"Juxtafacet cysts", a misleading name for cystic formations of mobile spine (CYFMOS).

To present 58 cystic space-occupying formations of the spinal canal in 53 cases; these formations are called "juxtafacet cysts". Fifty-Three patients (33 women and 20 men, with an average age of 60.8 years) were evaluated retrospectively by neurosurgery. All of the patients had received simple X-P, computed tomography (CT) and magnetic resonance imaging (MRI) before surgery. The neurological findings were evaluated on admission and in a follow-up review. Surgical intervention was performed on all patients and they underwent gross-total cyst removal. During surgery, the origin of a cyst was well observed. Follow-up data ranged from 6 to 46 months. Patient outcome was graded on a scale of excellent, good, or poor. Histological findings were evaluated. In 53 patients 58 cysts were identified. Four of the patients had multiple cysts. All cysts were associated with mobile spine. Fifty-five cysts were found in the lumbo-sacral region, two cysts were found in the cervico-thoracic region and one cyst in the thoracic region. Forty-two patients presented back pain and 52 patients presented radicular pain. Four patients had a cauda equina syndrome. Sensory disturbance was observed in 24 cases and motor weakness was observed in 21 cases. Claudication was observed in 19 cases. All cases with cervico-thoracic or thoracic cysts presented myelopathy. The duration of these clinical symptoms ranged from 10 days to 10 years. After surgery there was no case of a recurrent cyst during the follow-up period. Thirty-four cases had an excellent outcome, 18 a good outcome, and one a poor outcome. Out of 58 cysts 32 were joint cysts (11 synovial cysts, 21 ganglion cysts). A further 19 were flavum cysts, one was a posterior longitudinal ligament (PLL) cyst and six others were unknown pseudo cysts. In 34 of the cysts we found hemosiderin deposits and in eight amyloid deposits. Present investigation and findings in literature show a clear comparison of these cystic formations and the mobile part of the spine. An anatomical relation to a vertebral joint ("facet") is only found in some of the cases (32 of 58). Further to that, the name "cyst" is not correct either, because most of the cystic formations are presented without a cell lining on their internal wall and therefore they are pseudo-cystic. We think that these cystic formations should be called "cystic formations of mobile spine" (CYFMOS) rather than "juxtafacet cysts". A surgical intervention is the best treatment for these cysts if they cause a compression of nerve roots or/and of the spinal cord.