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C23 Contributions of microneurography to the study of the pathophysiology of neuropathic pain and other types of positive sensory phenomena
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Abstracts of the 13th European Congress of Clinical Neurophysiology / Clinical Neurophysiology 119 (2008), S1–S131
carpi radialis and quadriceps muscles and during voluntary activation in most muscles of the limbs. Responses of similar characteristics can be obtained by tapping on the muscle tendon, which elicits the T reflex. The study of T and H reflexes helps in the physiological study of motor control and in the clinical assessment of peripheral and central nervous system dysfunctions. Increasing the stimulus intensity induces an increase in the size of the reflex response until a significant number of motor fibers are recruited and there is collision between orthodromic and antidromic volleys. The H reflexes elicited with a stable stimulus intensity reflect the excitability of the segmental refex circuit and, therefore, they can be used to evaluate dysfunctions of the pyramidal tract. The H reflex is the probe used for testing spinal cord interneuronal function, such as reciprocal inhibition, presynaptic inhibition, recurrent inhibition or autogenetic inhibition, circuits that may be abnormal in many central nervous system disorders. Since they are elicited by activation of the largest nerve fibers, the abnormality of the H reflexes may also be due to peripheral neuropathies that involve large myelinated fibers. In distal axonopathies, the T reflex may be absent while the H reflex is still preserved. In radiculopathies, the H reflex may be absent or abnormally reduced while the sensory nerve conduction is preserved, as evidence for preganglionic lesion topography.
C21 Neurophysiological approach to dysphagia C. Ertekin Turkey Dysphagia is a severe and frequent symptom complex that can be lifethreating in a considerable number of patients. Three-forth of oropharyngeal dysphagia is caused by neurological diseases. The neurophysiology of swallowing has been reviewed in regard to deglutitional clinical problems, such as aspiration. There are many methods to investigate the swallows and its problems. But in this course, the EMG and other clinical neurophysiological methods are emphasized. Afterward the neurogenic dysphagia will be classified according to the clinical and electrophysiological data. Clinical and EMG data from cortex to the striated muscles of the oropharynx including cricopharyngeal sphincter will be given according to the disorders of pyramidal, extrapyramidal, bulbar central pattern generator or peripheral neuromuscular system
C22 Neurophysiological approach to dysphagia E. Alfonsi Italy Abstract not received.
C23 Contributions of microneurography to the study of the pathophysiology of neuropathic pain and other types of positive sensory phenomena J. Serra Department of Neurology, MC Mutual, Barcelona, Spain Patients with peripheral neuropathy commonly express positive sensory symptoms, such as paresthesias, dysesthesias and different types of pain. As opposed to negative sensory phenomena whose electrophysiological correlate can be readily measured through conventional laboratory methods, the study of positive sensory phenomena is problematic. In animals, possible electrophysiological correlates of positive sensory phenomena have been documented in traumatic neuromas and in demyelinated nerve fibers. In experimental human volunteers, ectopic nerve impulses generated in single myelinated sensory fibers have been correlated with post-ischemic and posttetanic paresthesias. In patients with peripheral neuropathy, abnormal nerve impulse activity in afferent fibers has occasionally been recorded. In all cases, such activity was either spontaneous or elicited by mechanical stimuli applied at injured mid-axon level. Recent microneurographic techniques permit recording from individual unmyelinated C fibers and allow their segregation into different functional classes having discrete electrophysiological properties of their membranes. Particularly important for the study of neuropathic pain is the recording from
mechano-sensitive as well as mechano-insensitive, or silent, nociceptors. Stimulation at low rates following a pause differentiates between them, while stimulation at 2 Hz for 3 minutes differentiates patterns of slowing among functional types of C fibres. Different abnormalities have been identified: spontaneous ectopic impulse generation, sensitization to mechanical, heat and cold stimuli, and “multispike” responses. It is becoming clear that Cnociceptor function abnormalities may explain some of the positive sensory phenomena expressed by patients with peripheral neuropathic pain. This has important implications to design future research strategies. References: [1] Two types of C nociceptors in human skin and their behavior in areas of capsaicin-induced secondary hiperalgesia. J Serra, M Campero, H Bostock, JL Ochoa. J Neurophysiol 2004 Jun;91:2770-81. [2] Activity-dependent slowing of conduction differentiates functional subtypes of C fibres innervating human skin. J. Serra, M. Campero, J. Ochoa, H. Bostock. J Physiol 1999;515:799-811.
C24 Routine EEG for epilepsy G. Rubboli Department of Neurosciences, Bellaria Hospital, Bologna, Italy Electroencephalography (EEG) remains an essential tool in the diagnosis and management of epilepsy. Indeed, it is still essential: a) in a first unprovoked seizure either for the diagnosis and for the prognosis, being able to predict the risk of seizure recurrence. After a first unprovoked seizure, EEG evidence of epileptiform activity (such as generalized spike and wave discharges or focal spikes) may indicate a greater risk of recurrence. Some data suggest that routine EEG performed within 24 hours from the first seizure, associated with sleep EEG and neuroimaging studies (CT/MRI scans) may yield information allowing a syndromic diagnosis of the epilepsy type. b) in the definition of the epileptic syndrome. Some EEG epileptiform abnormalities can be considered highly specific of certain epileptic syndromes (i.e., 3 c/sec generalized spike-and-wave discharge in childhood absence epilepsy). EEG supplemented by polygraphic channels may be crucial in some diagnostic processes: for instance, implementation of EMG polygraphic channels may add helpful data for the syndromic classification of epilepsies (i.e., demonstrating the occurrence of positive/negative myoclonia in relation of epileptiform activities). c) in the choice of antiepileptic treatment. EEG “per se“ has no absolute value regarding orientation for the treatment of epilepsy; however, when it is used to supplement the clinical data is a most valuable aide in choosing and modifying a treament. d) in the presurgical assessment of drug-resistant focal epilepsies. Interictal epileptiform abnormalities may have a diagnostic and prognostic significance in the selection of surgical candidates; however, issues such as when interictal epileptiform abnormalities may be relied upon in the absence of ictal recordings or whether different types of interictal temporal epileptiform abnormalities with different diagnostic and prognostic implications do exist are not completely resolved.
C25 Routine EEG for epilepsy P. Jallon Switzerland Abstract not received.
C26 Laser EPs M. Valeriani Italy In the seventies, the technique of laser evoked potential (LEP) has been introduced for pain research. Indeed, unlike the electrical stimuli used for the recording of the standard somatosensory evoked potentials, CO2 laser pulses delivered to the hairy skin activate the nociceptive A delta and C fibers selectively, without any concurrent stimulation of the non-nociceptive A beta
Abstracts of the 13th European Congress of Clinical Neurophysiology / Clinical Neurophysiology 119 (2008), S1–S131
carpi radialis and quadriceps muscles and during voluntary activation in most muscles of the limbs. Responses of similar characteristics can be obtained by tapping on the muscle tendon, which elicits the T reflex. The study of T and H reflexes helps in the physiological study of motor control and in the clinical assessment of peripheral and central nervous system dysfunctions. Increasing the stimulus intensity induces an increase in the size of the reflex response until a significant number of motor fibers are recruited and there is collision between orthodromic and antidromic volleys. The H reflexes elicited with a stable stimulus intensity reflect the excitability of the segmental refex circuit and, therefore, they can be used to evaluate dysfunctions of the pyramidal tract. The H reflex is the probe used for testing spinal cord interneuronal function, such as reciprocal inhibition, presynaptic inhibition, recurrent inhibition or autogenetic inhibition, circuits that may be abnormal in many central nervous system disorders. Since they are elicited by activation of the largest nerve fibers, the abnormality of the H reflexes may also be due to peripheral neuropathies that involve large myelinated fibers. In distal axonopathies, the T reflex may be absent while the H reflex is still preserved. In radiculopathies, the H reflex may be absent or abnormally reduced while the sensory nerve conduction is preserved, as evidence for preganglionic lesion topography.
C21 Neurophysiological approach to dysphagia C. Ertekin Turkey Dysphagia is a severe and frequent symptom complex that can be lifethreating in a considerable number of patients. Three-forth of oropharyngeal dysphagia is caused by neurological diseases. The neurophysiology of swallowing has been reviewed in regard to deglutitional clinical problems, such as aspiration. There are many methods to investigate the swallows and its problems. But in this course, the EMG and other clinical neurophysiological methods are emphasized. Afterward the neurogenic dysphagia will be classified according to the clinical and electrophysiological data. Clinical and EMG data from cortex to the striated muscles of the oropharynx including cricopharyngeal sphincter will be given according to the disorders of pyramidal, extrapyramidal, bulbar central pattern generator or peripheral neuromuscular system
C22 Neurophysiological approach to dysphagia E. Alfonsi Italy Abstract not received.
C23 Contributions of microneurography to the study of the pathophysiology of neuropathic pain and other types of positive sensory phenomena J. Serra Department of Neurology, MC Mutual, Barcelona, Spain Patients with peripheral neuropathy commonly express positive sensory symptoms, such as paresthesias, dysesthesias and different types of pain. As opposed to negative sensory phenomena whose electrophysiological correlate can be readily measured through conventional laboratory methods, the study of positive sensory phenomena is problematic. In animals, possible electrophysiological correlates of positive sensory phenomena have been documented in traumatic neuromas and in demyelinated nerve fibers. In experimental human volunteers, ectopic nerve impulses generated in single myelinated sensory fibers have been correlated with post-ischemic and posttetanic paresthesias. In patients with peripheral neuropathy, abnormal nerve impulse activity in afferent fibers has occasionally been recorded. In all cases, such activity was either spontaneous or elicited by mechanical stimuli applied at injured mid-axon level. Recent microneurographic techniques permit recording from individual unmyelinated C fibers and allow their segregation into different functional classes having discrete electrophysiological properties of their membranes. Particularly important for the study of neuropathic pain is the recording from
mechano-sensitive as well as mechano-insensitive, or silent, nociceptors. Stimulation at low rates following a pause differentiates between them, while stimulation at 2 Hz for 3 minutes differentiates patterns of slowing among functional types of C fibres. Different abnormalities have been identified: spontaneous ectopic impulse generation, sensitization to mechanical, heat and cold stimuli, and “multispike” responses. It is becoming clear that Cnociceptor function abnormalities may explain some of the positive sensory phenomena expressed by patients with peripheral neuropathic pain. This has important implications to design future research strategies. References: [1] Two types of C nociceptors in human skin and their behavior in areas of capsaicin-induced secondary hiperalgesia. J Serra, M Campero, H Bostock, JL Ochoa. J Neurophysiol 2004 Jun;91:2770-81. [2] Activity-dependent slowing of conduction differentiates functional subtypes of C fibres innervating human skin. J. Serra, M. Campero, J. Ochoa, H. Bostock. J Physiol 1999;515:799-811.
C24 Routine EEG for epilepsy G. Rubboli Department of Neurosciences, Bellaria Hospital, Bologna, Italy Electroencephalography (EEG) remains an essential tool in the diagnosis and management of epilepsy. Indeed, it is still essential: a) in a first unprovoked seizure either for the diagnosis and for the prognosis, being able to predict the risk of seizure recurrence. After a first unprovoked seizure, EEG evidence of epileptiform activity (such as generalized spike and wave discharges or focal spikes) may indicate a greater risk of recurrence. Some data suggest that routine EEG performed within 24 hours from the first seizure, associated with sleep EEG and neuroimaging studies (CT/MRI scans) may yield information allowing a syndromic diagnosis of the epilepsy type. b) in the definition of the epileptic syndrome. Some EEG epileptiform abnormalities can be considered highly specific of certain epileptic syndromes (i.e., 3 c/sec generalized spike-and-wave discharge in childhood absence epilepsy). EEG supplemented by polygraphic channels may be crucial in some diagnostic processes: for instance, implementation of EMG polygraphic channels may add helpful data for the syndromic classification of epilepsies (i.e., demonstrating the occurrence of positive/negative myoclonia in relation of epileptiform activities). c) in the choice of antiepileptic treatment. EEG “per se“ has no absolute value regarding orientation for the treatment of epilepsy; however, when it is used to supplement the clinical data is a most valuable aide in choosing and modifying a treament. d) in the presurgical assessment of drug-resistant focal epilepsies. Interictal epileptiform abnormalities may have a diagnostic and prognostic significance in the selection of surgical candidates; however, issues such as when interictal epileptiform abnormalities may be relied upon in the absence of ictal recordings or whether different types of interictal temporal epileptiform abnormalities with different diagnostic and prognostic implications do exist are not completely resolved.
C25 Routine EEG for epilepsy P. Jallon Switzerland Abstract not received.
C26 Laser EPs M. Valeriani Italy In the seventies, the technique of laser evoked potential (LEP) has been introduced for pain research. Indeed, unlike the electrical stimuli used for the recording of the standard somatosensory evoked potentials, CO2 laser pulses delivered to the hairy skin activate the nociceptive A delta and C fibers selectively, without any concurrent stimulation of the non-nociceptive A beta