Topic Editor: Robert Giles, MBBS, BPharm
Review Date: 11/11/2012
Definition 
Autonomic Dysreflexia is an acute potentially life-threatening condition which commonly occurs in patients with spinal cord injuries above the major splanchnic outflow, at or above T6. It typically occurs following exposure to a noxious stimulus below the level of the spinal cord injury, which results in massive sympathetic outflow. As a result of this sympathetic outflow, a sudden elevation in blood pressure (BP) occurs.
Description
- Autonomic Dysreflexia is a medical emergency and occurs in patients with spinal cord injuries or other spinal cord lesions (e.g. multiple sclerosis)
- Early recognition of signs and symptoms with early initiation of treatment being required to prevent serious complications arising from elevated BP
- Commonly observed early symptoms of autonomic dysreflexia include a pounding headache, sweating, blotchy skin, and goose bumps
- Any painful, irritating, or significant stimulus below the injury level can trigger an episode
- This condition is usually diagnosed on the basis of physical examination, history, and blood pressure measurement
- Serious consequences such as cerebral/retinal hemorrhage, cardiac arrest, and death has occurred in the absence of timely treatment
Epidemiology
Incidence/Prevalence
- Prevalence of autonomic dysreflexia in the US ranges from 48-90% amongst patients with quadriplegia or high paraplegia
- Approximately 16% of children and adolescents with spinal cord injury experience autonomic dysreflexia
- This condition occurs most commonly during the first year following injury
- 85% to 90% of pregnant women with spinal cord injury at or above T6 will experience autonomic dysreflexia during pregnancy
- Frequency of episodes tend to decline with return of sacral reflexes
Age
- The prevalence of autonomic dysreflexia is comparable in pediatric and adult onset spinal cord injury
Gender
- Spinal cord injury is significantly more common in men than women (4:1), and as such autonomic dysreflexia is more common in men
Risk Factors
- Recent (1 year) spinal cord injury
- Noxious stimuli - these stimuli are discussed in the etiology section below
Etiology
- Autonomic dysreflexia occurs in patients who have a spinal cord injury at T6 or higher
- Any painful, physically irritating or unpleasant stimulus below the level of the spinal cord injury may trigger autonomic dysreflexia
- Distension of the bladder is the most common precipitant followed by fecal impaction
- Stimuli that may precipitate an episode of autonomic dysreflexia include:
- Urinary tract
- Distended bladder
- Catheter obstruction
- Non-adherence to catheterization regimen
- Overfilled collection bag
- Cystoscopy and urodynamic testing
- Ureteral calculi
- Urinary tract infection
- Bowel
- Acute abdominal conditions such as gastritis, gastric ulcer, colitis or peritonitis
- Anal fissures
- Constipation or fecal impaction
- Distention during bowel program (digital stimulation)
- Gallstones
- Hemorrhoids
- Intra-abdominal infection/inflammation (appendicitis, diverticulitis, inflammatory bowel, etc)
- Skin-related
- Blisters
- Burns (sunburn, chemical or physical burns)
- Decubitus ulcers
- Direct irritant exposure below the level of injury
- Ingrown toenail
- Insect bites
- Pressure on skin from tightly fitting or constrictive garments, or from being seated for a long time on wrinkled garments
- Reproductive
- Ejaculation
- Epididymitis or scrotal compression
- Menstrual cramps
- Stimulation during sexual activity
- Pregnancy, particularly during labor and delivery
- Torsion (ovary or testicle)
- Vaginitis
- Other
- Deep vein thrombosis
- Fractured bones
- Heterotopic bone
- Pulmonary embolism
- Surgical or diagnostic procedures
- Temperature variations
- Trauma (blunt or sharp)
- Pathophysiology
- Most symptoms occur as a result of aberrant overactivity of the sympathetic nervous system below the injury level
- Sympathetic activity is usually regulated via feedback from higher centers in the brainstem. In spinal cord injury, the descending inhibition from these centers is blocked. Thus, the sympathetic activity at and below the injury level becomes independently governed by spinal circuits alone
- This sympathetic overactivity causes excessive release of neurotransmitters resulting in piloerection and elevated BP due to severe arterial vasoconstriction
- Above the level of the lesion, excessive parasympathetic output attempts to compensate leading to vasodilatation. The vasodilatation of intracranial vessels leads to headache
[Outline]
History
- Patients may present with the following symptoms
- Anxiety or apprehension
- Chest pain and palpitations
- Nausea and malaise due to parasympathetic/vagal effect
- Nasal congestion
- Pounding headache
- Profuse sweating above the level of injury
- Visual disturbances
Physical findings on examination
- Sudden, substantial elevations in systolic and diastolic blood pressures. Elevation of systolic BP by 20–40 mmHg above the patient's normal is sufficient to be concerning
- Spinal injury patients usually have low BP's, with 90/60 mmHg being a common baseline level. Therefore, a BP of 120/80 mmHg could indicate autonomic dysreflexia
- Other significant findings include:
- Appearance of spots in the visual field
- Blotching and/or flushing of the skin above the level of spinal injury
- Blurred vision and mydriasis
- Cold pale skin below the level of spinal injury
- Dyspnea
- Increased spasm
- Nasal congestion
- Piloerection below the level of spinal injury
- Profuse diaphoresis above the level of spinal injury
- Reflex bradycardia (secondary to elevated BP)
- Seizures (rare)
- Tachycardia (rare)
[Outline]
Blood test findings
There are no specific tests for diagnostic evaluation of autonomic dysreflexia and diagnosis is primarily based on clinical suspicion and physical findings.
Radiographic findings
- Computed tomography (CT) Scan
- In patients with autonomic dysreflexia, acute hypertension and symptoms consistent with subarachnoid hemorrhage (e.g. 'thunderclap headache' or acute confusional state), an urgent head CT scan is indicated to evaluate for intracranial hemorrhage
[Outline]
General treatment items
- If hypertension is evident the patient should be placed in an upright position, and legs should be lowered in order to produce an orthostatic drop in BP
- Any restrictive clothing or constrictive devices should be loosened or removed
- During an acute episode, monitor the BP every 2-5 minutes. Following resolution of symptoms, BP should be monitored every two hours to ensure there is no recurrence
- As one of the most common causes is bladder distension, the patient needs assessment for whether this is the case. Whether an indwelling urinary catheter is present of not. Bedside ultrasound to evaluate for distended bladder is indicated; if not available, a catheter should be placed, or existing catheter flushed with no more than 30 mL of saline, or replaced. During this procedure, avoid exerting manual pressure on the bladder
- If bladder distension is the cause, generally draining 500 mL initially, then 250 mL every 15 minutes thereafter until the bladder is empty is recommended
- If SBP
170 mmHg, medication to decrease blood pressure should be administered before proceeding further. In the event of needing to place a new urinary catheter, SBP170 mmHg should be treated before proceeding, along with the use of lidocaine gel in the urethra for at least 5 minutes - If bladder distension if not the issue, if SBP 170 mmHg treat with medication before proceeding. Once BP improved, checking for fecal impaction is the next step. Lidocaine gel should be inserted generously per rectum, then after 5 minutes or more, gentle PR exam should occur. If fecal impaction is present, it should be manually disimpacted once the SBP is 150 mmHg (use medication to achieve this if necessary). If BP increases with disimpaction, cease immediately, administer additional antihypertensive and once BP improves, reattempt
- If symptoms still persist and are not resolving with a review for bladder distension and bowel disimpaction, and systolic BP is >150 mmHg, pharmacological treatment for hypertension should be initiated to avoid the risk of complications
- In the event that fecal impaction or bladder distension is not the cause, review for other causes of nociception is required, such as:
- Burns
- Cervicitis/PID
- Epididymoorchitis
- Fractures
- Ingrown nail
- Intra-abdominal pathology
- Pregnancy
- Pressure sores
- Skin infection
- If a nociceptive stimuli is found, administer appropriate opioid analgesia systemically (morphine, fentanyl, hydromorphone)
- In the absence of symptomatic relief or if there is failure to identify the precipitant, admission or referral to a spinal specialist should be arranged
- Antihypertensive therapy
- When systolic BP is 150 mmHg, a short-acting antihypertensive agent with a rapid onset of action is preferred while investigating the precipitant
- Nifedipine and nitrates (eg, nitroglycerin) are the most commonly used agents. Nifedipine should be administered in immediate-release form (bite and swallow) rather than in the sublingual form
- Other commonly used antihypertensives include hydralazine, prazosin and clonidine. Antihypertensives should be administered with utmost caution in the elderly and in patients who have coronary artery disease
- Many patients with spinal cord injuries use phosphodiesterase inhibitors for the treatment of erectile dysfunction. The concomitant use of nitrates within 24 hours of sildenafil or vardenafil or within 4 days of tadalafil is contraindicated due to the risk of severe hypotension
- Surgery
- Use of transurethral sphincterotomy for detrusor sphincter dyssynergia may prevent damage to kidneys and development of autonomic dysreflexia
Medications indicated with specific doses
Antihypertensives
- Clonidine [Oral]
- Hydralazine [IM/IV]
- Nifedipine
- Nitroglycerin [IV]
- Nitroglycerin [Sublingual]
- Prazosin
Opioid analgesics- Fentanyl [IM/IV]
- Hydromorphone [Injectable]
- Morphine [Injectable]
Dietary or Activity restrictions
- A well-balanced, fiber-rich diet and adequate fluid intake are essential to maintain a regular bowel movement
- Constipating foods such as cheese, bananas, meat, should be avoided
Disposition
Admission Criteria
- Unknown etiology of autonomic dysreflexia
- Limited or no response to treatment
- Failure of antihypertensive measures necessitates intensive care unit admission
- Pregnant women with autonomic dysreflexia should be admitted. If in labor, epidural anesthesia is generally required
Discharge Criteria
- Normalization of BP and pulse with observation for 4 hours
- No evidence of cardiac failure or elevated intracranial pressure
- Precipitant of autonomic dysreflexia is determined and treated
- No other reason for admission, and the patient is stable otherwise
[Outline]
Prevention
- Prevention is the most important strategy in the management of autonomic dysreflexia
- Avoidance of urinary tract precipitants:
- Low-pressure filling of the bladder can be achieved with anticholinergic drugs and regular intermittent catheterization
- Sterility should be maintained during catheter insertions to prevent urinary tract infections
- Patients should be advised to faithfully adhere to a regular bowel program
- Pressure areas should be avoided by regular position changes
- Patients should be advised to use an SPF15 or higher sunscreen and be careful about water temperature
- Routine skin examination may be valuable to evaluate for ulcers, injury, or infection
Prognosis
- Hypertension and other complications associated with autonomic dysreflexia may result in significant morbidity
- Although the condition is life-threatening, mortality is rare
Pregnancy/Pediatric effects on condition
- Pregnant women with spinal cord injury are at significantly higher risk of developing autonomic dysreflexia, with greater chance of occurrence during labor and delivery
- Autonomic dysreflexia must be differentiated from pre-eclampsia
- Autonomic dysreflexia occurring during labor and delivery can be effectively managed with epidural anesthesia
Synonyms/Abbreviations
Synonyms
ICD-9-CM
- 337.3 Autonomic dysreflexia
ICD-10-CM
- G90.4 Autonomic dysreflexia
[Outline]
