Platybasia refers to flattening of the skull base, defined by an angle of more than 140 degrees between the clivus and the anterior cranial fossa1.
Measurement
The Welcher basal angle is used for measurement. This angle is defined as the angle between a line from the nasion to the tuberculum sellae and a line from the tuberculum sellae to the basion2. This angle averages 132° and is considered normal below 140°3.
Figure
Imaging
Clinical relevance
Isolated platybasia has no definite pathological significance4; however, platybasia occurs more frequently in association with basilar invagination or basilar impression5. This can then lead to compression-related neurological deficits and occipital headaches6.
References
Pinter, N.K., McVige, J. & Mechtler, L. Basilar Invagination, Basilar Impression, and Platybasia: Clinical and Imaging Aspects. Curr Pain Headache Rep 20, 49 (2016). ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩
Kimmig H. Platybasie. In: Hufschmidt A, Lücking C, Rauer S et al., ed. Neurologie compact. 7th edition. Stuttgart: Thieme; 2017. ↩ ↩