Neuroradiology

Platybasia

flattening of the skull base. The basal angle formed between a line drawn from the nasion to the centre of the sella turcica and a line passing along the posterior aspect of the clivus is a good parameter with which to describe and quantify the finding, values greater than 140 being considered abnormal. Platybasia may be caused by softening of the bony structures of the skull base, which is seen in several metabolic and haematological diseases such as Paget's disease, osteogenesis imperfecta and osteomalacia, which leads to a protrusion of the upper cervical spine in the foramen magnum (basilar invagination). Basilar invagination (or impression; see basilar impression) may be associated.

FS