Reduced Upper Limb Sensation Impairs Mental Chronometry for Motor Imagery After Stroke: Clinical and Electrophysiological Findings

Neurorehabilitation and Neural Repair, 05/25/2012

Liepert J et al. – Severe somatosensory deficits impaired mental chronometry. A controlled study is necessary to clarify if these patients benefit at all from Motor imagery as an additional treatment.

Methods

  • The Box and Block Test (BBT) was used to evaluate mental chronometry as 1 component of MI.
  • Two groups of stroke patients and an age-matched healthy control group (CG) were studied.
  • Patient group 1 (n = 10, PG1) had a severe somatosensory impairment on the affected side and PG2 (n = 10) had pure motor strokes.
  • All subjects first performed the BBT in a mental and in a real version.
  • The time needed to move 15 blocks from 1 side of the box to the other was measured.
  • To compare the groups independently of their performance level, a (real performance - MI)/(real performance) ratio was calculated.
  • Corticospinal excitability was measured by transcranial magnetic stimulation at rest and while the subjects performed an imagined pinch grip.

Results

  • The CG performed the BBT faster than both patient groups, and PG1 was slower than PG2.
  • MI ability was impaired in PG1 but only for the affected hand.
  • Transcranial magnetic stimulation data showed an abnormally low MI-induced corticospinal excitability increase for the affected hand in PG1, but not in PG2.

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