Mean Sagittal Diameter Research Articles

Posterior movement and enlargement of the spinal cord after cervical laminoplasty

We performed CT myelography in 38 patients with cervical myelopathy before and after laminoplasty to enlarge the canal. The sagittal and transverse diameters, the cross-sectional area, and the central point of the spinal cord were measured. After cervical laminoplasty, the mean sagittal diameter of the spinal cord at C5 increased by 0.8 mm, but the mean transverse diameter decreased by 0.9 mm. The mean cross-sectional area of the cord increased by 7.4% and that of the dural sac and its contents by 33.8% at C5. The centre of the spinal cord moved a mean 2.8 mm posteriorly at this level. Enlargement of the spinal canal is sufficient to decompress the spinal cord, but posterior movement may be the limiting factor in determining the decompressive effect of laminoplasty.

Sagittal measurements of the cervical spine in subaxial fractures and dislocations. An analysis of two hundred and eighty-eight patients with and without neurological deficits.

We analyzed three factors involved in fractures and dislocations of the cervical spine and their relation to the degree of injury of the spinal cord. The three factors were the space available for the spinal cord at the level of the injury, the sagittal diameter of the spinal canal at the uninjured levels, and the Pavlov ratio at the uninjured levels. Of the 288 patients analyzed, eighty-three had a complete injury of the spinal cord, ninety-two had an incomplete injury of the spinal cord, thirty had an isolated nerve-root injury, and eighty-three had no neurological deficit. The mean space available for the spinal cord at the level of the injury was 10.5 millimeters for the patients who had a complete injury of the spinal cord, 13.1 millimeters for those who had an incomplete injury of the spinal cord, 15.9 millimeters for those who had an isolated nerve-root injury, and 16.7 millimeters for those who had no neurological deficit. The difference between the groups was significant (p < 0.001) except for the difference between the patients who had an isolated nerve-root injury and those who had no neurological deficit. The mean sagittal diameter of the canal at the uninjured levels was 16.1 millimeters for the patients who had a complete injury of the spinal cord, 16.1 millimeters for those who had an incomplete injury of the spinal cord, 17.9 millimeters for those who had an isolated nerve-root injury, and 18.1 millimeters for those who had no neurological deficit. The difference between the patients who had a complete injury of the spinal cord and those who had an incomplete injury of the spinal cord and that between the patients who had an isolated nerve-root injury and those who had no neurological deficit were not significant (p > 0.05). However, the patients who had a complete injury of the spinal cord and those who had an incomplete injury of the spinal cord were significantly different from the patients who had an isolated nerve-root injury and those who had no neurological deficit (p < 0.001). The mean Pavlov ratio at the uninjured levels was 0.82 for the patients who had a complete injury of the spinal cord, 0.84 for those who had an incomplete injury of the spinal cord, 0.96 for those who had an isolated nerve-root injury, and 0.96 for those who had no neurological deficit.(ABSTRACT TRUNCATED AT 400 WORDS)

Sagittal diameters of the lumbar spinal canal in normal adult Saudis

The lumbar spinal canal may become narrowed as a result of a congenital defect (developmental stenosis) or following other changes associated with the vertebral column or its related structures (acquired stenosis). Stenosis of the canal may predispose the roots of the cauda equina to pressure or entrapment and consequently cause low back pain. Evidence suggests that the sagittal diameter is probably more frequently involved in stenotic lesions. Measurement of diameters from plain radiographs have been shown to yield valuable diagnostic information. In view of the diversity of shape and sizes in the human lumbar spinal canal, norms are needed for individual populations. In the present study, plain lateral radiographs of 150 male and 150 female adult Saudi subjects were measured. The mean sagittal diameters and standard deviations of lumbar levels L1 to L5 are reported for the first time within this population. A reliable method of delimiting the posterior boundary of the canal has also been described. The pattern of segmental variation of the diameters of the lumbar canal in normal adult Saudis was found to be similar to that in other populations, but the mean diameters were different. Norms of the canal: body ratio were also established for use in rapid evaluation of patients.

Comparison of computerized tomography parameters of the cervical spine in normal control subjects and spinal cord-injured patients.

The cross-sectional area and the sagittal and transverse diameters of the cervical spinal canal were measured, using high-resolution, thin-section computerized-tomography images, in 100 control subjects and forty-two patients who had a traumatic injury to the spinal cord. No significant differences were found between the control and the spinal cord-injured group with regard to the cross-sectional area of the spinal canal; however, the differences between the two groups were significant with regard to mean sagittal and transverse diameters of the spinal canal. The sagittal diameters of the spinal canal of the control group were significantly larger than those of the spinal cord-injured group. Conversely, the transverse diameters of the spinal canal of the spinal cord-injured group were significantly larger than those of the control group. These findings suggest that certain patients may be predisposed to spinal cord injury, given sufficient trauma. It is not the total volume of space in the spinal canal that is the critical factor; rather, it is the shape. An index of shape is the ratio of the sagittal to the transverse diameter. The difference between the two groups, based on the ratio of sagittal to transverse diameter, was highly significant. Because this measure is a ratio, there is no need to evaluate an individual on the basis of measurements of absolute values.

Effect of C1-C2 Rotation on Canal Size

An anthropometric study of the atlas and axis was undertaken to determine spinal canal diameters, the degree of narrowing with rotation, and odontoid tilt. The mean sagittal diameter of the atlas was 30.1 mm and the mean coronal diameter was 28.8 mm. The mean sagittal diameter of the axis was 19.0 mm and the mean coronal diameter was 22.8 mm. Approximately 64 degrees of rotation occurred at the atlantoaxial complex before sufficient narrowing caused spinal cord compression in the average specimen. An average of 63 degrees of rotation was required to cause facet dislocation. Most specimens examined had a posterior odontoid tilt up to 45 degrees and a facet angle between 1 degree and 29 degrees. Bilateral facet dislocation occurred at 63 degrees. Spinal canal narrowing to 1 cm occurred at 64 degrees. This narrowing would probably not damage the cord, which averages 1 cm in diameter; however, if the rotary motion of C1 and C2 progressed, cord damage could occur. Facet angles and posterior odontoid tilts that are not within the normal range indicate pathological changes.

Sagittal diameter of the cervical canal in normal Indian adults

This paper is based on a radiographic study of 300 normal individuals from 18 to 34 years of age comprising 207 males and 93 females. A lateral radiograph of the cervical spine with a focal-film distance of 6 ft was obtained of each subject to measure the sagittal diameter of the cervical spinal canal. The mean sagittal diamter ranged from 21.43 mm at C1 to 16.42 mm at C7 in males and from 20.13 mm at C1 to 15.54 mm C7 in females. This diameter decreased from C1 down to C4 or C5 where there was a gradual but marginal increase to C6. This diameter was smallest at C7. In general the sagittal diameters In females were about 1 mm less than in males at all vertebral levels. The smallest sagittal diamter from C3 to C7 in both sexes was 13 mm. The largest sagittal diameter varied from 20.5 to 28 mm in males and 18.5 to 26 mm in females. The mean sagittal diameter showed some relationship to height in males. No significant difference was observed in relation to weight. The posterior component of the sagittal diameter was smaller in females than in males due to a difference in development of the laminae.