Quantitative Assessment of Mirror Movements After Stroke

Abstract

Background and Purpose-Mirror movements (MM) are involuntary synchronous movements of one limb during voluntary unilateral movements of the opposite limb. We measured MM in stroke and control subjects and evaluated whether MM after stroke are related to motor function. Methods-Twenty-three patients and 16 control subjects were studied. A computerized dynamometer was used during two squeezing tasks to measure intended movements from the active hand as well as MM from the opposite hand. Motor deficits were measured with the arm motor component of the Fugl-Meyer scale. Results-During paretic hand squeezing, MM in the unaffected hand were detected in 70% (repetitive squeeze) to 78%(sustained squeeze) of stroke patients. For both tasks, this was significantly (PϽ0.05) greater than the incidence of MM in the paretic hand or in either hand of control subjects (17% to 44%), except when compared with the incidence of MM in the dominant hand of control subjects (56%; Pϭ0.17). The incidence of MM in the paretic hand was not significantly different from that seen in either hand of control subjects. Patients with MM in the unaffected hand had significantly greater motor deficit than patients without MM. Patients with MM in the paretic hand had significantly better motor function than patients without MM. Conclusions-Simultaneously recording motor performances of both hands provides precise information to characterize MM. MM in the unaffected hand and in the paretic hand are associated with different degrees of motor deficit after stroke. Evaluation of MM may be useful for studying mechanisms of stroke recovery.

Quantitative assessment of mirror movements in children and adolescents with hemiplegic cerebral palsy

“…There was a positive correlation between the force data and the visible mirror movements, but the sensitive quantitative method could detect covert mirror activity that was not amply visible. Mirror activity could be recorded on a continuous scale, which is more precise than ordinal rating scales (Nelles et al 1998). Furthermore, the force level of the voluntary motor act could be registered.…”

“…Such irradiations of motor activity to the contralateral side of the body are most pronounced during distal limb movements (Reitz and Müller 1998). Most authors use the term mirror movement when describing more or less symmetrical contralateral unintended reversals of voluntary hand and finger movements (Woods and Teuber 1978, Nass 1985, Carr et al 1993, Carr 1996, Nelles et al 1998. With some differences in context, the less specific terms of synkinesia, associated movement, and motor irradiation have been used by others (Cernacek 1961, Green 1967, Connolly and Stratton 1968, Lazarus 1992.…”

“…Visual feedback was used to facilitate the conscious inhibition of motor overflow. A better understanding of the relation between mirror movements and motor recovery after brain lesions may provide valuable clinical information and insight into restorative mechanisms of the CNS (Nelles et al 1998). …”

Effort-induced mirror movements

“…They are observed in a variety of hereditary and acquired disorders, and may relate to heterogeneous pathophysiological mechanisms such as coactivation of the contralateral hemisphere (Schott and Wyke 1981;Nelles et al 1998;Balbi et al 2000), activation of ipsilateral (uncrossing) projections (Regli et al 1967;Nirkko et al 1997;Balbi et al 2000), or bilateral branching of corticospinal neurons (Regli et al 1967;Woods and Teuber 1978;Schott and Wyke 1981;Farmer et al 1990;Carr et al 1993;Nirkko et al 1997;Nelles et al 1998;Balbi et al 2000). In healthy subjects, they occur during early childhood, but gradually disappear thereafter during the maturation of the central nervous system (CNS; Nass 1985;Heinen et al 1998;Mayston et al 1999).…”

Correlation between changes of contralesional cortical activity and motor function recovery in patients with hemiparetic stroke

“…Mirror movements those observed during volitional motor behavior by affected side are characteristic in patients with hemiplegic stroke and are supposed to reflect some aspects of the recovery process [16][17][18] . However, this neural mechanism is not clearly understood.…”