Anxiety and TMS are tied together. I have never met anyone with TMS Who doesn't also have anxiety, But I Have met people with anxiety who don't have tms (yet).
Anxiety is just fear projected into the future. I have noticed from living with someone who continually has meltdowns of anxiety that it isn't necessarily tied to any truth. (at first). People with anxiety are projecting some uncontrollable future where perceived negative things will or might happen. Pointing out the truth that these things usually don't end up manifesting as bad as they fear seems to be of little use. The anxiety, like TMS is there to occupy their attention, so just as if TMS goes untreated it turns into other symptoms, anxiety is never 'full' and is always 'hungry'. If the anxiety inducing situation resolves itself or proves to be benign they just move on to the next thing to be anxious about.
Eventually some of their anxious things become real...they are anxious say.... about a relationship or a job. Their continuous lack of presence and tending to the NOW eventually does bite them in the ass like a self fulfilling prophecy. Their partner leaves them or they get fired for not paying attention, proving the anxious thought 'correct'.
This can happen with TMS. Someone becomes so obsessed about harming themselves they cease to be active...and then all that sitting around DOES causes cramping, anxiety, symptoms.
So yes, they are first cousins of sorts