Cervical spinal canal plasticity in children as determined by the vertebral body ratio technique

Spinal cord reserve in multiple sclerosis

BACKGROUND

The spinal cord (SC) is a preferential target of multiple sclerosis (MS) damage highly relevant towards disability. Differential impact of such damage could be due to the initial amount of SC tissue, as described for the brain parenchyma (brain reserve concept). We aimed to test the existence of SC reserve by using spinal canal area (SCaA) as a proxy.

METHODS

Brain sagittal three-dimensional T1-weighted scans covering down to C5 level were acquired in 2930 people with MS and 43 healthy controls (HCs) in a cross-sectional, multicentre study. SC area (SCA) and SCaA were obtained with the Spinal Cord Toolbox. Demographical data and patient-derived disability scores were obtained. SC parameters were compared between groups with age-adjusted and sex-adjusted linear regression models. The main outcome of the study, the existence of an association between SCaA and Patient Determined Disease Steps, was tested with scaled linear models.

RESULTS

1747 persons with MS (mean age: 46.35 years; 73.2% female) and 42 HCs (mean age: 45.56 years; 78.6% female) were analysed after exclusion of post-processing errors and application of quality criteria. SCA (60.41 mm² vs 65.02 mm², p<0.001) was lower in people with MS compared with HC; no differences in SCaA were observed (213.24 mm² vs 212.61 mm², p=0.125). Adjusted scaled linear models showed that a larger SCaA was significantly associated with lower scores on Patient Determined Disease Steps (beta coefficient: -0.12, p=0.0124) independently of spinal cord atrophy, brain T2 lesion volume, age and sex.

CONCLUSIONS

A larger SCaA may be protective against disability in MS, possibly supporting the existence of SC reserve.

MRI morphometric characterisation of the paediatric cervical spine and spinal cord in children with MPS IVA (Morquio-Brailsford syndrome)

Nearly all children with MPS IVA develop skeletal deformities affecting the spine. At the atlanto-axial spine, odontoid hypoplasia occurs. GAG deposition around the dens, leads to peri-odontoid infiltration. Transverse/alar ligament incompetence causes instability. Atlanto-axial instability is associated with cord compression and myelopathy, leading to major morbidity and mortality. Intervention is often required. Does the presence of widened bullet shaped vertebra in platyspondily encroach on the spinal canal and cause spinal stenosis in MPS IVA? So far, there have been no standardised morphometric measurements of the paediatric MPS IVA cervical spine to evaluate whether there is pre-existing spinal stenosis predisposing to compressive myelopathy or whether this is purely an acquired process secondary to instability and compression. This study provides the first radiological quantitative analysis of the cervical spine and spinal cord in a series of affected children. MRI morphometry indicates that the MPS IVA spine is narrower at C1-2 level giving an inverted funnel shape. There is no evidence of a reduction in the Torg ratio (canal-body ratio) in the cervical spine. The spinal canal does not exceed 11 mm at any level, significantly smaller than normal historical cohorts (14 mm). The sagittal diameter and axial surface area of both spinal canal and cord are reduced. C1-2 level cord compression was evident in the canal-cord ratio but the Torg ratio was not predictive of cord compression. In MPS IVA the reduction in the space available for the cord (SAC) is multifactorial rather than due to congenital spinal stenosis.

Long-term impact of atlantoaxial arthrodesis on the pediatric cervical spine

BACKGROUND

This study was conducted to elucidate radiographically the long-term impact of atlantoaxial arthrodesis on the pediatric cervical spine.

METHODS

The records of eight children who underwent atlantoaxial arthrodesis for the treatment of upper cervical spinal disorders and were followed up to their adulthood were retrospectively reviewed. Changes in the curvature of the whole cervical spine, and anteroposterior diameters of the spinal canal at C1 and C2 levels were investigated on lateral radiographs before surgery, at 6 months after surgery, and at the final follow-up.

RESULTS

The cervical curvature was lordosis or straight before surgery in all children and became sigmoid in six children at 6 months after surgery. At the final follow-up, three of the six children with postoperative sigmoid curvatures regained some degree of lordosis and became straight. The anteroposterior diameters of the spinal canal at C1 and C2 levels did not increase during the follow-up period.

CONCLUSIONS

Development of postoperative malalignment of the lower cervical spine and impaired growth of the spinal canal at C1 and C2 levels are common after atlantoaxial arthrodesis in children. Postoperative malalignment diminishes during the follow-up period possibly due to remodeling of the pediatric cervical spine, although remodeling of the spinal canal diameter cannot be expected, suggesting the importance of anatomical reduction before or at the time of surgery.

Sex discrepancy in the canal/body ratio of the cervical spine implicating the prevalence of cervical myelopathy in men

STUDY DESIGN

A radiographic analysis of the cervical spine in healthy young adults.

OBJECTIVES

To investigate the size correlations among the vertebral height, the anteroposterior diameter of the vertebral body, and the anteroposterior diameter of the spinal canal and to investigate the sex discrepancy of the canal/body ratio.

SUMMARY OF BACKGROUND DATA

Narrow spinal canal, large vertebral body, and male gender have been thought to be risk factors for cervical myelopathy. However, the association among those risk factors has been seldom analyzed.

METHODS

The height and the anteroposterior diameter of the vertebral body as well as the anteroposterior diameter of the spinal canal were measured on the lateral radiographs of healthy young adults (105 men and 114 women) using a distance-measuring tool of computer software. The canal/body ratio was compared between men and women.

RESULTS

The height and the anteroposterior diameter of the vertebral body were both larger in males than in females throughout C3-C7, but the anteroposterior diameter of the spinal canal was similar for both sexes. The height of the vertebral body was not correlated with the spinal canal size at any measured segment in both sexes, whereas the anteroposterior diameter of the vertebral body was significantly correlated with the size of the spinal canal in males but not in females. The canal/body ratio was significantly larger in women than in men.

CONCLUSIONS

A significantly small canal/body ratio in men may implicate the male prevalence of cervical myelopathy.

Age-related changes in the cervical spines of front-line rugby players

Cervical spine trauma occurs frequently in front-line rugby players. To evaluate the accumulative effects of this trauma, magnetic resonance imaging scans of the cervical spine were performed on 47 rugby players and 40 age-matched control subjects. The aim of this study was to compare the changes in the cervical spine of players at different points in their careers. A study of cervical spine changes, including spinal curve, spinal constituents, posttraumatic deformities, and degenerative modifications, was completed by a study of cervical measurements. Front-line rugby players showed more early degenerative alterations on magnetic resonance imaging scans than did the control subjects of the same age. These changes correlated with age and were probably linked with repetitive cervical trauma throughout the players' careers. Particular attention should be paid to the data confirming cervical spine canal stenosis in front-line players, which may place these athletes at risk for acute neurapraxia while playing this collision sport.