Risk factors for progressive spinal deformity following resection of intramedullary spinal cord tumors in children: An analysis of 161 consecutive cases

Object. Gross-total resection of pediatric intramedullary spinal cord tumors (IMSCTs) can be achieved in the majority of cases, with preservation of long-term neurological function. However, progressive spinal deformity requiring subsequent fusion occurs in many cases. It remains unknown which subgroups of patients have the greatest risk for progressive spinal deformity. Methods. Data for 161 patients undergoing resection of IMSCTs at a single institution were retrospectively collected and analyzed with regard to the development of progressive spinal deformity requiring fusion and patient functional status (based on the modified McCormick Scale [mMS] and Karnofsky Performance Scale [KPS]) by conducting telephone interviews corroborated by medical records. The independent association of all clinical, radiographic, and operative variables to subsequent progressive spinal deformity was assessed using multivariate logistic regression analysis. Results. Patients were a mean of 8.6 ± 5.7 years old at the time of surgery. The tumor spanned a mean of six ± three spinal levels. Preoperative scoliotic deformity was present in 56 cases (35%). Seventy-six patients (47%) had undergone a previous biopsy procedure, and 28 (17%) a prior resection. Gross-total resection (> 95%) was achieved in 122 cases (76%). A median of 9 years (range 1-21) after surgery, progressive spinal deformity requiring fusion developed in 43 patients (27%). The median functional scores at the last follow-up were worse in patients who required fusion compared with those who did not (mMS: 3 compared with 2, p = 0.006; KPS: 80 compared with 90, p = 0.04) despite similar mMS scores between the groups at 3 months postoperatively. An age less than 13 years, preoperative scoliotic deformity (Cobb angle > 10°), involvement of the thoracolumbar junction, and tumor-associated syrinx independently increased the odds of a postoperative progressive deformity requiring fusion 4.4-, 3.2-, 2.6-, and 3.4-fold, respectively (p < 0.05). Each subsequent resection increased the odds of a progressive deformity 1.8-fold (p < 0.05). Symptoms lasting less than 1 month before resection decreased the odds of spinal deformity requiring fusion ninefold (p < 0.05). Conclusions. Progressive spinal deformity requiring fusion occurred in 27% of children undergoing resection of an IMSCT and was associated with a decreased functional status. Preoperative scoliotic deformity, an increasing number of resections, an age less than 13 years, tumor-associated syrinx, and surgery spanning the thoracolumbar junction increased the risk for progressive spinal deformity. Patients possessing one or more of these characteristics should be monitored closely for progressive spinal deformity following surgery.