Asynergia or dyssynergia is lack or impairment of synergy of sequential muscular contraction in the performance of complex movements, such that they seem to become broken up into their constituent parts, so called decomposition of movement. This may be evident when performing rapid alternating hand movements. Dyssynergy of speech may also occur, a phenomenon sometimes termed scanning speech (q.v.) or scanning dysarthria. This is typically seen in cerebellar syndromes, most often those affecting the cerebellar hemispheres, and may coexist with other signs of cerebellar disease, such as ataxia, dysmetria, and dysdiadochokinesia.