Synovial cysts of the lumbar spine: CT evaluation.

Seven cases of surgically proven intraspinal synovial cysts are reported. Computed tomographic (CT) scans demonstrated a series of low-density masses adjacent to the facet joints; in three cases, a dense rim indicated a calcified wall on the cyst; in one, the wall was partially calcified; and in three the mass appeared to be filled with gas. In all of these cases, there was severe degenerative facet disease at the same level as the synovial cyst. In six patients, the cysts were unilateral, while one was bilateral; seven cysts were located at the level of L4-L5, and one at L3-L4. We conclude from this study that the intraspinal synovial cyst can be identified reliably by the CT scan.