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Intracortical excitability in the hand motor representation in hand dystonia and blepharospasm
Author(s) -
Sommer Martin,
Ruge Diane,
Tergau Frithjof,
Beuche Wolfgang,
Altenmüller Eckart,
Paulus Walter
Publication year - 2002
Publication title -
movement disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.352
H-Index - 198
eISSN - 1531-8257
pISSN - 0885-3185
DOI - 10.1002/mds.10205
Subject(s) - transcranial magnetic stimulation , blepharospasm , facilitation , dystonia , focal dystonia , psychology , neuroscience , motor cortex , electromagnetic coil , hand muscles , medicine , stimulation , physics , quantum mechanics
We sought to determine the activity of inhibiting and facilitating cortical circuits in areas surrounding a hand muscle motor representation in focal dystonia and in controls. In 15 patients with hand dystonia, 16 patients with blepharospasm, and age‐matched controls, we applied suprathreshold transcranial magnetic stimuli with a figure‐eight coil over the optimal representation of the relaxed abductor digiti minimi muscle of the dominant hand. Additional conditioning stimuli were given through a second figure‐eight coil that was held either above the test coil or 2 cm or 4 cm apart in the anterior, posterior, lateral, or medial direction. We measured intracortical excitability in each of the nine positions of the conditioning coil. Intracortical inhibition was reduced in both patient groups at all conditioning coil positions. With both coils centered, the intracortical facilitation did not differ between patients and controls. After shifting the conditioning coil, the intracortical facilitation tended to be less diminished in patients than in controls, this difference between patients and controls was significant for the anterior, posterior, and medial 4‐cm conditioning coil shift. Our results demonstrate decreased intracortical inhibition in the cortical hand muscle representation not only in patients with hand dystonia, but also in patients with blepharospasm. In addition, our findings in both patient groups show a trend toward a relatively increased intracortical facilitation in surrounding motor areas. © 2002 Movement Disorder Society