Comparison of Intracranial Haemorrhage
Feature | Subarachnoid | Subdural | Extradural |
Location | The inner most layer around the brain tissue | Between the dura mater and arachnoid mater | The outermost layer, between the skull and dura mater |
Mechanism | Usually due to rupture of a blood vessel (e.g. berry aneurysm or AVM). Pain typically felt at the back of the head | Usually due to trauma causing damage to one of the bridging veins. Trauma may be minor and could be many months ago. Can be acute or chronic. | Due to direct moderate / severe head trauma. Typically around the eye, causing fracture of the temporal or parietal bone, resulting in laceration of the middle meningeal artery and/or vein |
Pain | Sudden onset, painful | Possible dull headache | Likely, and often severe, but not sudden onset |
Consciousness | May become impaired quickly – if so, a very bad prognostic indicator | Fluctuates, often over weeks or even months | Classically, an initial lucid period, followed by impaired consciousness |
Neurological signs | May be present; are a poor prognostic indicator | Often insidious. May involve memory impairment, epilepsy, drowsiness, dizziness. Often occur weeks / months after injury | |
Investigations | CT – should show irregular shaped bleed. If absent, and still suspicious, do LP to confirm (blood in CSF, CSF turn yellow when left to stand – xanthochromia) | CT / MRI – classically shows a crescent of blood around the brain tissue, and midline shift | CT / MRI – described as a lens shaped lesion – meaning it is biconvex. LP is contraindicated! X-ray may show skull fracture |
Management | If few symptoms, surgical clipping of platinum coiling of aneursm, or if AVM then balloon therapy and stening are beneficial. Give Nimodipine to reduce risk of vasospasm (and ↑ survival) as long as BP can be maintained. | Burr hole or craniotomy | Surgery to evacuate blood and ligate bleeding vessels |
Blood on CT scans
- Acutely appears more dense than surrounding brain
- Gradually, blood component are absorbed, and its density drops
- Can be hard to see in the subacute phase, as it may be isodense with brain tissue
- Chronically, it will appear hypodense (darker) than brain tissue
