Extradural and Acute Subdural Haematoma
A haematoma is a medical term for blood clot, which forms as a result of bleeding into an organ or cavity. Extradural haematoma (EDH) is a blood clot that forms on the outside of the natural covering of the brain (‘dura mater’), while acute subdural haematoma (ASDH) refers to a blood clot on the inner surface of the dura that appears within the first few days of head injury. Both extradural and acute subdural haematoma are serious conditions that can cause compression of the underlying brain, and usually are a result of significant head trauma, which may be associated with a brief episode of loss of consciousness.
Extradural haematoma (usually from a torn artery in the skull)…
- Head trauma.
- Fracture of skull.
Acute subdural haematoma (usually from an artery or vein on the surface of the brain)…
- Head trauma.
- Blood thinners, such as aspirin, clopidogrel, warfarin, NOAC’s or other medications.
- (Rarely) Brain aneurysms, AVMs, dAVF.
Classical symptoms of an EDH include brief loss of consciousness, followed by a ‘lucid interval’, then development of progressive headaches, weakness, numbness and increasing drowsiness, and dilated pupil in the eye. This progression is a sign of haematoma expansion and worsening pressure and compression of the brain. ASDH may have similar symptoms, but without the ‘lucid interval’. Both conditions require urgent medical attention.
Tests / Diagnosis
The definitive test to diagnose is a CT scan performed within the Emergency Department. This will determine the presence of EDH or ASDH, the volume of the haematoma and the amount of pressure and compression of the underlying brain. In EDH, there is usually an associated skull fracture. In patients who are taking blood-thinning medications, additional blood tests may be performed to determine whether treatments to reverse the blood-thinners are necessary.
Patients with EDH / ASDH will require admission into hospital for at least 24 hours to be observed. If the volume of the haematoma is large enough, or there is sufficient pressure on the brain, surgical removal of the haematoma is required. This is usually performed through a craniotomy, in which a section of skull is opened with a medical saw (‘craniotome’) to gain access to remove the haematoma. Since the clot in EDH or ASDH is thick in consistency, a large opening is required to relieve the pressure on the brain. Sometimes, the skull flap is not replaced immediately and kept secure in a bone bank (‘craniectomy’). This flap will be returned to the patient with a separate operation in a delayed fashion several months later once the brain swelling has subsided (‘cranioplasty’). Medications for EDH / ASDH are usually not beneficial to remove the clot.
Chronic Subdural Haematoma
Chronic Subdural Haematoma (CSDH) is a haematoma that has been present for at least 5 – 7 days, in which the thick consistency of ASDH gradually evolves to become more ‘fluid-like’. This occurs due to the body’s natural processes to dissolve the fresh clot, and in so doing, the break-down contents of the clot / haematoma accumulate and attract more fluid into the subdural space, which in turn can cause more pressure and compression of the brain. The fluid in CSDH ranges from a ‘thick motor oil’ consistency to a thinner yellow fluid, and can sometimes have clear water-like appearance.
Chronic Subdural Haematoma (usually from tearing of a small superficial vein on the brain)…
Minor head injury – May not be noticed or remembered by the patient. Blood thinners – Aspirin, clopidogrel, warfarin, NOACs or other medications. (Rarely) Cerebrospinal fluid leak into the spine, or after shunt surgery.
CSDH may have symptoms of progressively worsening headaches, confusion and stroke-like symptoms, such as weakness, numbness, loss of co-ordination, difficulty with speech, vision or walking. There may be a report of previous minor head trauma from several days to weeks ago, although this is not always necessary for diagnosis.
Tests / Diagnosis
Similar to EDH / ASDH, the main test is a CT scan of the brain. This allows diagnosis of the CSDH and demonstrates the amount of compression on the brain, and whether surgery is necessary to relieve pressure on the brain.
When there is excessive pressure on the brain from CSDH, treatment usually involves drainage of the fluid within the haematoma. This can be performed by drilling a hole in the skull (‘burrhole’) or removing a small section of skull (‘mini-craniotomy’) to release the CSDH fluid. Once the fluid is thoroughly washed out, a drain is placed into the space to allow for more CSDH fluid to be released. Following surgery, patients may be required to have flat bed rest for at least 24 hours before being discharged from hospital several days later. In approximately 10 – 15% of CSDH cases, repeat drainage may be necessary as CSDH can recur. Medications for CSDH are usually not beneficial to remove or dissolve the clot / fluid.