Brain stem – structure, functions, diseases, research. What is brain stem death?

Proven content

The brain stem is the part of the brain that connects directly to the spinal cord. It contains regions that modulate breathing and heart function, as well as the communication pathways between the brain and the spinal cord. The cranial nerves emerge from the brainstem, controlling movement and feeling in and around the face. Many conditions can affect the brainstem, and symptoms can vary, often including dizziness, double vision, and / or movement problems.

Where is the brainstem located?

The spinal cord enters the skull through an opening known as the great foramen (Latin. a large hole). It is around this point that the medulla connects to the medulla, which is the lowest part of the brainstem. The brain stem is therefore the stem that extends from the brain to the spinal cord and is clearly visible when the brain is looked at from any perspective that allows you to see the base of the brain. The brain stem consists of 3 main structures: the medulla (Latin. medulla oblongata), bridge (Latin. pons) and midbrain (lat. mesencephalon).

What is the brainstem and what parts is it divided into?

In addition to connecting the brain to the rest of the nervous system, the brainstem performs a number of important functions. To keep things simple, it is helpful to discuss some of the functions associated with each of the three major areas of the brainstem. However, it should be noted that the structure of the brain stem is very complex and this is just an overview.

Structure of the brain stem – medulla elongated

In addition to being the point where the brain stem connects to the spinal cord, the core contains a nucleus called the nucleus of the solitary strand (Latin. the core of the solitary tract) which is critical to our survival. The nucleus of the solitary strand receives information about blood flow, as well as information about the levels of oxygen and carbon dioxide in the blood from the heart and major blood vessels. When this information suggests a non-compliance with the body’s needs (e.g., blood pressure is too low), reflexes are initiated in the nucleus of the solitary strand to bring things back into the desired range.

Consequently, the core is essential for our survival as it ensures the proper functioning of important systems such as the cardiovascular and respiratory systems. Additionally, the core is responsible for a number of reflexive actions, including vomiting, swallowing, coughing and sneezing. Several cranial nerves also exit the brainstem at the level of the spine.

Structure of the brain stem – bridge

Another structure on our way up the brainstem is the bridge. It is hard to miss; it is a large, rounded and convex structure just above the core. The word “pons” in Latin means bridge and resembles a rounded bridge that connects the spine and midbrain.

The bridge is an important path for the roads that run from the forebrain (lat. telencephalon) to the medulla and spinal cord (Latin. spinal cord), and also for the pathways to the brain. It also makes important connections with the cerebellum (Latin. cerebrum) through bundles of fibers known as the branches of the cerebellum (Latin. cerebellar peduncles).

There are many nuclei of the cranial nerves in the bridge. The nerves that carry information about the sensations of touch, pain and temperature from the synapses of the face and head to the nucleus in the pons. Movement commands for eye movement, chewing, and facial expressions also come from the bridge. In addition, the nuclei of the cranial nerves in the pons are involved in a number of other functions, including swallowing, tear production, hearing, and balancing.

Structure of the brain stem – midbrain

The last part of the brain stem as we approach the brain is called the midbrain. There are many important stretches in and out of the brain and cerebellum in the midbrain, as well as several key nuclei.

The upper back of the midbrain is called roof, which means “roof”. The surface of the tectum is covered with four protrusions representing two paired structures: the upper and lower mounds. The upper mounds are involved in eye movements and visual reflexes, while the lower mounds are involved in auditory reflexes.

More or less at the level of the upper mounds, but more forward, there is another important nucleus called the black matter. substantia nigra, which literally means “black substance,” has been named because it appears very dark in an unstained piece of tissue. substantia nigra it is rich in dopaminergic neurons and is considered part of the basal ganglia (lat. basal ganglia), which are the set of nuclei crucial for proper motor movement. In patients with Parkinson’s disease, neurodegeneration occurs in the substantia nigra, and this neurodegeneration is associated with the characteristic movement dysfunction found in Parkinson’s disease.

Structure of the brain stem – nerve pathways

The brain stem contains nerves and neural pathways that provide motor and sensory functions throughout the body. Nerve pathways are made up of sequences of nerves that send messages quickly through a specific path.

The main nerve pathways in the brainstem include:

1. Spinal-thalamic road (pour. spinothalamic tract): This pathway runs in the outer part of the brainstem, transmitting sensory signals from the sensory nerves to the spinal cord, through the brainstem, and to the thalamus in the cerebral cortex.
2. Cortico-spinal way (pour. corticospinal tract): this path is medial, near the center of the brainstem, sending messages from the motor cortex through the brainstem, to the spinal cord, and ultimately to the muscles to control movement.
3. Spinal-cerebellar pathway (pour. spinocerebellar tract): this path runs along the side of the brainstem, transmitting messages between the cerebellum and the spinal cord to regulate the body position.

Although it is the oldest part of our brain evolutionarily, the brainstem is still very complex and has a long list of roles not covered here. The brain stem may not provide us with the higher intelligence that we normally associate with being human, but it carries all the information in and out of those areas that we associate with higher intelligence. And, just as importantly (if not more), it ensures the uninterrupted operation of the vital functions necessary to support these areas.

See also: He has been living without the cerebral cortex for 10 years

Brain stem anatomical changes

The most common changes to the brain stem include asymmetry in the blood supply or the cranial nerves. These differences are usually minor and usually do not result in clinical effects.

Aneurysms, which are blood vessel defects, can be congenital and develop in blood vessels near the brainstem. Brain aneurysms near the brain stem can be seriously affected by pressure or bleeding.

Brain stem – diseases and disorders

Several conditions can affect the brainstem, leading to neurological symptoms. Symptoms correspond to the specific area of ​​the brain stem that has been affected. Sometimes, very small areas of damage can cause deep symptoms.

Common symptoms of conditions that affect the brainstem include dizziness (the feeling that everything is spinning), imbalance, vomiting, severe headache, eye movement disturbances, weakness and / or loss of feeling on one side of the body.

1. Brain stem stroke: A stroke is damage to the brain caused by disrupted blood flow. This can happen as a result of severe narrowing of the blood vessels, or it can occur when a blood clot travels to the blood vessels of the brainstem, obstructing blood flow. Some subtypes of stroke include Wallenberg syndrome and Weber syndrome (limb syndrome of the midbrain), for example.
2. Multiple Sclerosis (MS): Demyelination in MS can affect the white matter of the brainstem, leading to symptoms that may be reversible, gradually worsen over the years, or be permanent depending on the type of MS.
3. Increased intracranial pressure: When there is swelling in the brain, for example from a head injury, stroke, or infection, it can put pressure on the brainstem, affecting its function. This can cause life-threatening effects such as breathing problems.
4. Movement disorders: Several movement disorders, including Parkinson’s disease, are associated with dysfunction and degeneration of certain areas of the brainstem, such as the black matter and red nucleus.
5. Brain aneurysm: A brain aneurysm can affect blood vessels anywhere in the brain, including blood vessels near the brainstem. An aneurysm can constrict structures in the brainstem, it can impair blood supply, or cause serious consequences if bleeding occurs.
6. Brain Tumor: A primary brain tumor can develop in any region of the brain, and cancer from elsewhere in the body can spread to the brain. Some types of primary brainstem tumors include glioma, meningioma, and acoustic neuroma.

What is brain stem death?

Brain stem death means that the person’s brainstem function has ceased. It occurs when something permanently damages the brain stem or cuts off the blood or oxygen supply to the brain. Brain stem death is considered the basic criterion for brain death, because when there is irreversible damage to the structures belonging to the brain stem, it is absolutely impossible for a person to function independently. To stay alive, they need an artificial life support. This condition is sometimes also called brain death.

In order to diagnose brain stem death, it should be assessed whether the patient has the so-called trunk reflexes, which are:

1. corneal reflex;
2. gag reflex;
3. cough reflex;
4. oculocerebral reflex.

In addition, the following is also checked:

1. the patient’s reaction to the pain stimulus,
2. spontaneous movement of the patient’s eyeballs;
3. pupil reaction to light.

However, before the aforementioned criteria can be checked, the subject must first be in a coma and must not have spontaneous respiration. Only then should we begin to verify whether the brain stem has died.

See also: What is the disconnection from life support equipment in Poland?

Can You Recover From A Brain Stem Injury?

Brainstem damage can be serious because the brainstem controls so many of the body’s most basic functions. However, people recover from certain types of brain stem injuries.

It’s important to get medical attention right away if you suspect a brainstem injury. The sooner we receive care, the more likely health professionals are to reduce the damage caused. After a brainstem injury, you may need rehabilitation and other special care.

Brain stem – research

If we have symptoms of brainstem damage, we should seek immediate medical attention. Your doctor will take a detailed medical history and perform a physical examination, which will include a detailed neurological examination.

Your doctor will check your eye movements carefully. Brain stem disease can cause double vision (diplopia), which can be seen as uneven eye movements. Nystagmus (eye jumping movements) is also a condition related to brain stem involvement.

Based on our history and physical condition, your doctor may order tests to further evaluate our condition.

The tests we may need most often include imaging tests.

1. Neuroimaging: Magnetic resonance imaging of the brain (MRI) is usually used to visualize the brainstem.
2. Angiography: If there is concern about vascular deformity, it may be necessary to visualize the blood vessels near the brainstem with an invasive or non-invasive test.
3. Evoked potentials: This is a non-invasive test that measures our response to stimuli such as light or sound. Evoked potential studies, such as auditory brainstem evoked potentials (BAERs), can help identify conditions that affect the brain, including the brainstem.

Brain stem – prophylaxis

Certain lifestyle changes can make the entire brain healthier. To keep your mind sharp and to support brain health, you can engage in activities related to improving your fitness and healthy lifestyle.

1. Drink alcohol only in moderation.
2. Be on a diet full of fruits, vegetables, whole grains, healthy fats, and lean protein.
3. Exercise your body regularly.
4. Exercise your mind with puzzles such as crosswords, puzzles, or word-books.
5. Sleep at least seven to eight hours a night.
6. Quit smoking.

Strong social ties have also been linked to brain health. Healthy relationships can help lower blood pressure, reduce stress, and extend life.