Visibility of the central canal on MRI

The central canal of the spinal cord is present at birth and becomes progre ssively obliterated. Cadaver studies have shown that it may persiste partia lly or completely. To our knowledge, this entity has not been described on MRI. We reviewed 794 MRI studies of the spinal cord, and found 12 patients (aged 14 to 65 years) who had an intramedullary cavity. The cavity was at t he junction of the ventral 1/3, and dorsal 2/3, of the spinal cord, except at the level of the lumbar enlargement, where it was central. It was filifo rm in most cases, although sometimes fusiform (3 to 4 mm in diameter), and had regular contours. The cavity were thoracic in 69% of cases. The clinica l features were totally unrelated to the image, and there were no anatomica l factors (Chiari malformation, dysraphism) predisposing to syringomyelia. The images were perfectly compatible with a persistent central canal, which we interpret as a variant of normal anatomy. Therefore it is important to regard these findings as normal, to avoid unnecessary treatment and follow- up.