title: Reduced upper limb sensation impairs mental chronometry for motor imagery after stroke: clinical and electrophysiological findings.
abstract: BACKGROUND
  Motor imagery (MI) is increasingly recognized as a treatment option after stroke, but not all stroke patients are able to perform MI.
  
  
  OBJECTIVE
  To examine if severe somatosensory deficits would affect MI ability.
  
  
  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.
  
  
  CONCLUSIONS
  Severe somatosensory deficits impaired mental chronometry. A controlled study is necessary to clarify if these patients benefit at all from MI as an additional treatment.
authors.affiliation: Kliniken Schmieder Allensbach, Allensbach, Germany. j.liepert@kliniken-schmieder.de
authors.forename: Joachim
authors.initials: J
authors.lastname: Liepert
authors.forename: Johanna
authors.initials: J
authors.lastname: Greiner
authors.forename: Violetta
authors.initials: V
authors.lastname: Nedelko
authors.forename: Christian
authors.initials: C
authors.lastname: Dettmers
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D016022:Case-Control Studies; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D006987:Hypesthesia / Q000209:etiology*; D007092:Imagination / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement / Q000502:physiology; D020521:Stroke / Q000150:complications* / Q000473:pathology; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation; D034941:Upper Extremity / Q000503:physiopathology*