Understanding Neurogenic Shock: A Critical Overview

What is Neurogenic Shock?

Neurogenic shock is a dangerous condition that impairs autonomic cardiovascular control after brain or spinal cord injuries.

A body’s nervous system is split into two main parts: the Central Nervous System and the Peripheral Nervous System. The peripheral nervous system is made up of all the nerves in the body. These nerves receive and send messages through the spinal cord from the brain.

The peripheral nervous system has two parts:

• ANS (Autonomic Nervous System) – Controls body functions that happen automatically
• SNS (Somatic Nervous System) – Controls muscle movements and sends information from the senses (like images seen by the eyes) to the brain so the brain can understand what is happening.

The ANS has three different parts: the sympathetic nervous system (SNS), parasympathetic nervous system (PNS), and enteric system. Each of these sends different messages to and from the brain through the spinal cord. When any part of the ANS doesn’t work properly, it can cause problems like dangerously low blood pressure (hypotension) and slow heart rate (bradycardia), which may be life-threatening.¹

Neurogenic shock can happen after a brain or spinal cord injury, and it can keep the brain from sending messages to the nerves. It affects the Autonomic Nervous System (ANS), which controls body functions like breathing, heart rate, and blood pressure.

Causes and Risk Factors for Neurogenic Shock

Three main health emergencies can lead to neurogenic shock: spinal cord injury, brain injury, and certain toxins.

The following health problems can cause Neurogenic Shock:²

• Damage to the spinal cord can stop messages from the brain from reaching the rest of the body. If the injury is in the upper part of the spine or in the neck, it can cause quadriplegia (loss of movement in both arms and legs). Injuries lower on the spine may cause paraplegia (paralysis of the legs). Spinal cord injuries, especially in the upper spine, increase the risk of developing neurogenic shock. They can also lead to loss of bladder control.
• Traumatic brain injury (TBI) occurs after a sudden impact to the head, such as from a fall, accident, or blow. While a stroke is not a TBI, it can cause similar brain damage. Both types of injury may harm the hypothalamus, the part of the brain responsible for sending messages to glands and organs. If the hypothalamus is injured, it can interfere with the autonomic nervous system (ANS) and lead to neurogenic shock.
• Toxins and rare causes like lead or mercury can damage the nerves in the spine. Other rare causes include spinal anesthesia, transverse myelitis, and Guillain-Barré syndrome. These problems can sometimes lead to neurogenic shock by hurting the spinal nerves.

Neurogenic Shock, Spinal Shock, and Spinal Cord Injury

Spinal cord fractures can lead to neurogenic shock, which affects blood pressure and heart rate.

Neurogenic shock most commonly occurs with spinal cord injuries at or above the T6 level, such as cervical or upper thoracic spine damage.³

There is another disorder called spinal shock that is different from neurogenic shock. Spinal shock is a process that causes the sudden, temporary loss or damage of spinal cord functions below the injury level after a spinal cord injury. The main difference between spinal shock and neurogenic shock is that neurogenic shock affects the cardiovascular system as well.⁴

Autonomic Dysfunction as a Cause of Neurogenic Shock

Damage to the autonomic nervous system during injury can lower blood pressure and cause heart and temperature problems.

Neurogenic shock is a serious problem that keeps the brain from sending messages to the nerves. Since all muscles, including the heart, have nerves, this can affect how the heart works. Neurogenic shock causes blood vessels to widen (vasodilation), leading to dangerously low blood pressure and slowed heart rate (bradycardia). People with spinal cord injuries who are paralyzed in all four limbs often have more health problems over time than those who aren’t paralyzed. This is partly because neurogenic shock affects the heart and blood vessels.

Neurogenic shock also affects other automatic body functions, like controlling body temperature. This can cause the body to heat up or cool down too quickly and without warning. For example, a person might have skin that feels warm and dry, even if their body temperature is too low. This happens because low blood pressure slows down blood flow in the veins.

That’s why it’s important to treat the problems caused by autonomic dysfunction to help people with spinal cord injuries feel better and avoid more serious problems.

Recognizing the Symptoms of Neurogenic Shock

Symptoms include low blood pressure, slow heart rate, and unusual skin warmth.

Neurogenic shock can be hard to spot because patients usually have other life-threatening symptoms at the same time. However, knowing the signs of neurogenic shock is very important for doctors and other healthcare workers in order to treat and manage neurogenic shock correctly.

Not all symptoms of neurogenic shock may be present in a person, but the main symptoms of neurogenic shock are:⁷

• Slow heart rate
• Low blood pressure
• Flushed, warm skin that switches to cold, clammy skin
• Lips and fingernails that look blue
• Difficulty breathing due to abnormally slow breathing rate

The Link Between Neurogenic Shock and Heart Function:

Nerve damage causes blood vessels to widen, dropping blood pressure and slowing the heart.

The sympathetic nervous system (SNS) normally causes vessels to tighten during stress. However, injuries to the brain or spinal cord stop this. The parasympathetic nervous system (PNS) can take over and wrongly signal vessels to relax, leading to dangerously low blood pressure and heart rate.

The Impact of Neurogenic Shock on the Nervous System:

Neurogenic shock throws off body balance and can lead to serious long-term health problems.

Neurogenic shock upsets the balanced state that is guided by the brain’s hypothalamus. If the ANS is not working right, as happens in neurogenic shock, a person can have wild swings in blood pressure, heart rate, breathing rate, and temperature. This can hurt overall health and increase the chance of organ failure and cardiac arrest.

In a person who has had neurogenic shock, the following are some common long-term effects:⁸

• Constant fatigue, dizziness, or poor sleep
• Weakened immune system
• Digestive, urinary, heart, and breathing problems

Comparing Neurogenic Shock with Other Types of Shock

Neurogenic shock has different causes and symptoms compared to other types of shock.

Neurogenic Shock versus Septic Shock:

Septic shock is caused by an infection.⁹ Bacterial infections are the most common causes of septic shock. While sepsis happens when an infection has spread to the bloodstream, its most severe and life-threatening state is called septic shock. The common symptoms of septic shock are:

• Low blood pressure, especially when standing
• Rapid heart rate (tachycardia), often in response to falling blood pressure
• Rapid breathing (tachypnea), which may occur as a compensatory response to metabolic acidosis
• Cool, clammy, or blotchy skin

Neurogenic Shock versus Hypovolemic Shock:

Hypovolemic shock happens as a result of a loss of the body’s blood or other essential fluids.¹⁰ Our bodies depend on having enough blood and fluids to function. Therefore, a loss of blood or fluid stops the heart’s ability to pump blood to the body’s organs. Without enough circulating blood supply, the cells of the organs cannot survive and the organs begin to fail.¹¹

Neurogenic Shock versus Anaphylactic Shock:

Anaphylactic shock is a rapid allergic reaction that can be life-threatening without treatment.¹² It is caused by the immune system’s reaction to the allergen.

Some common initial symptoms can be skin reactions like hives and itchy skin, decreasing blood pressure, tightening of the airways and a swollen tongue (resulting in wheezing and difficulty breathing), and dizziness or fainting. As the anaphylactic shock gets worse, the pulse can become weaker and more rapid.

Anaphylactic shock is treated by giving a shot of epinephrine (also called adrenaline) into the bloodstream.

The Impact of Neurogenic Shock on Critical Care

Quick and accurate diagnosis is essential to treat neurogenic shock and avoid complications.

Challenges in Diagnosing and Managing Neurogenic Shock:

It can be challenging to diagnose neurogenic shock when a patient arrives at the emergency room. The person with neurogenic shock may need treatment for the spinal cord or brain injury that led to the neurogenic shock. While a quick and correct diagnosis is necessary, the patient may also be having another type of shock that requires rapid medical treatment.

The first treatment for neurogenic shock in the emergency room is usually giving IV fluids to help raise low blood pressure, along with a medicine called norepinephrine.

Complications in Managing Neurogenic Shock:

The five most common complications of neurogenic shock are:¹³

• Aspiration pneumonia: a severe lung infection that happens after food or liquid gets into the lungs instead of traveling through the esophagus toward the stomach
• Deep vein thrombosis (DVT): a deep blood clot in the arm or leg that can cut off blood flow to the arm or leg or travel in the blood to the heart and/or lungs
• Persistent low blood pressure: low blood pressure that stays low after the end of neurogenic shock and causes heart damage
• Imbalance in blood electrolyte levels: may result in damage to the muscles, nervous system, and heart, and can also cause seizures
• Autonomic dysreflexia: a life-threatening overreaction of the ANS, which can cause a blood pressure spike and rapid heartbeat

Prognosis and Long-term Effects of Neurogenic Shock:

Neurogenic shock can be fatal in 20–50% of cases when associated with severe trauma or multiple injuries.¹⁴ However, with modern treatment, the mortality rate from neurogenic shock alone, especially when caused by isolated SCI, is significantly lower. Even when treated, it can continue to cause heart and brain issues such as weakened heart, organ failure, and lifelong “brain health” problems. These problems include difficulty concentrating or paying attention; therefore, neurogenic shock requires ongoing care.

Managing and Recovering from Neurogenic Shock

Recovery from neurogenic shock requires immediate treatment, long-term medical care, and rehabilitation to help patients regain as much function as possible.

Managing neurogenic shock requires immediate treatment of the shock, as well as treatment of the underlying cause, such as a spinal cord injury, TBI, or stroke.

Long-term Strategies to Prevent Complications:

Lifelong treatment is needed to keep the blood pressure, heart rate, and breathing rate within normal range. Multiple daily medications may be needed as well as frequent and regular medical check-ups.

Occupational and Physical Therapy to Regain Strength and Mobility

Therapy helps restore movement, boost strength, and reduce muscle damage.

Spinal cord injuries can be treated by occupational therapy and/or physical therapy (OT and/or PT). The goal of rehab therapy is decreasing the risk for permanent loss of joint range-of-motion and muscle movements.

Standard therapy exercises for neurogenic shock survivors can include any or all of the following:

• Range-of-motion activities
• Strength training
• Balance work
• Training with assistive tools
• Relearning self-care tasks

Psychological Caregiving and Support to Address Emotional Impact:

People who have survived neurogenic shock due to a spinal cord break, TBI, or severe stroke need support from family, friends, and their healthcare providers to recover their lost functional abilities. Mental health care is key to helping survivors stay motivated and hopeful during recovery.

Conclusion – Key Takeaways about Neurogenic Shock

Neurogenic shock is a medical emergency that requires immediate treatment and lifelong medical care to prevent serious complications and death.

Key Takeaways about Neurogenic Shock:

Neurogenic shock can happen as a result of a spinal cord injury or traumatic brain injury (TBI). Certain rare stroke types, particularly those involving the brainstem, may also lead to neurogenic shock, but this is uncommon. This type of shock is typically life-threatening and affects the body’s ANS. It often results in chronic health problems, so frequent and regularly scheduled medical check-ups are essential for someone who has had neurogenic shock.

While living with the effects of neurogenic shock can present significant challenges, it’s important to remember that with proper medical care and commitment to rehabilitation, patients can work toward recovery and improved quality of life and regain some function and independence.

References:

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