Secondary Condition: Autonomic Dysreflexia

Spinal Cord Injury Secondary Condition: Autonomic Dysreflexia

What is it?
Autonomic dysreflexia (AD) is a very serious medical emergency that can be life threatening. It is a sudden increase in blood pressure, which if left untreated can lead to stroke or death. 

Who gets it?
This condition can occur in individuals injured at the T6 (sixth thoracic) level and above. For example, it can occur in anyone who has a spinal cord injury from C1 to T6. There are cases that have been described at the level of T8, but it is questionable whether these cases were related to another cause of increased blood pressure.

What causes it?
AD is caused by a stimulus inside or outside the body that would normally be removed, adjusted or changed. It used to be described as a stimulus that would be considered painful or annoying, but it has been shown to occur with sexual stimulation as well. Therefore, any type of increased stimulation can lead to autonomic dysreflexia and require intervention or removal of the stimulus.

 

Skin
• Sitting or lying in one position for a prolonged period of time causes the able-bodied person to shift their weight or change positions. For example, when the able-bodied person sits in a car or chair in a movie for too long, they automatically change their position , relieving the pressure and discomfort. Most people do this without even being aware of it. After a spinal cord injury, the sensation of discomfort is minimalized or absent ;this warning sign of skin protection is no longer present. Therefore, autonomic dysreflexia can occur in this situation and frequent changes in position to relieve pressure on the skin are mandatory.
• Pressure ulcers (skin breakdown or bedsores) can cause a continuous stimulation of pain or discomfort. Patients should avoid having direct pressure on pressure ulcers which may decrease or eliminate autonomic dysreflexia.
• Clothing that is too tight
• Urinary collection bags with tight leg straps
• Sunburns are common and frequent causes of autonomic dysreflexia. Sunburns can be painful for a prolonged period of time which makes management of autonomic dysreflexia difficult because of the constant prolonged painful stimulation. Therefore, precautions should be taken, including use of sunscreen and limiting time with direct sun exposure.
• Touching hot objects to skin that has limited or no sensation can quickly lead to burns, which are obviously dangerous. 
• Neuromuscular electrical stimulation is occasionally used with the rehabilitation patient. This simulation can be enough to lead to autonomic dysreflexia. Therefore, if electrical stimulation is used in individuals with spinal cord injury at T6 or above, initially blood pressure should be measured to evaluate for an increase in blood pressure in relationship to its use.
• Sexual stimulation can cause autonomic dysreflexia; this needs to be considered, evaluated and if present, discussed with your physiatrists or urologist.

Urology
• Overdistention of the bladder is a very common cause of autonomic dysreflexia. If AD is occurring with a full bladder, then bladder management should be adjusted accordingly to prevent this stimulus.
• Urinary tract infections are also a very common cause of autonomic dysreflexia. This requires treatment with antibiotics and may take 24 hours or more for this noxious stimulus to be eliminated. During this time, blood pressure should be watched closely and medications may need to be used.
• Bladder and kidney stones
• Infections other than bladder infections can also lead to autonomic dysreflexia. These may include infection of the prostate (prostatitis) or epididymitis (infection of the testicle).

Gastrointestinal
• Bowel constipation or impaction is a very common cause of autonomic dysreflexia and is one of the first common causes to consider.
• Hemorrhoids
• Enemas, suppositories or digital stimulation
• Stomach or esophagus irritation or ulcers
• Gallbladder
• Appendicitis is an infection of the appendix and can often be a serious medical emergency that is undetected in people with spinal cord injury. Autonomic dysreflexia is often the only symptom of this condition. Therefore, appendicitis must always be a top consideration as a cause of autonomic dysreflexia if the cause is not known or doesn’t become obvious in a short period of time.

Medical Tests
• Urological test such as urodynamics or cystoscopy
• Routine blood draw from a vein that is below the level of neurological injury
• Colonoscopy

Other
• Surgical procedures must be performed with appropriate anesthesia. A common mistake is to assume that because a person with a spinal cord injury has no feeling in a certain area of the body that no anesthesia is required. Although there is no feeling with a surgical cut in an area with no sensation, the ability to cause autonomic dysreflexia exists. Childbirth is possible after spinal cord injury (discussed further in sexuality and fertility section) and causes a very noxious stimulus that leads to autonomic dysreflexia. Anesthesia with an epidural is most often recommended for individuals with a spinal cord injury at T6 and above who are giving birth vaginally or by cesarean section.
• Blood clot in either the leg (deep vein thrombosis) or the lung (pulmonary embolism).
• Electroejaculation which is used during infertility treatment
• Spasticity
• Sex
• Fractures (broken bones) below the level of lesion
• Menstruation
• Ingrown toenails.

It is important to remember that this is not a completely comprehensive list and that there are other causes of autonomic dysreflexia. Understanding potential causes of autonomic dysreflexia before it happens is important, so that you can either avoid the stimulus or take precautions to limit its negative impact on your health.

Why does a spinal cord injury at T6 or above lead to autonomic dysreflexia?
Any noxious or painful (or in some cases sexual) stimulus below the level of injury sends a message up the peripheral nerves to the spinal cord. The message then travels up the spinal cord to the sympathetic nervous system, which is located between T1 and L2. 

The response of the sympathetic nervous system to pain is to cause contraction of the blood vessels. A very important group of blood vessels called the splanchnic blood vessels provide blood to the intestines. The splanchnic blood vessels receive their nerve supply from the spinal cord at T5 to T12. A very large volume of blood is supplied to the intestines through these splanchnic blood vessels. When these vessels contract, it causes a significant increase in blood pressure, which will continue to rise until the stimulation of the sympathetic nervous system stops. This dramatic increase in blood pressure is detected by two pressure-sensing areas in the carotid artery and the aorta that comes off the heart.

These pressure sensing areas then report to the brain which attempts to lower the blood pressure by two maneuvers. First, a message is sent from the brain down the spinal cord to tell the rest of the body to relax and stop contracting the blood vessels. Unfortunately, these messages never reach the rest of the body because they are blocked as they are traveling down the spinal cord. The second attempt by the brain is to slow down the heart by increasing the parasympathetic nervous system (Vagus nerve) stimulation of the heart. This does slow down the heart but is ineffective at lowering the blood pressure. This condition of a slowed heart rate is called bradycardia. This is important because bradycardia is usually not associated with high blood pressure and this is a fairly unique combination that is seen in autonomic dysreflexia. Therefore, if someone sees significant high blood pressure in a spinal cord injured patient with bradycardia (heart rate less than 60 beats per minute), they should be considering autonomic dysreflexia.

This all explains the importance of the T6 level in determining the development of autonomic dysreflexia. The splanchnic blood vessels receive their nerve supply from the spinal cord at T5 to T12. A painful message in the leg can travel up the spinal cord and stimulate and contract all of the splanchnic blood vessels. None of the message from the brain that tells this to stop reaches the spinal cord at the level of the splanchnic blood vessels. In contrast, if the spinal cord injury is below T6, the message from the brain reaches at least some of the sympathetic nervous system and this apparently is enough to lower the blood pressure and prevent autonomic dysreflexia.

What are the signs and symptoms of autonomic dysreflexia?
• Increase in blood pressure above normal levels with a slowing of the heart rate. This has been defined as an increase in the systolic blood pressure (SBP) of 20-40 mm Hg above the patient’s normal blood pressure. The systolic blood pressure is the top number of a recorded blood pressure. For example, 115 is the systolic blood pressure number in the recorded blood pressure of 115/65. 
(Note: the normal systolic blood pressure for an individual with a cervical or high thoracic spinal cord injury can normally be as low as 90-110.)

• Pounding headache that usually occurs in the front and back parts of the head
• Goosebumps on the skin above or below the neurological level
• Excessive sweating above the neurological level
• Flushing of the skin above the neurological level
• Nasal congestion
• Anxiety, which can be mild to overwhelming
• Blurred vision or seeing spots
• Irregular heart beat or racing heart.

Treatment of Autonomic Dysreflexia
Recognition of autonomic dysreflexia is the most important step before appropriate treatment can take place. In addition to the classic signs and symptoms, there is a phenomenon that has been described as “silent autonomic dysreflexia.” This condition is referred to as silent because there are no classic signs or symptoms. The patient has no idea that the blood pressure is in the dangerous range and requires intervention and treatment. Therefore, it is very important to understand the possible causes and always monitor blood pressure if you suspect an excessive stimulation of the sensory fibers of the nervous system during any situation.

Once autonomic dysreflexia has been identified to be present, the following intervention is recommended from the clinical practice guidelines of “Acute Management of Autonomic Dysreflexia” published by the Paralyzed Veterans of America (PVA) on behalf of the Consortium for Spinal Cord Medicine. The recommendations are summarized here and can be found at the following link:

http://www.pva.org/site/DocServer/ADC.pdf?docID=569

When autonomic dysreflexia is identified, the following steps should be taken:
(if any of the interventions described below cause the blood pressure to lower without medication, then stop and continue to monitor blood pressure for two hours).

1. Immediately change positions and sit up or raise the head of the bed. This will cause blood to pool in the legs and lower the blood pressure to the brain which is desired in this condition.
2. Loosen or remove any clothing or tight devices. If there is a leg bag strap in place, it should be removed. A brace on a leg should be removed if it is not stabilizing a broken bone.
3. If an indwelling catheter (Foley) or suprapubic tube is present,
a. check for kinks or bends and straighten tubing
b. if tube is straight and there is no flow of urine, gently flush the catheter with approximately 20-30 mL of normal saline
c. if there is still no flow of urine, remove catheter (if trained) and insert a new one.
4. If using an external catheter or performing intermittent catheterization, insert an intermittent catheter
5. If blood pressure remains elevated with a systolic blood pressure (SBP) greater than 150 mm Hg, then begin a short acting blood pressure medication such as Nitropaste ointment (start with ½ inch of ointment on forehead or chest) or nifedipine (bite and swallow). Nitropaste is often the first medication used while searching for a cause of autonomic dysreflexia. This medication can be quickly removed if high blood pressure is quickly reversed. If the source of irritation leading to autonomic dysreflexia is discovered and removed, then the blood pressure may return to normal very quickly. If the patient's normal systolic blood pressure is 90-100 and medication has been given to lower blood pressure during the AD event, the patient may develop a dangerously low blood pressure. If Nitropaste is used during AD it can be removed once the situation has resolved; this prevents the problem of having a blood pressure lowering medication in your body for several hours.
6. If the systolic blood pressure remains elevated but less than 150 mm Hg after checking all the above possibilities, then the focus is directed towards the bowels. It is now recommended to check for fecal impaction after placing lidocaine gel into the rectum. If fecal impaction is discovered with a gloved finger, it is then recommended to manually disimpact the fecal material.
7. If all the above interventions do not lead to a reversal of autonomic dysreflexia, then admission to the hospital is recommended to control blood pressure while other possible causes are investigated.