoplasia, and the association was considered to be the mechanism underlying the occurrence of myelopathy in adulthood.

Treatment of pediatric atlantoaxial instability with traditional and modified Goel-Harms fusion constructs

There are several treatment options for rigid fixation at C1-C2 including Brooks and Gallie type wired fusions and C1-2 transarticular screws. The use of a Goel-Harms type fusion, a construct with C1 lateral mass screws and C2 pedicle screws, has not been extensively described in pediatric patients. Here, we describe its relatively safe and effective use for treating pediatric patients by retrospective chart review of patients treated by the senior author for atlantoaxial instability with a Goel-Harms-type constructs during a 3-year period (2005-2007). Six patients were treated using Goel-Harms-type constructs. Five patients were treated utilizing a construct containing C1 lateral mass screws and C2 pedicle screws; one patient was treated using construct containing C1 lateral mass screws and C2 trans-laminar screws. The patients ranged in age from 7 to 17 years old (mean 12.7). All patients had findings of an os odontoideum on CT scans and three of the six patients had T2 hyperintensity on MRI. Three of the six patients presented with transient neurologic deficits: quadraplegia in two patients and paresthesias in two patients. In each patient C1 lateral mass and C2 screws were placed and the subluxation was reduced to attain an anatomical alignment. No bone grafts were harvested from the iliac crest or rib. Local morsalized bone and sub-occipital skull graft was used. All patients tolerated the procedure well and were discharged home on post-operative day 3-4. The patients wore a hard cervical collar and no halo-vests were needed. All patients had solid fusion constructs and normal alignment on post-operative imaging studies performed on average 14 months post-operatively (range: 7-29). The results demonstrated that Goel-Harms fusions are a relatively safe and effective method of treating pediatric patients with atlantoaxial instability and are not dependent on vertebral anatomy or an intact ring of C1. Follow-up visits and studies in this limited series of patients demonstrated solid fusion constructs and anatomical alignment in all patients treated.

The frequency and clinical significance of congenital defects of the posterior and anterior arch of the atlas

OBJECT

In this study the authors investigated the anatomical, clinical, and imaging features as well as incidence of congenital defects of the C-1 arch.

METHODS

The records of 1104 patients who presented with various medical problems during the time between January 2006 and December 2006 were reviewed retrospectively. The craniocervical computed tomography (CT) scans obtained in these patients were evaluated to define the incidence of congenital defects of the posterior arch of C-1. In addition, 166 dried C-1 specimens and 84 fresh human cadaveric cervical spine segments were evaluated for anomalies of the C-1 arch.

RESULTS

Altogether, 40 anomalies (2.95%) were found in 1354 evaluated cases. Of the 1104 patients in whom CT scans were acquired, 37 (3.35%) had congenital defects of the posterior arch of the atlas. The incidence of each anomaly was as follows: Type A, 29 (2.6%); Type B, six (0.54%); and Type E, two (0.18%). There were no Type C or D defects. One patient (0.09%) had an anterior arch cleft. None of the reviewed patients had neurological deficits or required surgical intervention for their anomalies. Three cases of Type A posterior arch anomalies were present in the cadaveric specimens.

CONCLUSIONS

Most congenital anomalies of the atlantal arch are found incidentally in asymptomatic patients. Congenital defects of the posterior arch are more common than defects of the anterior arch.

New onset focal weakness in children with Down syndrome

New onset focal weakness is relatively common in patients with Down syndrome (DS), and has broad differential diagnosis. Ten cases of new onset focal weakness in patients with DS were encountered or are currently being followed in two DS clinics, with a combined population of patients of approximately 850, for a clinic population prevalence of 1.2%. The median age at presentation was 4 years old (range 1 month-44 years). The causes of new onset focal weakness were: stroke from Moyamoya disease (two patients); stroke from vaso occlusive disease (one patient); stroke from venus sinus thrombosis (one patient); traumatic subdural hematoma (one patient); brain abscess (one patient); spinal cord injury (SCI) from cervical spinal stenosis (two patients); SCI from atlantoaxial instability (AAI) (one patient); and brachial plexus injury (one patient). Of the 10 patients with focal weakness, 8 had potentially treatable conditions, and 5 had surgery. The differential diagnosis of new onset focal weakness in DS is broad, with diseases reported involving all levels of the nervous system from brain to muscle. For some diagnoses, expeditious diagnosis may improve outcome.

Agenesis of the posterior arch of the atlas

PURPOSE

To illustrate the radiological findings and review the current literature concerning a rare congenital abnormality of the posterior arch of the atlas.

CASE REPORT

An adult female without neurological symptoms presented with an absent posterior arch of the atlas, examined with plain films and helical computerized tomography. Complete agenesis of the posterior arch of the atlas is a rare entity that can be easily identified by means of plain films. Although it is generally asymptomatic, atlantoaxial instability and neurological deficits may occur because of structural instability. Computerized tomography provides a means of assessing the extent of this abnormality and can help evaluate the integrity of neural structures. Although considered to be rare entities, defects of the posterior arch of the atlas may be discovered as incidental asymptomatic findings in routine cervical radiographs. Familiarity with this abnormality may aid medical professionals in the correct management of these cases.

Atlas hypoplasia manifesting as myelopathy in a child--case report

A 14-year-old Japanese boy presented with myelopathy due to atlas hypoplasia with complete posterior arch. Decompressive laminectomy of the atlas produced good neurological recovery, and follow-up T2-weighted magnetic resonance imaging showed disappearance of spinal cord edema. Congenital atlas stenosis may be symptomatic even in children, with no accompanying cervical spondylotic change. Such cases have previously occurred only in Asian adults. A radiological study of the patient's brother showed median cleft formation of the posterior arch of atlas, indicative of a wide spectrum of atlas anomalies and a possible genetic relationship between these anomalies.

Down syndrome: imaging of multiorgan involvement

Down syndrome (trisomy 21) has many manifestations that affect multiple organ systems, and we describe the wide array of imaging findings. Common cardiovascular and gastrointestinal entities are congenital heart disease (atrioventricular canal), bowel atresias (duodenal and anal), and Hirschsprungs disease. Children with Down syndrome have an 18-20 fold increased incidence of leukemia. Pulmonary hypoplasia, lung cysts, and pig bronchus (origin of the right upper lobe bronchus from the trachea) have been described. Neurologic findings include mineralizing vasculopathy of the basal ganglia, Moyamoya disease, and cerebellar/vermian hypoplasia. Musculoskeletal manifestations are numerous and include eleven ribs, hypersegmented sternum, abnormal pelvis, joint laxity/dislocations, and DDH (developmental dysplasia of the hip). Of special importance is the "triple jeopardy" of the upper cervical spine (atlanoaxial subluxation, hypoplastic posterior arch of C1, and atlantooccipital instability) and the resulting controversial cervical spine radiographic screening of children with Down syndrome. Knowledge of the many anomalies associated with Down syndrome can aid the clinician, not only in diagnosing abnormalities in these patients, but also in counseling families for potential problems that can occur in these children.

Cervical spondylarthrotic myelopathy with early onset in Down's syndrome: five cases and a review of the literature

Progressive walking difficulties and bladder dysfunction may be attributed to Alzheimer disease or atlanto-axial subluxation in people with Down's syndrome (DS). The present authors describe five patients with DS suffering from the above symptoms as a result of cervical spondylarthrotic myelopathy. Clinical and radiological data were collected from all patients with DS who underwent surgery for cervical spondylarthrotic myelopathy at the Leiden University Medical Centre during the period between 1991 and 1995. Five patients with DS (four males and one female) were identified. Their mean age at diagnosis was 42 years. The main clinical features were weakness of the arms and legs, ataxic gait, hyperreflexia and bilateral Babinski signs. Radiological examination showed spondylarthrosis, compression of the spinal cord and myelomalacia. The mean delay in diagnosis was 3 years. All five individuals showed clinical stabilization after laminectomy. Cervical spondylarthrotic myelopathy seems a rather frequent disorder in DS, occurring at a relatively young age. Early diagnosis may prevent irreversible neurological deficits.

Cervical spine disorders in infants and children

The evaluation of children with cervical spine disorders requires an understanding of the anatomic and developmental features that are particular to the pediatric spine. In this article, cervical spine developmental anatomy is briefly reviewed, along with common radiographic features of the pediatric cervical spine. The epidemiology, clinical presentation, and management of congenital cervical anomalies are considered. The evaluation and management of pediatric cervical trauma are also reviewed. Other disorders with common cervical spine involvement, such as skeletal dysplasias, connective tissue disorders, inflammatory arthritides, and storage disorders, are discussed.