Sickle Cell Disease: explain the pathophysiology of acute SCD crisis. why is pain the predominate feature of acute crises?

 Sickle Cell Disease (SCD)

A 15-year-old male with known sickle cell disease (SCD) present to the ER in sickle cell crisis. The patient is crying with pain and states this is the third acute episode he has had in the last 10-months. Both parents are present and appear very anxious and teary eyed. A diagnosis of acute sickle cell crisis was made.

Question

Explain the pathophysiology of acute SCD crisis. Why is pain the predominate feature of acute crises?