Craniovertebral abnormalities in Down's syndrome

Atlantoaxial Subluxation in a 10-Year-Old Girl With Down Syndrome: A Case Report

Down syndrome is the most common inherited chromosomal disorder caused by trisomy 21. Atlantoaxial instability (AAI) is more common in children with Down syndrome, resulting from ligament laxity and odontoid dysplasia. We report the case of a 10-year-old girl with Down syndrome submental. She came to the ER with a history of abnormal gait for one week and was admitted with a case of ataxia for investigations. Moreover, we discovered that she had atlantoaxial subluxation, which was treated surgically.

The relationship between atlas hypoplasia and os odontoideum in children with Down syndrome: a preliminary case report

The purpose of this study was to evaluate the relationship of os odontoideum and the size of atlas among children with Down syndrome. Understanding the risk of developing myelopathy in asymptomatic cases is important in children with Down syndrome. Children with os odontoideum are considered to be at high risk of developing myelopathy because of instability; however, in cases that are complicated by atlas hypoplasia, the risk remains the same, regardless of instability. This retrospective case-control study assessed atlas hypoplasia in children with Down syndrome with or without os odontoideum. We retrospectively assessed the records of 59 patients (36 males and 23 females) with Down syndrome who underwent spinal X-ray evaluations at our hospital. The average age at examination was 5.0 years (range, 4-7). We evaluated the following radiologically: the presence of os odontoideum; atlas-dens interval; space available for the spinal cord at the atlas level (C1SAC); instability index; sagittal atlas diameter (SAD) as an index of atlas hypoplasia and C5 level SAC (C5SAC), adjusted for child growth. Os odontoideum was present in seven cases (12%). Between the groups with and without os odontoideum, there was no significant difference in age (mean, 5.2 vs. 5.0 years) or male/female ratio (57 vs. 62% males). The SAD/C5SAC (mean, 1.6 vs. 1.9) was significantly smaller in the group with os odontoideum than in those without os odontoideum. The instability index was not significantly different between the two groups. Children with Down syndrome and os odontoideum have small SAD. Evaluations for atlas hypoplasia are necessary.

Current management of juvenile idiopathic arthritis affecting the craniovertebral junction

PURPOSE

Craniovertebral instability is a rare and serious problem. While previously treated surgically, better understanding of disease processes has permitted the field to move towards conservative management. Juvenile idiopathic arthritis (JIA) is one cause of pediatric craniovertebral instability. Early recognition and institution of appropriate medical therapy and bracing in a multidisciplinary fashion is critical to avoid long-term instability, joint abnormalities, or morbid surgical procedures. We seek to highlight cases of this rare problem and provide a principled approach to management decisions.

METHODS

We review 6 cases that have presented over the last 6 years and highlight 3 cases in particular regarding craniovertebral instability as a presentation of JIA. We reviewed the clinical records and radiographic features with particular emphasis of the stability of the craniovertebral junction.

RESULTS

Age range of the subjects was from 5 to 12. All patients presented with neck pain and abnormal head rotation. Four of the patients responded to medical management and/or cervical bracing with no long-term sequelae or instability. Two patients had refractory rotary subluxation, one that responded to manual reduction under pharmacological paralysis and bracing; the other had an incompetent transverse ligament requiring surgical reduction and fixation.

CONCLUSIONS

Neck pain and abnormal head rotation in an older child is rare finding but should prompt suspicion as a manifestation of JIA to the general pediatrician or initial provider. Appropriate serologic studies and MRI studies with contrast at the craniovertebral junction is necessary for evaluation. Early institution of medical management and cervical bracing under a multidisciplinary team of pediatric rheumatology and neurosurgery is key to avoiding surgical intervention and long-term abnormalities at the craniovertebral junction.

Pattern of Pulmonary Dysfunctions in Craniovertebral Junction Anomaly and Its Persistence after Rigid Occipitocervical Fixation

Introduction Despite a significant advancement in operative techniques of occipitocervical fixation, there is a poor postoperative patient outcome. This can be attributed to restrictive lung pattern in craniovertebral junction anomalies (CVJAs) patients resulting from repeated trauma to cervicomedullary junction by the pincer action of the bony anomalies and compression of the brainstem. We evaluate the changes in pulmonary function tests (PFTs) following rigid occipitocervical fixation in CVJA.

Methods PFTs of 20 CVJA patients were measured pre and postoperatively using spirometry. Measurements included forced vital capacity (FVC), forced expiratory volume in one second (FEV1), maximum forced mid-expiratory flow rate (FEF25–75%), and ratio of FEV1 and FVC (FEV1%). The parameters were compared with the predicted normal values based on their age and sex. PFTs were repeated on the seventh postoperative day. McCormick grading was used to assess neurological function.

Results  The values of PFTs in the preoperative period were significantly lower than predicted normal values. The mean values of FVC, FEV1, FEF25–75% were 72, 68, and 71% of their mean predicted values, with FEV1% in the range of 70 to 95% with a mean of 81.4%. Postoperatively there was further significant reduction in the mean values of FVC, FEV1, FEF25–75%, and FEV1% compared with the preoperative values. There was neurological improvement in McCormick grades of patients postoperatively (from grade III and IV to grade II).

Conclusion A significant restrictive lung disease is present in patients of CVJA, even though not clinically apparent, and it persists in the early postoperative period. However, a long-term follow-up is required to assess whether pulmonary function parameters improve subsequently.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cervical medullary syndrome secondary to craniocervical instability and ventral brainstem compression in hereditary hypermobility connective tissue disorders: 5-year follow-up after craniocervical reduction, fusion, and stabilization

A great deal of literature has drawn attention to the "complex Chiari," wherein the presence of instability or ventral brainstem compression prompts consideration for addressing both concerns at the time of surgery. This report addresses the clinical and radiological features and surgical outcomes in a consecutive series of subjects with hereditary connective tissue disorders (HCTD) and Chiari malformation. In 2011 and 2012, 22 consecutive patients with cervical medullary syndrome and geneticist-confirmed hereditary connective tissue disorder (HCTD), with Chiari malformation (type 1 or 0) and kyphotic clivo-axial angle (CXA) enrolled in the IRB-approved study (IRB# 10-036-06: GBMC). Two subjects were excluded on the basis of previous cranio-spinal fusion or unrelated medical issues. Symptoms, patient satisfaction, and work status were assessed by a third-party questionnaire, pain by visual analog scale (0-10/10), neurologic exams by neurosurgeon, function by Karnofsky performance scale (KPS). Pre- and post-operative radiological measurements of clivo-axial angle (CXA), the Grabb-Mapstone-Oakes measurement, and Harris measurements were made independently by neuroradiologist, with pre- and post-operative imaging (MRI and CT), 10/20 with weight-bearing, flexion, and extension MRI. All subjects underwent open reduction, stabilization occiput to C2, and fusion with rib autograft. There was 100% follow-up (20/20) at 2 and 5 years. Patients were satisfied with the surgery and would do it again given the same circumstances (100%). Statistically significant improvement was seen with headache (8.2/10 pre-op to 4.5/10 post-op, p < 0.001, vertigo (92%), imbalance (82%), dysarthria (80%), dizziness (70%), memory problems (69%), walking problems (69%), function (KPS) (p < 0.001). Neurological deficits improved in all subjects. The CXA average improved from 127° to 148° (p < 0.001). The Grabb-Oakes and Harris measurements returned to normal. Fusion occurred in 100%. There were no significant differences between the 2- and 5-year period. Two patients returned to surgery for a superficial wound infections, and two required transfusion. All patients who had rib harvests had pain related that procedure (3/10), which abated by 5 years. The results support the literature, that open reduction of the kyphotic CXA to lessen ventral brainstem deformity, and fusion/stabilization to restore stability in patients with HCTD is feasible, associated with a low surgical morbidity, and results in enduring improvement in pain and function. Rib harvest resulted in pain for several years in almost all subjects.

Os odontoideum: a rare cause of syncope

Syncopal events are a concerning presentation and timely evaluation is warranted. Common aetiologies include cardiac and neurological pathology such as arrhythmias, vertebrobasilar arterial disease and vasovagal syncope. We describe the case of a 65-year-old man who presented to our emergency department with symptoms of vertigo and syncope. He was investigated extensively for both cardiac and neurological causes of his symptoms which returned negative results. An outpatient CT scan demonstrated the presence of Os odontoideum and dynamic instability of the atlantoaxial junction, with presumed dynamic obstruction of the vertebral arterial system. This was successfully managed with a posterior atlantoaxial lateral mass fusion with resolution of syncopal symptoms.

Morphological classification of the tubercle of insertion of the transverse atlantal ligament: A computer tomography-based anatomical study of 200 subjects

BACKGROUND AND PURPOSE

The atlantal tubercle is the attachment point of the transverse atlantal ligament, the main stabilizer of the atlantoaxial complex. No system of classification of the tubercle exists in the literature. We aimed to develop a morphologically based classification system of the atlantal tubercle to aid clinicians who deal with craniocervical pathology.

MATERIALS AND METHODS

A retrospective review of computed tomography (CT) scans of the cervical spine was performed. The morphology of the atlantal tubercle was classified into four variants: rounded (classical), pointed, flattened, and hypoplastic. Age, presence, and morphological type were recorded.

RESULTS

A total of 200 CT scans were identified and reviewed. The tubercle was present bilaterally in all patients. Patients were equally distributed over various age ranges. The following morphological types were recorded: rounded (227/400; 56.8%), pointed (13/400; 3.3%), flattened (126; 31.5%), and hypoplastic (34/400; 8.5%). The same type was seen bilaterally in 68% (135/200) of patients. Morphological types appear equally on the right and left side of the atlas.

CONCLUSIONS

The first morphologically based classification system of the atlantal tubercle utilizing CT is presented. Morphology type, especially hypoplastic type, may confer an increased risk for subsequent need for posterior fusion.

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.

A new variant ligament of the atlantooccipital joint: the lateral oblique atlantooccipital ligament

PURPOSE

During routine dissection of the anterior craniocervical junction (CCJ), a variant ligament just anterior to the articular capsule of the atlantooccipital joint was observed. To our knowledge, no literature has previously described this ligament. Therefore, the aim of this study was to clarify the anatomy, incidence, and biomechanics of this undescribed structure of the anterior atlantooccipital joint.

METHODS

Twenty-six sides from 13 fresh-frozen adult cadavers were used for this study and the morphology of the variant ligament examined. When present, its length, width, thickness, and the angle from the midline of the CCJ were measured.

RESULTS

The variant ligament identified, when present, is distinct and located anterior to the atlantooccipital joint capsule traveling between the occipital bone and the transverse process of the atlas. The ligament was found on 12 of 26 sides (46.2%). The mean length of the ligament was 32.0 ± 5.5 mm. The ligament became taut with contralateral lateral flexion and the ipsilateral rotation of the atlantooccipital joint.

CONCLUSIONS

We propose that this ligament may be termed the lateral oblique atlantooccipital ligament. To date, this structure has not been described in any textbooks or reports in the extant medical literature. Although its function is not clear, based on its course and connections, it might function as a secondary stabilizer of the atlantooccipital joint. As the stability of the craniocervical junction is of paramount importance, knowledge of normal and variant anatomical structures in this region is important for the surgeon treating patients with pathology of this region. These slides can be retrieved under Electronic Supplementary Material.

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.

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.

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

STUDY DESIGN

This is a meta-analysis.

OBJECTIVE

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

SUMMARY OF BACKGROUND DATA

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Identifying Factors Predictive of Atlantoaxial Fusion Failure in Pediatric Patients: Lessons Learned From a Retrospective Pediatric Craniocervical Society Study

STUDY DESIGN

Multicenter retrospective cohort study with multivariate analysis.

OBJECTIVE

To determine factors predictive of posterior atlantoaxial fusion failure in pediatric patients.

SUMMARY OF BACKGROUND DATA

Fusion rates for pediatric posterior atlantoaxial arthrodesis have been reported to be high in single-center studies; however, factors predictive of surgical non-union have not been identified by a multicenter study.

METHODS

Clinical and surgical details for all patients who underwent posterior atlantoaxial fusion at seven pediatric spine centers from 1995 to 2014 were retrospectively recorded. The primary outcome was surgical failure, defined as either instrumentation failure or fusion failure seen on either plain x-ray or computed tomography scan. Multiple logistic regression analysis was undertaken to identify clinical and technical factors predictive of surgical failure.

RESULTS

One hundred thirty-one patients met the inclusion criteria and were included in the analysis. Successful fusion was seen in 117 (89%) of the patients. Of the 14 (11%) patients with failed fusion, the cause was instrumentation failure in 3 patients (2%) and graft failure in 11 (8%). Multivariate analysis identified Down syndrome as the single factor predictive of fusion failure (odds ratio 14.6, 95% confidence interval [3.7-64.0]).

CONCLUSION

This retrospective analysis of a multicenter cohort demonstrates that although posterior pediatric atlantoaxial fusion success rates are generally high, Down syndrome is a risk factor that significantly predicts the possibility of surgical failure.

LEVEL OF EVIDENCE

3.

Goldenhar syndrome: Cardiac anesthesiologist's perspective

Goldenhar syndrome or oculo-auriculo-vertebral dysplasia was defined by Goldenhar in 1952 and redefined by Grolin et al. later. As the name denotes, children with this syndrome present with craniofacial and vertebral anomalies which increase the risk of airway compromise. Neonates and infants with this syndrome often have premature internal organs, low birth weight, and airway disorders. For this reason, safe anesthesia in such infants requires a complete knowledge regarding metabolism and side effects of the drugs. The association of cardiovascular abnormalities is not uncommon and possesses additional challenge for anesthetic management. The aim of this review is to draw attention to the various perioperative problems that can be faced in these infants when they undergo surgery or the correction of the underlying cardiac problem.

Evaluation of Fetal First and Second Cervical Vertebrae: Normal or Abnormal?

OBJECTIVES

To use 3-dimensional sonographic volumes to evaluate the variable appearance of the normal fetal cervical spine and craniocervical junction, which if unrecognized may lead to misdiagnosis of malalignment at the first and second cervical vertebrae (C1 and C2).

METHODS

Three-dimensional sonographic volumes of the fetal cervical spine were obtained from 24 fetuses at gestational ages between 12 weeks 6 days and 35 weeks 1 day. The volumes were reviewed on 4-dimensional software, and the vertebral level was determined by labeling the first rib-bearing vertebra as the first thoracic vertebra. The ossification centers of the cervical spine and occipital condyles were then labeled accordingly and evaluated for alignment and structure by rotating the volumes in oblique planes. The appearance on multiplanar images was assessed for possible perceived anomalies, including malalignment, particularly at the C1 and C2 levels. Evidence of head rotation was correlated with the presence of possible malalignment at C1-C2. Head rotation was identified in the axial plane by measuring the angle of the anteroposterior axis of C1 to the anteroposterior axis of C2.

RESULTS

Of the 24 fetuses, 16 had adequate quality to assess the entire cervical spine and craniocervical junction. All 16 cases showed an osseous component of C1 that did not align directly with C2 on some of the multiplanar images when the volumes were rotated, which could lead to suspected diagnosis of spinal malalignment or a segmental abnormality, as occurred in 2 clinical cases in our practice. All 16 cases showed at least some degree of head rotation, ranging from 2° to 36°, which may possibly explain the apparent malalignment. The lateral offset from C1 to C2 ranged from 0.0 to 3.3 mm.

CONCLUSIONS

The normal C1 and C2 ossification centers may appear to be malaligned due to normal offsetting (lateral displacement) of C1 on C2. An understanding of the normal development of the cervical spine is important in assessing spinal anatomy.

New Radiographic Index for Occipito-Cervical Instability

Study Design

Retrospective study.

Purpose

To propose a new radiographic index for occipito-cervical instability.

Overview of Literature

Symptomatic atlanto-occipital instability requires the fusion of the atlanto-occipital joint. However, measurements of occipito-cervical translation using the Wiesel-Rothman technique, Power's ratio, and basion-axial interval are unreliable because the radiologic landmarks in the occipito-cervical junction lack clarity in radiography.

Methods

One hundred four asymptomatic subjects were evaluated with lateral cervical radiographs in neutral, flexion and extension. They were stratified by age and included 52 young (20–29 years) and 52 middle-aged adults (50–59 years). The four radiographic reference points were posterior edge of hard palate (hard palate), posteroinferior corner of the most posterior upper molar tooth (molar), posteroinferior corner of the C1 anterior ring (posterior C1), and posteroinferior corner of the C2 vertebral body (posterior C2). The distance from posterior C1 and posterior C2 to the above anatomical landmarks was measured to calculate the range of motion (ROM) on dynamic radiographs. To determine the difference between the two age groups, unpaired t-tests were used. The statistical significance level was set at p<0.05.

Results

The ROM was 4.8±7.3 mm between the hard palate and the posterior C1, 9.9±10.2 mm between the hard palate and the posterior C2, 1.7±7.2 mm between the molar to the posterior C1, and 10.4±12.1 mm between the molar to the posterior C2. There was no statistically significant difference for the ROM between the young- and the middle-aged groups. The intra-observer reliability for new radiographic index was good. The inter-observer reliability for the ROM measured by the hard palate was low, but was better than that by the molar.

Conclusions

ROM measured by the hard palate might be a useful new radiographic index in cases of occipito-cervical instability.

Craniocervical instability in the setting of os odontoideum: assessment of cause, presentation, and surgical outcomes in a series of 279 cases

BACKGROUND

Our clinical understanding of os odontoideum (OO) remains incomplete. Congenital and traumatic causes have been proposed and advocated. Clinical presentations range from asymptomatic to axial pain to myelopathy or vertebral-basilar ischemia. A consensus for surgical management exists for those found to have an unstable atlantoaxial complex or symptomatic cranial-vertebral junction compression.

OBJECTIVE

To evaluate the clinical presentation and surgical outcomes of patients with OO and an unstable atlantoaxial complex or symptomatic cranial-vertebral junction compression.

METHODS

Patients with a diagnosis of OO who underwent surgical management were included. Patients were excluded on the basis of previous C2 fracture, Fielding diagnostic criteria, and inadequate follow-up. History of trauma and presenting symptoms were assessed. Clinical and neurological improvements were measured with the use of patient satisfaction scores and the Japanese Orthopaedic Association scores. Fusion status was documented with the use of radiographs and computed tomographic imaging.

RESULTS

Of 279 patients, 112 reported a history of cranial-vertebral junction trauma, whereas 28 were diagnosed with congenital malformations. Clinically, 84.9% of patients presented with myelopathy, with pain presented in 42.6%. Atlantoaxial fixation was performed in 240 patients, occiput-to-C2 fixation in 35 patients, and extended occipito-cervical fixation in 4 patients. Mean follow-up was 40.3 months. Complications were reported in 2.4% of patients. Japanese Orthopaedic Association scores improved from a preoperative mean of 12.4 to 14.8. Two hundred thirty-five patients (77.7%) improved, with 30 patients experiencing no change in symptoms and 14 patients deteriorating. Fusion was achieved in 96.8% of patients.

CONCLUSION

Our data reveal that surgical treatment for OO using the indications and techniques delineated is associated with high satisfaction rates, improved functional scores, and high fusion rates with low complication rates.

Os odontoideum syndrome: pathogenesis, clinical patterns and indication for surgical strategies in childhood

Os odontoideum is a rare condition with a controversial pathogenesis and poorly understood natural history. Hypoplasia of the odontoid associated with an independent oval ossicle, with smooth margins widely separated from C2 and well above the superior facets of the axis, is termed "os odontoideum". The neurological manifestations arise from bulbospinal compression both at rest and during motion, due to the craniovertebral junction (CVJ) instability itself. Consequently, the surgical management of os odontoideum should aim at achieving both neural decompression and stabilization of the CVJ. The aims of this paper are to introduce the embryological steps involved in the CVJ development, to underline the updated theories propounded to interpret developmental and congenital disorders of the os odontoideum, to introduce the most updated surgical techniques and to discuss some exemplary cases selected from our personal experience.

Occipital condyle to cervical spine fixation in the pediatric population

Fixation at the craniovertebral junction (CVJ) is necessary in a variety of pediatric clinical scenarios. Traditionally an occipital bone to cervical fusion is preformed, which requires a large amount of hardware to be placed on the occiput of a child. If a patient has previously undergone a posterior fossa decompression or requires a decompression at the time of the fusion procedure, it can be difficult to anchor a plate to the occipital bone. The authors propose a technique that can be used when faced with this difficult challenge by using the occipital condyle as a point of fixation for the construct. Adult cadaveric and a limited number of case studies have been published using occipital condyle (C-0) fixation. This work was adapted for the pediatric population. Between 2009 and 2012, 4 children underwent occipital condyle to axial or subaxial spine fixation. One patient had previously undergone posterior fossa surgery for tumor resection, and 1 required decompression at the time of operation. Two patients underwent preoperative deformity reduction using traction. One child had a Chiari malformation Type I. Each procedure was performed using polyaxial screw-rod constructs with intraoperative neuronavigation supplemented by a custom navigational drill guide. Smooth-shanked 3.5-mm polyaxial screws, ranging in length from 26 to 32 mm, were placed into the occipital condyles. All patients successfully underwent occipital condyle to cervical spine fixation. In 3 patients the construct extended from C-0 to C-2, and in 1 from C-0 to T-2. Patients with preoperative halo stabilization were placed in a cervical collar postoperatively. There were no new postoperative neurological deficits or vascular injuries. Each patient underwent postoperative CT, demonstrating excellent screw placement and evidence of solid fusion. Occipital condyle fixation is an effective option in pediatric patients requiring occipitocervical fusion for treatment of deformity and/or instability at the CVJ. The use of intraoperative neuronavigation allows for safe placement of screws into C-0, especially when faced with a challenging patient in whom fixation to the occipital bone is not possible or is less than ideal.

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.

Treatment strategies for severe C1C2 luxation due to congenital os odontoideum causing tetraplegia

PURPOSE

High-grade C1C2 luxation is a rare pathology. There is no clear evidence as to how to treat this deformity. There is only limited evidence about the different surgical techniques and possible approaches including advantages, disadvantages, and complications.

METHODS

This is an uncommon case of a 13-year-old child with progressive, tetraplegia due to congenital os odontoideum with translational instability between C1 and C2, and progressive luxation of C2. An irreducible dislocation of the C0/C1 complex caused significant compression at the cervicomedullary junction and neurologic deficit. In this paper we highlight the different types of os odontoideum, a review of existing evidence of surgical correction. We will discuss the different treatment strategies which could be applied and the current solution will be described.

RESULTS

Continuous skeletal traction and translational reduction was achieved by a specially designed halo traction system including continuous skeletal traction in a wheelchair for 6 weeks. The surgical treatment consisted of a posterior only release, translational reduction and posterior instrumentation from C0 to C4 with a Y plate and homologous bone graft. Neurological deficits started to improve during halo traction. After surgery the patient was ambulatory without any assistance and reached a Frankel stage E. Postoperative X-rays and CT scan revealed complete reduction at the C1/C2 level and a decompressed cervicomedullary junction.

CONCLUSION

Treatment of severe C1C2 luxation is difficult with limited evidence in the literature. The current case shows a successful treatment strategy to reduce the deformity and lists alternative approaches.

A torcular encephalocele with proatlas defect and os-terminale

Encephalocele means if meninges and brain tissue protrude out of the cranium. There are different types of encephalocele. The occipital encephaloceles are the most common type. Craniocervical junction and upper cervical spine abnormalities can rarely be associated with occipital encephalocele. We discuss this case because there is rare association between torcular encephalocele and proatlas anomalies.

Posterior instrumentation for occipitocervical fusion

Since 1995, 29 consecutive patients with craniocervical spine instability due to several pathologies were managed with posterior occipitocervical instrumentation and fusion. Laminectomy was additionally performed in nineteen patients. The patients were divided in two groups: Group A which included patients managed with screw-rod instrumentation, and Group B which included patients managed with hook-and-screw-rod instrumentation. The patients were evaluated clinically and radiographically using the following parameters: spine anatomy and reconstruction, sagittal profile, neurologic status, functional level, pain relief, complications and status of arthrodesis. The follow-up was performed immediately postoperatively and at 2, 6, 12 months after surgery, and thereafter once a year. Fusion was achieved in all but one patient. One case of infection was the only surgery related complication. Neurological improvement and considerable pain relief occurred in the majority of patients postoperatively. There were neither intraoperative complications nor surgery related deaths. However, the overall death rate was 37.5% in group A, and 7.7% in group B. There were no instrument related failures. The reduction level was acceptable and was maintained until the latest follow-up in all of the patients. No statistical difference between the outcomes of screw-rod and hook-and-screw-rod instrumentation was detected. Laminectomy did not influence the outcome in either group. Screw-rod and hook-and-screw-rod occipitocervical fusion instrumentations are both considered as safe and effective methods of treatment of craniocervical instability.

Embryology and bony malformations of the craniovertebral junction

BACKGROUND

The embryology of the bony craniovertebral junction (CVJ) is reviewed with the purpose of explaining the genesis and unusual configurations of the numerous congenital malformations in this region. Functionally, the bony CVJ can be divided into a central pillar consisting of the basiocciput and dental pivot and a two-tiered ring revolving round the central pivot, comprising the foramen magnum rim and occipital condyles above and the atlantal ring below. Embryologically, the central pillar and the surrounding rings descend from different primordia, and accordingly, developmental anomalies at the CVJ can also be segregated into those affecting the central pillar and those affecting the surrounding rings, respectively.

DISCUSSION

A logical classification of this seemingly unwieldy group of malformations is thus possible based on their ontogenetic lineage, morbid anatomy, and clinical relevance. Representative examples of the main constituents of this classification scheme are given, and their surgical treatments are selectively discussed.

Ligaments of the craniocervical junction

The specialized ligaments of the craniocervical junction must allow for stability yet functional movement. Because injury to these important structures usually results in death or morbidity, the neurosurgeon should possess a thorough understanding of the anatomy and function of these ligaments. To the authors' knowledge, a comprehensive review of these structures is not available in the medical literature. The aim of the current study was to distill the available literature on each of these structures into one offering.

Novel technique of reduction of a chronic atlantoaxial rotatory fixation using a temporary transverse transatlantal rod

BACKGROUND CONTEXT

Chronic atlantoaxial rotatory fixation (AARF) is uncommon as acute AARF is easily reduced either spontaneously or by conservative methods. Various anterior and posterior surgical approaches for a chronic AARF have been reported because of the difficulty encountered in obtaining reduction.

PURPOSE

To describe a novel technique of reduction of a chronic AARF using a temporary transverse transatlantal rod.

STUDY DESIGN

Technical report.

METHODS

A 13-year-old girl presented with an 8-month-old chronic AARF with typical torticollis and "cock-robin" posture of the head with a normal neurology. As closed reduction with skull traction for 2 weeks failed to reduce the deformity, the patient underwent C1-C2 fusion. C1 lateral mass and C2 pedicle screws were inserted under computer navigation. A temporary transverse rod across the atlas and axis was placed to secure a three-column fixation to derotate the subluxed atlas into anatomical alignment. Rods were then connected between the C1 lateral masses and the C2 pedicle screws and fusion obtained with autologous iliac crest grafts.

RESULT

Anatomic reduction of the atlantoaxial region was obtained without neural compromise, and satisfactory fusion was observed at 6-months follow-up.

CONCLUSION

A temporary transatlantal rod provides a secure anchor point for easy maneuverability for reduction of a chronic AARF and has the advantage of being used even in the absence of the posterior arch of the atlas.

Basilar invagination

BACKGROUND

Basilar invagination is a developmental anomaly of the craniovertebral junction in which the odontoid abnormally prolapses into the foramen magnum. It is often associated with other osseous anomalies of the craniovertebral junction, including atlanto-occipital assimilation, incomplete ring of C1, and hypoplasia of the basiocciput, occipital condyles, and atlas. Basilar invagination is also associated with neural axis abnormalities, including Chiari malformation, syringomyelia, syringobulbia, and hydrocephalus. Patients frequently present with neurologic symptoms and deficits and warrant surgical treatment to prevent progression.

OBJECTIVE

To review the management of basilar invagination.

METHODS

The literature was reviewed in reference to the evaluation and management of basilar invagination, with particular emphasis on the surgical treatment.

RESULTS

Reducible basilar invagination may be treated with posterior decompression and stabilization. Ventral decompression may be necessary for basilar invagination with neural compression that is not reducible with axial cervical traction. Posterior cervical stabilization is necessary after ventral decompression. Modern rod and screw systems combined with autogenous bone graft enable correction of deformity, immediate stabilization, and high fusion rates.

CONCLUSION

Basilar invagination is a developmental anomaly and commonly presents with neurologic findings. Treatment is typically surgical and involves anterior decompression followed by posterior stabilization for irreducible invagination and posterior decompression and stabilization for reducible invagination.

Os odontoideum: etiology and surgical management

OBJECTIVE

Os odontoideum is an independent ossicle of variable size with smooth circumferential cortical margins separated from the foreshortened odontoid peg. The etiology of os odontoideum remains controversial, but there is now emerging consensus on the traumatic etiology of os odontoideum rather than a congenital source.

RESULTS

We reviewed the literature of os odontoideum. Patients with this condition can be asymptomatic or present with wide range of neurological dysfunctions. Although the diagnosis of os odontoideum can be made with plain x-rays, further imaging modalities including magnetic resonance imaging and computed tomography angiography have improved the preoperative planning.

CONCLUSION

There is a role for conservative treatment of an asymptomatic incidentally found, radiologically stable, and noncompressive os odontoideum. Conversely, surgery has a definite role in symptomatic cases. The main method of surgical treatment today is posterior decompression after reduction and fusion via independent C1 and C2 instrumentation. Irreducible, persistent anterior compression from os odontoideum can be approached by a transoral route with good results in experienced hands.

Posterior occipitocervical (C0–3) fusion using polyaxial occipital condyle to cervical spine screw and rod fixation: a radiographic and cadaveric analysis

Numerous conditions affect the occipitocervical junction requiring treatment with occipitocervical fixation. In this paper the authors present their technique of craniocervical fixation achieved with the cephalad extension of posterior C1–3 polyaxial screw and rods to polyaxial screws placed in the occipital condyles. They retrospectively analyzed occipital condyle morphology obtained from CT analyses of 40 patients with normal cervical spines, evaluated occipital condyle screw placement feasibility in 4 cadavers, and provided a case report of a 70-year-old woman with rheumatoid arthritis, basilar invagination, and atlantoaxial instability who was treated with this novel technique. Based on radiographic analysis of occipital condyle anatomy, they concluded that on average a 3.5-mm-diameter × 20- to 30-mm-long screw can be safely placed at an angle of 20–33° from the sagittal plane. Overall, measuring the condylar heights (mean [± SD] 10.8 ± 1.5 mm, range 8.1–15.0 mm), widths (mean 11.1 ± 1.4 mm, range 8.5–14.2 mm), lengths (20.3 ± 2.1 mm, range 15.4–24.6 mm), and angles (mean 32.8 ± 5.2°, range 20.2–45.8°) by using CT studies is an accurate and precise method. This finding correlates with the results of prior anatomical studies of occipital condyles and is important in the planning of craniovertebral junction surgery.

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.

Occipitocervical instrumentation in the pediatric population using a custom loop construct: initial results and long-term follow-up experience

OBJECT

Rigid occipitocervical instrumentation for craniovertebral instability is gaining widespread acceptance for use in pediatric patients; however, most of the instrumentation has been modified from adult-sized hardware. The Wasatch loop system (formerly the Avery-Brockmeyer-Thiokol loop system) is a rigid occipitocervical fixation device designed specifically for use in children. It affixes to the occiput and incorporates either C1-2 transarticular screws or C-2 pars screws. It is preformed and is available in a variety of sizes. The authors describe their clinical experience and long-term follow-up experience with the first 22 patients.

METHODS

An institutional review board-approved retrospective review of medical records and radiographs was performed for patients who underwent occipitocervical fusion with the Wasatch loop. The mean patient age was 4.9 years (1.2-13 years), and the overall mean follow-up was 4 years (1.5-6.5 years). Six patients had posttraumatic instability, and 16 patients had congenital instability.

RESULTS

Twelve patients underwent placement of bilateral C1-2 transarticular screws, 6 patients had placement of a combination of C1-2 transarticular and C-2 pars screws, and 4 patients had placement of bilateral C-2 pars screws. One patient required a halo orthosis; the others were treated postoperatively with a hard cervical collar. All patients had radiographic evidence of solid occipitocervical arthrodesis on last follow-up examination.

CONCLUSIONS

The Wasatch loop system is a novel internal fixation device for children who have posttraumatic or congenital occipitocervical instability. Successful arthrodesis was achieved in all patients with minimal use of halo orthoses.

Atlantoaxial rotatory fixation in the setting of associated congenital malformations: a modified classification system

STUDY DESIGN

A case report.

OBJECTIVE

To raise awareness of the development of atlantoaxial rotatory fixation (AARF) in the setting of congenital vertebral anomalies/malformations.

SUMMARY OF BACKGROUND DATA

Klippel-Feil Syndrome (KFS) is a complex, heterogeneous condition noted as congenital fusion of 2 or more cervical vertebrae with or without spinal or extraspinal manifestations. Although believed to be a rare occurrence in the population, KFS may be underreported. Proper diagnosis of KFS and other congenital conditions affecting the spine is imperative to devise proper management protocols and avoid potential complications resulting from the altered biomechanics associated with such conditions and their abnormal vertebral morphology. Craniovertebral dislocation and AARF may cause severe cervicomedullary and spinal cord compression and could thereby be potentially fatal, especially in patients with KFS who present with congenitally-associated comorbidities.

METHODS

A 13-year-old boy with Chiari type I malformation, craniofacial abnormalities, and other irregularities underwent thoracolumbar spine surgery for his scoliosis curve correction at another institution, which immediately following surgery he became a quadriparetic. The initial preoperative assessment of his cervical spine was limited and the associated KFS was initially undiagnosed. At 14 years of age, he presented to our clinic with an ASIA-C spinal cord injury. Plain radiographs, normal and 3-dimensional reformatted computed tomographs (CT), and magnetic resonance imaging (MRI) noted assimilation of the patient's occiput to the atlas (occipitalization) with congenital fusion of C2-C3, indicative of KFS, and the presence of anterior craniovertebral dislocation with a Fielding and Hawkins type II AARF. Closed reduction of the craniovertebral dislocation was noted, but his atlantoaxial rotatory subluxation was nonresponsive and fixed (AARF). As such, at the age of 14, the patient underwent posterior instrumentation and fusion from the occiput to C4 to maintain reduction of thecraniovertebral dislocation and reduce his AARF.

RESULTS

At 9 months postoperative follow-up of his craniovertebral surgery, the instrumentation remained intact, reduction of the atlantoaxial rotatory subluxation was maintained, and posterior bone fusion was noted. Neurologically, he remained an ASIA-C without any substantial return of function.

CONCLUSION

This report raises awareness for the need of a thorough evaluation of the cervical spine to determine patients at high risk for craniovertebral dislocation and atlantoaxial rotatory subluxation, primarily in the context of KFS or other congenital conditions. Three-dimensional CT and MR imaging are ideal radiographic methods to determine the presence and extent of craniovertebral dislocation, AARF, and of abnormal vertebral anatomy/malformations. In addition, the authors propose a modification to the Fielding and Hawkins classification of AARF to include variants and subtypes that account for abnormal anatomy and congenital anomalies/malformations.

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

STUDY DESIGN

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

OBJECTIVE

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

SUMMARY OF BACKGROUND DATA

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

METHODS

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

RESULTS

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

CONCLUSION

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

Reducible and irreducible os odontoideum in childhood treated with posterior wiring, instrumentation and fusion. Past or present?

BACKGROUND

The aim of the study was to evaluate the results of instrumented rod and wire fusion in children with craniovertebral junction (CVJ) instability and os odontoideum.

METHODS

We evaluated seven children (mean age 9.85 years) with Down and Morquio's syndromes and primary os odontoideum. X-ray, computerized tomography (CT) scan and magnetic resonance (MR) imaging of the CVJ showed reducible instability in all of the cases but one. All the children underwent surgical correction by means of posterior wiring, instrumentation, fusion and external orthosis. A posterior wiring technique was also utilized in the only child with irreducible preoperative atlantoaxial instability, which, however, proved to be reducible under general anesthesia.

FINDINGS

At maximum follow-up (observation range 28 to 106 months, mean 59.42 months), the clinical picture was improved in all the patients. The postoperative neuroradiological investigations demonstrated satisfactory bony fusion with neural decompression in all patients.

CONCLUSIONS

A wiring technique to correct atlantoaxial instabilities has been shown to be more relevant in these children with syndromic atlantoaxial dislocation and os odontoideum due to its simplicity, safety (continuous fluoroscopic assistance is not necessary and there is no risk of neuro-vascular injuries) and lower costs (no complex hardware devices; no neuronavigation systems are required). Preoperative irreducibility of the C1-C2 shift is not an absolute criterion for transoral decompression in children since os odontoideum can be reduced under general anesthesia.

Pre-operative irreducible C1-C2 dislocations: intra-operative reduction and posterior fixation. The "always posterior strategy"

BACKGROUND

According to Menezes' algorithm, pre-operative dynamic neuroradiological investigation in C1-C2 dislocations (C1C2D) instability is strongly advocated in order to exclude those patients not eligible for posterior fixation and fusion without previous anterior trans-oral decompression. Anterior irreducible compression due to C1C2D instability, it is said, needs trans-oral anterior decompression. We reviewed our experience in order to refute such a paradigm.

METHODS

The study involves 23 patients who were operated on for cranio-vertebral junction (CVJ) instability; all of them had C1C2D of varying degree on x-ray, computerised tomography (CT) and magnetic resonance (MR) imaging of the CVJ. Pre-operatively, irreducible C1C2D was demonstrated only in 3 patients, (2 with Down's Syndrome, one of them was harbouring os odontoideum, 1 Rheumatoid Arthritis), i.e. 13.04%; the remaining 19 (86.9%) had reducible C1-C2 dislocation. After an unsuccessful traction test conducted in the pre-operative phase under sedation, it was possible to completely reduce the C1C2D (with a combination of axial traction with light extension of the neck on the chest and a light flexion of the head on the neck by using a Mayfield head holder) and proceed to posterior fixation in all the patients under general anaesthesia using a precise "timing sequences fixation technique". Wiring (C0 and C3 were fixed first being stretched up to approximately 10 lbs, then C2 in order to pull up this vertebra last by forcing approximately 8 lbs) or screw fixation methods were used to achieve fusion along with post-operative external orthosis and neuroradiological assessment of the C1C2D. The instrumentation produced a lever and pulley effect which assisted reduction of the dislocation.

FINDINGS

At follow up (range 34-55 months-mean 45.33 months) the clinical picture was improved or stable in all patients.

CONCLUSIONS

Pre-operative irreducibility of the C1C2D should not be an absolute indication for trans-oral decompression. An attempt to reduce the dislocation under general anaesthesia and during posterior fixation should be attempted in Down's syndrome, os odontoideum and rheumatoid arthritis.

Failed age-dependent maturation of the occipital condyle in patients with congenital occipitoatlantal instability and Down syndrome: a preliminary analysis

OBJECT

Normative morphological data pertaining to the development of the occipital condyle have not been reported. The first goal of this study was to establish normative data characterizing the shape of the occipital condyle in healthy children. The second objective of the study was to compare these data with measurements collected in patients with congenital occipitoatlantal instability (COI) or Down syndrome (DS). The effectiveness of CT and plain radiography data was also compared.

METHODS

The authors retrospectively reviewed data obtained in 39 patients (14 with DS/COI and 25 age-matched controls). Patients underwent plain lateral radiography and CT scanning of the cervical spine. Normalized measurements of the occipital condyle were obtained for both groups using plain radiography and CT imaging techniques.

RESULTS

The curvature of the occipital condyle in healthy children increased by 60% from infancy to adolescence. Comparison of condylar morphology on plain lateral radiographs and CT scans in patients with DS/COI and in age-matched controls demonstrated a significant difference in mean normalized depth/length ratios. Comparison of curvature data obtained using plain lateral cervical radiography with measurements obtained using cervical CT scanning demonstrated a correlation coefficient of 0.63. However, intra- and interobserver reliability for plain radiographic analysis of the occipital condyle was poor (r(2) = 0.40 and 0.44, respectively).

CONCLUSIONS

Patient with DS/COI who have occipitoatlantal instability fail to develop the curved architecture in the occipital condyle that occurs in age-matched controls over time. Sagittal 2D CT reconstructions accurately determine the precise structure of the occipital condyle, although the indications for CT scanning are limited. Because of the poor intra- and interrater reliability on static plain radiographs, dynamic flexion/extension cervical spine radiographs remain the study of choice by which to directly evaluate occipitocervical motion.

Specific entities affecting the craniocervical region: Down's syndrome

INTRODUCTION

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

CONCLUSION

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

Os odontoideum: report of three cases

Os odontoideum is a condition in which a smoothly corticated ossicle exists dorsal to the anterior arch of C1, taking the place of the rostral dens, but with no bony connection to the body of the axis. Three patients presented with this condition: the first with Lhermitte's phenomenon 10 years after significant trauma, the second as an incidental finding during routine cervical spine imaging following a road traffic accident, and the third with recurrent transient quadriparesis precipitated by falls from a surfboard. Patients had at least 10 mm of sagittal instability on dynamic imaging and the second patient had a minimum sagittal canal diameter of only 11.5 mm. Posterior atlanto-axial fixation was successfully achieved in all cases using polyaxial screws and rods with the assistance of computed tomography-based image guidance. Image guidance provided an invaluable aid to preoperative planning and intraoperative placement of the posterior spinal instrumentation.

[Neurological complications in Down syndrome]

The aim of this study was to look over the neurological disorders associated with Down syndrome.

MATERIAL AND METHOD

We reviewed 12 patients with Down syndrome hospitalized from 1997 to 2003, suffering from various neurological complications.

RESULTS

Among the 5 patients with epilepsy, 3 presented with West syndrome and 2 with partial epilepsy; after treatment all were seizure-free. Four patients had ischemic lesions; 1 presented with Moya-Moya syndrome. Four patients presented with C1-C2 vertebral dislocation; all underwent surgery. One of the patients with epilepsy had neurological ischemic sequelae.

CONCLUSION

West syndrome is the most frequent type of epilepsy encountered in Down syndrome. Outcome is favourable if appropriate treatment is initiated early. Any suspicion or sign of vascular lesion in patients with Down syndrome should be promptly investigated. The hyperlaxity associated with Down syndrome could lead to C1-C2 dislocation and a systematic screening is mandatory in order to avoid neurological complications.

Spinal disorders associated with skeletal dysplasias and syndromes

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

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

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

Medical Screening for Red Flags in the Diagnosis and Management of Musculoskeletal Spine Pain

When a patient presents with pain in the different regions of the spine, the clinician executes a region-appropriate basic examination that includes appropriate historical cues and specific physical examination tests that can be used to identify red flags. The clinical tests include a specific examination of the sensory and motor systems. Test outcomes are best interpreted in context with the entire examination profile, where the sensitivity and specificity of these tests can influence their utility in uncovering red flags. These red flags can be categorized based on the nature and severity or the specific elements of the patient's presentation. Many general red flags can be observed in any region of the spine, while specific red flags must be categorized and discussed for each spinal region. This categorization can guide the clinician in the direction of management, whether that management is aimed at redirecting the patient's care to another specialist, reconsidering the presentation and observing for clusters of findings that may suggest red flags, or managing the patient within the clinician's specialty in context with the severity of the patient's presentation.

Superior odontoid migration in the Klippel-Feil patient

Klippel-Feil syndrome (KFS) is an uncommon condition noted primarily as congenital fusion of two or more cervical vertebrae. Superior odontoid migration (SOM) has been noted in various skeletal deformities and entails an upward/vertical migration of the odontoid process into the foramen magnum with depression of the cranium. Excessive SOM could potentially threaten neurologic integrity. Risk factors associated with the amount of SOM in the KFS patient are based on conjecture and have not been addressed in the literature. Therefore, this study evaluated the presence and extent of SOM and the various risk factors and clinical manifestations associated therein in patients with KFS. Twenty-seven KFS patients with no prior history of surgical intervention of the cervical spine were included for a prospective radiographic and retrospective clinical review. Radiographically, McGregor's line was utilized to evaluate the degree of SOM. Anterior and posterior atlantodens intervals (AADI/PADI), number of fused segments (C1-T1), presence of occipitalization, classification-type, and lateral and coronal cervical alignments were also evaluated. Clinically, patient demographics and presence of cervical symptoms were assessed. Radiographic and clinical evaluations were conducted by two independent blinded observers. There were 8 males and 19 females with a mean age of 13.5 years at the time of radiographic and clinical assessment. An overall mean SOM of 5.0 mm (range = -1.0 to 19.0 mm) was noted. C2-C3 (74.1%) was the most commonly fused segment. A statistically significant difference was not found between the amount of SOM to age, sex-type, classification-type, AADI, PADI, and lateral cervical alignment (P > 0.05). A statistically significant greater amount of SOM was found as the number of fused segments increased (r = 0.589; P = 0.001) and if such levels included occipitalization (r = 0.616; P = 0.001). A statistically significant greater amount of SOM was also found with an increase in coronal cervical alignment (r = 0.413; P = 0.036). Linear regression modeling further supported these findings as the strongest predictive variables contributing to an increase in SOM. A 7.20 crude relative risk (RR) ratio [95% confidence interval (CI) = 1.05-49.18; risk differences (RD) = 0.52] was noted in contributing to a SOM greater than 4.5 mm if four or more segments were fused. Adjusting for coronal cervical alignment greater than 10 degrees , five or more fused segments were found to significantly increase the RR of a SOM greater than 4.5 mm (RR = 4.54; 95% CI = 1.07-19.50; RD = 0.48). The RR of a SOM greater than 4.5 mm was more pronounced in females (RR = 1.68; 95% CI = 0.45-6.25; RD = 0.17) than in males. Eight patients (29.6%) were symptomatic, of which symptoms in two of these patients stemmed from a traumatic event. However, a statistically significant difference was not found between the presence of symptoms to the amount of SOM and other exploratory variables (P > 0.05). A mean SOM of 5.0 mm was found in our series of KFS patients. In such patients, increases in the number of congenitally fused segments and in the degree of coronal cervical alignment were strongly associated risk factors contributing to an increase in SOM. Patients with four or greater congenitally fused segments had an approximately sevenfold increase in the RR in developing SOM greater than 4.5 mm. A higher RR of SOM more than 4.5 mm may be associated with sex-type. However, 4.5 mm or greater SOM is not synonymous with symptoms in this series. Furthermore, the presence of symptoms was not statistically correlated with the amount of SOM. The treating physician should be cognizant of such potential risk factors, which could also help to indicate the need for further advanced imaging studies in such patients. This study suggests that as motion segments diminish and coronal cervical alignment is altered, the odontoid orientation is located more superiorly, which may increase the risk of neurologic sequelae.

Morphometric and qualitative analysis of congenital occipitocervical instability in children: implications for patients with Down syndrome

OBJECT

Congenital occipitocervical (OC) instability is uncommon in healthy children but can occur in many children with Down syndrome. A simple morphometric method of evaluating the OC joint in children with OC instability is presented, supported by a qualitative image analysis based on computed tomography (CT).

METHODS

Thin-cut CT scans of the OC joint were obtained in eight patients with Down syndrome and one patient with congenital OC instability. These patients' CT scans were compared with those of 15 healthy age-matched control individuals. Morphometric analysis was performed by measuring the depth and length of the superior articular surface (SAS) of C-1, and these values were normalized for a comparison between groups. Qualitative data were acquired using a surface-rendering technique for a visual comparison of the C-1 SAS. Morphometric analysis demonstrated an absence of the concave C-1 SAS anatomy in patients with congenital OC instability compared with age-matched control individuals (0.083 compared with 0.202, p < 0.001). Three-dimensional (3D) image analysis of the C-l SAS supported this finding.

CONCLUSIONS

Congenital differences in the shape of the OC joint are highly associated with atraumatic OC instability in children with Down syndrome. High-resolution CT imaging combined with 3D rendering techniques and surface mapping provides support for this assessment. It appears that abnormal OC joint shape is a contributing factor to congenital OC instability, especially in patients with Down syndrome.