In a patient with an axial load spinal injury who experiences fluctuating blood pressures ranging from normal to hypertensive and hypotensive, what is the most likely cause?

Neurogenic Shock from Spinal Cord Injury

The fluctuating blood pressures in a patient with axial load spinal injury are most likely caused by neurogenic shock with loss of sympathetic tone, resulting in characteristic hemodynamic instability that includes both hypotension (from vasodilation and loss of vascular tone) and paradoxical hypertension (from unopposed parasympathetic activity or autonomic dysreflexia). 1

Understanding the Pathophysiology

In axial load spinal injuries, particularly those affecting the cervical or upper thoracic cord (above T6), the entire sympathetic outflow becomes separated from cerebral control. This creates a unique pattern of cardiovascular dysfunction:

The Blood Pressure Pendulum

• Hypotensive episodes occur because sympathetic innervation to blood vessels is lost, causing vasodilation and pooling of blood in the periphery 2

• Hypertensive episodes can occur from:

  • Unopposed parasympathetic (vagal) activity
  • Spinal reflex-mediated sympathetic surges below the level of injury (autonomic dysreflexia)
  • Activation of intact spinal cord reflexes working independently of the brain 2

• Normal pressures may occur intermittently as compensatory mechanisms temporarily stabilize

Critical Management Priorities

Immediate Blood Pressure Targets

Maintain systolic blood pressure > 110 mmHg initially to reduce mortality 1. Hypotension at hospital admission (SBP < 110 mmHg) is an independent factor for patient mortality after spinal cord injury.

Target mean arterial pressure (MAP) ≥ 70 mmHg during the first week to limit worsening neurological deficit 1. The correlation between MAP and neurological improvement exists primarily for the first 2-3 days after admission, with optimal outcomes seen when MAP > 70-75 mmHg.

Monitoring Requirements

• Continuous arterial line monitoring is essential 1. Studies show that even with aggressive management, MAP falls below target 25% of the time, making intermittent cuff measurements inadequate 1

• Blood pressure variability itself is independently associated with poor functional outcomes at 6 months 3

Common Pitfalls to Avoid

1. Don't assume stable blood pressure means stable injury: Even patients with transient neurological recovery need specialized care and continuous monitoring 1

2. Avoid all episodes of acute hypotension (SBP < 90 mmHg) through day 5-7 post-injury 1

3. Don't use steroids: Early methylprednisolone administration is NOT recommended and increases infectious complications without improving neurological outcomes 1

4. Recognize that both extremes are harmful: While hypotension clearly worsens outcomes, the frequency and severity of both hypo- and hypertensive events correlate with increased arterial stiffness and worse long-term outcomes 4, 5

Clinical Algorithm for BP Management

First 24 hours:

• Establish arterial line immediately
• Maintain SBP > 110 mmHg and MAP ≥ 70 mmHg
• Avoid any episodes of SBP < 90 mmHg
• Transfer to specialized spinal cord injury center to reduce morbidity and mortality 1

Days 2-7:

• Continue MAP target ≥ 70 mmHg
• Monitor for autonomic dysreflexia (sudden SBP increases > 20 mmHg above baseline)
• Address triggers of dysreflexia (bladder distension, bowel impaction, pressure injuries)

Beyond first week:

• Hemodynamic instability typically persists chronically in high cervical/upper thoracic injuries
• Long-term management focuses on preventing both orthostatic hypotension and autonomic dysreflexia episodes

The evidence strongly supports that this blood pressure instability directly impacts neurological recovery, with time spent below MAP 65-70 mmHg inversely correlating with neurological improvement 1.