Narrowing of the left renal vein (LRV) between the superior mesenteric artery (SMA) and the aorta, known as Nutcracker phenomenon (NCP), can obstruct venous outflow, rerouting blood through collateral pathways such as the left second lumbar vein (L2LV) and congesting the epidural venous plexus (EVP). This may disrupt the venous-CSF pressure balance, contributing to chronic headaches. The use of time-resolved magnetic resonance angiography (trMRA) for this evaluation has been previously studied, …