Author/Editor		Kojović, Maja; Carroni, Antonio; Bologna, Matteo; Rothwell, John C.; Bhatia, Kailash P.; Edwards, Mark J.
Title		Botulinum toxin injections reduce associative plasticity in patients with primary dystonia
Type		članek
Vol. and No.		Letnik 26, št. 7
Publication year		2011
Volume		str. 1282-1289
ISSN		0885-3185 - Movement disorders : official journal of the Movement Disorder Society
Language		eng
Abstract		Botulinum toxin injections ameliorate dystonic symptoms by blocking the neuromuscular junction and weakening dystonic contractions. We asked if botulinum toxin injections in dystonia patients might also affect the integrity of sensorimotor cortical plasticity, one of the key pathophysiological features of dystonia. We applied a paired associative stimulation protocol, known to induce long-term potentiation%like changes in the primary motor cortex hand area to 12 patients with cervical dystonia before and 1 and 3 months after botulinum toxin injections to the neck muscles. Primary motor cortex excitability was probed by measuring transcranial magnetic stimulation-evoked motor evoked potentials before and after paired asso- ciative stimulation. We also measured the input%output curve, short-interval intracortical inhibition, intracortical facilitation, short afferent inhibition, and long afferent inhibition in hand muscles and the clinical severity of dystonia. Before botulinum toxin injections, paired asso- ciative stimulation significantly facilitated motor evoked potentials in hand muscles. One month after injections, this effect was abolished, with partial recovery after 3 months. There were significant positive correlations between the facilitation produced by paired associative stimulation and (1) the time elapsed since botulinum toxin injections and (2) the clinical dystonia score. One effect of botulinum toxin injection treatment is to modu- late afferent input from the neck. We propose that sub- sequent reorganization of the motor cortex representation of hand muscles may explain the effect of botulinum toxin on motor cortical plasticity.
Keywords		botulinum toxin primary dystonia cervical dystonia cortical plasticity paired associative stimulation transcranial magnetic stimulation TMS