If you are living with peroneal nerve palsy — dealing with foot drop, a dragging gait, weakness when lifting the front of your foot, or numbness along the outer shin and top of the foot — you have probably been told to wait, brace, and hope for the best.

If you are living with burning, tingling, or numbness spreading through your foot and ankle, chances are you have already been told to rest, use orthotics, and perhaps try a cortisone injection. Some people improve.

If you are a runner, cyclist, or military athlete who feels a building pressure, burning, or numbness in your lower legs during exercise — symptoms that vanish within minutes of stopping and return every time you push past a certain threshold — you are already familiar with how difficult this experience is to explain.

If you or someone you care about has received a diagnosis of polyarteritis nodosa, you already know how disorienting it can be. PAN is a rare systemic vasculitis — inflammation of medium-sized blood vessel walls — that can affect the kidneys, nerves, skin, gut, and muscles, often in unpredictable combinations.

Tingling that starts in the toes and creeps upward. A burning sensation at night that no position fixes. Feet that feel like they're wrapped in cotton, or hands that fumble buttons they used to manage without thinking.

If you or someone close to you has been through Guillain-Barré syndrome, you already know that the standard advice — rest, physical therapy, "give it time" — doesn't answer the questions that actually keep you up at night.