Long lasting near-obstruction stenosis of mesencephalic aqueduct without development of hydrocephalus

Aim To present 5 years longitudinal MRI follow up of a patient with incidental finding of near-obstruction stenosis of aqueduct of Sylvius due to the large pineal cyst. Methods Patient was scanned 3 times during period of 5 years on 3T MR device with set of standard structural sequences supplemented with high-resolution constructive interference of steady state (CISS) T2 sequence for precise delineation of aqueduct of Sylvius and cardiac-gated phase-contrast sequences for analysis of cerebrospinal fluid (CSF) movement. Results During 5 years longitudinal follow up period near-obstruction stenosis of aqueduct of Sylvius due to the large pineal cyst was present on all MRI scans without significant morphological changes. At the same time there was no significant ventricular enlargement despite the fact that structural CISS sequence showed near-obstruction stenosis and that cardiac-gated phase-contrast sequences did not detect movement of CSF through aqueduct of Sylvius. Conclusion Our findings are opposed to the classical hypothesis of CSF physiology based on secretion, circulation and absorption of CSF which predict that impairment of CSF circulation through aqueduct of Sylvius inevitably lead to development of hypertensive hydrocephalus in lateral and third ventricles. Our research group previously proposed new concept of CSF physiology which is more suitable for explanation of similar clinical cases