What is Neurogenic Shock?
Neurogenic shock is a serious condition where the body can’t supply enough blood to its organs. This happens when some nerves lose control over blood vessels, usually due to injuries to the spinal cord. It often occurs in the neck and upper back area, especially for injuries above a certain level in the spine (T6 level).
This shouldn’t be confused with spinal shock, where all functions of the spinal cord are temporarily lost below the site of the injury. Telling the difference between neurogenic shock and spinal shock is very important. This is because spinal shock refers to a temporary complete loss of spinal cord function below the injury site.
If someone has neurogenic shock, it’s essential to spot the signs quickly and treat it right away. This condition can greatly increase the risk of death and complications in people with spinal cord injuries. Quick and assertive treatment is necessary to improve the situation for these patients. Recognizing and treating this shock can improve the care provided to people who experience it.
What Causes Neurogenic Shock?
Neurogenic shock is a serious condition triggered by issues with our body’s automatic nervous system, which usually comes from a spinal cord injury. This typically happens in the upper parts of the spine, especially above what’s known as the T6 level, and is often due to traumatic events.
The problems arise from a lack of “sympathetic tone”, which is the constant level of activity that helps keep body functions normal, and an unchecked response from the parasympathetic nervous system, another part of the automatic nervous system that helps the body rest and digest.
Though less common, other things can also cause neurogenic shock. These include spinal anesthesia (numbing medicine used during surgeries), Guillain-Barre syndrome (a rare disorder where your body’s immune system attacks the nerves), toxins that affect the automatic nervous system, transverse myelitis (inflammation of both sides of a section of the spinal cord), and different nerve diseases that involve the upper part of the spinal cord.
Risk Factors and Frequency for Neurogenic Shock
Every year in the United States, between 8,000 and 10,000 people suffer from traumatic spinal cord injuries. A thorough review of 490 such injuries revealed that neurogenic shock, a specific impact of spinal cord injury, was only present in about 19.3% of cases. Still, in a larger facility dealing with a high volume of level 1 trauma situations, it was noted that 31% of patients with upper cervical spine injuries (specifically, those located between the first and fifth cervical vertebrae, also known as C1-C5) experienced this kind of shock.
The exact physiological signs of neurogenic shock haven’t been universally agreed upon. However, most studies typically look for a systolic blood pressure lower than 90 mm Hg, and a heart rate under 80 beats per minute. It’s complicated to fully understand the prevalence of neurogenic shock, in part because it’s not clear how other injuries and types of shock, such as hemorrhagic shock, may influence the effects of spinal cord injury on blood flow and heart performance.
Signs and Symptoms of Neurogenic Shock
For a doctor to identify and treat neurogenic shock (a life-threatening condition that can occur after a severe spinal injury) promptly and accurately, they must take a careful and thorough approach. This condition usually affects patients who have suffered an injury above the T6 level of the spinal cord. Accordingly, doctors must be vigilant, assess the type and nature of injury, be aware of potential spinal problems via symptoms like back pain or vertebra misalignment, and account for other injuries that can distract attention from the spine. They also need to consider other factors such as blackout, impairment of brain or nerve functionality, or the impact of drugs or alcohol, which could complicate the medical exam.
In order to correctly diagnose neurogenic shock, doctors must cross out other potential causes of the condition swiftly, such as severe blood loss, pneumothorax (collapsed lung), a direct injury to the heart, or issues with the adrenal glands, which produce vital hormones.
Patients with neurogenic shock often display low blood pressure combined with a slower-than-normal heart rate. This is different from the symptoms of non-spinal cord injuries causing low blood volume shock, where the patient would have low blood pressure combined with a fast heart rate. Additionally, neurogenic shock patients might appear to have warm and pink skin, which is unlike hypovolemic shock patients who typically show cool and pale skin.
Testing for Neurogenic Shock
If a patient comes in with signs of severe trauma, doctors utilize a recognized method called the “Advanced Trauma Life Support (ATLS)” to quickly assess the situation. This protocol involves examining the patient in an order of urgency: airway, breathing, circulation, and also controlling any severe bleeding. Only after these life-threatening issues have been addressed, doctors will conduct a focused brain and spinal cord examination. During this time, it’s crucial that the patient’s spine remains immobilized or still, just in case there’s a spinal cord injury.
Once the patient has been evaluated and stabilized, the doctors will use more specialized diagnostic procedures. High-quality computed tomography (CT), basically high-powered x-rays, is used to look for any fractures or misalignments in the spine — especially if doctors are still concerned about a spinal cord injury. When the patient’s health condition has stabilized, doctors might do a magnetic resonance imaging (MRI), which gives a more detailed view of the body, to get a closer look at the ligaments in the spine. The MRI scan can also show if there are any abnormal changes in the spinal cord and also check for issues like slipped or herniated discs, which can press on the nerves in the spine and cause pain.
This step-by-step approach makes sure doctors can quickly evaluate patients who might be going into neurogenic shock, a state where the nervous system starts to fail. It helps in boosting their care and allowing doctors to implement the needed tests and treatment. The diagnosis of neurogenic shock is a combination of reviewing images like X-rays or MRIs, monitoring the patient’s heart and blood pressure, and physically examining the patient’s body.
Treatment Options for Neurogenic Shock
The main goal in treating neurogenic shock, or shock caused by damage to the nervous system, is to stabilize the patient’s blood pressure and heart function. Treatment usually takes place in the intensive care unit (ICU) where the patient’s condition can be closely monitored.
The first step in treatment involves replenishing the patient’s body with fluids through an IV, which helps to restore normal blood pressure. However, healthcare providers need to be careful not to overdo it, because giving too much fluid can create problems.
If the patient’s blood pressure is still low after their body’s fluid levels have been restored, medications called vasopressors and inotropes may be used. These medications narrow the blood vessels and increase the force of the heart’s contractions. Different types of these medications are available, and the best one for a patient depends on their specific circumstances. For example, phenylephrine is often used to tighten the blood vessels and increase blood pressure, but it sometimes slows the heart rate too much. Norepinephrine, on the other hand, can increase both blood pressure and heart rate, so it’s often a preferred choice.
Doctors aim to maintain the patient’s average blood pressure within a certain range for one week to support the blood flow to the spinal cord. However, it’s important to use these medications with caution because they can make other injuries worse.
For low heart rate, medications such as atropine and glycopyrrolate are used to counteract the excessive slowing of the heart seen in neurogenic shock. In some cases, substances called methylxanthines can help with stubbornly slow heart rates by stimulating the central nervous system.
It’s also essential to immobilize the patient’s neck to prevent further injury. Devices such as the Miami J or Philadelphia collar are used for this purpose. While steroids have been tested in animal models for this use, their impact on humans is less clear, and their use can also increase the risk of complications like infections. In some cases, surgery may be necessary to relieve pressure on the spinal cord and aid in the treatment of neurogenic shock.
If a patient’s neurogenic shock doesn’t respond to standard treatments, another option is a procedure called resuscitative endovascular balloon occlusion of the aorta (REBOA). This technique, which is primarily used in cases of shock caused by blood loss, can increase the pressure in the central part of the aorta and improve blood flow to the brain, heart, and spinal cord.
It’s important to note that in trauma patients, neurogenic shock is not the first diagnosis to consider. The initial focus has to be on ruling out hemorrhagic shock, which is a common cause of low blood pressure caused by blood loss. Once that possibility has been eliminated, doctors can start looking for signs of neurogenic shock.
What else can Neurogenic Shock be?
Shock is a medical condition that means there’s not enough blood flow to the body’s vital organs. Different types of shock can be identified by looking at specific factors like resistance in the blood vessels, heart performance, and body fluid levels.
Hypovolemic Shock
This type of shock generally happens due to severe blood loss such as in an injury, or loss of body fluids from diarrhea, vomiting, severe burns, or dehydration. This shock type results in a reduction in heart performance, body fluid levels, and an increase in blood vessel resistance. Symptoms can include low blood pressure, rapid heartbeat, and pale, cold skin.
Cardiogenic Shock
Cardiogenic shock often occurs after a severe heart attack, a build-up of fluid within the heart layer, a collapsed lung, or a large blood clot in the lungs. It is marked by a decrease in heart performance, an increase in blood vessel resistance, and an increase in body fluid levels. Signs of this kind of shock can also include low blood pressure, fast heartbeat, and pale, cold skin.
Septic Shock
Septic shock is caused by a serious infection that leads to low blood pressure and reduced blood flow to the body’s organs. It’s characterized by a decrease in heart performance, body fluid levels, and an increase in blood vessel resistance. Symptoms may include low blood pressure, fast heartbeat, fever or very low body temperature, and signs of infection.
Note: we also need to distinguish neurogenic shock, which is marked by a decline in heart performance, blood vessel resistance, and body fluid levels. It’s critical not to confuse this with spinal shock, which involves the sudden loss of muscle, sensory and reflex activity after a spinal injury and is similar to but distinct from traditional shock, characterized by inadequate blood supply to the body.
What to expect with Neurogenic Shock
The outcome for people who experience neurogenic shock, or a dangerous drop in blood pressure caused by damage to the nervous system, can vary depending on a number of factors. Two of these are particularly critical:
Severity of Spinal Cord Injury: The outcome heavily depends on the intensity of the spinal cord injury. The American Spinal Injury Association has a scale that helps us understand this severity and what it might mean for the patient’s future.
Response to Treatment: How a person responds to the treatments and care strategies that their doctors use can also greatly affect what their recovery might look like.
Apart from these, there are a few more factors that can play a significant role.
Existing Neurological Problems: The presence and severity of any other neurological issues at the beginning of treatment can also make a big difference in how well the patient recovers.
Age: Younger patients often have a better chance of recovery and adjustment in these cases.
Other injuries: If the patient has also been injured in other organs at the same time, this can affect how well they are able to recover.
Glasgow Coma Scale Score: This is a tool used to assess consciousness and neurological function. It helps doctors understand how likely the patient is to recover.
Every person who experiences neurogenic shock has their own unique combination of these factors, making each case different.
Possible Complications When Diagnosed with Neurogenic Shock
: Neurogenic shock might lead to long-lasting and severe low blood pressure, and in some cases, it might demand vasopressor therapy as treatment. This low blood pressure condition could linger on for weeks following the original injury. In some instances, people with neurogenic shock might confront more problems like autonomic dysreflexia long afterwards.
Autonomic dysreflexia is a condition in which there is a disruption in the normal regulation of spinal cord due to interference in the central nervous system. It was first identified by Anthony Bowlby in 1890 and was later detailed by Guttmann and Whitteridge in 1947. It is characterized by an excessive and unbalanced response to stimuli below the level of the spinal cord injury. Things like distention, stimulation, or manipulation of the bladder or bowel could add to this condition.
Those with spinal cord injuries have a higher chance of developing deep vein thrombosis (DVT). Studies show that around 13.10% of patients with spinal fractures have DVT before surgery. Furthermore, older people are more prone to getting DVT. Other factors that can result in DVT are muscle paralysis causing blood stasis in the limbs, venodilation, and a state of increased blood coagulation.
Patients may also go through changes in electrolyte balance which might result in conditions like hypokalemia. This imbalance of electrolytes could be due to low blood pressure and low blood volume, which could increase plasma aldosterone levels. Dysfunctions of the gastrointestinal tract, especially paralytic ileus, could be associated with spinal cord injuries. This situation occurs due to the dysfunctional blood vessels in the mesenteric region accompanying the spinal cord injury.
Resulting Complications:
- Prolonged and severe low blood pressure
- Autonomic dysreflexia
- Deep vein thrombosis (DVT)
- Changes in electrolyte balance causing conditions like hypokalemia
- Gastrointestinal dysfunction, especially paralytic ileus
Preventing Neurogenic Shock
Understanding neurogenic shock and its associated consequences is very crucial for people who have endured injuries to their spinal cord. Informing patients and their loved ones includes explaining the following crucial details.
Prevention and treatment: It’s important for patients to know how to prevent neurogenic shock. Doing things like drinking enough fluids, avoiding quick actions, and sticking to prescribed medications can help.
Response in Emergencies:: Patients should know what to do if they have a neurogenic shock episode. This can include lying down, putting their legs up, and quickly looking for medical help.
Thoughts for the long run:: Patients should also be informed about the long-lasting effects of neurogenic shock and how it can affect their daily living. Therefore, discussing any worries about changes in lifestyle, rehabilitation, and continuous medical care is vital.
Potential complications and check-ups:: Patients should be fully educated about possible complications from neurogenic shock, such as a condition called autonomic dysreflexia. It’s essential they know about the importance of going to regular follow-up check-ups with their doctors.
Support for coping:: Patients should have resources like support groups, counseling, and mental health services offered to them to help them deal with the challenges of neurogenic shock and spinal cord injuries.
