Brief Report| Volume 64, ISSUE 3, P248-251, August 01, 2008

Corticospinal System Excitability at Rest Is Associated with Tic Severity in Tourette Syndrome

  • Michael Orth
    Address reprint requests to Michael Orth, M.D., Ph.D., Department of Neurology, Universitätsklinikum Eppendorf, Martinistr.52, 20246 Hamburg, Germany
    Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London

    Raymond Way Unit, Institute of Neurology, The National Hospital for Neurology and Neurosurgery, London, United Kingdom

    Department of Neurology, Universitätsklinikum Eppendorf, Hamburg, Germany.
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  • Alexander Münchau
    Department of Neurology, Universitätsklinikum Eppendorf, Hamburg, Germany.
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  • John C. Rothwell
    Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London
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Published:February 13, 2008DOI:


      Several measures of motor cortex excitability are abnormal in Gilles de la Tourette syndrome (GTS). However, it is not clear whether these represent abnormalities of specific pathways or reflect a more widespread reduction of motor cortex excitability. Their significance for the clinical phenotype is also unknown.


      We measured motor thresholds, input-output (I/O) curves, short interval intracortical inhibition (SICI), and cortical silent period (SP) with transcranial magnetic stimulation in 20 untreated GTS patients (12 uncomplicated, 4 with comorbid attention-deficit/hyperactivity disorder, 4 with comorbid obsessive-compulsive disorder) and 24 healthy subjects. Tics were rated with standard clinical scales and detailed video analysis.


      Thresholds did not differ between groups. At rest, patients had shallower I/O curve slopes, despite their tics, and reduced SICI. Slopes were equal during voluntary muscle activation, as was the SP duration. Resting I/O slopes correlated, in uncomplicated GTS patients, most strongly to ratings of complex tics, hand and finger tics, and vocal tics, with shallower slopes predicting fewer tics. In complicated patients, good correlations were seen with neck/shoulder tics and vocal tics.


      Corticospinal excitability in patients at rest is reduced. We suggest this is an adaptive response that may reduce release of unwanted movements.

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        • Orth M.
        • Amann B.
        • Robertson M.M.
        • Rothwell J.C.
        Excitability of motor cortex inhibitory circuits in Tourette syndrome before and after single dose nicotine.
        Brain. 2005; 128: 1292-1300
        • Ziemann U.
        • Paulus W.
        • Rothenberger A.
        Decreased motor inhibition in Tourette's disorder: Evidence from transcranial magnetic stimulation.
        Am J Psychiatry. 1997; 154: 1277-1284
        • Robertson M.
        • Eapen V.
        The National Hospital Interview Schedule for the assessment of Gilles de la Tourette syndrome.
        Int J Methods Psychiatr Res. 1996; 6: 203-226
        • Leckman J.F.
        • Riddle M.A.
        • Hardin M.T.
        • Ort S.I.
        • Swartz K.L.
        • Stevenson J.
        • et al.
        The Yale Global Tic Severity Scale: Initial testing of a clinician-rated scale of tic severity.
        J Am Acad Child Adolesc Psychiatry. 1989; 28: 566-573
        • Goetz C.G.
        • Pappert E.J.
        • Louis E.D.
        • Raman R.
        • Leurgans S.
        Advantages of a modified scoring method for the Rush Video-Based Tic Rating Scale.
        Mov Disord. 1999; 14: 502-506
        • Robertson M.M.
        • Banerjee S.
        • Kurlan R.
        • Cohen D.J.
        • Leckman J.F.
        • McMahon W.
        • et al.
        The Tourette syndrome diagnostic confidence index: Development and clinical associations.
        Neurology. 1999; 53: 2108-2112
        • Orth M.
        • Amann B.
        • Ratnaraj N.
        • Patsalos P.N.
        • Rothwell J.C.
        Caffeine has no effect on measures of cortical excitability.
        Clin Neurophysiol. 2005; 116: 308-314
        • Orth M.
        • Snijders A.H.
        • Rothwell J.C.
        The variability of intracortical inhibition and facilitation.
        Clin Neurophysiol. 2003; 114: 2362-2369
        • Sparing R.
        • Meister I.G.
        • Wienemann M.
        • Buelte D.
        • Staedtgen M.
        • Boroojerdi B.
        Task-dependent modulation of functional connectivity between hand motor cortices and neuronal networks underlying language and music: A transcranial magnetic stimulation study in humans.
        Eur J Neurosci. 2007; 25: 319-323
        • Chen R.
        • Yaseen Z.
        • Cohen L.G.
        • Hallett M.
        Time course of corticospinal excitability in reaction time and self-paced movements.
        Ann Neurol. 1998; 44: 317-325
        • Gilbert D.L.
        • Bansal A.S.
        • Sethuraman G.
        • Sallee F.R.
        • Zhang J.
        • Lipps T.
        • et al.
        Association of cortical disinhibition with tic, ADHD, and OCD severity in Tourette syndrome.
        Mov Disord. 2004; 19: 416-425
        • Serrien D.J.
        • Orth M.
        • Evans A.H.
        • Lees A.J.
        • Brown P.
        Motor inhibition in patients with Gilles de la Tourette syndrome: Functional activation patterns as revealed by EEG coherence.
        Brain. 2005; 128: 116-125