[Dynamic MRI in the evaluation of syringomyelic cysts].

We report the results of a MR velocity study of the cerebrospinal fluid including 36 patients with syringomyelic cysts (25 with a foraminal syringomyelia, 7 with a post-traumatic cyst, 2 with a tumoral spinal cord cyst, 2 with a spinal arachnoiditis). Velocity measurements were performed in the cysts and in the pericystic subarachnoid spaces and compared with clinical data, evolutive pattern of the disease, cyst volume, degree of stenosis of the cranio-cervical junction (in patients with Chiari I) or of the spinal canal (in post-traumatic cases), and with the extension of the cyst (post-traumatic cases). Cyst velocities correlated in the pre operative course with the clinical status of the patients and with the volume of the cyst. Correlation with the degree of foraminal stenosis was uncertain and no correlation was found with the duration of the disease course. In the post-operative course cyst velocity decreased and velocity of the subarachnoid spaces increased. Onset of the systolic peak occurred sooner in the cyst than in the subarachnoid spaces. We believe that this point may be important in the pathogenesis of the disease. We consider that systolic and diastolic cyst velocities respectively greater than 2.3 cm/s and 1.5 cm/s in the post-operative course may characterize aggressive cysts. In the future comparison of velocity measurements in patients with Chiari I without syrinx and patients with Chiari I related syringomyelia may be helpful for a better understanding of the natural history of the syringomyelia.