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ME1 Utility of EMG in adults: when and why?
S2
Abstracts of the 13th European Congress of Clinical Neurophysiology / Clinical Neurophysiology 119 (2008), S1–S131
of neuronal assemblies for task execution; indeed they also have the timediscrimination which is needed when exploring brain function (in the order of milliseconds). Neurophysiological measures can be integrated with structural and functional imaging and biological markers data, offering a widely available, low-cost and non-invasive evaluation of at risk population.
KN3 Twenty years of TMS J.C. Rothwell Institute of Neurology, London, United Kingdom In 1986, Tony Barker and Reza Jalinous came to London from London to Sheffield to demonstrate their nerve stimulator to Pat Merton and Bert Morton in the Department of Clinical Neurophysiology. After they had demonstrated the stimulator on peripheral nerve, Merton then placed the coil on his own head to stimulate his motor cortex. His hand twitched and TMS was born as a technique. In the intervening years, TMS has gone from a method of monitoring function in central motor pathways to a common tool in cognitive neuroscience and even rehabilitation therapy. It has joined the ranks of “brain imaging” methods. Despite the advances in its use, we are still remarkably ignorant of the precise action of TMS on cerebral cortex: what neurones does it stimulate; where are they and how do the induced action potentials interact with normal patterns of brain activity? Furthermore, why and how does repeated TMS (rTMS) lead to long term effects on brain excitability and function? Some answers can be obtained from experimental studies in animal brains, but because of the difficulties in replicating the pattern of current flow induced in the human brain in smaller animal skulls, the data is limited. I will illustrate how physiological studies on the primary motor cortex, in conjunction with invasive recordings from electrodes implanted in the brain and spinal cord in human patients have provided answers to some of these questions. One of the most exciting potential new uses of TMS is as a therapy. This relies on harnessing the long term effects of rTMS. However, at present rTMS has been reported to have efficacious effects in such a wide variety of conditions from depression, schizophrenia, Parkinson’s disease, central pain, migraine, tinnitus etc, that questions have been raised about whether it ever does any more than act as an efficient placebo. I will review the possible mechanisms of action of rTMS and show how these depend on a wide variety of factors including the past history of brain activity, drug therapy and even genetic factors. This leads to a high variance in the action of rTMS, which when understood may help us to target therapeutic studies much more carefully than in the past.
KN4 Neurophysiology of vestibular system Abstract not received.
KN5 Mirror neurons, imitation and the language L. Fadiga Italy Modern research in neuroscience is providing increasing evidence in favor of a more cognitive role played by motor and premotor centers. Clear motor activations become evident when one simply imagines a motor act. Moreover, the observation of actions of other individuals activates motor and premotor areas in the observer’s brain, motorically ‘mirroring’ the seen act. Which is the function of this high-level motor involvement? Why, to understand how others act our brain looks inside its own motor representations? Is this motor involvement functional to perception, or does it represent a mere epiphenomenon? These will be the topics that I will discuss in the first part of my talk. In the second part, I will provide new evidence that Broca’s area, the frontal area for speech, is necessary for correctly representing the action syntax. This data may shed new light on the origin of the human language, particularly if one takes into account the anatomical and functional homologies linking Broca’s area to area F5, the ventral premotor area of the macaque brain where we originally found the mirror neurons.
MEET THE EXPERT ME1 Utility of EMG in adults: when and why? Jose M. Fernandez Dept. of Clinical Neurophysiology, University Hospital of Vigo, Vigo, Spain Electromyography is the generic name used to designate a wide range of electrophysiological techniques, including electromyography itself – the extra cellular recording of muscle action potentials – together with nerve conduction studies (neurography) and allied techniques. Recording of muscle action potentials can be carried out with concentric needle electrode or others (Single Fiber EMG, Macro EMG etc). The fundamental concept in the pathology and physiology of the neuromuscular system is the Motor Unit (MU) which comprises the alpha motor neuron, its axon, the motor end-plates and all muscle fibers innervated by this axon. The number of MUs in different muscles varies considerably and the exact numbers are unknown. Motor unit counting methods estimate the number to be 100–500 in normal human limb muscles. EMG is an essential diagnostic tool in neurology and can be considered an extension to neurological examination. Nevertheless, EMG is more sensitive than the clinical exam and allows the detection of subtle abnormalities that are not clinically detectable. EMG reveals the type and distribution of neuromuscular disorder and quantifies severity of the neurological deficits providing invaluable information complementing the history and clinical findings. The right methods must be chosen for each clinical problem to increase efficiency and avoid unnecessary discomfort to the patient to reach a final diagnosis. Optimal results are achieved combining standardization of methods, rigorous quality control and adequate research.
ME2 When and why to do EMG in children A. Covanis Neurology Department The Childrens’ Hospital “Agia Sophia” Athens Electromyography (EMG) records the electrical activity from a muscle by means of surface or needle electrodes and is of great value for the diagnosis of neuromuscular diseases. Neuromuscular diseases are disorders of the motor unit, which consists of the motor neuron, peripheral nerve, neuromuscular junction and all muscle fibers innervated by a single motor neuron. Diseases of the motor unit produce changes in the EMG, which will help to differentiate myopathic from neurogenic processes. Such a diseases may be genetically determined, congenital or acquired, acute or chronic, and progressive or static. Therefore, whenever we suspect a disorder of the motor unit we ask for an EMG, in order to collect all relevant information, which will support the clinical diagnosis of a specific genetic condition or syndrome, and provide prognostic information and therapeutic options. By far in children the most common cause for EMG referral, is the floppy syndrome in infancy (80% of CNS origin) where multiple disorders affecting each motor unit level from the anterior horn to the muscle exist. In addition, the information obtained from the EMG, in this age group, correlates well with the findings of the muscle biopsy. Although the EMG does not diagnose the specific type of myopathy, certain myopathic conditions, such as myotonia can easily be demonstrated (dive-bomber sound). Further more, in certain cases repetitive electrical stimulation of a motor nerve innervating a muscle is useful in demonstrating myasthenic decrimental responses for disorders of neuromuscular transmission. This test is always done after needle electromyography and nerve conduction studies have excluded disorders with denervation and reinnervation. In children however, EMG is a very uncomfortable test, induces mental discomfort and stress not only to the child but also to the parents who are usually present to give support. It is therefore absolutely necessary to evaluate the child completely in order to tailor EMG and NCS to the specific diagnostic question. Today, in some cases such as congenital myotonic dystrophy and spinal muscular atrophy, molecular testing has supplemented the need of EMG.
Abstracts of the 13th European Congress of Clinical Neurophysiology / Clinical Neurophysiology 119 (2008), S1–S131
of neuronal assemblies for task execution; indeed they also have the timediscrimination which is needed when exploring brain function (in the order of milliseconds). Neurophysiological measures can be integrated with structural and functional imaging and biological markers data, offering a widely available, low-cost and non-invasive evaluation of at risk population.
KN3 Twenty years of TMS J.C. Rothwell Institute of Neurology, London, United Kingdom In 1986, Tony Barker and Reza Jalinous came to London from London to Sheffield to demonstrate their nerve stimulator to Pat Merton and Bert Morton in the Department of Clinical Neurophysiology. After they had demonstrated the stimulator on peripheral nerve, Merton then placed the coil on his own head to stimulate his motor cortex. His hand twitched and TMS was born as a technique. In the intervening years, TMS has gone from a method of monitoring function in central motor pathways to a common tool in cognitive neuroscience and even rehabilitation therapy. It has joined the ranks of “brain imaging” methods. Despite the advances in its use, we are still remarkably ignorant of the precise action of TMS on cerebral cortex: what neurones does it stimulate; where are they and how do the induced action potentials interact with normal patterns of brain activity? Furthermore, why and how does repeated TMS (rTMS) lead to long term effects on brain excitability and function? Some answers can be obtained from experimental studies in animal brains, but because of the difficulties in replicating the pattern of current flow induced in the human brain in smaller animal skulls, the data is limited. I will illustrate how physiological studies on the primary motor cortex, in conjunction with invasive recordings from electrodes implanted in the brain and spinal cord in human patients have provided answers to some of these questions. One of the most exciting potential new uses of TMS is as a therapy. This relies on harnessing the long term effects of rTMS. However, at present rTMS has been reported to have efficacious effects in such a wide variety of conditions from depression, schizophrenia, Parkinson’s disease, central pain, migraine, tinnitus etc, that questions have been raised about whether it ever does any more than act as an efficient placebo. I will review the possible mechanisms of action of rTMS and show how these depend on a wide variety of factors including the past history of brain activity, drug therapy and even genetic factors. This leads to a high variance in the action of rTMS, which when understood may help us to target therapeutic studies much more carefully than in the past.
KN4 Neurophysiology of vestibular system Abstract not received.
KN5 Mirror neurons, imitation and the language L. Fadiga Italy Modern research in neuroscience is providing increasing evidence in favor of a more cognitive role played by motor and premotor centers. Clear motor activations become evident when one simply imagines a motor act. Moreover, the observation of actions of other individuals activates motor and premotor areas in the observer’s brain, motorically ‘mirroring’ the seen act. Which is the function of this high-level motor involvement? Why, to understand how others act our brain looks inside its own motor representations? Is this motor involvement functional to perception, or does it represent a mere epiphenomenon? These will be the topics that I will discuss in the first part of my talk. In the second part, I will provide new evidence that Broca’s area, the frontal area for speech, is necessary for correctly representing the action syntax. This data may shed new light on the origin of the human language, particularly if one takes into account the anatomical and functional homologies linking Broca’s area to area F5, the ventral premotor area of the macaque brain where we originally found the mirror neurons.
MEET THE EXPERT ME1 Utility of EMG in adults: when and why? Jose M. Fernandez Dept. of Clinical Neurophysiology, University Hospital of Vigo, Vigo, Spain Electromyography is the generic name used to designate a wide range of electrophysiological techniques, including electromyography itself – the extra cellular recording of muscle action potentials – together with nerve conduction studies (neurography) and allied techniques. Recording of muscle action potentials can be carried out with concentric needle electrode or others (Single Fiber EMG, Macro EMG etc). The fundamental concept in the pathology and physiology of the neuromuscular system is the Motor Unit (MU) which comprises the alpha motor neuron, its axon, the motor end-plates and all muscle fibers innervated by this axon. The number of MUs in different muscles varies considerably and the exact numbers are unknown. Motor unit counting methods estimate the number to be 100–500 in normal human limb muscles. EMG is an essential diagnostic tool in neurology and can be considered an extension to neurological examination. Nevertheless, EMG is more sensitive than the clinical exam and allows the detection of subtle abnormalities that are not clinically detectable. EMG reveals the type and distribution of neuromuscular disorder and quantifies severity of the neurological deficits providing invaluable information complementing the history and clinical findings. The right methods must be chosen for each clinical problem to increase efficiency and avoid unnecessary discomfort to the patient to reach a final diagnosis. Optimal results are achieved combining standardization of methods, rigorous quality control and adequate research.
ME2 When and why to do EMG in children A. Covanis Neurology Department The Childrens’ Hospital “Agia Sophia” Athens Electromyography (EMG) records the electrical activity from a muscle by means of surface or needle electrodes and is of great value for the diagnosis of neuromuscular diseases. Neuromuscular diseases are disorders of the motor unit, which consists of the motor neuron, peripheral nerve, neuromuscular junction and all muscle fibers innervated by a single motor neuron. Diseases of the motor unit produce changes in the EMG, which will help to differentiate myopathic from neurogenic processes. Such a diseases may be genetically determined, congenital or acquired, acute or chronic, and progressive or static. Therefore, whenever we suspect a disorder of the motor unit we ask for an EMG, in order to collect all relevant information, which will support the clinical diagnosis of a specific genetic condition or syndrome, and provide prognostic information and therapeutic options. By far in children the most common cause for EMG referral, is the floppy syndrome in infancy (80% of CNS origin) where multiple disorders affecting each motor unit level from the anterior horn to the muscle exist. In addition, the information obtained from the EMG, in this age group, correlates well with the findings of the muscle biopsy. Although the EMG does not diagnose the specific type of myopathy, certain myopathic conditions, such as myotonia can easily be demonstrated (dive-bomber sound). Further more, in certain cases repetitive electrical stimulation of a motor nerve innervating a muscle is useful in demonstrating myasthenic decrimental responses for disorders of neuromuscular transmission. This test is always done after needle electromyography and nerve conduction studies have excluded disorders with denervation and reinnervation. In children however, EMG is a very uncomfortable test, induces mental discomfort and stress not only to the child but also to the parents who are usually present to give support. It is therefore absolutely necessary to evaluate the child completely in order to tailor EMG and NCS to the specific diagnostic question. Today, in some cases such as congenital myotonic dystrophy and spinal muscular atrophy, molecular testing has supplemented the need of EMG.