They stop growing only when the pressure of the hematoma equalizes with the intracranial pressure, as the space for expansion shrinks. Chronic
In chronic subdural hematomas, blood accumulates in the dural space as a result of damage to the dural border cells. The resulting inflammation leads to new membrane formation through fibrosis and produces fragile and leaky blood vessels through angiogenesis, permitting the leakage of red blood cells, white blood cells, and plasma into the hematoma cavity. Traumatic tearing of the arachnoid mater also causes leakage of cerebrospinal fluid into the hematoma cavity, increasing the size of the hematoma over time. Excessive fibrinolysis also causes continuous bleeding.Pro-inflammatory mediators active in the hematoma expansion process include Interleukin 1α (IL1A), Interleukin 6, and Interleukin 8, while the anti-inflammatory mediator is Interleukin 10. Mediators that promote angiogenesis are angiopoietin and vascular endothelial growth factor (VEGF). Prostaglandin E2 promotes the expression of VEGF. Matrix metalloproteinases remove surrounding collagen, providing space for new blood vessels to grow.Craniotomy for unruptured intracranial aneurysm is another risk factor for the development of chronic subdural hematoma. The incision in the arachnoid membrane during the operation causes cerebrospinal fluid to leak into the subdural space, leading to inflammation. This complication usually resolves on its own. Diagnosis
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 subdural hematomas.Subdural hematomas occur most often around the tops and sides of the frontal and parietal lobes.
For the aforementioned reasons, researchers have developed predictive grading scales to identify patients at high risk of CSDH recurrence, one of which is the Puerto Rico Recurrence Scale developed by Mignucci-Jiménez et al. See also
Concussion
Diffuse axonal injury
Extra-axial hemorrhage
Intra-axial hemorrhage

References
External links

Subdural Hematoma at eMedicine
Imaging and Mechanism of Subdural Hematoma - MedPix