Autonomic Dysreflexia: A Life-Threatening Medical Emergency
Autonomic dysreflexia is a potentially life-threatening medical emergency characterized by massive sympathetic discharge in response to noxious stimuli below the level of spinal cord injury, typically occurring in patients with injuries at or above T6, resulting in severe hypertension that requires immediate intervention to prevent serious complications including stroke, seizures, and death. 1
Definition and Pathophysiology
Autonomic dysreflexia (AD) is a syndrome that occurs in individuals with spinal cord injuries, particularly those with lesions above the sympathetic outflow at T6. It represents a disruption of normal autonomic responses characterized by:
- Massive sympathetic discharge from the isolated spinal cord below the level of injury
- Uncontrolled sympathetic activity in response to noxious stimuli below the injury level
- Inability of descending inhibitory pathways to regulate this response due to the spinal cord lesion
- Resulting "sympathetic storm" causing severe, potentially fatal hypertension 2
Clinical Presentation
Patients with autonomic dysreflexia typically present with:
- Sudden, severe hypertension (primary clinical concern)
- Pounding headache (most common symptom)
- Flushing and sweating above the level of injury
- Bradycardia (paradoxical, despite sympathetic surge)
- Visual disturbances
- Nasal congestion
- Anxiety or sense of impending doom
- Piloerection (goosebumps) above the level of injury 1, 3
Common Triggers
The most frequent triggers for autonomic dysreflexia include:
- Bladder distension or manipulation (most common trigger)
- Bowel distension or impaction
- Skin irritation, pressure ulcers, or ingrown toenails
- Tight clothing or compression stockings
- Surgical or diagnostic procedures, especially urological
- Sexual activity
- Menstruation or pregnancy-related changes
- Temperature extremes 1, 4
Risk Factors
Patients at highest risk include:
- Spinal cord injuries at or above T6 level
- Complete spinal cord injuries
- History of previous episodes of autonomic dysreflexia
- Presence of spinal cord irritation or syringomyelia
- Recent spinal surgery 1, 3
Management Algorithm
1. Immediate Actions
- Position patient upright to utilize orthostatic response to reduce blood pressure
- Loosen tight clothing, constrictive devices, or compression stockings
- Monitor vital signs every 2-5 minutes until stable 1
2. Identify and Remove Triggering Stimulus
- Check bladder first:
- If indwelling catheter present, check for kinks or blockages
- If no catheter present, perform gentle catheterization with lidocaine gel
- Check for bowel impaction and disimpact if present (using topical anesthetic)
- Examine skin for pressure areas, wounds, or other irritants 1, 4
3. Pharmacological Management (if BP remains elevated)
- For systolic BP >150 mmHg despite above measures:
- Administer nitroglycerin 0.4 mg sublingually OR
- Nifedipine 10 mg bite and swallow (immediate-release)
- For severe, persistent hypertension:
- Consider IV antihypertensives under close monitoring
- Options include labetalol, hydralazine, or sodium nitroprusside 1
4. Escalation of Care
Indications for escalation include:
- Systolic BP remaining >150 mmHg despite interventions
- Persistent symptoms despite removal of apparent triggers
- Development of seizures, altered mental status, or visual changes
- Signs of end-organ damage 1
Prevention Strategies
- Regular bladder and bowel programs to prevent distension
- Proper skin care to prevent pressure injuries
- Patient and caregiver education about triggers and early symptoms
- Prophylactic antihypertensives before procedures in high-risk patients
- Clear communication with all healthcare providers about AD risk 1, 5
Complications
If not promptly treated, autonomic dysreflexia can lead to:
Autonomic dysreflexia represents one of the most serious emergencies in spinal cord injury patients. Prompt recognition and immediate treatment are essential to prevent life-threatening complications. All healthcare providers caring for individuals with spinal cord injuries should be familiar with this condition and its management.