A 78-year-old male with history of multiple prior falls is brought into the local ED from his care facility because his caretaker noticed his altered mental status. A head CT was obtained.

What type of head injury is seen in this image, and what space does this injury involve?

Non-contrast CT is the best initial study. MR is better able to depict extent and age.

CT findings: Extra-axial collection of blood located between inner border cell layer of dura and arachnoid with a crescentic shape that spreads diffusely across cranial convexities as it can extend across cranial sutures but not dural attachments.
- Hyperacute phase (<6 hrs) can be of heterogeneous density or hypodense on CT
- Acute phase (6h – 3d) hematoma is homogeneously hyperdense ~60% of the time and mixed hyper- and hypodense 40% of the time.

MR findings: Variable in appearance secondary to the different appearance of blood on MR depending on its age.

Typically, subdural hemorrhage is secondary to traumatic tearing of bridging cerebral veins. The trauma may be very minor, especially in elderly patients as they are predisposed tearing secondary to cerebral atrophy.
Patient’s with ventricular shunts are at higher risk due to the shunted system not acting as a natural tamponade.
Can grow slowly with increasing risk for mass effect and herniation if not identified and treated early.
Recurrent hemorrhage is common.
SDH is a neurological emergency that often requires surgical treatment, however the decision between operative or non-operative management is based on multiple factors. Typically, If size is < 1cm with no cerebral edema, they can be managed non-operatively.
High-dose mannitol is often given to decrease risk of brain herniation prior to surgery.