Normalization of sensorimotor integration by repetitive transcranial magnetic stimulation in cervical dystonia

Abstract

Previous studies indicated that sensorimotor integration and plasticity of the sensorimotor system are impaired in dystonia patients. We investigated motor evoked potential amplitudes and short latency afferent inhibition to examine corticospinal excitability and cortical sensorimotor integration, before and after inhibitory 1 Hz repetitive transcranial magnetic stimulation over primary sensory and primary motor cortex in patients with cervical dystonia (n = 12). Motor evoked potentials were recorded from the right first dorsal interosseous muscle after application of unconditioned transcranial magnetic test stimuli and after previous conditioning electrical stimulation of the right index finger at short interstimulus intervals of 25, 30 and 40 ms. Results were compared to a group of healthy age-matched controls. At baseline, motor evoked potential amplitudes did not differ between groups. Short latency afferent inhibition was reduced in cervical dystonia patients compared to healthy controls. Inhibitory 1 Hz sensory cortex repetitive transcranial magnetic stimulation but not motor cortex repetitive transcranial magnetic stimulation increased motor evoked potential amplitudes in cervical dystonia patients. Additionally, both 1 Hz repetitive transcranial magnetic stimulation over primary sensory and primary motor cortex normalized short latency afferent inhibition in these patients. In healthy subjects, sensory repetitive transcranial magnetic stimulation had no influence on motor evoked potential amplitudes and short latency afferent inhibition. Plasticity of sensorimotor circuits is altered in cervical dystonia patients.

Physiological effects of subthalamic nucleus deep brain stimulation surgery in cervical dystonia

“…Similarly an increased SAI in our study during DBS OFF possibly represented a compensatory mechanism in response to worsening of dystonia symptoms. However in another study by Zittel et al ,12 SAI was found to be reduced in CD, which is in contrast to our DBS OFF findings. We believe a lack of complete washout from the effects of DBS may likely explain the discrepant finding.…”

Contribution of TMS and rTMS in the Understanding of the Pathophysiology and in the Treatment of Dystonia

“…This improvement was maintained during the three following weeks (Havrankova et al, 2010). The normalization of the sensorimotor integration, as demonstrated by the increase to normal values of the short afferent inhibition as measured with a sensory conditioning stimulus applied with ring electrodes at the index finger (Zittel et al, 2015), after an inhibitory 1Hz rTMS session targeting the SSC of nine cervical dystonia patients, in a randomized controlled trial, supports the therapeutic effect of inhibitory 1 Hz rTMS of the SSC in dystonia patients.…”

Disrupted superior collicular activity may reveal cervical dystonia disease pathomechanisms

“…This shortfall in gene discovery has stimulated a search for endophenotypes and alternative pathomechanistic theories 22 . Aberrant sensorimotor plasticity has been linked to the pathogenesis of dystonia 8 , 23 , 24 , in particular focal-hand dystonia, a phenotype of AOIFD frequently associated with overuse 24 – 28 ; cervical dystonia has been less well studied 29 . The concept of sensory dysfunction as being primary to the development of cervical dystonia is supported by the co-existence of sensory symptoms including geste-anatagoniste 30 – 32 .…”