Newly characterized anatomic variations in the vertebral bodies of children with spinal muscular atrophy (SMA) may not only explain the spinal deformity frequently seen in these patients, but also influence their treatment, according to a study recently published in World Neurosurgery.

“Surgeons should be aware of anatomical differences for choosing implant devices accordingly,” the authors wrote.

Seventeen patients with SMA with signs of neuromuscular scoliosis who were under 15 years of age underwent radiographic imaging to determine the measurements of their vertebral bodies. The authors further assessed pedicle diameters in the adolescents aged 11 to 15 years with computed tomography scans of the spine to later compare the results with age-matched healthy controls.

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In the SMA group, the average scoliosis angles were 65.6° for children under 11 years of age and 94.4° for adolescents. All of the patients with SMA had a significantly decreased height of the anterior edge of the vertebrae, with average decreases of 3.9 mm in children and 5.6 mm in adolescents compared to controls. The average thoracic and lumbar vertebral heights in children with SMA were 11.9 mm and 17.2 mm, respectively, compared to 15.2 mm and 21.7 mm in healthy individuals.

Moreover, the depth of the vertebral bodies also seemed to decrease in the SMA group, with an average of 15.7 mm compared to 26.0 mm in the healthy controls. Normally, the depth increases caudally in children. However, this pattern was not present in the participants with SMA, who maintained similar depths throughout all vertebral bodies.

Adolescents showcased similar findings on the depth of vertebral bodies. This age group also had a marked reduction in pedicle diameter in the lower thoracic and lumbar spine compared to healthy participants. Both groups exhibited increases in diameter towards the lumbar section.

These findings objectively describe the spinal anomalies seen in children with SMA, which may influence decision-making in terms of the approach, tools, and materials used in the surgical treatment of this condition.

“Performing dorsal spinal fusion in SMA adolescents, the surgeon has to be prepared to use smaller screws than usual in both diameter (eg, 4.5 mm) and length (eg, 25 to 35 mm) especially in the lower thoracic and lumbar area,” the authors concluded.


Hell AK, Grages A, Braunschweig L, et al. Children with spinal muscular atrophy have reduced vertebral body height, depth and pedicle size in comparison to age-matched healthy controls. World Neurosurg. Published online June 16, 2022. doi:10.1016/j.wneu.2022.06.054