Autonomic Dysreflexia ,Hyperreflexia - Causes, Symptoms, Diagnosis, Complications and Treatment

Introduction:

Our autonomic nervous system controls all body functions, including involuntary actions such as breathing. The sympathetic autonomic nervous system speeds up the reactions, whereas the parasympathetic responses slow down the reaction. This balance between the sympathetic and parasympathetic autonomic nervous systems keeps the body functioning in harmony. When there is a threat to this balance, then it results in conditions like autonomic dysreflexia causing the responses to the stimuli to be too high. Autonomic dysreflexia is a potentially severe and dangerous condition that occurs in individuals most often following a spinal cord injury resulting in acute uncontrolled hypertension. Uncontrolled hypertension can lead to fatal complications. There is a potentially high risk of stroke of 30 % to 40 % in individuals with autonomic dysreflexia.

What Is Autonomic Dysreflexia or Hyperreflexia?

Autonomic dysreflexia refers to the abnormal and overreaction of the autonomic nervous system to something that is happening externally or to bodily stimuli. The autonomic nervous system is the involuntary action that you do without thinking, such as breathing, digestion, and circulation. This autonomic dysreflexia is an emergency and a life-threatening situation that needs immediate medical attention. Autonomic dysreflexia is otherwise known as autonomic hyperreflexia. This overreaction can cause the following scenarios:

• Changes in the heartbeat.

• High blood pressure.

• Excessive sweating.

• Muscle spasms.

• Changes in the skin color like paleness, redness, or blue-gray color.

• Other changes in the body’s autonomic functions.

What Are the Causes for Autonomic Dysreflexia?

The first and foremost cause of autonomic dysreflexia is spinal cord injury, typically when the injury is above the T6 level. This condition occurs in 20 % to 70 % of patients one month to one year after the spinal cord injury. However, it can also occur in the first few days or weeks after the spinal cord injury. The higher the level of injury greater the risk of autonomic dysreflexia. It is less likely to occur if the level is below T10.

In around 85 % of the cases, the stimulus is from a urological source such as urinary tract infections, a distended bladder, or a blocked or clogged Foley catheter. The nervous system of people with autonomic dysreflexia overreacts to the types of stimulation, which usually does not bother healthy people.The next most common causes are bowel distension and fecal impaction. It accounts for about 13 % to 19 % of the cases.

The other possible causes include:

• Guillain-Barre syndrome, a disorder in which the body’s immune system mistakenly attacks the nervous system.

• Severe head trauma, including brain injuries.

• Subarachnoid hemorrhage, a form of bleeding from the brain.

• Side effects from using certain drugs or medications.

• Use of illegal stimulant drugs like Cocaine.

How Does Autonomic Dysreflexia Happen in the Body?

When there is a cutaneous stimulation below the level of spinal cord injury, then a reflex sympathetic activity is provoked, resulting in an increase in the blood pressure and diffuse vasoconstriction. Normally when the blood pressure increases, parasympathetic compensation is stimulated, causing vasodilation and blood pressure correction. But when the spinal cord is injured, the parasympathetic response will not be able to travel down the spinal cord lesion resulting in continued vasoconstriction leading to continued severe hypertension.

However, when the spinal cord lesion is below T10, the splanchnic vascular bed innervation remains intact, causing compensatory parasympathetic dilatation in that region.

What Are the Common Symptoms of Autonomic Dysreflexia?

The common possible symptoms of autonomic dysreflexia are listed below. Some of these include:

• The first presenting symptom is usually a headache that can be severe. Individuals who have spinal cord injuries above T6 level and when report headaches they should immediately get their blood pressure checked.

• High blood pressure.

• Excessive sweating.

• Irregular heartbeat.

• Anxiety

• Blurred vision.

• Lightheadedness, dizziness, or fainting.

• Muscle spasms.

• Bladder problems.

• Nasal congestion.

• Nausea and vomiting.

• Flushing above the level of the injury.

It is not necessary that all the symptoms should be present. There are instances when the person does not show any symptoms, even with extremely high blood pressure.

What Diagnostic Tests Are Done to Diagnose This Condition?

The doctor collects the detailed medical history of the patient. A track of medications that were taken before or the medications the patient is currently on is recorded to see if these medications are contributing to the patient’s condition. Depending on the medical history, the doctor may decide which diagnostic test is required.

Here are a few diagnostic tests that are commonly recommended while diagnosing autonomic dysreflexia:

• Blood tests.

• Urine tests.

• CT (computed tomography) or MRI (magnetic resonance imaging) scan.

• ECG (electrocardiogram) to determine the heart’s electrical activity.

• Lumbar puncture.

• X-rays.

• Toxicology screening tests to test for any medications in the bloodstream.

• Tilt-table testing to measure blood pressure at various body positions.

What Are the Possible Complications for Dysreflexia?

The complications of autonomic dysreflexia can be severe and life-threatening. Hypertension is itself severe enough, and when it is combined with cerebral vasodilation, it puts the patient at high risk for a hemorrhagic stroke which can be fatal. Bradycardia can also lead to cardiac arrest.

Hypertension can lead to pulmonary edema, left ventricular dysfunction, intracranial hemorrhage, retinal detachment, bleeding in the eyes, seizures, and even death.

How Is Autonomic Dysreflexia Treated?

Autonomic dysreflexia is an emergency and a life-threatening condition; hence it has to be treated immediately. The treatment relies on the underlying cause. Proper and appropriate treatment can be given only when the underlying cause is addressed. If blood pressure is high, then medications such as vasodilators are prescribed to control and manage the high blood pressure.

The second most important is to eliminate the stimuli that are triggering the reaction. For instances:

• If certain medications or illegal substances such as Cocaine are causing the condition, then it needs to be stopped.

• Check if there is a blocked catheter that is responsible for the condition.

• If slowing of the heart rate is contributing to autonomic dysreflexia, then anticholinergics are prescribed.

• Remove tight clothing.

• Drain the distended bladder using a catheter.

• If you have fecal impaction, then get it treated.

• Move the person to a sitting position. This allows blood to flow to the feet.

Can Autonomic Dysreflexia Be Prevented?

• If taking certain medications is causing this condition, then talk to your doctor for an alternative to these medications.

• If you have high blood pressure, then taking the medication appropriately will help improve the condition.

In people with a spinal cord injury then, you need to follow the enlisted tips to prevent autonomic dysreflexia:

• Do not wait till the bladder becomes full.

• If there is pain, then the pain should be managed.

• Try practicing proper bowel care to avoid stool impaction.

• You need to maintain good hygiene to prevent urinary tract infections.

• Practice proper routine skincare to avoid bed sores or skin infections.

Conclusion:

The prognosis for autonomic dysreflexia is uncertain because various factors contribute to it. Proper treatment relies on addressing the right causes. Consult your doctor to determine the triggers for your condition, as managing the triggers helps in the betterment of the condition.