Autonomic Dysreflexia in SCI

Q: Autonomic dysreflexia can be a major clinical issue after spinal cord injuries (SCI) above which level? 

A) T6 
B) T11 
C) L1 
D) S1
E) At any level of SCI 



Answer: A

Autonomic dysreflexia can be a major clinical issue after spinal cord injuries (SCI) above T6. This is due to loss of coordinated autonomic responses on heart rate and vascular tone. Uninhibited sympathetic responses to stimuli (such as urinary bladder distention, constipation, pressure ulcers, sexual arousal, labor, and delivery) below the level of the injury lead to diffuse vasoconstriction and hypertension, and a compensatory, but not enough, parasympathetic response producing bradycardia and vasodilation above the level of the lesion. It is manifested by a headache, diaphoresis, hypertension. flushing, anxiety, nausea, and bradycardia. In its worst form, it can cause intracranial hemorrhage and seizures. Also,  hypertensive crisis complicated by bradycardia may lead to cardiac arrest. The severity and frequency of attack correlate with the severity of the SCI.

Point of learning to this question is to highlight the importance of level T6 in SCI as below this level intact splanchnic innervation allows for compensatory dilatation of the splanchnic vascular bed. 


Reference:

1. Bycroft J, Shergill IS, Chung EA, et al. Autonomic dysreflexia: a medical emergency. Postgrad Med J 2005; 81:232.