The presence and severity of akathisia can be measured using the Barnes Akathisia Scale ,   which assesses both objective and subjective criteria.  Precise assessment of akathisia is problematic, as it is difficult to differentiate from a multitude of disorders with similar symptoms. In a study of movement disorders induced by neuroleptics, akathisia was found in only 26% of patients originally diagnosed with akathisia.  The primary distinguishing features of akathisia in comparison with other syndromes are primarily subjective characteristics, such as the feeling of inner restlessness.  Akathisia can commonly be mistaken for agitation secondary to psychotic symptoms or mood disorder , antipsychotic dysphoria, restless legs syndrome (RLS), anxiety, insomnia , drug withdrawal states, tardive dyskinesia , or other neurological and medical conditions.