Surgical Outcome of a Posterior Approach for Large Ventral Intradural Extramedullary Spinal Cord Tumors

Abstract

Case series. The object of this study is to present surgical outcomes for treatment of large ventral intradural extramedullary (IDEM) spinal cord tumors with conventional laminectomy. Most IDEM spinal cord tumors are meningiomas and schwannomas, which are separated from the spinal cord by a discrete anatomical barrier (the arachnoid or pia membrane). As a result of this anatomical barrier, a tumor can be removed using the posterior approach with conventional laminectomy. Although many reports have demonstrated the feasibility of the posterior approach for ventral tumors, there have been no studies detailing large ventral IDEM tumors. From 2001 to 2008, we operated on 18 consecutive patients with a large ventral IDEM tumor using the posterior approach (8 cervical and 10 thoracic). Preoperatively, eight patients were classified as having Nurick grade 1 myelopathy, six patients had grade 2, and four had grade 3. Tumors were removed through a slit-like space between the dura and spinal cord without retraction of the spinal cord. Complete removal of the tumor was possible in 17 cases. The follow-up period was 39 ± 28 months (range = 10-97 months). There were 7 cases of meningiomas and 11 of schwannomas. One schwannoma was mixed with the cervical rootlets and the mass in the foramen was left behind. Clinical symptoms improved in 16 patients and stabilized in 2. The one residual mass was stable for 62 months. There were no cases of recurrence. Neither kyphotic change nor instability developed in any of the patients during the follow-up period. Large ventral IDEM spinal cord tumors can be completely removed using a posterior approach and conventional laminectomy. An understanding of the anatomical and growth characteristics of these tumors is extremely important for successful removal. However, this approach should be applied prudently and with a thorough understanding of its limitations.