A schwannoma of the S1 dural sleeve was resected while the intact nerve fibers were preserved using a microscope. Report of a case with early MRI findings.

In this report, we describe a small schwannoma of the dural sleeve and mention that it is often difficult to differentiate this tumor from lumbar disc herniation, especially a sequestered hernia, or a discal cyst. Gadolinium-enhanced MR images were a useful preoperative examination modality for differentiating this lesion from other diseases. Microscopically, the intradural tumor was successfully removed. The dura mater of the S1 nerve root was opened microsurgically, allowing the nerve fibers involved in the tumor to be identified. The involved fibers were cut around the tumor, and the lesion was resected while the intact nerve fibers were preserved. Based on histological examination of the resected specimen, the tumor was diagnosed as a schwannoma with multilocular cystic degeneration. Microsurgery allowed the tumor to be removed with minimal impairment from cutting of nerve fibers in the nerve root.