We report 20 cases (11 males, 9 females) who were operated upon between 1985 and 1993 for treatment of intradural spinal cord tumors using the posterior approach. The age of patients at surgery ranged from 8 to 70 years. They were followed up from 2 months to 6 years and 3 months (mean 2 years and 3 months).
On MRI, posterior shift of the spinal cord was observed after tumor removal in 4 cases with intramedullary tumors, in one case with extramedullary tumor, and in one case with an arachnoid cyst. However, no cases with cauda equina tumors showed posterior shift. The dorsal tissue behind the shifted spinal cord was enhanced by gadolinium in a case with positive Lhermitte sign. Cine MRI revealed that the posteriorly shifted spinal cord stopped the cerebrospinal fluid flow in 4 cases. These results suggested that the posteriorly shifted cord resulted from adhesion of the spinal cord to the arachnoid membrane or the dura.