What are brain haemorrhages and what do they look like?
Brain haemorrhages (also spelled as hemorrhages, depending on dialect) are also known as bleeds within the brain, and they can occur in several different areas within the brain tissue. There are several underlying causes which can lead to a brain haemorrhage, and they include hypertension (high blood pressure) and other forms of brain injury. An example of a brain haemorrhage is seen in the picture alongside. They can also arise in other circumstances such as a brain tumour, an AVM (an arteriovenous malformation, which I’ll discuss in Other Cerebrovascular Diseases) or a cavernous malformation. Depending on the location, it can either form a pattern associated with trauma and/or produce aneurysms, which I’ll discuss below. Haemorrhages within the dura in the meninges and with the brain tissue itself tend to exhibit a pattern associated with trauma, however within the subarachnoid mater, it tends to form aneurysms.
What are the types of haemorrhage?
There are three subtypes of haemorrhage: rupturing of saccular aneurysms, non-traumatic intraparenchymal haemorrhages (i.e. bleeds within the brain tissue itself) and cerebral amyloid (protein) angiopathy. First of all though, I’ll introduce you to aneurysms.
What are aneurysms?
Aneursyms are weakened parts of arteries. Over time, these blood vessels expand at the weakest point to try and compensate, and they blow up like a balloon. A special component of arteries is that unlike veins, they have a layer known as the elastic lamina; like the name suggests, it stretches and compresses like an elastic band constantly in rhythm with the heart beating. You can use this special quality to determine your blood pressure. If left unchecked, like a balloon, the aneurysm will eventually burst and lead to haemorrhage (to a bleed).
Saccular haemorrhages are also known as berry haemorrhages and they are the most common type of aneurysm that happens within the brain. Under the majority of circumstances, saccular haemorrhages can happen as a result of genetics that lead to weaknesses within the arterial walls, but they can be exacerbated by environmental factors such as exercise and high levels of stress. They often
occur within the subarachnoid mater within the meninges. These haemorrhages tend happen when the blood pressure is elevated for whatever reason, as the high blood pressure makes the blood vessels expand and retract more forcefully than at rest. Symptoms that may arise before the (saccular) aneurysm ruptures include sudden, excruciating headaches and loss of consciousness. Most of the ruptures tend to happen within the arteries at the front of the brain. The odds of surviving a (first) brain aneurysm are fairly high (from 50-75%) after a period of unconsciousness, but unfortunately the chances of another aneurysm bursting are also quite high and the prognosis after subsequent haemorrhages is worse. For those that survive the first haemorrhage, the brain then undergoes a healing phase through inflammation, which leads to scarring of the meninges. This scarring can interfere with the movement of CSF and may even block it entirely.
Cerebral Amyloid Angiopathy
Cerebral amyloid angiopathy is the formation of proteins within the blood vessel walls located in the brain. These proteins can eventually lead to a bleed in the brain because of the vessels weakening. These protein (amyloid) formations tend to be similar to those of Alzheimer’s disease, and can be found in a brain biopsy by using Congo Red stain. Instead of the blood vessels being flexible, they become rigid and appear like pipes. In the picture alongside, you can see the protein accumulated in white lines. The haemorrhaging associated with this disease tend to appear different to that of typical brain haemorrhaging.
There are several types of brain haemorrhages: the different types can be seen on the picture below. The symptoms associated with the bleed differ, depending on the location.
They tend to occur at mid to late adult life, usually at around 60 years of age. These tend to be triggered by high blood pressure (hypertension) which eventually leads to small leakages. The regions in which brain haemorrhaging tends to occur (as a result of high blood pressure) include the cerebellum, pons, thalamus and basal ganglia. If the haemorrhaging affects a large portion of the brain, it can be devastating. Eventually, over a period of weeks or months, the haematoma (solid swelling of blood within the tissues) resolves itself through the inflammatory process and there can occasionally be significant improvement.