Final answer:
The most likely consideration for a 6-year-old boy with cerebral palsy and spastic quadriplegia undergoing surgery is hyperkalemia after succinylcholine administration, due to increased sensitivity to this muscle relaxant which can lead to dangerously high potassium levels.
Step-by-step explanation:
The consideration that is most likely in a 6-year-old boy with cerebral palsy and spastic quadriplegia presenting to the OR for lower-extremity contracture release is hyperkalemia after succinylcholine. Patients with spastic quadriplegia are susceptible to the risk of hyperkalemia, particularly after the administration of succinylcholine, due to an upregulation of acetylcholine receptors outside of the neuromuscular junction. This upregulation can lead to an exaggerated release of potassium into the bloodstream when succinylcholine is given, potentially causing life-threatening high potassium levels, also known as hyperkalemia. Since succinylcholine is often used as a muscle relaxant during anesthesia, special precautions must be taken with patients who have conditions like spastic quadriplegia.