Cerebral Edema: Types & Causes

Instructor: Justine Fritzel

Justine has been a Registered Nurse for 10 years and has a Bachelor's of Science in Nursing degree.

The brain is an amazing organ that is essential to life and needs to be protected. In this lesson, we will learn about different types of cerebral edema and what causes them.

Brain

The brain is an amazing organ that is highly sophisticated. Life depends on the functioning of the brain. Thoughts, emotions, movement, speech, and essentially everything else happens because the brain is the mastermind of the body!

The brain consists of three main parts. The cerebrum, the cerebellum, and the brainstem. The brain is surrounded by cerebral spinal fluid or CSF. CSF is constantly produced and absorbed by the brain to keep it in good balance.

The brain also has it's own security system to protect it. The blood brain barrier or BBB is an advanced system of blood vessels that directs what enters the brain and what doesn't. The BBB allows essential nutrients to enter the brain but keeps out many substances, sometimes even medications that would be life-saving for the brain.

Brain Anatomy
Brain

The brain is enclosed in our skull, which is a tight, inflexible compartment. Therefore, if anything causes increased pressure in the brain, it can be very damaging. It's kind of like a bottle of soda that gets shook up. As long as the bottle is closed, there is nowhere for the increased pressure to go. But don't let that fool you, as soon as you open the bottle, the soda comes spraying out. If the brain has increased pressure, it has nowhere to go other than down the spinal cord, which can result in death.

Cerebral edema is swelling of the brain. It can occur for various reasons, all of which have to be taken very seriously as they can result in death if untreated. In this lesson, we'll take a look at the different types of cerebral edema along with what may cause them.

Vasogenic Cerebral Edema

Vasogenic cerebral edema is one of the most common types of cerebral edema. It occurs because of a disruption in the normal blood brain barrier function. Due to this disruption, proteins and fluid that are usually not allowed to cross are allowed to enter the brain. Once these cross over into the brain, they spread quickly throughout the brain and cause swelling. Vasogenic cerebral edema often occurs due to brain tumors or brain abscesses. It can also occur with brain contusions or brain hemorrhage.

Cytotoxic Cerebral Edema

Cytotoxic cerebral edema is another of the most common types of cerebral edema. A big difference between vasogenic and cytotoxic cerebral edema is that in cytotoxic cerebral edema, the blood brain barrier remains intact. Cytotoxic cerebral edema is instead a result of the sodium and calcium pumps not functioning correctly. This results in the brain retaining sodium and water, which causes the swelling. Various types of intoxications, such as alcohol intoxication, can cause cytotoxic cerebral edema. Early ischemia or inadequate blood supply to the brain tissue can also cause this type of cerebral edema.

Osmotic Cerebral Edema

Osmotic cerebral edema is another type of cerebral edema. Normally, cerebral spinal fluid and the fluid in the brain have a lower osmolality than blood. Osmolality refers to the concentration of the fluid. Think of the CSF like water and the blood like syrup. CSF (water) is a lower osmolality than blood (syrup).

If the blood becomes more diluted, and therefore a lower osmolality than the CSF, osmosis causes fluid to enter the brain. To explain further, osmosis is when a substance of lower concentration (thinner) moves towards the substance of higher concentration (thicker) in an effort to balance them. The blood is now thinner and the fluid in the brain is thicker. This causes fluid from the blood to enter the fluid in the brain. This increased fluid in the brain causes swelling.

So why would blood become less concentrated? A few of the causes include excessive water intake, low sodium levels, or hemodialysis. Hemodialysis is a procedure for people whose kidneys don't function correctly. It is a procedure to clean waste and fluid from the blood and balance electrolytes.

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