Cortico-cortical evoked potential (CCEP) mapping is a rapidly developing method for visualizing the brain network and estimating cortical excitability. The CCEP comprises the early N1 component the occurs at 10-30 ms poststimulation, indicating anatomic connectivity, and the late N2 component that appears at < 200 ms poststimulation, suggesting long-lasting effective connectivity. A later component at 200-1,000 ms poststimulation can also appear as a delayed response in some studied areas. Such delayed responses occur in areas with changed excitability, such as an epileptogenic zone. CCEP mapping has been used to examine the brain connections causally in functional systems such as the language, auditory, and visual systems as well as in anatomic regions including the frontoparietal neocortices and hippocampal limbic areas. Task-based CCEPs can be used to measure behavior. In addition to evaluations of the brain connectome, single-pulse electrical stimulation (SPES) can reflect cortical excitability, and so it could be used to predict a seizure onset zone. CCEP brain mapping and SPES investigations could be applied both extraoperatively and intraoperatively. These underused electrophysiologic tools in basic and clinical neuroscience might be powerful methods for providing insight into measures of brain connectivity and dynamics. Analyses of CCEPs might enable us to identify causal relationships between brain areas during cortical processing, and to develop a new paradigm of effective therapeutic neuromodulation in the future.
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The electrodiagnostic findings in Guillain-Barré syndrome (GBS) play important roles in both understanding its pathophysiology and its diagnosis. Only demyelinating neuropathies were thought to be present when GBS patients were first diagnosed in Western countries, but the concept changed when many axonal GBS patients were reported in Asia. Reversible conduction failure was subsequently revealed, and it was recognized as a pathophysiologic continuum of axonal GBS. Thus, the electrodiagnostic findings in GBS have had a profound effect on the history of this disease.
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Suk-Won Ahn, Byung-Nam Yoon, Jee-Eun Kim, Jin Myoung Seok, Kwang-Kuk Kim, Young Min Lim, Ki-Han Kwon, Kee Duk Park, Bum Chun Suh, on behalf of the Korean Society of Clinical Neurophysiology Education Committee
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Nerve conduction study (NCS) is an electrophysiological tool to assess the overall function of cranial and peripheral nervous system, therefore NCS has been diagnostically helpful in the identification and characterization of disorders involving nerve roots, peripheral nerves, muscle and neuromuscular junction, and are frequently accompanied by a needle Electromyography. Furthermore, NCS could provide valuable quantitative and qualitative results into neuromuscular function. Usually, motor, sensory, or mixed nerve studies can be performed with using NCS, stimulating the nerves with the recording electrodes placed over a distal muscle, a cutaneous sensory nerve, or the entire mixed nerve, respectively. And these findings of motor, sensory, and mixed nerve studies often show different and distinct patterns of specific abnormalities indicating the neuromuscular disorders. The purpose of this special article is to review the neurophysiologic usefulness of NCS, to outline the technical factors associated with the performance of NCS, and to demonstrate characteristic NCS changes in the setting of various neuromuscular conditions.
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Background: Electrophysiological study has been known as a useful method to evaluate the therapeutic effect of operation in idiopathic carpal tunnel syndrome (CTS). The purpose of this study was to evaluate the clinical and electrophysiological changes after carpal tunnel release (CTR) compared to the preoperative results. Methods: We analyzed the changes of nerve conduction study (NCS) before and after minimal open carpal tunnel release in 18 patients (25 hands) with CTS. Follow-up study was performed over 6 months after operation. Results: Clinical improvement was seen in all cases after CTR. In contrast, electrophysiological improvement was various depending on the parameters; the mean median sensory latency and nerve conduction velocity (NCV) improved significantly (p = 0.001). The mean median motor latency also improved, but NCV and compound muscle action potential (CMAP) amplitude did not change. The extent of improvement was evident in moderate CTS, but not in severe CTS. Conclusions: In this preliminary study, all subjects who underwent CTR achieved a clinical relief along with a significant improvement of electrophysiological parameters such as median sensory latency, sensory NCV and median distal motor latency. After CTR, a number of cases with mild to moderate CTS showed a prominent improvement of clinical and electrophysiological parameters, while fewer improvements were seen in severe CTS, although it did not reach the statistical significance.
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Background: Local steroid injection is used to treat carpal tunnel syndrome (CTS). The aim of this study was to evaluate the clinical and electrophysiological effects of local steroid injection in patients with CTS over a 3-months period. Methods: Twenty-one satients (35 hands) with clinical and electrophysiological evidence of CTS were treated by injection of triamcinolone 40 mg to the carpal tunnel. Visual analog scale (VAS), Boston Carpal Tunnel Questionnaire (BCTQ), rates of paresthesia, night awakening, and electrophysiological studies were used as outcomes. Clinical and electrophysiological assessments were performed before, 1 and 3 months after treatment. Results: Prior to treatment, 86% of patients complained of night awakening. At 1 and 3 months after injection, only 17% and 29% of the patients, respectively, had night awakening (p<0.001). All patients complained of paresthesia before the treatment. This symptom disappeared in 60% and 31% of the patients after 1 and 3 months, respectively (p<0.001). Compared to baseline, both BCTQ and VAS show significant improvement during the 3 months of the study (p<0.005). Although significant improvements in clinical parameters were shown, electrophysiological parameters were not significantly improved at 1 and 3 months. Conclusions: Local corticosteroid injection for the treatment of CTS provides significant improvement in symptoms for 3 months. On the other hand, no significant improvement was observed in electrophysiological parameters.
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A Narrative Review of Carpal Tunnel Syndrome in Traditional Chinese Medicine: Using China National Knowledge Infrastructure Database Hyun-A Jeon, Won-Bin Shin, Su-Yeon Lim, Young-Joo Moon, Ji-Yun Lee, Seung-Hyeok Ku, Sung-Hyun Kim, Hyun-Woo Moon Journal of Korean Medicine Rehabilitation.2020; 30(4): 119. CrossRef
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Background Floppy infant syndrome has a number of different etiologies.
Methods: One hundred twenty-three consecutive patients of floppy infant syndrome were included in this study. We reviewed all the electrophysiologic tests of these patients and the medical record of patients showing abnormalities in the electrophysiologic studies.
Results Of the 123 patients, twenty-six (21.1%) showed definite abnormalities in electrophysiologic tests; 8 myopathies, 14 neuropathies and 4 unclassified. The neuropathy was further classified as 5 neuronopathies and 9 sensorimotor polyneuropathies. With muscle or sural nerve biopsy and genetic test, a final diagnosis was made of Duchenne muscular dystrophy in 4, Becker muscular dystrophy in 1, spinal muscular atrophy in 2, and metachromatic leukodystrophy in 1.
Conclusions About 21% of patients presented with floppy infant syndrome showed abnormalities in the neuromuscular system. The electrophysiologic test is valuable to guide further investigations in diagnosing the cause of floppy infant syndrome.
Eye movements serve vision by placing the image of an object on the fovea of each retina, and by preventing slippage of images on the retina. The brain employs two modes of ocular motor control, fast eye movements (saccades) and smooth eye movements. Saccades bring the fovea to a target, and smooth eye movements prevent retinal image slip. Smooth eye movements comprise smooth pursuit, the optokinetic reflex, the vestibulo-ocular reflex (VOR), vergence, and fixation. Saccades achieve rapid refixation of targets that fall on the extrafoveal retina by moving the eyes at peak velocities that can exceed 700?s. Various brain lesions can affect saccadic latency, velocity, or accuracy. Smooth pursuit maintains fixation of a slowly moving target. The pursuit system responds to slippage of an image near the fovea in order to accelerate the eyes to a velocity that matches that of the target. When smooth eye movements velocity fails to match target velocity, catch-up saccades are used to compensate for limited smooth pursuit velocities. The VOR subserves vision by generating conjugate eye movements that are equal and opposite to head movements. If the VOR gain (the ratio of eye velocity to head velocity) is too high or too low, the target image is off the fovea, and head motion causes oscillopsia, an illusory to-and-fro movement of the environment.
Spasticity is one of the most common clinical condition that we encounter in neurological practice. It is characterized by increased deep tendon reflexes, clonus, and other associated features. In this review, the basic anatomy of the spinal cord along with descending pathways subserving the muscle tone and reflexes is presented. Historical animal experiments and clinical studies are discussed to help understand the neurophysiology of spasticity.
High voltage electrical injury can cause considerable damage to the nervous system including spinal cord, but, thepathophysiology of myelopathy remains to be studied. A 44-year old man with paraparesis after electrical injury wasdiagnosed as electrical injury induced- myelopathy by normal spine MRI and somatosensory evoked potential showingcentral conduction abnormality. It implicates that the presumed mechanism of the myelopathy prefers the electroporationor electroconformational protein denaturation to the joule heating.
Background Electrophysiologic study accurately predicts the degree of degenerated motor axons but cannot giveprecise information on the type of injury that occurred in Bell
Background Essential tremor (ET) is a common movement disorder that often causes functional disability. There have been very few investigations about the clinical characteristics of ET in Korea. Therefore, we performed a study showing the clinical features and electrophysiological findings of ET. Methods: We analyzed medical records and accelerometry data of 152 patients (male vs female; 79 vs 73) with ET, who visited the Neurology Clinic of Hospital from 2000 to 2003. Clinical characteristics of ET were summarized including the age of onset, family history, tremor type, body part involved, and associated symptoms. The frequency of tremor was recorded and the spectral analysis of tremor was performed. Results: The age of tremor onset showed bimodal distribution with peaks in the 2nd and 5th decades. Family history was found in 46 patients (30.3%). The patients with the family history presented earlier onset of tremor than patients without the history (mean age of onset, y: 35.2 vs. 49.9, P < 0.001). Tremor appeared most frequently in hands (94%), and followed by head (25%). In head tremor,
Introduction : Orthostatic tremor develops in the legs while standing up with no weakness, pain or imbalance in theleg and the tremor is characteristically not observed when walking. However there have been some confusions aboutorthostatic tremor in several aspects. For the past ten years, we have observed 4 patients with orthostatic tremor. In eachcase tests were performed to investigate the following three important areas of inquiry about orthostatic tremor. Firstly,whether this disorder is an independent diagnostic entity or a variant of essential tremor. Secondly, whether the progressof this disorder is specifically related with standing posture. Lastly, the nature of the pathophysiologic mechanismbehind the appearance of the tremor when standing after the lapse of a certain latent period and its disappearance uponthe commencement of walking.Methods : Our 4 cases of orthostatic tremor were studied clinically, electrophysiologically, and pharmacologically.Electrophysiological tests included tremor spectrum test and electromyography.Results : We observed the presence of this tremor in several other tonic postures, as well as its absence, in a verticallylifted position from all our cases. Our cases registered a variable tremor frequency between 5 and 12 Hz according tothe tremor spectrum test and EMG. Furthermore all our 4 cases demonstrated patterns of both synchronous EMG activityand alternating EMG activity at various times in homologous muscles of both legs. Orthostatic tremor was improvedsignificantly with propranolol as well as clonazepam.Conclusions : From the results of our study we drew the following conclusions. It is probable that orthostatic tremoris simply a variant of essential tremor rather than being an independent diagnostic entity and that in most cases itsdevelopment is specifically related with muscle contraction rather than merely with the act of standing. Furthermore wediscovered a clue in the previously described neural control mechanism that the nuclear bag fibers in the muscle spindlehave lag time of several seconds in their response to muscle strength and that their baseline does not reset fully in rapidlymoving muscle. This neural control mechanism could offer sufficient explanation for the phenomena of tremorappearance when standing and disappearance when walking in orthostatic tremor.
A 32-year-old man who had worked at aluminum processing plant for 4 months visited us. He complained of numbnessand paresthesia of both foot and hands and weakness of all extremities. Electrophysiologic study showed motorsensorypolyneuropathy of diffuse axonal type with focal conduction block. And we discovered higher concentration ofn-Hexane in his workplace. On sural nerve biopsy, bubbly enlarged nerve fibers in light microscope and thick myelinsheath and axonal degeneration on electron microscope were found. We diagnosed it as n-Hexane induced neuropathy.
Background Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy caused by compression of themedian nerve beneath the transverse carpal ligament. CTS can be correctly diagnosed by the patients' description of symptomsand electrophysiological tests that measure nerve conduction through the wrist. Many previous studies reported variousrisk factors of CTS, such as obesity, diabetes mellitus, thyroid disease and trauma. Obesity is associated with both hyperlipidemiaand CTS. This study focused on the relationship between severity of CTS and serum lipid level. Methods: Onehundred fourteen patients with CTS and 74 controls were divided into four groups according to the severity; normal, mild,moderate and severe. And then serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL-C) andhigh-density lipoprotein (HDL-C) were measured in each group. Results: There was a positive correlation between TG andCTS severity (p<0.001). But TC, LDL-C and HDL-C were not correlated with CTS severity. Conclusions: These results suggestthat high serum TG may act as an aggravating factor of CTS.
Transcranial magnetic stimulation (TMS) is a non-invasive tool used to study aspects of human brain physiology, includingmotor function and the pathophysiology of various brain disorders. A brief electric current passed through a magnetic coilproduces a high-intensity magnetic field, which can excite or inhibit the cerebral cortex. Although various brain regions canbe evaluated by TMS, most studies have focused on the motor cortex where motor evoked potentials (MEPs) are produced.Single-pulse and paired-pulse TMS can be used to measure the excitability of the motor cortex via various parameters, whilerepetitive TMS induces cortical plasticity via long-term potentiation or long-term depression-like mechanisms. Therefore,TMS is useful in the evaluation of physiological mechanisms of various neurological diseases, including movement disordersand epilepsy. In addition, it has diagnostic utility in spinal cord diseases, amyotrophic lateral sclerosis and demyelinatingdiseases. The therapeutic effects of repetitive TMS on stroke, Parkinson disease and focal hand dystonia are limited sincethe duration and clinical benefits seem to be temporary. New TMS techniques, which may improve clinical utility, are beingdeveloped to enhance clinical utilities in various neurological diseases.
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