In spinal cord injury, which autonomic dysfunction is common acutely and what triggers autonomic dysreflexia later on?

In spinal cord injury, which autonomic dysfunction is common acutely and what triggers autonomic dysreflexia later on?

• A. Neurogenic shock with hypotension and bradycardia acutely; autonomic dysreflexia triggered by bladder distension or stool burden; management involves removing triggers and BP control.
• B. Autonomic dysreflexia occurs acutely with hypertension only; there are no triggers later on.
• C. There is no autonomic dysfunction in spinal cord injury.
• D. Neurogenic shock presents with hypertension and tachycardia.

Answer: (A)

The question tests how autonomic problems evolve after spinal cord injury. Right after injury, the loss of sympathetic nervous system input below the lesion leads to neurogenic shock: blood vessels dilate, causing low blood pressure, and heart rate often slows (bradycardia) because the vagus nerve is unopposed. This acutely present dysfunction is a medical emergency because it can impair organ perfusion and mask other injuries. Later, especially with injuries above roughly the T6 level, autonomic dysreflexia can develop. It’s triggered by stimuli below the level of injury, such as bladder distension or a full stool. Those below-injury stimuli trigger an intense sympathetic response that the injured spinal cord can’t modulate, so blood vessels below the lesion constrict massively and raise blood pressure. The body tries to compensate above the injury with parasympathetic signals, causing symptoms like bradycardia and flushing above the injury, but the dangerous hypertension below the injury persists. Management focuses on removing the triggers—emptying a distended bladder, relieving stool burden, and addressing other noxious stimuli—and on reducing blood pressure, including keeping the patient upright and using appropriate antihypertensive measures as needed. This combination of an acute, hypotensive neurogenic state and a later, trigger-driven hypertensive autonomic crisis is what the correct option describes.

The question tests how autonomic problems evolve after spinal cord injury. Right after injury, the loss of sympathetic nervous system input below the lesion leads to neurogenic shock: blood vessels dilate, causing low blood pressure, and heart rate often slows (bradycardia) because the vagus nerve is unopposed. This acutely present dysfunction is a medical emergency because it can impair organ perfusion and mask other injuries.

Later, especially with injuries above roughly the T6 level, autonomic dysreflexia can develop. It’s triggered by stimuli below the level of injury, such as bladder distension or a full stool. Those below-injury stimuli trigger an intense sympathetic response that the injured spinal cord can’t modulate, so blood vessels below the lesion constrict massively and raise blood pressure. The body tries to compensate above the injury with parasympathetic signals, causing symptoms like bradycardia and flushing above the injury, but the dangerous hypertension below the injury persists.

Management focuses on removing the triggers—emptying a distended bladder, relieving stool burden, and addressing other noxious stimuli—and on reducing blood pressure, including keeping the patient upright and using appropriate antihypertensive measures as needed. This combination of an acute, hypotensive neurogenic state and a later, trigger-driven hypertensive autonomic crisis is what the correct option describes.