Differential diagnosis & surgical outcome of primary cauda equina tumors

Abstract

Objective: This study was designed to identify surgical outcomes of primary cauda equina tumors and help differential diagnosis. Patients & Methods: We retrospectively reviewed 60 patients who underwent surgery for cauda equina tumors from April 1999 to May 2009 at Severance spine and spinal cord center. We analyzed clinical features, preoperative MRI findings, extent of surgical resection, histology and surgical outcomes. The surgical outcome was analyzed on the basis of Visual Analog Scale(VAS) score, the modified Japanese Orthopaedic Association(JOA) score. Results: The tumors of cauda equina were divided into two groups: tumors of neural sheath origin(TNS)(42), tumors of non-neural sheath origin(TNNS)(18). There were schwannomas (Sch)s(42) in the TNS, hemangioblastoma(HGB)s(5), cellular ependymoma(CEP)s(6), myx-opapillary ependymoma(MEP)s(5) and paraganglioma(PG)s(2) in TNNS. Leg pain was more common symptom in TNS, but neurological deficit was common in TNNS. TNS and TNNS were hyperintense or isoinstense on T2-weighted(T2W) images, isointense or hypointense on T1-weighted(T1W) images and are enhanced on postcontrast images, however flow voids on T2W images are more prominent in TNNS. Total resection was achieved in all cauda equina tumors after first surgery. There was no recurrence after total resection of TNS whereas there were 4 recurrences after total resection of TNNS. Patients with TNS complain more severe pain(VAS score, 5.51±1.42) than patients with TNNS(VAS score, 4.27±2.45) before surgery(p<0.05), but patients in two groups showed same pain intensity after surgery. Patients with TNNS showed poor neurological status before surgery(p < 0.05), after surgery(p<0.05) compared to patients with TNS. Conclusion: It is very important to differentiate TNS and TNNS before surgery, because there is significant difference in functional outcomes and TNNS carry a risk of partial resection, a recurrence risk even after total resection. Although they have similar clinical features and MRI findings, poor neurological status before surgery and flow voids on T2W images may facilitates differentiation of two tumor groups and planning of presurgical strategy.