Pud, muscles cause stiffness. They can tighten up while your sleeping as well as when you walk around using them.
You can try some light stretching at night, that helps me. Otherwise when I first wake up, I walk like Frankenstein. I get stiff legged or I get Charlie horse like cramps in my calves and feet. My thighs too at times.
But many need a muscle relaxing drug. Some use Zanaflex. There are milder ones like Flexiril brand name for Cyclobenzaprine, both area muscle relaxants.
Then there is Baclofen, which is stronger and many people find they need small doses or they get jelly legs. A little stiffness is needed to walk and remain erect. All dosages can be adjusted to your needs. Start out on small dosages.
All are prescription drugs. Good luck with your new Neuro.