According to neuropathological and embryological knowledge, syringomyelia is a cyst which arises from secondary deformation of the normal spinal cord. This pathology pertains to several etiologies, which have been described in the present study. Syringomyelia is frequently combined with the Chiari abnormality, a familial form suggesting a possible genetic origin. Our clinical study of Chiari abnormality-associated syringomyelia included 285 patients showing homogeneous results after neurological evaluation and follow-up. Thus, a functional classification, based upon their neurological status and degree of dependence was used in order to analyze the treatment efficiency.

Clinical data analysis showed that the prior duration of symptoms did not influence the results of surgery. Postoperative data demonstrated that 80 % of the patients with pain improved, and that finally 90 % were stabilized. Mortality was only 0.7 % and morbidity was extremely low. These results were confirmed by pediatric data obtained from the study of 442 children bearing syringomyelia. Among them, 188 had Chiari abnormality and were all operated, resulting in improvement or stabilization for 95 % of the cases. In children with additional scoliosis (65 %, one of the major vertebral abnormalities associated with syringomyelia), surgery induced improvement or stabilization for 44 % of the cases.

Early management of injured patients, who had a post-traumatic syringomyelia, allowed a reduction of the cavity incidence, this latter being strongly correlated with the persistence of a cyphosis or a decrease of the size of the spinal canal.

MRI have given rise to much progress in the treatment of syringomyelia, allowing a precise diagnosis, an acute etiologic analysis and a proper operative preparation. MRI is also required for patient follow-up, allowing an evaluation of the course of the cyst and foramen magnum enlargement.

MR velocity study of CSF in the cysts and pericystic and foraminal regions correlated, in the preoperative course, with the clinical status and the volume of the cyst but not with course duration. Cyst velocities decreased in the postoperative course whereas the velocity of the subarachnoid space increased, dynamic MRI study allowing a simple follow-up of the CSF movement normalization.

Surgical intervention is recommended in most of the syringomyelia cases with two technical options. On the one hand, the cause of syringomyelia can be treated by enlarging the foramen magnum (hindbrain-related syringomyelia) or by dissecting arachnoiditis (post-traumatic syringomyelia). On the other hand, the consequences of syringomyelia can be treated by shunting the cyst toward the peritoneal cavity, a higher rate of reintervention occurring in this case.

Thus, to decide on reoperation surgeons must take three criteria into account : the absence of clinical stabilization, a persistent abnormality of flow velocity and a non-reducing cyst.