Brainstem

What is the brainstem?

Your brainstem connects your brain to your spinal cord. It sits near the bottom of your brain. It helps regulate vital body functions that you don’t have to think about, like breathing and your heart rate. Your brainstem also helps with your balance, coordination and reflexes.

It’s part of your central nervous system and has three parts that work together. Each part does a specific job to help you adapt to your environment, move and function.

What is the function of the brainstem?

Your brainstem sends messages back and forth between your brain and other parts of your body. It regulates many involuntary actions — functions your body performs automatically, like:

• Balance.
• Blood pressure.
• Breathing.
• Eye movements.
• Facial movements and sensations.
• Hearing.
• Heart rate.
• Sleep and wakefulness.
• Swallowing.
• Taste.

What are brainstem reflexes?

Brainstem reflexes are your body’s immediate and involuntary motor responses that help you survive and adapt to changes in your environment. You aren’t consciously thinking about performing these actions. Instead, your brainstem automatically tells your body to do them.

Brainstem reflexes include:

• Cardiovascular reflexes: A group of reflexes that regulate your heartbeat and blood pressure.
• Gag reflex: This reflex protects your airways.
• Swallowing reflex: This reflex moves food and liquids from your mouth to your stomach.
• Pupillary light reflex: This adjusts the size of your pupil (the black center of your eye) to adapt to lighting changes.
• Vestibulo-ocular reflex: This reflex steadies your eyes when you move your head or the rest of your body.
• Respiratory reflexes: A group of reflexes that regulate breathing, coughing and sneezing.

Where is the brainstem located?

Your brainstem is located near the bottom of your brain, at the back of your skull. It connects your brain to your spinal cord.

What are the three parts of the brainstem?

Your brainstem is made up of three parts:

• Midbrain: The top part of your brainstem. The midbrain is involved in several functions, including motor control, particularly eye movements and processing of vision and hearing.
• Pons: The middle portion of your brainstem that coordinates face and eye movements, facial sensations, hearing and balance.
• Medulla oblongata: The bottom part of your brainstem that regulates your breathing, heartbeat, blood pressure and swallowing.

Your brainstem also contains your reticular activating system (RAS). The RAS is a network of neurons (nerve cells that carry electrical signals and chemicals through your brain). It works with your thalamus to manage your:

• Wakefulness (alertness).
• Awareness of your surroundings.
• Sleep and wake cycles.

Brainstem cranial nerves

Your brainstem contains 10 of the 12 cranial nerves (nerves that start in your brain) including cranial nerves 3 through 12. They help with your movements, sensations, taste and hearing.

What does the brainstem look like?

Your brainstem looks like a flower stalk or a stem of a plant. It’s a tube-like structure made of neural (or nervous system) tissue. It’s about 2 to 3 inches (5 to 7 centimeters) long.

What are common conditions that affect the brainstem?

A wide range of injuries and health conditions can damage your brainstem. Some of these include:

• Blood clots.
• Brain tumors.
• Encephalitis.
• Heart attack (myocardial infarction).
• Stroke.
• Sudden cardiac arrest.
• Traumatic brain injury (TBI).

What are common signs and symptoms of brainstem conditions?

Because so many issues can affect your brainstem, signs and symptoms can vary significantly. In general, signs or symptoms of a brainstem injury or condition can include:

• Balance problems or dizziness.
• Inability to gag or cough.
• Insomnia or other disruptions to your usual sleep patterns.
• Nausea or vomiting.
• Slurred speech.
• Eye movement problems
• Stroke symptoms (facial or one-sided weakness, confusion, difficulty speaking, vision changes, etc.).
• Sudden difficulty swallowing, drinking or eating.
• Problems with your autonomic system.
• Impairment of consciousness.

What happens if the brainstem is damaged?

If you experience an injury that damages your brainstem, you might have the following symptoms:

• Difficulty breathing.
• Difficulty swallowing, coughing or gagging.
• Dizziness or vertigo.
• Feeling off balance.
• Heartbeat irregularities.
• Trouble sleeping.
• Changes in consciousness.
• Double vision.
• Weakness and sensory changes.
• Impairment in hearing.
• Problems with coordination and walking.

Brainstem damage is an emergency. Many people experience brainstem damage after a severe car accident, for example. Damage can affect how well your brainstem can work. In severe cases, your heart may stop beating, you won’t be able to move (paralysis) and you may be in a coma.

Many brainstem conditions are life-threatening or fatal. You may need life support. It’s important to call emergency services right away if you experience any symptoms related to brainstem damage.

What is brainstem death?

Brainstem death means your brainstem stops functioning. It occurs when something permanently damages the brainstem or cuts off your brain’s blood or oxygen supply.

Because your brainstem controls essential life functions, you won’t be able to regain consciousness. You’ll need artificial life support to remain alive. This condition is also called brain death.

Can you recover from a brainstem injury?

A brainstem injury can have severe effects because your brainstem controls so many of your body’s most important functions. But people do recover from some types of brainstem injuries.

It’s important to get care right away if you think you might have a brainstem injury. The sooner you get care, the more likely your healthcare providers can reduce the severity of the damage. You may need rehabilitation and other special care after a brainstem injury.

What tests check the health of my brainstem?

Imaging tests, like an MRI, are more sensitive than a CT scan in detecting problems with the brainstem. Brainstem Auditory Evoked Potentials (BAEPs) can also provide information on brainstem function.

As your brainstem is responsible for many vital functions and reflexes, during an exam, your provider may also:

• Listen to your heartbeat and breathing.
• Shine a light over your eyes to check your pupil size.
• Ask you to move certain parts of your body.

How do I keep my brainstem healthy?

Your brainstem is part of your brain. Anything you can do to maintain your brain health will also keep your brainstem healthy, including:

• Drinking alcohol in moderation.
• Following a healthy eating and physical activity plan.
• Practicing puzzles, such as crosswords, jigsaw puzzles or word searches.
• Getting enough sleep each night.
• Quitting smoking.

Research also suggests maintaining a strong social network plays a role in brain health. Healthy relationships can also help lower your blood pressure and decrease stress.