Cleveland Clinic: Typically, restless legs syndrome (RLS) affects one leg or both legs. But sometimes it can affect other areas of the body, such as the arms and torso. When this happens, it’s usually a sign that the condition is worsening.
With RLS, the areas of the brain and the pathways that connect to those areas are mainly responsible for sensations in the legs. So it usually starts off in the legs, but in severe cases it may spread to other parts of the body.
Restless legs syndrome can also be associated with involuntary jerking of the legs and arms, known as periodic limb movements in sleep (PLMS). These movements can be seen in a sleep study with most patients with RLS, but PLMS can be seen in people who don’t have RLS and usually doesn’t affect sleep quality.