para>For children, AD is defined as an increase in BP 15 mm Hg above baseline.
For adolescents, AD is defined as an increase in BP 15 to 20 mm Hg above baseline.
BPs >140 mm Hg in an adolescent, 130 mm Hg in children 6 to 12 years old, or 120 mm Hg in children <5 years old warrant antihypertensive medications.
Give guidelines, baseline BP, and description of AD to the child's pediatrician and school.
Pregnancy Considerations
AD occurs during labor in 2/3 of pregnancies of patients with SCI at T6 or above.
Can also occur antepartum or postpartum
Epidural block is effective treatment or prophylaxis for AD during labor.
Consult OBGYN for:
Life-threatening AD
First episode of AD
AD in the 3rd trimester
Vaginal bleeding or suspected labor
Persistent symptoms despite treatment
Guidance in choosing antihypertensive therapy
Prevalence
- 91% of tetraplegic patients with complete SCI present with AD versus 27% of patients with incomplete lesions.
- Children and adolescents with SCI: 16%
ETIOLOGY AND PATHOPHYSIOLOGY
- Normal regulation of the sympathetic system is modulated by input from higher centers. After SCI, that input is lost, leading to a disconnection between the sympathetic and parasympathetic nervous systems.
- Noxious stimulus below the SCI spurs impulses transmitted via the intact peripheral nerves to the sympathetic neurons of the thoracic spinal cord. Unopposed sympathetic outflow causes a massive release of catecholamines, resulting in severe vasoconstriction below the lesion and a sudden elevation of BP.
- Simultaneously, baroreceptors in the brain, carotid sinus, and aorta detect the rising BP and attempt to trigger visceral and peripheral vasodilatation, but the impulses cannot pass through the SCI. The parasympathetic response is limited to vagal slowing of the heart rate and vasodilatation above the SCI.
- SCI below T6 rarely causes AD, as the intact greater splanchnic nerve is able to respond with a compensatory dilation of the splanchnic vasculature.
RISK FACTORS
- SCI at or above T6
- Any noxious stimulus below the lesion can cause AD.
- Urologic stimuli: bladder distention, urinary tract infection, cystoscopy, transurethral litholapaxy, and extracorporeal shock-wave lithotripsy (most common precipitants)
- Anorectal stimuli: fecal impaction, rectal exam, enema (second most common precipitants)
- Competitive athletes may induce AD (e.g., by clamping Foley) to enhance performance with resultant increased peak HR, BP, norepinephrine levels, and O2 uptake compare with nonboosted athletes.
GENERAL PREVENTION
- Good bladder and bowel care
- Anesthetic lubricants for urethral catheterization
- Nerve blocks for procedures below the SCI even if the patient does not feel pain
- Topical lidocaine might not reduce occurrence of AD with anal procedures; consider intersphincteric anal block.
- Patient and provider education
DIAGNOSIS
AD is a clinical diagnosis. Most studies use a 20 to 30 mm Hg increase in the systolic BP in response to a noxious stimulus to define AD in adult patients.
HISTORY
- Minimal or no symptoms despite an elevated BP (silent AD is common)
- Headache
- Pallor below SCI
- Piloerection
- Profuse sweating and/or flushing above the SCI
- Nasal congestion
- Chest pain
- Palpitations
- Nausea
- Malaise
- Blurred vision
PHYSICAL EXAM
- BP of at least 20 to 30 mm Hg above normal for adults with SCI (pediatric range is different, see "Pediatric Considerations")
- Normal SBP for a patient with SCI is 90 to 110 mm Hg (1)[A], so a normal BP for an able-bodied individual could indicate AD in a patient with SCI.
- BP elevation ranges from mild to extreme: Systolic BPs of 250 to 300 mm Hg have been reported.
- Bradycardia is more common in young patients and only occurs in a minority of cases (2)[B].
- Tachycardia is rare.
- Profuse sweating above the level of SCI
- Flushed skin above the level of SCI
- Cold, pale skin below the level of SCI
- Piloerection
- Horner syndrome (3)
- Blurred vision
- Retinal hemorrhages
DIFFERENTIAL DIAGNOSIS
- Spinal cord plaque above T6 in multiple sclerosis
- Catecholamine-secreting tumor (e.g., pheochromocytoma)
- Eclampsia
DIAGNOSTIC TESTS & INTERPRETATION
- No lab test or imaging makes the diagnosis. Clinical suspicion and physical exam are paramount in diagnosing AD.
- Head CT if patient complains of severe headache, is altered, or has new focal neurologic deficits, as an abrupt increase in BP could cause cerebral hemorrhage
- Place patient on cardiac monitor, as arrhythmias such as atrial fibrillation can complicate AD (1)[B]. BP should be monitored closely until patient is stable.
TREATMENT
- Patient should be sat upright: Orthostasis reduces BP (1)[A].
- Most important step is removing the causative stimulus (1)[A]. Specific recommendations:
- Loosening constrictive clothing or devices
- Pressure relief
- Check urinary catheter for kinks.
- Irrigate blocked catheter using 10 to 15 mL of saline. If blockage remains, remove catheter, insert 2% lidocaine jelly into the urethra, wait 2 minutes and insert new catheter (1)[A].
- If BP is significantly elevated, it may need to be lowered before checking for fecal impaction with digital rectal examination (1)[A].
- Gentle rectal exam using lidocaine jelly (rectal exam can aggravate AD) (1)[A]
- Rectal disimpaction if constipated, using lidocaine jelly (unless procedure started AD) (1)[A]
- Minimizing aggravation by using an enema instead of digital manipulation might decrease the occurrence of AD (4)[B].
MEDICATION
Use antihypertensive agents with rapid onset and short duration of action (1)[A] while determining etiology or if the systolic BP is >150 mm Hg. The best agent has not been demonstrated in large studies. Nifedipine, nitrates, and captopril are used most often.
First Line
- Nifedipine (5)[B]: immediate-release form, 10-mg capsule initially; bite and swallow is the mainstay of therapy (5)[B], but sublingual is another alternative:
- Hypotension caused by the short-acting form of nifedipine can be avoided by using a pin or needle to puncture the nifedipine capsule and in administering the liquid medication one drop at a time to titrate to effectiveness.
- The dose of nifedipine can be repeated in 15 minutes if needed. Care should be exercised to avoid hypotension.
- Nitrates (5,6)[C]:
- Sublingual 0.4-mg spray
- 2% nitroglycerine ointment: 0.5- to 1-inch strip to chest wall (above SCI) and titrate as needed; this is safer but slower (6)[C].
- Nitroglycerin: 0.15- to 0.6-mg tablet SL
- Nitrates are contraindicated if patient has taken any phosphodiesterase inhibitors such as sildenafil (Viagra) or vardenafil (Levitra) within the past 24 hours or tadalafil (Cialis) within the previous 48 hours. Use of these agents is common in the SCI population for treatment of sexual dysfunction due to their injury.
- Captopril (5)[B]: 25 mg sublingually during AD
Second Line
- Prazosin (5)[B]: 0.5 to 1 mg PO q8h PRN for prophylaxis of AD; advantage of minimal effect on cardiac function
- Terazosin (5)[C]: 5 mg PO QHS for prophylaxis. During AD starting dose: 1 mg PO for adults, 0.5 mg PO for children, and titrating to effect; added advantage of inhibition of urinary sphincter and smooth muscles relaxation
- Phenoxybenzamine (5)[B]: conflicting evidence: One study showed no effect on AD occurrence and severity; another showed a positive treatment effect.
- Initial dose 10 mg for prophylaxis, with daily increases to 20 to 40 mg BID or TID
ISSUES FOR REFERRAL
See "Pregnancy Considerations."
ADDITIONAL THERAPIES
- Physical and occupational therapy is essential for SCI patients, thus therapists should be aware of AD's manifestations and basic management.
- If stretching/exercise during therapy evokes AD, it should be stopped immediately. Care should be taken not to disrupt catheters during therapy. Occupational therapists can assist with bowel and bladder programs and educate patients and families on these activities.
SURGERY/OTHER PROCEDURES
Transurethral sphincterotomy for chronic form of AD related to detrusor sphincter dyssynergia and overdistention of bladder (5)[B]
INPATIENT CONSIDERATIONS
Admission Criteria/Initial Stabilization
- Poor response to treatment (1)[A]
- Undetermined cause (1)[A]
- Obstetrical complications (see "Pregnancy Considerations")
- Consider transfer to ICU if antihypertensive measures fail; for IV medications, including nitroprusside, 0.5 Ī¼g/kg/min IV (contraindicated with previous sildenafil use) and possibly spinal anesthesia (1)[A].
- Epidural anesthesia in pregnant woman with AD during labor
Nursing
Monitor BP frequently, every 5 minutes until normal, and then every 30 minutes for 4 hours, as BP tends to fluctuate during AD.
Discharge Criteria
- BP and HR back to patient's normal range (1)[A]
- Asymptomatic, without signs of heart failure or raised intracranial pressure (1)[A]
- Etiology of the episode is ascertained and addressed (1)[A].
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
- Patient and family education regarding early recognition and prevention of AD
- For recurrent AD, consider the Ī±1-blockers prazosin (5)[B] or terazosin as above (5)[C].
Patient Monitoring
Monitor symptoms and BP for at least 2 hours after resolution of AD because of the risk of developing hypotension.
PATIENT EDUCATION
- All patients with high SCI should be counseled about AD's causes, manifestations, prevention, and treatment.
- Optimal bladder and bowel care
- Patients should carry a MedicAlert bracelet and AD emergency medical card that summarizes the causes and treatment of AD.
PROGNOSIS
- Life-threatening if unrecognized and untreated due to massive elevation in BP
- Rapid resolution of acute episode with removal of noxious stimulus if addressed quickly
- Can be recurrent
COMPLICATIONS
- Retinal hemorrhage
- Intracranial hemorrhage
- Posterior reversible encephalopathy syndrome (PRES)
- Hypertensive encephalopathy
- Seizures
- Pulmonary edema
- Arrhythmias
- Myocardial infarction
- Cardiac arrest
REFERENCES
11 Consortium for Spinal Cord Medicine. Acute Management of Autonomic Dysreflexia. 2nd ed. Washington, DC: Paralyzed Veterans of America; 2001. http://www.pva.org/atf/cf/%7BCA2A0FFB-6859-4BC1-BC96-6B57F57F0391%7D/cpg_autonomic%20dysreflexia.pdf. Accessed 2014.22 Huang YH, Bih LI, Chen GD, et al. Autonomic dysreflexia during urodynamic examinations in patients with suprasacral spinal cord injury. Arch Phys Med Rehabil. 2011;92(9):1450-1454.33 Cragg JJ, Krassioukov AV. Pearls and oysters: transient Horner syndrome associated with autonomic dysreflexia. Neurology. 2013;81(6):e35-e37.44 Furusawa K, Tokuhiro A, Sugiyama H, et al. Incidence of symptomatic autonomic dysreflexia varies according to the bowel and bladder management techniques in patients with spinal cord injury. Spinal Cord. 2011;49(1):49-54.55 Krassioukov A, Warburton DE, Teasell R, et al. A systematic review of the management of autonomic dysreflexia after spinal cord injury. Arch Phys Med Rehabil. 2009;90(4):682-695.66 Rabchevsky AG, Kitzman PH. Latest approaches for the treatment of spasticity and autonomic dysreflexia in chronic spinal cord injury. Neurotherapeutics. 2011;8(2):274-282.
ADDITIONAL READING
- Cormier CM, Mukhida K, Walker G, et al. Development of autonomic dysreflexia after spinal cord injury is associated with a lack of serotonergic axons in the intermediolateral cell column. J Neurotrauma. 2010;27(10):1805-1818.
- Krassioukov A. Autonomic dysreflexia: current evidence related to unstable arterial blood pressure control among athletes with spinal cord injury. Clin J Sport Med. 2012;22(1):39-45.
- Liu N, Zhou M, Biering-S ørensen F, et al. Iatrogenic urological triggers of autonomic dysreflexia: a systematic review. Spinal Cord. 2015;53(7):500-509.
- Matias AC, Rocha JM, Cerqueira ME, et al. Autonomic dysreflexia and posterior reversible encephalopathy syndrome. Am J Phys Med Rehabil. 2013;92(5):453-458.
- Wan D, Krassioukov AV. Life-threatening outcomes associated with autonomic dysreflexia: a clinical review. J Spinal Cord Med. 2014;37(1):2-10.
CODES
ICD10
G90.4 Autonomic dysreflexia
ICD9
337.3 Autonomic dysreflexia
SNOMED
autonomic dysreflexia (disorder)
CLINICAL PEARLS
- AD is a potentially life-threatening but reversible disorder, so early recognition and prevention are vital.
- Normal BP for a quadriplegic could be 90/60 mm Hg; hence, even 120/80 mm Hg could indicate AD.
- Always examine Foley catheters.