A<unk>  demonstrated by CT Chronic subdural after treatment with burr holes It is important that a person receive medical assessment, including a complete neurological examination, after any head trauma. A CT scan or MRI scan will usually detect significant<unk> s.<unk> s occur most often around the tops and sides of the frontal and parietal lobes. They also occur in the posterior cranial fossa, and near the falx cerebri and tentorium cerebelli. Unlike epidural hematomas, which cannot expand past the sutures of the skull,<unk> s can expand along the inside of the skull, creating a concave shape that follows the curve of the brain, stopping only at dural reflections like the tentorium cerebelli and falx cerebri. On a CT scan,<unk> s are classically crescent-shaped, with a concave surface away from the skull. However, they can have a convex appearance, especially in the early stages of bleeding. This may cause difficulty in distinguishing between subdural and epidural hemorrhages. A more reliable indicator of subdural hemorrhage is its involvement of a larger portion of the cerebral hemisphere. Subdural blood can also be seen as a layering density along the tentorium cerebelli. This can be a chronic, stable process, since the feeding system is low-pressure. In such cases, subtle signs of bleeding—such as effacement of sulci or medial displacement of the junction between gray matter and white matter—may be apparent. Age Attenuation (HU) First hours +75 to +100 After 3 days +65 to +85 After 10–14 days +35 to +40 Fresh subdural bleeding is hyperdense, but becomes more hypodense over time due to dissolution of cellular elements. After 3–14 days, the bleeding becomes isodense with brain tissue and may therefore be missed. Subsequently, it will become more hypodense than brain tissue. Classification<unk> s are classified as acute, subacute, or chronic, depending on the speed of their onset. Acute bleeds often develop after high-speed acceleration or deceleration injuries. They are most severe if associated with cerebral contusions. Though much faster than chronic subdural bleeds, acute subdural bleeding is usually venous and therefore slower than the arterial bleeding of an epidural hemorrhage. Acute<unk> s due to trauma are the most lethal of all head injuries and have a high mortality rate if they are not rapidly treated with surgical decompression. The mortality rate is higher than that of epidural hematomas and diffuse brain injuries because the force required to cause<unk> s tends to cause other severe injuries as well. Chronic subdural bleeds develop over a period of days to weeks, often after minor head trauma, though a cause is not identifiable in 50% of patients. They may not be discovered until they present clinically months or years after a head injury. The bleeding from a chronic hematoma is slow and usually stops by itself. Because these hematomas progress slowly, they can more often be stopped before they cause significant damage, especially if they are less than a centimeter wide. In one study, only 22% of patients with chronic subdural bleeds had outcomes worse than "good" or "complete recovery". Chronic<unk> s are common in the elderly. Differential diagnosis
Subdural hematoma
Hepatic encephalopathy
Subdural empyema
Epidural hematoma
Subarachnoid hemorrhage
ROSAH syndrome
Migraine
Migraine 