Constant dripping wears away the bone: intraosseous C2 and suboccipital intradiploic cerebrospinal fluid collection after Chiari I decompressive surgery.

The objective of decompressive surgery for Chiari I malformation is to create additional space to accommodate the ectopic cerebellar tonsils and to improve the flow of cerebrospinal fluid. To the best of our knowledge, we report the first case of a patient with previous Chiari I decompression presenting 5 years after surgery at the same time as an intraosseous C2 and a suboccipital intradiploic cerebrospinal fluid accumulation. Because of the progressive nature of the C2 cerebrospinal fluid collection causing bone destruction, surgical management was indicated. To avoid the erosion of the bone, we propose that the iatrogenic exposure of the diploe and the vertebral spongiosa that may come into contact with the cerebrospinal fluid should be sealed off with bone wax or a similar material.