The evolution of spinal growth after irradiation

Spinal growth has been monitored in 13 children treated with craniospinal irradiation for brain tumours. Six were irradiated prepubertally and seven peripubertally, all with 30 Gy to the whole spine over four weeks. The change in (subischial leg length (SILL)--sitting height (SH)) standard deviation score (SDS) was used as an index of disproportionate segmental growth, which allowed the influence of growth hormone deficiency on growth to be discounted. Spinal growth over the prepubertal years was relatively normal: annual change in (SILL-SH) SDS was +0.07 SD 0.2. However, over puberty, annual change in (SILL-SH) SDS had increased significantly to +0.41 SD 0.14 (P = 0.03). If irradiated peripubertally, annual change in (SILL-SH) SDS to final height was +0.22 SD 0.23, not significantly different from the change over puberty in the prepubertal group. Relatively normal spinal growth after irradiation in the prepubertal child should be interpreted with caution, as it is during puberty that skeletal disproportion manifests itself.