PM&R News   •   September 1, 2017

First you have to remember some of the basic principals of brain imaging. This is a head CT which is best at viewing acute pathology in the form of bleeds but often misses acute cerebrovascular accidents. The three main type of bleeds you should be thinking of are subdural hematoma, epidural hematoma, and subarachnoid hemorrhage, with intraparenchymal hemorrhage being an additional type. This bleed is clearly outside of the brain parenchyma so we will save intraparenchymal hemorrhages for another day. Subdural hematomas are below the dura and tend to be long and thin, almost like a crescent moon. Since they are below the dura they do cross suture lines. Epidural hematomas are below the bone but above the dura and therefore do not cross suture lines. They are biconvex and are often associated with skull fractures.  Lastly, subarachnoid hemorrhages (SAH) are underneath the arachnoid but outside of the brain tissue, in the space that cerebrospinal fluid circulates. These are severely life-threatening and often have an acute onset, sometimes without trauma. In this image, you can see the abrupt onset of the hemorrhage with the bulging peak, indicating it is being contained by suture lines. This would make you diagnose an epidural hematoma!