Growing evidence points toward involvement of the human motor cortex in the control of the ipsilateral hand. We used focal transcranial magnetic stimulation (TMS) to examine the pathways of these ipsilateral motor effects. Ipsilateral motor‐evoked potentials (MEPs) were obtained in hand and arm muscles of all 10 healthy adult subjects tested. They occurred in the finger and wrist extensors and the biceps, but no response or inhibitory responses were observed in the opponens pollicis, finger and wrist flexors and the triceps. The production of ipsilateral MEPs required contraction of the target muscle. The threshold TMS intensity for ipsilateral MEPs was on average 1.8 times higher, and the onset was 5.7 ms later (in the wrist extensor muscles) compared with size‐matched contralateral MEPs. The corticofugal pathways of ipsilateral and contralateral MEPs could be dissociated through differences in cortical map location and preferred stimulating current direction. Both ipsi‐ and contralateral MEPs in the wrist extensors increased with lateral head rotation toward, and decreased with head rotation away from, the side of the TMS, suggesting a privileged input of the asymmetrical tonic neck reflex to the pathway of the ipsilateral MEP. Large ipsilateral MEPs were obtained in a patient with complete agenesis of the corpus callosum. The dissociation of the pathways for ipsilateral and contralateral MEPs indicates that corticofugal motor fibres other than the fast‐conducting crossed corticomotoneuronal system can be activated by TMS. Our data suggest an ipsilateral oligosynaptic pathway, such as a corticoreticulospinal or a corticopropriospinal projection as the route for the ipsilateral MEP. Other pathways, such as branching of corticomotoneuronal axons, a transcallosal projection or a slow‐conducting monosynaptic ipsilateral pathway are very unlikely or can be excluded.
COVID-19 is an emerging infection caused by a novel coronavirus that is moving so rapidly that on 30 January 2020 the World Health Organization declared the outbreak a Public Health Emergency of International Concern and on 11 March 2020 as a pandemic. An early diagnosis of COVID-19 is crucial for disease treatment and control of the disease spread. Real-time reverse-transcription polymerase chain reaction (RT-PCR) demonstrated a low sensibility, therefore chest computed tomography (CT) plays a pivotal role not only in the early detection and diagnosis, especially for false negative RT-PCR tests, but also in monitoring the clinical course and in evaluating the disease severity. This paper reports the CT findings with some hints on the temporal changes over the course of the disease: the CT hallmarks of COVID-19 are bilateral distribution of ground glass opacities with or without consolidation in the posterior and peripheral lung, but the predominant findings in later phases include consolidations, linear opacities, "crazy-paving" pattern, "reversed halo" sign and vascular enlargement. The CT findings of COVID-19 overlap with the CT findings of other diseases, in particular the viral pneumonia including influenza viruses, parainfluenza virus, adenovirus, respiratory syncytial virus, rhinovirus, human metapneumovirus, etc. There are differences as well as similarities in the CT features of COVID-19 compared with those of the severe acute respiratory syndrome. The aim of this article is to review the typical and atypical CT findings in COVID-19 patients in order to help radiologists and clinicians to become more familiar with the disease.
Brief interruption of voluntary EMG in a handAbbreviations BB, biceps brachii; CSP, cortical silent period; ECR, extensor carpi radialis; EIP, extensor indicis proprius; EMG, electromyographic; FDI, first dorsal interosseous; IHI, interhemispheric inhibition; ISP, ipsilateral silent period; L-IHI, long-interval interhemispheric inhibition; M1, primary motor cortex; MEP, motor-evoked potential; MSO, maximum stimulator output; RMS, root mean squares; RMT, resting motor threshold; RT, reaction time; S-IHI, short-interval interhemispheric inhibition; TA, tibialis anterior; TMS, transcranial magnetic stimulation. IntroductionIn humans, intricate and independent finger movements are enabled by a largely crossed system of fast-conducting axons that provides mono-synaptic connections between primary motor cortex (M1) and contralateral spinal motoneurones (Porter & Lemon, 1993). Execution of unimanual or asymmetric bilateral movements relies on a neural network that is capable of lateralising motor cortical output (Carson, 2005;Cincotta & Ziemann, 2008). While a full characterisation of this distributed network is still lacking, data from lesioned monkeys (Brinkman, 1984) and human patients (Chan & Ross, 1988) are in keeping with the view that it probably includes the supplementary motor area and the cingulate gyrus. Positron emission tomography (PET) findings (Sadato et al. 1997) transcranial magnetic stimulation (TMS) data in healthy human subjects (Meyer-Lindenberg et al. 2002;Cincotta et al. 2004;Giovannelli et al. 2006) suggest that the dorsal premotor cortex is also involved. This notion of a neuronal network for movement lateralisation upstream of M1 by no means rules out the possibility that movement lateralisation is supported, in addition, by active inhibition from the voluntarily active M1 to the opposite M1. TMS studies that examined interhemispheric inhibition (IHI) by a paired-pulse protocol with the conditioning stimulus delivered to one M1 and the test stimulus delivered to the other M1 support this hypothesis (Ferbert et al. 1992;Mochizuki et al. 2004;Duque et al. 2007;Hübers et al. 2008). In particular, volitional activity in the M1 receiving the conditioning pulse, e.g. slight unilateral contraction of the contralateral hand, facilitates inhibition of the motor-evoked potential (MEP) elicited by a test stimulus delivered 10 ms later to the opposite M1 (interhemispheric inhibition at short-interstimulus interval, S-IHI) when compared to the rest condition (Ferbert et al. 1992;Mochizuki et al. 2004;Talelli et al. 2008).Besides S-IHI of the MEP, interhemispheric inhibition can also be studied by a short attenuation or interruption of ongoing voluntary electromyographic (EMG) activity in hand muscles induced by focal TMS of the ipsilateral M1 (Wassermann et al. 1991;Ferbert et al. 1992;Meyer et al. 1995;Trompetto et al. 2004;Cincotta et al. 2006). This ipsilateral silent period (ISP) begins 30-40 ms after a single magnetic pulse and lasts, on average, 25 ms (Meyer et al. 1995). Studies in patients with ca...
Summary:Purpose: To assess the effectiveness of slow repetitive transcranial magnetic stimulation (rTMS) as an adjunctive treatment for drug-resistant epilepsy.Methods: Forty-three patients with drug-resistant epilepsy from eight Italian Centers underwent a randomized, doubleblind, sham-controlled, crossover study on the clinical and EEG effects of slow rTMS. The stimulus frequency was 0.3 Hz. One thousand stimuli per day were given at the resting motor threshold intensity for 5 consecutive days, with a round coil at the vertex.Results: "Active" rTMS was no better than placebo for seizure reduction. However, it decreased interictal EEG epileptiform abnormalities significantly (p < 0.05) in one-third of the patients, which supports a detectable biologic effect. No correlation linked the rTMS effects on seizure frequency to syndrome or anatomic classification, seizure type, EEG changes, or resting motor threshold (an index of motor cortex excitability).Conclusions: Although the antiepileptic action was not significant (p > 0.05), the individual EEG reactivity to "active" rTMS may be encouraging for the development of more-powerful, noninvasive neuromodulatory strategies.
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