muscle spasm
"MRI reveals badly blown out cervical disc @ c4-5. Now, as long as I didn't do much, I wouldn't have much pain but getting anything done (like yardwork, working out with pushups, painting a wall...etc) was another story and would leave me in severe pain but always THE NEXT DAY and for at least several days afterward (I never really felt the pain on the day of the activity). Then, my doctor gave me Zanaflex, and now I take one 4 mg tab that night, the next day is pain free! I haven't noticed any side effects, no next day grogginess and even the quality of sleep is normal with pleasant dreaming; in fact, if anything my dreams are slightly easier to remember which shows plenty of REM."