In normal anatomy, the LRV travels between the SMA and the AA. Occasionally, the LRV travels behind the AA and in front of the spinal column. NCS is divided based on how the LRV travels, with anterior NCS being entrapment by the SMA and AA and posterior NCS being compression by the AA and spinal column. NCS can also be due to other causes such as compression by pancreatic cancer, retroperitoneal tumors, and abdominal aortic aneurysms. Although other subtypes exist, these causes are more uncommon in comparison to entrapment by the SMA and the AA. Patients with NCS have a tendency to have a tall and lean stature, as this can lead to a narrower gap between the SMA and the AA for the LRV.
Nutcracker syndrome
Wieacker syndrome
MASS syndrome
Emmonsiosis
Pellegrini–Stieda syndrome
Riddoch syndrome
Aortoenteric fistula
EAST syndrome