Catheter system, devices and methods for diagnosing and treating lateral stenosis causing back pain and or leg pain. The devices comprise a tubular part for insertion into a working cannula to self-position itself safely within the foramen, and minimize the risk of displacement medially or laterally, to prevent nerve or dura injury. An expandable membrane is configured to maintain the catheter device within the foramen. Expansion of this membrane would decompress the nerve within the foramen by opening the foraminal canal as the membrane expands. Inserts may be used in connection with the expandable member.
