A friend commented that it might be hard to evaluate someone who could only move their hands/arms. Basically the same principles apply whether the movement is with legs through the space or being still with a posture, or moving the arms.
Arms and especially hands are the most common movement elements, feet and legs are next and of course not everybody can move everything so an assessment/evaluation is made with what you can get from a patient/client.
Of course an assessment is guided by the intention. If I want to know how someone is feeling and they are reluctant to share verbally I might ask them to express with their hands (which I often do at the hospital) if they are unclear how they are feeling and how to express that with their hands I might switch to a simple game with the intention of warming them up.
A warm up involving the hands could be tossing and catching a small stuffed animal and at some point adding words by answering easy questions like; my favorite food is "____". If the person is nonverbal than you can interact with facial/postural/gestural expressions when tossing the animal and/or mirroring to interact and experience/create a response.
The assessment/evaluation happens when observing/witnessing the force and effort used to toss the cow and/or the facial, posture, gesture. Does the effort change during the session and how is that change related to the activity. For instance people will typically have smaller movements to start out with and as they become more comfortable their movements become larger. This happens whether the person is moving by feet/wheels through the space, or sitting tossing something or making gestures or changing their posture. I look at the whole body and don’t just observe/witness the active bits but also what the rest of the body is doing during the activity. For example is there a slight movement in the foot when tossing and is that from an old injury or a current muscle tightness or is it an emotional based issue.
If something comes up in a session that seems like it needs further exploration I might engage the client/patient in an activity that focuses on that "something". If the left foot turns I might ask the person to focus on their feet when they toss or to make a sound. Or I might simply mention that I noticed you always turn your foot when you toss the stuffed animal and see what response the client/patient has.
The fun and useful part about being a Dance Movement Therapist is that you get to use verbal counseling skills and body counseling skills. The entire person is given a chance/opportunity to express with all of themselves, body and mind.