The importance of early postoperative radiation in spinal myxopapillary ependymomas

Abstract

We read with interest the report by Aykurek et al. [1] on the success rates of combined surgical and radiation treatment of myxopapillary ependymomas. Myxopapillary ependymomas are commonly found within the cranio-spinal axis and are typically found in the caudal spinal canal, conus and cauda equina [2–4]. Total surgical extirpation has been found to a highly effective treatment in these low grade ependymomas [5, 6]. Subtotal resection of these tumors requires postoperative radiation, which has been also highly effective in preventing recurrence [5, 7]. The time frame between surgical resection and radiation therapy is yet to be fully elucidated. We recently operated on a 47 year-old male who presented for neurosurgical evaluation of an enhancing lesion within the conus. The patient was originally seen by an orthopedic surgeon for an L5-S1 disc herniation and an enhancing lesion was discovered on the preoperative MRI. The patients’ past medical history was insignificant. On neurological examination the patient had classic right S1 radiculopathy. The MRI revealed mild foraminal stenosis with a 4 mm disc bulge at L5-S1 while also demonstrating a 7 mm homogeneous contrast enhancing lesion within the conus (Fig. 1). The craniospinal axis was subsequently scanned via MRI and demonstrated no other lesions. After informed consent the patient was taken to the operating room for a microscopic L5-S1 discectomy and an L1-L2 laminectomy, durotomy for resection of conus lesion. The patient had continuous EMG and SSEP monitoring throughout the surgery. The lesion was gray in color and had several roots traversing the core of the tumor. Microdissection allowed for approximately 80% resection of the mass. Direct nerve root stimulation demonstrated several sacral roots in the core of the tumor. Postoperatively the patient was neurologically intact with full resolution of the S1 radiculopathy. The MRI performed approximately six weeks after surgery demonstrated three additional lesions cephalad to the initial surgery (Fig. 2). Further imaging of the entire craniospinal axis demonstrated no other lesions. The patient subsequently underwent stereotactic radiation therapy at a dose of 50 gy on the four lesions without complications. The metastatic potential of myxopapillary ependymomas is well documented, although not routinely recognized [8–10]. The reports of myxopapillary dissemination are reported as long as forty years ago with reports of both intracranial seeding and extraneural metastasis [3, 8–12]. Graf et al [8] report on a case of pulmonary metastasis of a myxopapillary ependymoma, although this occurred decades after the initial surgery and no focal radiation was performed after surgery. We report the first case of metastasis of myxopapillary spinal ependymoma within six weeks of initial surgery. Our case exemplifies the classic pattern of metastasis, through cerebrospinal fluid, cephalad into the ascending spinal cord. Davis et al. [3] reported two decades ago on three cases of aggressive behavior of a supposed ‘benign’ myxopapillary spinal ependymoma, speculating that a few of these tumors while R. D. Dickerman (&) A. S. Reynolds E. Gilbert B. Morgan Neurosurgery Research Foundation of Texas — Brain and Spinal Cord Tumor Institute, North Texas Neurosurgical Associates, Plano Presbyterian and Medical Center of Plano Hospitals, 6200 West Parker Road, Suite 1-503, Plano, TX 75093, USA e-mail: drrdd@yahoo.com