Presentation
Headache.
Patient Data
There is a moderate volume of chronic subdural hemorrhage over the left frontal convexity causing a midline shift of 1 cm, rightward uncal herniation, and rightward transtentorial herniation.
Diagrams showing how to measure midline shift and how to identify uncal and transtentorial herniation.
Case Discussion
This case is a good example of mild degree of subfalcine, uncal, and transtentorial herniations.
To measure midline shift, draw a line through the midline and measure the displacement of the septum pellucidum. It is a good marker of the shift of the cingulate gyrus (which is the structure that herniates under the falx in a subfalcine herniation).
To find the uncus, locate the coronal slice showing the basilar artery. The uncus should be at that slice, or an adjacent slight.
To identify transtentorial herniation, scroll to the mid aspect of the falx but anterior to the incisura, and identify any brain parenchyma protruding lower than an imaginary line from the margin of the tentorium to the falx.
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