Neurological recovery after posterior decompression surgery for anterior dural compression in paralytic spinal metastasis.

PURPOSE: Paralysis in spinal metastasis is often caused by anterior dural compression, and anterior approach has been frequently chosen for decompression despite its dreadful complications. On the other hand, the effectiveness of posterior indirect decompression has not specifically established. The objective of the present study was to investigate the anatomical patterns of dural compression, and to clarify the effectiveness of posterior surgery for anterior lesions. METHODS: We retrospectively analyzed the anatomical patterns of spinal metastasis on MRI images and the neurological recovery in the paralytic patients who underwent posterior decompression and fusion surgery with intraoperative radiation therapy. The recovery rate was compared between those with an anterior or circumferential dural compression (A+), who were indirectly decompressed, and those with a posterior and/or lateral dural compression (A-), who were directly decompressed. RESULTS: A total of 135 cases were included in the study, and 81.5% had anterior dural compression (A+). In the A+ group, 88.2% of preoperatively non-ambulatory cases regained the gait. Full recovery was achieved in 50% of preoperatively ambulatory cases. These rates were not significantly different from those in the A- group. The rate of gait regain was diminished in the surgeries of the middle thoracic spine (T5-8). CONCLUSIONS: Most spinal metastases cause paralysis by anterior compression; however, the result of posterior indirect decompression was similar to that of posterior direct decompression, although kyphosis negatively affected the result. Anterior decompression might not always be necessary for soft tumor compression as long as the adjuvant therapy is effective for the local control.