BACKGROUND/OBJECTIVE: As prior studies analysed predictive factors for various post-laminectomy spinal deformities in mixed spinal regions, age groups or pathologies, their validity and conclusions were unclear. The objective of this study was to determine predictive factors for worsened cervical or thoracic spinal sagittal alignment following laminectomy or laminotomy for primary intramedullary spinal cord tumours in children. METHODS: In this retrospective study, patients treated between 1980 and 1998 were reviewed. Changes in spinal alignment at the last follow-up compared to the pre-operative state were studied. Factors analysed were age, pre-operative spinal alignment, procedure types (laminectomy or laminoplasty), number of laminae operated, surgery of C2 or T1 laminae, histological grade, presence of post-operative neurological deficit and post-operative radiotherapy. RESULTS: There were 27 patients. The mean age was 5.6 years (range 1.3-14.0 years), and the mean duration of follow-up was 3.7 years (range 0.075-9.9 years). In the cervical-cervicothoracic surgical group (n = 12), alignment worsened post-operatively in 3 patients. The number of laminae operated upon had a statistically significant impact on the development of post-operative kyphosis (p = 0.07). In the thoracic-thoracolumbar surgical group (n = 15), alignment worsened in 9 patients. Procedure types were statistically significantly different, with laminectomy associated with an increased risk of post-operative kyphosis (p = 0.01). All 5 patients who had spinal fusion for worsened post-operative alignment were in the thoracic-thoracolumbar group; no patients in the cervical-cervicothoracic group required spinal fusion (p = 0.047). Other predictive factors did not reach statistical significance (p > 0.05). CONCLUSIONS: Worsened spinal sagittal alignment following laminectomy or laminoplasty and the need for spinal fusion is more common in the thoracic-thoracolumbar region than in the cervical-cervicothoracic region. In the cervical-cervicothoracic region, operation on a greater number of laminae tends to increase the risk of worsened alignment. In the thoracic-thoracolumbar region, laminectomy is associated with worsened alignment, while laminoplasty reduces this risk; also, pre-operative kyphotic deformity tends to increase the risk of worsened alignment post-operatively.