Clinical and Experimental Investigation of Mediobasal Skull Fracture

Abstract

Mediobasal skull fractures which encroach through or near the sella turcica are often associated with injury of the midline structures. The purpose of this study is to clarify the correlation between clinical symptoms and fractures. Experimental studies such as the stress coat, a strain gage method and free drop impacts allowed assessement of mediobasal skull fractures.
Patterns of the fractures in autopsy cases were classified into four types from the impact site as follows. Type 1 : frontal blow. Type 2 : frontolateral blow. Type 3 : temporal blow. Type 4: occipital blow. Patterns of the fractures in clinical cases analysed by skull x-rays were almost consistent with the autopsied cases except for the absence of Type 4.
In experimental cases of midfrontal loading related to Type 1, the stress was concentrated in the midline on the anterior cranial base and lateral to the sella turcica on the middle cranial base.
CSF rhinorrhea, impariment of the optic chiasma, and the III and V cranial nerves were closely associated with Type 1 and 2 fractures. In Type 3 fractures, CSF otorrhea, VI and VII cranial nerve injuries and damage of the internal carotid artery were prominent findings. Structural derangement through or near the superior orbital fissure on the middle cranial fossa might impair small branches of the internal carotid artery distributed to the hypothalamus and pituitary stalk or optic chiasma, thus causing diabetes insipidus and bitemporal hemianopsia, respectively.