Platybasia

Diagnosis

• Abnormal flattening of the skull base, defined as a base of skull angle > 143º.
  • Angle formed by a line joining the nasion with the centre of the pituitary fossa and a line joining the centre of the pituitary fossa with the basion.
• Often coexists with basilar invagination.

Association

Congenital / Developmental

Conditions with maldevelopment of the craniocervical junction

• Chiari malformations
• Klippel-Feil syndrome
• Atlanto-occipital assimilation
• Pierre Robin sequence
• Down syndrome

Skeletal dysplasias / Storage diseases

• Achondroplasia
• Osteogenesis imperfecta
• Hajdu-Cheney syndrome
• Morquio syndrome
• Cleidocranial dysplasia
• And many others

Acquired / Metabolic

Bone softening/remodelling disorders

• Paget disease
• Fibrous dysplasia
• Rickets
• Osteomalacia
• Hyperparathyroidism
• Renal osteodystrophy