Excitability of cortico-spinal system at rest is associated with tic severity in Gilles de la Tourette syndrome

Background: In Gilles de la Tourette syndrome (GTS) motor cortex excitability changes have been shown measured with transcranial magnetic stimulation (TMS), in particular reduced short interval cortical inhibition (SICI), reduced short interval afferent inhibition (SAI) and shortened cortical silent periods. At higher intensities, SICI is recruited more gradually than normal. Objectives: 1) To determine in patients with GTS whether reduced intracortical inhibition is restricted to inhibitory inter-neurones or represents one feature of a more widespread reduction of motor cortex excitability. 2) To evaluate the s…