Incidence of spinal deformity after resection of intramedullary spinal cord tumors in children who underwent laminectomy compared with laminoplasty
Authors: McGirt Matthew J. , Chaichana Kaisorn L. , Atiba April , Bydon Ali , Witham Timothy F. , Yao Kevin C. , Jallo George I. 
Published: January 2008

Object
Gross-total resection of pediatric intramedullary spinal cord tumor (IMSCT) can be achieved in the majority of cases while preserving long-term neurological function. Nevertheless, postoperative progressive spinal deformity often complicates functional outcome years after surgery. The authors set out to determine whether laminoplasty in comparison with laminectomy has reduced the incidence of subsequent spinal deformity requiring fusion after IMSCT resection at their institution.

Methods
The first 144 consecutive patients undergoing resection of IMSCTs at a single institution underwent laminectomy with preservation of facet joints. The next 20 consecutive patients presenting for resection of IMSCTs underwent osteoplastic laminotomy regardless of patient or tumor characteristics. All patients were followed up with telephone interviews corroborated by medical records for the following outcomes: 1) neurological and functional status (modified McCormick Scale [MMS] score and Karnofsky Performance Scale [KPS] score); and 2) development of progressive spinal deformity requiring fusion. The incidence of progressive spinal deformity and the long-term neurological function were compared between the laminectomy and osteoplastic laminotomy cohorts. The means are expressed ± the standard deviation.

Results
Overall, the patients' mean age was 8.6 ± 5 years, and they presented with median MMS scores of 2 (interquartile range [IQR] 2–4). A > 95% resection was achieved in 125 cases (76%). There were no differences (p > 0.10) between patients treated with osteoplastic laminotomy and those treated with laminectomy in terms of the following characteristics: age; sex; duration of symptoms; location of tumor; incidence of preoperative scoliosis (Cobb angle > 10°: 7 [35%] with laminoplasty compared with 49 [34%] with laminectomy); involvement of the cervicothoracic junction (7 [35%] compared with 57 [40%]); thoracolumbar junction (4 [20%] compared with 36 [25%]); tumor size; extent of resection; radiation therapy; histopathological findings; or mean operative spinal levels (7.5 ± 2 compared with 7.5 ± 3). Nevertheless, patients who underwent osteoplastic laminotomy had better median preoperative MMS scores than those treated with laminectomy (2 [IQR 2–2] compared with 2 [IQR 2–4]; p = 0.04). A median of 3.5 years (IQR 1–7 years) after surgery, only 1 patient (5%) in the osteoplastic laminotomy cohort required fusion for progressive spinal deformity, compared with 43 (30%) in the laminectomy cohort (p = 0.027). Adjusting for the inter-cohort difference in preoperative MMS scores, osteoplastic laminotomy was associated with a 7-fold reduction in the odds of subsequent fusion for progressive spinal deformity (odds ratio 0.13, 95% confidence interval 0.02–1.00; p = 0.05). The median MMS and KPS scores were similar between patients who underwent osteoplastic laminotomy and those in whom laminectomy was performed (MMS Score 2 [IQR 2–3] for laminotomy compared with 2 [IQR 2–4] for laminectomy, p = 0.54; KPS Score 90 [IQR 70–100] for laminotomy compared with 90 [IQR 80–90] for laminectomy, p = 0.545) at a median of 3.5 years after surgery.

Conclusions
In the authors' experience, osteoplastic laminotomy for the resection of IMSCT in children was associated with a decreased incidence of progressive spinal deformity requiring fusion but did not affect long-term functional outcome. Laminoplasty used for pediatric IMSCT resection may decrease the incidence of progressive spinal deformity requiring subsequent spinal stabilization in some patients.