Which statement about injury level and autonomic dysfunction is true?

Which statement about injury level and autonomic dysfunction is true?

• A. Higher injuries tend to produce more significant autonomic dysfunction
• B. Lower injuries produce more autonomic dysfunction
• C. The level has no effect on autonomic dysfunction
• D. Autonomic dysfunction cannot occur with spinal injuries

Answer: (A)

Higher spinal injuries interrupt more of the autonomic pathways that run along the spinal cord. The sympathetic outflow arises from the T1–L2 levels, and when a lesion is higher than this, especially above T6, you lose supraspinal control over a large portion of the sympathetic system. In the acute phase, this leads to neurogenic shock with hypotension and bradycardia because of unopposed vagal activity and loss of sympathetic tone. Later, injuries above T6 can also give rise to autonomic dysreflexia, a dangerous overreaction of the sympathetic system to stimuli below the injury that isn’t properly moderated by the brain, causing severe hypertension. Injuries lower in the spine spare more of these autonomic pathways, so the dysfunction is less pronounced or may not occur at all. That’s why higher injuries tend to produce more significant autonomic dysfunction. The other statements are not correct because autonomic dysfunction can occur with spinal injuries, and the level of injury does affect the degree of autonomic disruption.

Higher spinal injuries interrupt more of the autonomic pathways that run along the spinal cord. The sympathetic outflow arises from the T1–L2 levels, and when a lesion is higher than this, especially above T6, you lose supraspinal control over a large portion of the sympathetic system. In the acute phase, this leads to neurogenic shock with hypotension and bradycardia because of unopposed vagal activity and loss of sympathetic tone. Later, injuries above T6 can also give rise to autonomic dysreflexia, a dangerous overreaction of the sympathetic system to stimuli below the injury that isn’t properly moderated by the brain, causing severe hypertension.

Injuries lower in the spine spare more of these autonomic pathways, so the dysfunction is less pronounced or may not occur at all. That’s why higher injuries tend to produce more significant autonomic dysfunction. The other statements are not correct because autonomic dysfunction can occur with spinal injuries, and the level of injury does affect the degree of autonomic disruption.