What causes a tortuous esophagus if its not a hiatal hernia?

Motility disorder: It could be a motility disorder such as distal (formerly diffuse) esophageal spasm or a nutcracker esophagus. High resolution Manometry is the test to find out. A small tube is placed into the esophagus and you swallow water 10 times. It measures the valve pressures and the coordination and strength of the muscle contractions. Hope this helps!

Not straight path,: "Tortuous" just means not straight (as expected). Scar tissue, lung disease/abnormalities, vascular issues, tumor, lymph node swelling, and others could produce this finding. Result needs taken in consideration of medical history, other results--and a plan for how to further evaluate if even necessary.