If you have a spinal cord injury it is possible that you have had spasms. Involuntary muscle movements or tremors that in many cases can cause pain. I get these myself and yes they are very painful when the spasms happen. I however have a different way of looking at it.
Spasms for me can be annoying and painful but sometimes if you listen to your body long enough you will learn that they are also a way of your body communicating with you. I get spasms when I have waited to long to go to the bathroom or if I have to go empty my bowels. I have spasms sometimes when I get a urinary infection. And in the end most of the time when I listen and say "ok my legs are having a spasm let me find out why?" I do usually find that something is wrong. One day I was cooking and some grease fell on my thigs and I didn't feel it so I was having small spasms all day and I was really angry and frustrated thinking of why I was getting all of these spasms. In the end it w as because I ended up having second degree burns on my legs.
Spasms can be a pain in he butt, but they can also send you messages. Are you Listening?