Neuropathology – Understanding Severe Brain Injury Pathology
Neuropathology – Understanding Severe Brain Injury Pathology
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We turn now to neuropathology – the pathology of severe closed head injury. (Click here for our treatment of normal brain anatomy). If you are in a waiting room and someone you love is in a coma, you may have heard some of these diagnostic labels. But for many, no one has taken the time to explain what the diagnosis means. Thus, this part of Braininjuryhelp.com will address the most common diagnosis of the cause of severe brain injury.
Increases in Intracranial Pressure
Before we discuss the more specific diagnosis, I want to talk about the overriding concern in severe brain injury crisis – increases in intracranial pressure (ICP). While there are other causes of coma and other reasons for brain surgery, in a traumatic injury, there should always at least be a consideration that ICP may increase. Increases in ICP are the biggest cause of secondary brain damage. They are also most often the cause of death after someone arrives in a trauma center. As pressure within the skull and brain increases, it becomes harder for blood to flow through the brain (for the blood to perfuse). The capillaries, which are the smallest blood vessels in the brain, are the vessels which provide the fuel (glucose) and oxygen for the brain to function.
Think of brain function as a fire occurring on the cellular/microscopic level. Like any fire, the cell needs fuel, (blood sugar called glucose) and oxygen to combust. Like any fire, it must also exhaust the by-product of this fire. If you don’t exhaust from a room, you will become poisoned by the smoke. If you fail to remove the spent glucose from the cell, the cell becomes toxic. The build up of toxic waste will actually kill brain cells faster than absence of oxygen. So sticking with the analogy, when ICP increases in the brain, it as if the size of a chimney were constricted, forcing smoke to back up. A shortage of fuel and oxygen will also kill cells. The greater the increase in ICP, the more blood will be effected. A large enough increase in pressure will compress the brain stem. The brain stem is the home of the involuntary nervous system. Disrupting blood flow there impacts heart rate and blood pressure, and can result in death.