[P2.047] Sensory Tricks Reverse Intracortical Facilitation Changes In Cervical Dystonia. A Transcranial Magnetic Stimulation Study

Stefano Amadio,1Elise Houdayer,1Francesca Bianchi,1Habtom Tesfaghebriel Tekle,1Ivan P. Urban,1Calogera Butera,1Roberta Guerriero,2Marco Cursi,1Letizia Leocani,1Giancarlo Comi,1Ubaldo Del Carro1
1Milan, Italy, 2Milan, Jordan

OBJECTIVE: sensory tricks such as touching the face with fingertips often improve cervical dystonia [CD]. This study is to determine whether sensory tricks may modulate motor cortex excitability in CD, assessed by paired-pulse transcranial magnetic stimulation [p-pTMS].
BACKGROUND: several transcranial magnetic stimulation (TMS) studies, performed with paired cortical stimuli at several interstimulus interval (ISI), previously provided conflicting evidences of decreased rather than unchanged intracortical inhibition (ICI) in patients affected by task-specific arm dystonia. However, no neurophysiological studies are presently available about the influence of sensory tricks over intracortical inhibition/facilitation cycle in CD, as well as other kinds of dystonia.
DESIGN/METHODS: 8 botulinum toxin-treated patients with rotational cervical CD high responsive to sensory tricks were studied with p-pTMS, at rest and when the sensory trick was applied. The amplitude ratio between conditioned and unconditioned cortical motor evoked potential was measured at several intestimuls intervals (ISI 1, 3, 15 and 20 ms) to test either intracortical inhibition (ICI) or facilitation (ICF). ICI/ICF were compared among groups and conditions using a two-way ANOVA.
RESULTS: at rest, a significant ICF enhancement was found at ISIs 15-20 in patients compared with controls, while no significant ICI changes were observed. Sensory tricks significantly reduced the abnormal ICF in patients and did not induce any change in controls.
CONCLUSIONS: the enhanced facilitatory output coming from the motor cortex of our CD patients might be the pathophysiological substrate of dystonic muscle spasms, which are in turn significantly inhibited by exteroceptive afferent input of the sensory trick. Thus, the hypothesis that sensory tricks improve dystonia through an inhibitory effect on motor cortex hyperexcitability seems to be confirmed by this experiment.
Study Supported by:
Category - Movement Disorders: Dystonia

Tuesday, April 29, 2014 7:30 AM

P2: Poster Session II: Movement Disorders: Dystonia (7:30 AM-11:00 AM)


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