I find I do it occasionally
Fist clenching could be something called clonus they can test this by testing the reflexes in your hands. They can use medications to help. Which drugs used depend on what works for you. They can use anti seizure drugs, anti depressants, and or muscle relaxants to help. They can't always cure it just help it. Not all people with MS have this issue but it is common.
Alex
Hummmm. Interesting question. One I cannot help you with so thought I would bump it up for you.
I do clench my fists at night sometimes but that is a direct result of stress, like grinding my teeth.
Julie