Epidemiology

• Occurs with Spinal Cord Injury Above T6 (see Spinal Cord Injury)
  • Lesions Below T6 Do Not Result in Autonomic Dysreflexia, Since Intact Splanchnic Innervation Allows for Compensatory Vasodilation of the Splanchnic Vascular Bed

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Physiology

• Loss of Coordinated Autonomic Responses to Physiologic Demands Placed on the Heart Rate and Vascular Tone
  • Noxious Stimuli Below the Level of Injury Lead to Exaggerated Sympathetic Responses with Resulting Diffuse Vasoconstriction and Hypertension
    • Compensatory Parasympathetic Responses Lead to Bradycardia and Vasodilation Above the Level of Injury: however, this is not sufficient to decrease the hypertension

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Diagnosis

• xxx

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Clinical Manifestations

General Comments

• Relationship of Clinical Manifestations to the Severity of Spinal Cord Injury: severity of spinal cord injury is associated with the severity and frequency of autonomic dysreflexia attacks
• Triggers of Autonomic Dysreflexia
  • Bladder Distention: common precipitant
  • Bone Fracture
  • Bowel Impaction: common precipitant
  • Decubitus Ulcer
  • Labor/Delivery
  • Medical Procedure
  • Occult Visceral Disturbance
  • Sexual Activity

Cardiovascular Manifestations

• Bradycardia (see Sinus Bradycardia)
  • Epidemiology: common
• Hypertension (see Hypertension)
  • Epidemiology: common
  • Clinical
    • May Be Severe Enough to Result in Hypertensive Emergency
• Hypotension (see Hypotension)
  • Epidemiology: may occur in some cases
• Sinus Tachycardia (see Sinus Tachycardia)
  • Epidemiology: may occur in some cases

Dermatologic Manifestations

• Diaphoresis (see Diaphoresis)
• Flushing (see Flushing)
• Piloerection

Gastrointestinal Manifestations

• Nausea (see Nausea and Vomiting)

Neurologic Manifestations

• Anxiety (see Anxiety)
• Blurred Vision
• Headache (see Headache)

Pulmonary Manifestations

• Nasal Obstruction
• Neurogenic Pulmonary Edema (see Neurogenic Pulmonary Edema)
  • Epidemiology: rare
    • May Occur with Chronic Cervical Spinal Cord Injury Above T6

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Prophylaxis

Agents Which Have Been Reported to Prevent Attacks

• Nifedipine (seeNifedipine)
• Prazosin (see Prazosin)
• Terazosin (see Terazosin)

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Treatment

General Measures

• Determination of Noxious Stimuli Contributing to the Event
  • Foley Catheter (see Foley Catheter): to relieve bladder distention
    • If Already Present, Ensure that the Catheter is Not Obstructed
  • Rectal Exam: to evaluate for fecal impaction
• Monitoring of Blood Pressure
• Removal of Tight-Fitting Garments

Anti-Hypertensive Measures/Agents

• Immediate Upright Positioning: to orthostatically lower blood pressure
• Short-Acting, Rapid-Acting Anti-Hypertensive Agents are Preferred
  • Nitropaste (see Nitroglycerin)
  • Oral Nifedipine (see Nifedipine)
  • Sublingual Captopril (see Captopril)
  • Intravenous Hydralazine (see Hydralazine)
  • Intravenous Labetalol (see Labetalol)

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References

• Consortium for Spinal Cord Medicine. Acute Management of Autonomic Dysreflexia. Clinical practice guideline for healthcare providers. 3rd Edition 2016 [MEDLINE]