“Hyperkinetic” and “Hypokinetic”: Is There a Need for a Third Category (i.e., “Mixed”)?

Terminology in the field of movement disorders has evolved multiple times over the years. Traditionally, classification schema have utilized a two-category approach, with a hyper- and hypokinetic branchpoint as the first step towards describing movement disorders and elucidating phenomenological diagnoses. However, this terminology falls short, as it does not adequately capture the complexity of several abnormalities of movement- including ataxia and rigidity- at the electrophysiologic and phenotypic levels. Rather, these movement disorders are characterized by mixed hyper- and hypokinetic phenomena. We propose a third category, “mixed”, which would optimally classify the full range of movements.