A subdural haematoma is an intracranial bleed which occurs between the inner layer of dura mater and the arachnoid mater.
Pathophysiology
- Subdural bleeds usually occur secondary to venous bleeds. The cranial venous drainage involves bridging veins which drain blood from the brain into the venous sinuses.
- It is usually trauma (tends to be more minor traumas) and subsequent tearing of the bridging veins that results in these subdural bleeds.
- In cases of atrophy of the brain (often seen in elderly/alcohol patients), bridging veins need to travel a further distance to get to the dural venous sinus which means they start to stretch out.
- These longer, stretched bridging veins are more prone to tears. Thus, a trivial knock to head in an elderly patient may well lead to a subdural haematoma.
Risk Factors
- Excess alcohol use
- Use of anticoagulation
- Coagulopathies
- History of trauma
- Advanced age
Clinical Features
- Headache
- Confusion
- Changes in GCS
- Nausea/vomiting
Classification
Subdural haematomas can be categorised based on when the bleed presents from the point of injury.
- Acute Subdural: Bleed has presented less than 72 hours since injury.
- Subacute Subdural: Bleed has presented 4-21 days after the injury.
- Chronic Subdural: Bleed has presented more than 21 days. These are usually the trivial knocks and bumps that patients don’t even realised happened.
Investigations
Bloods
- FBC, U&E, CRP: Baseline
- Clotting Screen: For any coagulopathies
- Group and save: In case patient requires surgery
Imaging
CT head scans are the mainstay diagnostic test for subdural bleeds. Depending on the chronicity of the bleed, the image will vary in terms of attenuation whereby acute bleeds tend to be hyperattenuated/hyperdense and chronic bleeds hypoattenuated/hypodense. The characteristic appearance of a subdural haematoma is a sickle shaped bleed i.e. concave.
Management
- Initial treatment should always be with the A-E emergency resuscitation approach to ensure the patient is stable. Reversal of anticoagulation therapies/correcting clotting abnormalities should be done.
- Subdural haematomas can be treated both conservatively and surgically, but neurosurgical opinion should always be sought.
- If surgery is performed, it is usually via craniotomy or burr hole.
- Craniotomy: Involves temporary removal of part of the skull which gives the surgeon access to the haematoma and removal of the clot. This relieves any present mass effect. These are usually performed for acute SDHs.
- Burr Hole: Drilling a small hole into the skull and inserting a temporary drain. This is usually performed for chronic SDHs.
References
https://emedicine.medscape.com/article/1137207-overview
