A subdural haematoma (SDH) is a collection of blood and blood products in the subdural space. The subdural space is located on the surface of the brain but deep to the dura, which is the tough outer lining that covers the brain and cerebrospinal fluid.
Subdural haematoma in an acute setting is often caused by tearing of the veins in the subdural space, and is often the consequence of trauma. There are other various factors that increase the risk of sustaining a subdural haematoma including brain atrophy, increasing age, medications that increase bleeding (anticoagulant and antiplatelet medications) and heavy alcohol intake. Due to the fragile nature of the veins in the subdural space, in some instances even trivial trauma, such as a fall from standing height, could precipitate a subdural haematoma.
The symptoms and signs of subdural haematoma are quite variable. They include headache, nausea and vomiting, and in more severe cases drowsiness and stroke like symptoms (speech disturbance, weakness). Sometimes the symptoms can be quite non-specific such as cognitive/memory impairment, reduced balance and coordination.
SDH is diagnosed using either CT or MRI.
Though SDH can occur acutely, they can also become a recurring and chronic issue.
Is this a serious condition?
An acute SDH can be a serious and life threatening condition due to brain compression. In this scenario it is necessary to relieve the pressure, usually done by a surgical procedure to drain the blood (craniotomy, burr holes).
In cases where the blood collection is small, it can be monitored with repeat scans.
Over time the body can reabsorb the blood resolving the collection, though in many cases the body is unable to completely absorb the fluid or the body produces more fluid that fills the subdural space, despite a surgical procedure, resulting in a recurrent subdural haematoma.
A chronic subdural haematoma (CSDH) occurs when the body is unable to resorb the fluid adequately and there is ongoing bleeding/leakage from the blood vessels. In the long term this can cause significant morbidity and reduction in function.
The dura receives blood supply from the meningeal arteries. Middle meningeal artery embolisation (MMAE) is a recently recognised technique to treat chronic subdural haematomas.
A small catheter is placed into the meningeal arteries and the arteries are blocked using a special glue like material. By reducing the ongoing bleed/leakage from blood vessels the body is able to reabsorb the subdural fluid. MMAE has been shown to be safe and effective with a very low risk of complication. Anticoagulant and antiplatelet medications do not need to be withheld (unlike open surgery which usually requires withholding such medications). MMAE can be performed in isolation, or as an adjunct to subdural haematoma evacuation. MMAE can in some cases be performed awake without the need for an anaesthetic.