Review article
The phenomenon of anarchic hand – a disorder of intentional movement

Feeling of strangeness of one’s own limb and/or its unwanted spontaneous actions are phenomena observed in clinical practice for a long time, and often described by a general term alien hand. In fact, a large heterogenic group of disorders with different characteristics (in terms of symptomatology and etiology) should be considered. There are many attempts to classify a range of such disorders; in this paper the authors further discuss a concept of anarchic hand (AH) to denote the complex actions of the limb, taking place beyond intention of the patient. Such movements are not accompanied by a specific feeling of non-belonging of own hand, which is the most important feature of the alien hand syndrome. The key issue of anarchic hand is a dissociation of correct movements (in terms of praxis) and the ability to control them (i.e. the intentionality of action). In search of the pathomechanism of the phenomenon a hypothesis assuming the functional differentiation of premotor cortex is considered (dual premotor systems hypothesis – DPMS). The lateral premotor system is involved in movements which constitute a direct response to stimuli from the environment, while the medial premotor system – structurally located within the supplementary motor area (SMA) – can play a key role in the regulation of conscious, intentional motor activity. Experimental studies support the hypothesis of the dissociation between the intended reaction and the automatic response as a primary mechanism of AH; they also highlight the relationship of anarchic hand syndrome with attentional processes. A hypothesis alternative to DPMS claims that the control of intentional human activity (including control of unwanted limb movement, which is the case in AH) is carried out by a parent, nonspecific supervisory system. Currently no established standards exist in the treatment of AH. However, to date a few reports on rehabilitation of AH patients have been published.