Wiktionary
platybasia
n. (context medicine English) A developmental condition characterized by an upward bulge in the base of the posterior cranial fossa.
Wikipedia
Platybasia
Platybasia is a spinal disease of a malformed relationship between the occipital bone and cervical spine. It may be caused by Paget's disease. Platybasia is also a feature of Gorlin-Goltz syndrome, commonly known as basal cell nevus syndrome.