Autonomic Hyperreflexia

 

 

Background 

 

  • Spinal cord injury above T6

  • Frequency variable: 20-70% of patients

  • Above lesion: reflex bradycardia & vasodilation (flushed) 

  • Below lesion: unopposed sympathetic stimulation (vasoconstriction/hypertension)  

  • Common clinical manifestations:

    • Headache, diaphoresis, BP, bradycardia

    • Flushing, piloerection, blurred vision, nasal obstruction, anxiety, nausea

  • Consequences of event:

    • Bradycardia, AV block, PACs, PVCs 

    • Severe headache, seizures, subarachnoid hemorrhage,  level of consciousness

    • Dyspnea, LV failure, pulmonary edema

    • Blurred vision 

    • Anxiety, agitation 

    • Chest pain/myocardial ischemia 

 

 

Considerations 

 

  • Potential for hypertensive emergency with end-organ damage 

  • Considerations of chronic SCI 

  • Need for invasive monitoring 

  • Difficult to assess success of neuraxial technique 

 

 

Management 

 

  • Discussion with surgeon regarding plan for procedure 

  • Remove potential triggers (e.g., full bladder, foley insertion, full rectum, surgical stimulus) 

  • General anesthetic vs neuraxial technique (if GA, consider a deep anesthetic)

  • Management of hypertensive event:

    • Consider deepening level of anesthesia if under GA 

    • If epidural, consider top-up 

    • Treat severe hypertension with fast-acting titratable agents:

      • Nitroprusside 0.5-3mcg/kg/min or nitroglycerin 5-200mcg/min

      • Hydralazine 10-20mg IV prn 

      • Phentolamine 5mg IV prn 

      • Look for evidence of end-organ involvement & treat accordingly 

 

 

Pregnancy Considerations 

 

  • Multidisciplinary discussion regarding plan for labor & delivery 

  • Consider scheduled elective cesarean section

  • If vaginal delivery:

    • Admit early to monitored bed with telemetry 

    • Need continuous BP monitoring with arterial line 

    • Remove all preventable triggers of autonomic hyperreflexia (vaginal exams, full bladder = foley insertion) 

    • Start early epidural to prevent hypertensive episodes from contractions 

    • Difficult to assess success of epidural:

      • May need larger test dose to rule out subarachnoid placement 

      • Chestnut suggests two ways to assess level of epidural

        1. Sensory block cephalad to level of spinal cord lesion 

        2. Evaluating segmental reflexes below level of the lesion: lightly stroke each side of the abdomen above & below the umbilicus, looking for contraction of the abdominal muscles & deviation of the umbilicus toward the stimulus (reflexes are absent below the level of the block)

  • If cesarean delivery:

    • Either general anesthetic or neuraxial technique:

      • Must have arterial line

      • Vasodilators drawn up & ready 

      • Succinylcholine contraindicated

      • Severe respiratory insufficiency or technical difficulties with neuraxial anesthesia may necessitate the use of general anesthesia

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