Computed tomographic signs of the Chiari II malformation. Part I: Skull and dural partitions.

Lückenschädel, scalloping of the posterior surface of the petrous pyramids, falx hypoplasia, falx fenestration, and tentorial hypoplasia with wide incisura and tiny posterior fossa are readily identified by computed tomography (CT) in patients with Chiari II malformation. Enlargement of the foramen magnum may be appreciated on axial section CT in some cases. None of these findings is pathognomonic and each may be observed in some patients with other conditions. In the aggregate, however, these findings strongly suggest the presence of Chiari II malformation.