Autonomic Dysreflexia (AD), also known as Autonomic Hyperreflexia, is a potentially life threatening condition where the blood pressure in a person with a spinal cord injury above T5-6 becomes excessively high due to the over activity of the Autonomic Nervous System. The cause of AD is usually a noxious stimuli, that is either pain or irritation or full bladder, which occurs below the level of injury. Once the noxious stimuli is removed AD is relieved.
How AD is caused?
Autonomic nervous system (ANS) functions as a control system, functioning largely below the level of consciousness, and controls several involuntary functions. Some of them are heart rate, digestion, respiration rate, salivation etc.
ANS is divided into two subsystems called Sympathetic nervous system (SNS) and Parasympathetic nervous system (PSNS). PSNS nerves exit mainly from brain and SNS nerves from thoracic-lumbar spine. These subsystems have complementary roles.
SNS promotes a "fight or flight" response, corresponds with arousal and energy generation, and inhibits digestion. Some of its funtions are, dilation of the pupils, increased heart rate, vasoconstiction (narrowing of blood vessels), Inhibits digestive peristalsis.
PSNS has an opposite "rest and digest" response. Some of its funtions are, constriction of the pupil, decreased heart rate, vasodilation (dialation of bloodvessels) as well as increased peristalsis
The SNS and PSNS work in sync with a feedback system, with PSNS negating the effect of SNS once the emergency is over and viceversa. In a person with SCI above the level T5-6 this feedback loop is broken and SNS and PSNS work independently out of sync.
When a noxious stimuli occur below the injury level in an SCI, it causes a sympathetic response by the SNS, characterized by hypertension, pounding headache, visual changes, anxiety, and goose bumps below the level of injury due to increased blood pressure, heart rate and constriction of blood vessels.
The PSNS is not able to negate these through the injured spinal cord below the injury level. PSNS causes low heartrate and vasodialation above the injury level, which is characterised by low pulse, reddened face, nasal stuffiness. etc. But no change occurs below the injury level.
If not attented immidiately, - the best remedy is to remove the noxious stimuli; the systolic (high) pressure may rise above 200mm/hg and can lead to stroke, and even death.
Signs & Symptoms
These symptoms are usually seen with AD,
- Pounding headache and visual changes(caused by the elevation in blood pressure)
- Goose Pimples, below the injury
- Cold, clammy skin below level of injury
- Hypertension (blood pressure greater than 200/100)
- Sweating above the level of injury
- Red blotches on the skin above level of injury
- Nasal Congestion
- Slow Pulse (< 60 beats per minute)
- Restlessness, Nausea, anxiety
Causes of noxious stimuli
In general, noxious stimuli are irritants that would normally cause pain to areas of body below the level of spinal injury, if sensation were present.
Bladder (most common) - from over distension or irritation of bladder wall
Urinary tract infection (most common)
Urinary retention
Blocked catheter
Overfilled collection bag
Bowel - over distention or irritation
Constipation / impaction
Distention during bowel program (digital stimulation)
Hemorrhoids or anal fissures
Infection or irritation (eg. appendicitis, stomach ulcers)
Skin-related Disorders
Any direct irritant below the level of injury (eg. - prolonged pressure by object in shoe or chair, cut, bruise, abrasion)
Pressure sores
Ingrown toenails (not easily found out)
Burns (eg. - sunburn, burns from using hot water)
Tight or restrictive clothing or pressure to skin from sitting on wrinkled clothing
Sexual Activity
Over stimulation during sexual activity
Menstrual cramps
Labor and delivery
Other
Heterotopic ossification (growth of excess bones in hip etc)
Acute abdominal conditions (gastric ulcer, colitis, peritonitis)
Skeletal fractures
Medications.
Medications are required if the symptoms fail to releive even after the stimuli is removed. The blood pressure will have to be controlled immediately.
It may be required to take prolonged medication to control recurring stimuli.
Tips to do when you have AD
Keep your head up, its better to sit or if your are lying down keep your head elevated. This reduces blood pressure into brain.
Identify and remove the noxious stimuli.
Check catheter or Catheterise if required.
Obtain emergency medical treatment if you fail to find the stimulus causing AD.
