Impersistence is an inability to sustain simple motor acts, such as conjugate gaze, eye closure, protrusion of the tongue, or keeping the mouth open. It is most commonly seen with lesions affecting the right hemisphere, especially central and frontal mesial regions, and may occur in association with left hemiplegia, neglect, anosognosia, hemianopia, and sensory loss. These patients may also manifest perseveration, echolalia and echopraxia.
Impersistence is most often observed following vascular events but may also be seen in Alzheimer’s disease and frontal lobe dementias, and metabolic encephalopathies. Impersistence of tongue protrusion and hand grip may be seen in Huntington’s disease. Neuropsychologically, impersistence may be related to mechanisms of directed attention which are needed to sustain motor activity.
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Kertesz A, Nicholson I, Cancelliere A, Kassa K, Black SE. Motor impersistence: a right-hemisphere syndrome. Neurology 1985; 35: 662-666