Morphometric analysis of lumbar pedicles in patients with spinal dysraphism

Increased medial pedicle angulation of the lumbar spine as a function of the posterior osseous defect in patients with myelomeningocele

PURPOSE

Bony anatomy in patients with immature spines has been previously characterized. Alterations in lumbosacral morphology in patients with myelodysplasia, demonstrating increasing medial pedicle angulation (MPA) from L1-S1, have been examined; however, MPA related to size of the defect in myelomeningocele patients has not been defined. We aimed to establish that magnitude of posterior vertebral arch defects determines the extent of MPA in the lumbar spine, with larger posterior defects associated with increased MPA.

METHODS

This retrospective case-control study compared lumbar morphometric measurements of patients with and without myelomeningocele. Eighteen patients with myelomeningocele underwent computed tomography with three-dimensional reconstruction; there was no concurrent pathology. Advanced imaging software was utilized to manipulate the axial, sagittal, and coronal axes at each lumbar level, and obtain accurate measurements of pedicle width, height, length, MPA, and posterior laminar defect.

RESULTS

In lumbar vertebrae with a posterior arch defect (PAD), increased magnitude was associated with a concurrent increase in MPA between 16.2° (43.4%) and 28.1° (299.4%) depending on lumbar level. At levels without a PAD, increases in MPA were between 0.8° (4.3%) and 5.7° (60.6%) depending on lumbar level. Although the actual degree of medial angulation increases from cephalad to caudal levels, the percentage of deviation from normal is higher at the more cephalad levels compared with controls.

CONCLUSION

In patients with myelomeningocele, larger posterior vertebral arch defects were associated with increased MPA in the lumbar spine. Lumbar levels without a PAD also demonstrated increases in MPA compared with normal values.

Evaluation of lateral atlantodental interval asymmetry in the pediatric age group: normative values

OBJECTIVE The revelation of normative radiographic measurements for the developing pediatric spine is incomplete. The purpose of this analysis was to determine the normal range of asymmetry of the lateral atlantodental interval (LADI) and define age- and sex-related differences. METHODS A total of 3072 children aged 0-18 years who underwent CT scanning of the cervical spine were identified at Riley Hospital for Children between 2005 and 2017. Patients were stratified by sex and age (in years) into 36 cohorts. Following this stratification, patients within each group were randomly selected for inclusion until 15 patients in each group had been measured (quota sampling). A total of 540 patients were included for study. Right and left linear measurements were performed in the CT axial plane at the C-1 midlateral mass level. RESULTS The overall mean difference between the right and left LADI was 0.09 ± 1.23 mm (range -6.05 to 4.87 mm). The magnitude of this asymmetry remained statistically insignificant across age groups (p = 0.278) and sex (p = 0.889). The intraclass correlation coefficient was 0.805 (95% CI 0.779-0.829). CONCLUSIONS Asymmetry of the LADI is not unusual in asymptomatic children. There is no appreciable difference in magnitude of this asymmetry across age ranges and sex. Measurement of LADI asymmetry shows "good" reliability and is easy to perform. Pediatric neurosurgeons, emergency department physicians, and radiologists should be aware of normative values of asymmetry when interpreting CT scans of the cervical spine. This may prevent unnecessary further workup with dynamic CT or MRI.