Table 5. Prevalence of anatomical variations in the sinonasal region.

SS: sphenoid sinus, ICA: internal carotid artery, ON: optic nerve

Empty cells correspond to not reported data.

First author, year	n	ICA protrusion into SS (%)	ON protrusion into SS (%)	SS hypoplasia (%)
Mokhasanavisu, 2018 [1]	64	2	7
Turna, 2014 [10]	6224	3	5.5	0.9
Dasar, 2016 [22]	400	46	35.3	14.5
Rereddy, 2014 [30]	100	17	18
Yazici, 2019 [41]	120	20.8		5.8