Treatment of Down syndrome-associated craniovertebral junction abnormalities

Os odontoideum: database analysis of 260 patients regarding etiology, associated abnormalities, and literature review

Introduction

Since the first description of os odontoideum in 1886, its origin has been debated. Numerous case series and reports show both a possible congenital origin and origin from the secondary to craniovertebral junction (CVJ) trauma. We conducted a detailed analysis of 260 surgically treated cases to document the initial symptoms, age groups, radiographic findings, and associated abnormalities, aiming to enhance the confirmation of the etiology. A literature search (1970-2022) was performed to correlate our findings.

Methods and materials

A total of 260 patients underwent surgical management of a referral database of 520 cases (1978-2022). All patients were examined by plain radiography and myelotomography as needed until 1984, and since then, CT and MRI have been employed. History of early childhood (aged below 6 years) CVJ trauma was investigated, including obtaining emergency department's initial radiographs from the referral and subsequent follow-up. Associated radiographic and systemic abnormalities were noted, and the atlas development was followed.

Results

The age of the patients ranged from 4 to 68 years, mostly between 10 and 20 years. There were 176 males and 86 females. Orthotopic os odontoideum was identified in 24 patients, and 236 patients had dystopic os odontoideum. Associated abnormalities were found in 94 of 260 patients, with 73 exhibiting syndromic abnormalities and 21 having Chiari I malformation. Two sets of twins had spondyloepiphyseal dysplasia. Of 260 patients, 156 experienced early childhood trauma /. Among these, 54 initially presented with normal radiographs but later demonstrated anterior atlas hypertrophy. In addition, a smaller posterior C1 arch was observed, leading to the development of os odontoideum. Two children had initial CVJ trauma as documented by MRI, with subsequent classical findings of os odontoideum and atlas changes. Syndromic patients had an earlier presentation. The literature reviewed confirms the multifactorial etiology.

Conclusions

The early presentation and associated abnormalities (such as Down syndrome, Klippel-Feil syndrome, Chiari I malformation, spondyloepiphyseal dysplasia, Morquio syndrome, and others) along with case reports documenting familial, hereditary, and twin presentations strongly support a congenital origin. Likewise, surgical complications are more prevalent in syndromic patients (40%) compared to 15% in other cases, as reported in the literature. The documentation of normal odontoid in early childhood trauma cases followed by the later development of os odontoideum provides evidence supporting trauma as an etiological factor. This process also involves vascular changes in both the atlas and the formation of os odontoideum. Associated abnormalities exhibit an earlier presentation and are only seen in cases with a non-traumatic origin.

Reference values of four measures of craniocervical stability using upright dynamic magnetic resonance imaging

PURPOSE

To establish reference ranges for four most commonly used diagnostic measures of craniocervical instability (CCI) in three cervical sagittal positions. This necessitated development of a reliable measurement protocol using upright, dynamic MRI (udMRI), to determine differences in the extent of motion between positions, and whether age and sex correlate with these measures.

MATERIALS AND METHODS

Deidentified udMRIs of 50 adults, referred for reasons other than CCI, were captured at three positions (maximal flexion, maximal extension and neutral). Images were analyzed, providing measures of basion-axial interval, basion-axial angle, basion-dens interval (BDI) and the Grabb-Oakes line (GOL) for all three positions (12 measures per participant). All measures were independently recorded by a radiologist and neurosurgeon to determine their reliability. Descriptive statistics, correlations, paired and independent t-tests were used. Mean (± 2 SD) identified the reference range for all four measures at each craniocervical position.

RESULTS

The revised measurement protocol produced inter-rater reliability indices of 0.69-0.97 (moderate-excellent). Fifty adults' (50% male; mean age 41.2 years (± 9.7)) reference ranges for all twelve measures were reported. Except for the BDI and GOL when moving between neutral and full flexion, significant extents of movement were identified between the three craniocervical positions for all four measures (p ≤ 0.005). Only a minor effect of age was found.

CONCLUSIONS

This is the first study to provide a rigorous standardized protocol for four diagnostic measures of CCI. Reference ranges are established at mid and ends of sagittal cervical range corresponding to where exacerbations of signs and symptoms are commonly reported.

Suture Repair in Endoscopic Surgery for Craniovertebral Junction

Objective

Endoscopic approaches to the craniovertebral junction (CVJ) have been established as viable and effective surgical treatments in the past decade. One of the major complications is leakage of the cerebrospinal fluid (CSF). This study aimed to investigate the efficacy and feasibility of suture closure at the nasopharyngeal mucosa upon durotomy.

Methods

A series of consecutive patients who underwent different endoscopic approaches to the CVJ were retrospectively reviewed. The pathologies, surgical corridors, neurological and functional outcomes, radiological evaluations, and complications were analyzed. Different strategies of repair for the intraoperative CSF leakage were described and compared.

Results

A total of 22 patients covering 13 years were analyzed. There were 12, 2, and 8 patients who underwent transnasal, transoral, and combined approaches, respectively. There were 8 patients (36.4%) who experienced intraoperative CSF leakage, and were grouped into 2: 4 in the nonsuture (NS) group and 4 in the suture-repaired (SR) group. The NS group had 3 (75%) persistent CSF leakages postoperation that caused 1 mortality, whereas patients of the SR group had only 1 minor CSF rhinorrhea that healed spontaneously within days.

Conclusion

In this series of 22 patients who required anterior endoscopic resection of pathologies at the CVJ, there was 1 (4.5%) serious complication related to CSF leakage. For patients who had no durotomy, the mucosal incision at the nasopharynx usually healed rapidly and there were few procedure-related complications. For patients with intraoperative CSF leakage, suture closure was technically challenging but could significantly lower the risks of postoperative complications.

Down syndrome-A narrative review with a focus on anatomical features

Down syndrome (DS) is the most common aneuploidy of chromosome 21, characterized by the presence of an extra copy of that chromosome (trisomy 21). Children with DS present with an abnormal phenotype, which is attributed to a loss of genetic balance or an excess dose of chromosome 21 genes. In recent years, advances in prenatal screening and diagnostic tests have aided in the early diagnosis and appropriate management of fetuses with DS. A myriad of clinical symptoms resulting from cognitive, physical, and physiological impairments caused by aberrations in various systems of the body occur in DS. However, despite these impairments, which range from trivial to fatal manifestations, the survival rate of individuals with DS has increased dramatically from less than 50% during the mid-1990s to 95% in the early 2000s, with a median life expectancy of 60 years reported recently. The aim of this narrative review is to review and summarize the etiopathology, prenatal screening and diagnostic tests, prognosis, clinical manifestations in various body systems, and comorbidities associated with DS. Clin. Anat. 29:568-577, 2016. © 2015 Wiley Periodicals, Inc.

Nosographic identification and management of pediatric craniovertebral junction anomalies: evolution of concepts and modalities of treatment

The clinical significance of abnormalities of the craniocervical junction has gained tremendous momentum with the increasing interest in the area as a result of better neurodiagnostic imaging. Abnormalities of the bone, soft tissue, and neural structures are easily recognized and there is a better understanding of the biomechanics of this complex region as well as the embryology. A database of symptomatic patients, children, and adults with neurological symptoms and signs secondary to abnormalities at the craniocervical junction have been evaluated by the author at the University of Iowa Hospitals and Clinics. This large database comprises 6,000 patients and provides a better awareness of the natural history of abnormalities as well as diseases affecting this area.A surgical physiological approach to pathology at this region was proposed in 1977 and still holds true. However, with the advent of better imaging as well as surgical approaches and instrumentation, treatment of problems in this region can be divided into the clinical syndromes, surgical approaches, and techniques of stabilization. A brief outline of the evolving nature of this is provided in this manuscript.

Variable morphology of the axis vertebrae in 100 specimens: implications for clinical palpation and diagnostic imaging

OBJECTIVE

The purpose of this study was to investigate and measure the variable morphologies of axis vertebrae and explore the clinical significance of variations as it may pertain to clinical palpation and diagnostic imaging.

METHODS

The common variable morphologies in 100 specimens of intact dry adult axis vertebrae (Chinese) were investigated and measured. The frequencies in deviation of odontoid processes, deviation of spinous processes, and presence of bifid spinous processes were observed. The distances between the apices of transverse processes and inferior articular facets were also measured.

RESULTS

Variable morphologies of C2 that we observed were deviation of odontoid processes (14 cases, 14.0%), deviation of spinous processes (3 cases, 3.0%), and bifid spinous processes (95 cases, 95.0%). Of the bifid spinous processes, 56 had a process on the left side equal to the right side, 21 were longer on the left, and 18 were longer on the right. The distances between apices of transverse processes and inferior articular facets in the left side of C2 were 17.67 +/- 2.47 mm, and that of the right side were 17.81 +/- 2.55 mm.

CONCLUSIONS

Because variable morphology of the axis is common, congenital deviation of the odontoid process, deviation of the spinous process, and asymmetrical bifid spinous processes should be taken into account during clinical palpation and diagnostic imaging.

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.

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.

Clinical Study of a Modified Brooks Technique for Atlanto-axial Subluxation Using Polyethylene Tape

Forty-four patients, 15 males and 29 females (3-71 years old; mean age, 52.9), were treated for the control of cervical instability with a modified Brooks operation using Tekmilon tape (an ultrahigh molecular weight polyethylene tape) instead of metal wires. Forty of the patients had rheumatoid arthritis (RA) with atlanto-axial subluxation (AAS), three patients had os odontoideum, and one patient had a cervical spine injury. The mean follow-up period was 8 years and 4 months. These patients were divided into three groups: 30 years or less, 31 to 60 years, and over 60 years. Atlanto-dental interval (ADI), inclination angle of atlanto-axial vertebrae (A-A angle), and bone fusion were examined on plain radiographs. The proportion of patients with reduced neck pain (Ranawat's grade 0 or grade 1) increased from 42.5% to 97.9% at the time of postoperative evaluation. Surgical complications, such as dural tear, lamina fracture, and spinal cord injury did not occur in any cases. Thirty-nine patients (88.6%) achieved bone union. ADI in the maximum flexed position improved from 10.3 to 2.5 mm. There was no statistical difference between ADI in males and females. ADI did not change in any age group both before and after surgery. A-A angle also improved from 9.4 to 24.4 degrees. The polyethylene tapes, used for internal fixation, caused no neurologic complications during sublaminar wiring and produced no MR artifacts. This modified Brooks technique using Tekmilon tape was proved to be a simple and safe treatment of AAS.

[Rare pathological alterations of the upper cervical spine requiring surgical treatment]

Because of its unique anatomy, specific diseases and lesions arise in the upper cervical spine, which differ widely from the rest of the spine. During the last two decades standardised diagnostic and therapeutic algorithms have been defined for most of the craniocervical pathologies often occurring in combination with an underlying disease requiring surgical intervention as well. On the other hand there are some very rare phathological alterations: about 20% of the patients suffering from neurofibromatosis type I develop spinal deformities. These are mostly found in the thoracic and lumbar spine (dystrophic/non-dystrophic type). In rare cases the dystrophic neurofibromatosis type I involves the upper cervical spine leading to bizarre deformities endangering the spinal cord. An aggressive, timely and combined operative therapy is necessary. Patients with Down syndrome should be investigated regularly for affections of the upper cervical spine. Though only in about 1% of all patients with Down syndrome do instabilities require surgical intervention, the upper cervical spine should be screened on a regular basis, since neurological changes due to the pathognomy of the underlying disease often remain undetected for a long time. The operative therapy of the instable os odontoideum in Down syndrome follows the general principles of this pathoanatomical variation. Even though the Klippel-Feil syndrome is generally not linked with neuropathological findings, rare associated deformities of the upper cervical spine should be excluded by proper diagnostic procedures.

Anomalous vertebral artery at the craniovertebral junction in a patient with Down syndrome

✓ The authors report a case of a patient with Down syndrome in whom the abnormal course of the right vertebral artery (VA) at the craniovertebral junction (CVJ) was accurately demonstrated on three-dimensional (3D) computerized tomography (CT) angiography. The patient was a 5-year-old boy, who developed severe myelopathy. Bone abnormalities were also present at the CVJ, including atlantoaxial and occipitoatlantal instabilities, a hypoplastic odontoid process, and ossiculum terminale. Three-dimensional CT angiography revealed that the right VA was duplicated after emerging from the C-2 transverse foramen. One half of the duplication, an artery that was as large as the left VA, turned posteromedially and entered the spinal canal between C-1 and C-2. The other half, a very small artery, ran as usual and passed through the C-1 transverse foramen. The authors performed an occipitocervical posterior fusion and a C-1 laminectomy. Intraoperatively the course of the anomalous VA was identified on Doppler ultrasonography, and the surgical approach and bone excision were undertaken carefully to avoid VA injury. Postoperatively, resolution of myelopathy was marked. In the surgical treatment of patients with Down syndrome, surgeons should consider the possibility that a VA anomaly is present at the CVJ. With preoperative 3D CT angiography, the anomalous VA can be identified precisely and the possible risk of intraoperative VA injury predetermined.