What are the symptoms and management of neurogenic shock?

Neurogenic Shock: Symptoms and Management

Neurogenic shock is characterized by hypotension and bradycardia due to disruption of sympathetic nervous system outflow, typically following spinal cord injury, particularly at cervical or high thoracic levels. 1, 2

Clinical Presentation

Primary Symptoms

• Hypotension - Systolic blood pressure <90 mmHg 3
• Bradycardia - Often accompanying hypotension 2, 4
• Warm, dry skin - Due to loss of sympathetic tone causing vasodilation
• Normal or decreased heart rate - Unlike other forms of shock where tachycardia is common

Associated Findings

• Occurs primarily in cervical (29% incidence) and high thoracic spinal cord injuries 1
• Typically develops within minutes to hours after injury
• May persist for days to weeks (acute phase) 4
• Decreased peripheral vascular resistance (33% of cases) 5
• Loss of vascular capacitance (22% of cases) 5
• Mixed vascular resistance and capacitance issues (33% of cases) 5
• Cardiac dysfunction (11% of cases) 5

Management Algorithm

Immediate Interventions

1. Fluid Resuscitation

   • Initial management with adequate fluid resuscitation 3
   • Careful monitoring to avoid fluid overload

2. Vasopressor Therapy

   • Norepinephrine is recommended as the first-line vasopressor for persistent hypotension after fluid resuscitation 3
   • Target mean arterial pressure (MAP) ≥80 mmHg in TBI patients 3

Pharmacological Management

1. First-line vasopressors:

   • Norepinephrine - First choice for persistent hypotension 3
   • Vasopressin (up to 0.03 UI/min) - Can be added to reduce norepinephrine requirements 3

2. Second-line agents:

   • Midodrine - Beneficial for neurogenic orthostatic hypotension with dose-dependent effect on standing blood pressure 3, 6
   • Fludrocortisone - Increases plasma volume with resultant improvement in orthostatic symptoms 3, 6
   • Dopamine - Consider only in hypotensive patients with bradycardia 3

3. Adjunctive measures:

   • Droxidopa - Can improve symptoms in neurogenic orthostatic hypotension 3
   • Compression garments - At least thigh-high, preferably including abdomen 3
   • Acute water ingestion - 240-480 mL for temporary relief 3

Non-pharmacological Interventions

1. Physical counter-pressure maneuvers

   • Isometric contractions (leg crossing, lower body muscle tensing)
   • Squatting when possible 3

2. Salt and fluid intake

   • Consider increased salt (6-9g daily) and fluid intake in selected patients 3
   • Not recommended in patients with hypertension, renal disease, or heart failure

Monitoring and Follow-up

• Continuous hemodynamic monitoring
• Regular neurological assessment to detect secondary neurological aggravation 3
• Monitor for complications of vasopressor therapy:
  • Midodrine: Supine hypertension, scalp tingling, piloerection, urinary retention 3
  • Fludrocortisone: Edema, hypokalemia, headache, supine hypertension 3
  • Droxidopa: Supine hypertension, headache, dizziness, nausea 3

Special Considerations

• Avoid phenylephrine except as salvage therapy 3
• Strict spinal immobilization is necessary during early management 2
• Early surgical decompression may be indicated for incomplete spinal cord deficits 2
• Steroids are not recommended for neurogenic shock management 2
• Cardiac dysfunction requires specific treatment approaches 4

Pitfalls and Caveats

• Neurogenic shock must be differentiated from spinal shock, which refers to the transient suspension of reflexes below the injury level 4
• Hypovolemia can mimic or exacerbate neurogenic shock and must be ruled out 1
• Autonomic dysreflexia may develop after resolution of spinal shock in injuries above T5-T6 level 4
• Supine hypertension is a common side effect of medications used to treat neurogenic hypotension 3
• Vasopressor weaning can be challenging and may require gradual transition to oral agents 6