I actually think mine improved with more Baclofen. I attributed it to the spasticity. The nerve responses get excitable with spasticity, so it made sense to me that my muscles could feel like they are vibrating. It usually affected me the most when I went to bed. It felt like they were trying to calm down from being used too much. I pictured a bungee cord that is under pressure and when released it bounces (vibrates) until it comes to a stop.