Hemimotor neglect

Hemimotor neglect or simply motor neglect is a neuropsychological condition, after damage to one hemisphere of the brain has occurred, characterized by a failure of spontaneous use more-or-less complete hemi-body in the absence of paralysis, pyramidal syndromes, extrapyramidal symptoms, strength and primary sensory deficit.[1]

Presentation

Motor neglect can occur in isolation from hemispatial neglect, or in association making the pathological state more complicated at least in 30% of patients with brain damage.[2] The motor neglect has been described by different terms and a significant confusing (?) exists: disorders and intentional neglect, motor hemi neglect and thalamic, nonsensory neglect and callosal neglect.

Laplane and Degos coined term motor neglect and had given his definition:"Absent or low use spontaneous contralesional limb (lower and/or higher), despite preserved motor skills and is not explained by weakness or lack of sensitivity, it improves with the verbal suggestion".[3]

Clinical features

The motor neglect is concerns all proximal and distal movements, involving both the upper and lower limb in automatic gestures. The taxonomy of symptoms of motor neglect is diverse: poor use of the affected limb, difficulty in bimanual activities (such as open a bottle); spontaneous gestures reduced especially during the speech, lack of "swing" of the arm while walking. The path is unbalanced; the lower limb is often dragged with the consequent risk of falls. The movements with the limb neglected, when executed, are initiated with delay hypokinesia, reduced in their amplitude, and accompanied by bradykinesia[1][3] One the most distinctive feature of motor neglect is his verbal prompt. Specifically, patients with motor neglect have relatively normal movement when encouraged to use the contralesional limb, but do not perform the same movement spontaneously.

Motor neglect is different from directional hypokinesia,[4] "motor neglect component",[5] two forms of motor deficits that are associated with neglect, but that stand out from motor neglect. The directional hypokinesia refers to a deficit of startup of the movements with the limb ipsilesional contralesional space. These patients are slowed down when they have to perform an action with the limb not neglected in space account side, despite the control and motor coordination is preserved. The "motor neglect component" likes motor neglect, but that unlike the latter, it doesn't improve through direct verbal command, but only through vestibular caloric stimulation.

Causes

Recently, two different proposals have been introduced to try to interpret the motor neglect.

The first hypothesis sustained that motor neglect may be due to a deficit in the inhibition of automatic actions involving the right hand and his left hand. The primary motor cortex of patients with motor neglect fails to inhibit programming of the movements of the right hand. In practice, the planning of the left limb movement is disturbed from planning right limb; this produces a slowing of the movement of the limb left or the inability of the movement itself. This hypothesis was tested through the use of an experimental paradigm for the study of inhibitory control automatic.[6] On the other hand motor neglect can be attributed to a disorder of intention motor.[7]

See also

References

  1. ↑ 1.0 1.1 Sampanis, D.S. e Riddoch, J. (2013) Motor neglect and future directions for research. Frontiers Human Neuroscience, 7, 110
  2. ↑ Saevarsson, S (2013). Motor Response Deficits of Unilateral Neglect: Assessment, Therapy, and Neuroanatomy. Applied Neuropsychology Adult, 0, 1–14
  3. ↑ 3.0 3.1 Laplane, D. e Degos, J. D. (1983). Motor neglect. Journal of Neurology, Neurosurgery, and Psychiatry, 46(2), 152–158
  4. ↑ Harvey, M. (2004). Perceptual and premotor neglect: is there an ideal task to categorise patients? Cortex; a Journal Devoted to the Study of the Nervous System and Behavior, 40(2), 323–328
  5. ↑ Rode, G., Perenin, M. T., Honoré, J., Boisson, D. (1998). Improvement of the motor deficit of neglect patients through vestibular stimulation: evidence for a motor neglect component. Cortex; a Journal Devoted to the Study of the Nervous System and Behavior, 34(2), 253–261
  6. ↑ Coulthard, E., Rudd, A., Husain, M. (2008). Motor neglect associated with loss of action inhibition. Journal of Neurology, Neurosurgery, and Psychiatry, 79(12), 1401–1404
  7. ↑ Garbarini, F., Rabuffetti, M., Piedimonte, A., Pia, L., Ferrarin, M., Frassinetti, F., Gindri, P., Cantagallo, A., Driver, J., Berti, A. (2012). Moving a paralysed hand: bimanual coupling effect in patients with anosognosia for hemiplegia. Brain, 35(5),1486–97
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