03|05|2018
STROKE AND THE BRAIN
A study on the body’s most remarkable organ
WARNING! This post contains graphic images of brains
In my PhD, I often get to work with extreme cases of brain diseases and neurodegenerative disorders. My thesis is about trauma and the brain, but in our lab, we often work with individuals who have Parkinson’s, Alzheimer’s and multiple sclerosis. Normally, we are given a patient’s medical notes alongside their brain, so we can make an accurate diagnosis and help the doctors and families understand what had occurred during their loved ones (and patient’s) life. Whilst each case is important and informative, one case in particular, however, was truly fascinating. We were given a case in which a woman was believed to have Parkinson’s disease. She had a stroke in her 40s but recovered shortly afterwards. She did, however, lose a lot of control in the left side of her body, but otherwise for many years was relatively normal. That was until she developed tremors and shakes and was eventually hospitalised, where she passed away in her late 50s. The case seemed fairly straight forward, and we were expecting a fairly simple diagnosis.
To diagnose certain diseases, you have to look at specific landmarks in the brain. These can be either big landmarks that you can see with the naked eye (macroscopic) or tiny ones that you have to use a microscope for (microscopic). In Parkinson’s the macroscopic change that we see is associated with an area called the substantia nigra, which is normally filled with black pigmented cells. However, in Parkinson’s many of the cells die and it’s no longer black. Nobody knows why this happens, but the loss of these cells explains why people with Parkinson’s have problems with movement, such as shaking and tremors. Microscopically, we look for proteins in the brains that tell us more about the cellular processes in the disease.
a frontal view
When we took the brain out, we were shocked. It seemed that the stroke that the patient had in her 40s was more devastating than we were led to believe. The entire right side of her brain had nearly disintegrated! A stroke is an event where the blood supply to a certain area of the brain is stopped. Once blocked, oxygenated blood can no longer get that area, and the cells (and tissue) in that area will starve and die. As certain areas have specific functions in the brain, strokes can have wildly different symptoms. These symptoms can let us know where in the brain the stroke has occurred. Blood supply to the brain can be thought of like a large river flowing into smaller rivers and tributaries. You have large arteries in your brain that divide into arterioles and then into smaller capillaries that go everywhere in your brain. If you block a small capillary, then only that small area of the brain is affected, and a stroke is mostly contained to a small region. However, if a large artery is blocked, then EVERYTHING downstream is blocked. In our case, it appeared that the patient's artery (middle cerebral artery if you want to know specifics) was blocked and all vessels that the artery fed into died. In essence, the entire front of her right hemisphere atrophied (died).
What makes this so interesting is that with a stroke of this size, we would expect the patient to not be able to do very much of anything afterwards. She should have been bed bound, with a massive personality change. However, her brain somehow coped for years and she was able to live a life. Her language was unaffected, as language centres are in the left hemisphere, and she was able to walk (with the help of a walker) for a few years. It is no wonder then that she experienced some movement symptoms but were not on the level that they should have been! This case was an incredible insight into the wonder of how amazing the brain can be. Not only could this woman speak and communicate, but she could even move with the help of others and half of her brain had died! In cases like these, we often learn so much about how the brain copes and changes with diseases and disorders. In some rare cases, we learn how amazing the human body can be, and how it can surpass our wildest expectations.
A frontal view of the brain, showing widespread tissue atrophy and death with the healthy lobe as a backdrop.
This image is taken from a side angle showing the temporal lobes as well as the ventral (underneath) side of the brain. You can see that the tissue death is only in a specific region that was fed by a single artery. The occipital lobe (back of the brain) is spared.
The left hand side (right hemisphere) shows generalised atrophy and cell death whilst the right (left hemisphere) is in good health. Showing the extent of the damage by comparison.
A central view of the tissue which is relatively spared by the stroke, save for a small section of temporal lobe.
Tissue is routinely dissected into coronal slices (front to back) and later out to take for further examination. You can see the extent of damage throughout the brain in the cortex.