Intraoperative sonography for spinal tumors. Correlations with MR findings and surgery.

BACKGROUND: To investigate the role of intraoperative ultrasonography during surgery for spinal tumors and the correlation between echographic, magnetic resonance and surgical findings. METHODS: Twenty patients with spinal tumor, explored by MRI of the spine, have been treated with ultrasound-guided surgery. The ultrasound exploration has been performed during laminectomy on the dural surface in all cases and, after the dural opening, on the spinal cord surface for intramedullary tumors. RESULTS: In all patients the ultrasound exploration has allowed to exactly define the extent of the laminectomy, the dural opening and the myelotomy. Meningiomas were hyperechoic and homogeneous, with well defined margins and often visible hyperechoic dural attachment; neurinomas were less hyperechoic and less homogeneous than meningiomas. Intramedullary tumors showed hyperechoic solid and hypoechoic cystic-necrotic components, although a specific tissue characterization (tumor infiltration, gliosis, edema) is not possible. CONCLUSIONS: Intraoperative ultrasonography should be used routinely during surgery for spinal tumors in order to reduce the extent of the laminectomy, dural opening and myelotomy. A good correlation exists between signal intensity on T1-weighted images of MR, the echographic aspect of the tumor and the pathological findings at operation.