Vol.:(0123456789) 1 3 Acta Neurologica Belgica https://doi.org/10.1007/s13760-018-1001-1 ORIGINAL ARTICLE Is the triple stimulation technique a better quantifcation tool of motor dysfunction than motor evoked potentials in multiple sclerosis? Xavier Gifroy 1,2  · Dominique Dive 1  · Jean‑François Kaux 2  · Nathalie Maes 3  · Adelin Albert 3  · Catherine Göbels 2  · François Wang 2 Received: 25 April 2018 / Accepted: 13 August 2018 © Belgian Neurological Society 2018 Abstract The triple stimulation technique (TST) was rarely used in multiple sclerosis (MS). This study aimed to compare TST and motor evoked potentials (MEP) for the quantifcation of motor dysfunction. Central motor conduction based on MEP (four limbs) and TST (upper limbs) was assessed in 28 MS patients with a median Expanded Disability Status Scale (EDSS) of 4. EDSS, timed 25-foot walk (T25FW), grasping strength and motor components of the MS functional composite were evaluated. Regression analysis was used to assess the relationship between MEP, TST and clinical fndings. TST was nega- tively correlated with EDSS (r = − 0.74, p < 0.0001) and to a lesser extent with T25FW (r = − 0.47, p < 0.05), and grasping strength (r = − 0.43, p < 0.05). A multiple regression analysis underlined the better correlation between clinical data and TST (R 2 = 0.56, p < 0.0005) than with MEP (0.03 < R 2 < 0.22, p > 0.05). This study evidenced the value of TST as a quantifcation tool of motor dysfunction. TST appeared to refect a global disability since it was correlated not only to hand function but also to walking capacity. Keywords Triple stimulation technique · Motor evoked potentials · Multiple sclerosis · Conduction failure · Axonopathy · Disability Introduction Transcranial magnetic stimulation (TMS) is a neurophysi- ological technique eliciting motor evoked potentials (MEP) useful for the diagnostic and functional assessment of the pyramidal track impairment [1, 2]. The diagnostic efcacy of MEP in multiple sclerosis (MS), however, is limited by the high sensitivity of magnetic resonance imaging (MRI) mainly at the brain level [3]. Conversely, to document patho- logical changes occurring during the course of MS, MRI is less useful because of its weak association with clinical fndings, known as the “functional–anatomical paradox” [4], while MEP evaluating long eloquent motor pathway is better correlated with functional involvement [5–9]. The increased central motor conduction time (CMCT), theoretically related to the demyelination process, is the most widely used MEP parameter in clinical studies [8, 10, 11] despite weak correlations with the functional capaci- ties [12, 13]. The MEP size reduction might be regarded as the axonal loss consequence [14] which is closely linked to disability, as demonstrated by MRI [15]. However, the * Xavier Gifroy xgifroy@chuliege.be Dominique Dive dominique.dive@chuliege.be Jean-François Kaux jfkaux@chuliege.be Nathalie Maes nmaes@uliege.be Adelin Albert aalbert@uliege.be Catherine Göbels cgobels@chuliege.be François Wang FC.Wang@chuliege.be 1 Department of Neurology, University Hospital of Liege, Rue Grandfosse 31-33, 4130 Esneux, Belgium 2 Department of Physical Medicine and Rehabilitation, University Hospital of Liege, B35, 4000 Liège, Belgium 3 Department of Biostatistics and Medico-Economic Information, University Hospital (CHU, ULg) of Liege, B35, 4000 Liège, Belgium