Baclofen
"I have a partially paralyzed left leg due to SCI with extreme tone and strong muscle spasms.  The first time I tried Baclofen the side effects were so severe that I could not tolerate the medicine at all.  The second time I worked up to 60mg per day at 5mg intervals over a couple of months. Virtually no side effects at all this time but it takes a while.  Baclofen with Botox injections to my hip flexor, hamstrings, and dorsiflexor make my situation bearable. Baclofen works well at 20mg, less than the prescribed dosage."