Since Hans Berger reported the first paper on the human electroencephalogram in 1920s, huge technological advance have made it possible to use a number of electrophysiological approaches to neurological diagnosis in clinical neurology. In majority of the neurology training hospitals they have facilities of electroencephalography(EEG), electromyography(EMG), evoked potentials(EP), polysomnography(PSG), electronystagmography(ENG) and, transcranial doppler(TCD) ete. Clinicials and electrophysiologists should understand the technologic characteristics and general applications of each electrophysiological studies to get useful informations with using them in clinics. It is generally agreed that items of these tests are selected under the clinical examination, the tests are performed by the experts, and the test results are interpretated under the clinical background. Otherwise these tests are sometimes useless and lead clinicians to misunderstand the lesion site, the nature of disease, or the disease course. In this sense the clinical utility of neurophysiological tests could be summerized in the followings. First, the abnormal functioning of the nervous system and its environments can be demonstrated when the history and neurological examinations are equivocal. Second, the presence of clinically unsuspected malfunction in the nervous system can be revealed by those tests. Finally the objective changes can be monitored over time in the patient's status. Also intraoperative monitoring technique becomes one of the important procedures when the major operations in the posterior fossa or in the spinal cord are performed. In 1996, the Korean Society for Clinical Neurophysiology(KSCN) was founded with the hope that it will provide the members with the comfortable place for discussing their clinical and academic experience, exchanging new informations, and learning new techniques of the neurophysiological tests. The KSCN could collaborate with the International Federation of Clinical Neurophysiology(IFCN) to improve the level of the clinical neurophysiologic field in Korea as will as in Asian region.1 In this paper the clinical neurophysiological tests which are commonly used in clinical neurology and which will be delt with and educated by the KSCN i the future will be discussed briefly in order of EEG, EMG, EP, PSG, TCD, ENG, and Intraoperative monitoring.

Purpose
: The rapid development and wide popularity of Digital EEG(DEEG) is due to its convenience, accuracy and applicability for quantitative analysis. These advantages of DEEG make one hesitate to use analog EEG(AEEG). To assess the advantage of DEEG system utilizing AEEG(DAEEG) over conventional AEEG and the clinical applicability, a DAEEG system was developed and applied to animal model. Methods : Sprague-Dawley rat as status epilepticus model were used for collecting the EEG data. After four epidural electrodes were inserted and connected to 8-channel analog EEG(Nihon-kohden, japan), continous EEG monitoring via computer screen was done from two rats simultaneously. EEG signals through analog amplifier and filters were digitized at digital signal processor and stored in Window-based pentium personal computer. Digital data were sampled at a rate of 200 Hz and 12 bit of resolution. Acquisition software was able to carry out 'real-time view, sensitivity control and event marking' during continuous EEG monitoring. Digital data were stored on hard disk and backed-up on CD-ROM for off-line review. Review system consisted of off-line review, saving and printing out interesting segment ad annotation function. Results : This DAEEG system could utilize most major functions of DEEG sufficiently while making a use of an AEEG. It was easy to monitor continuously compared to conventional AEEG and to control sensitivity during ictal period. Marking the event such as a clinical seizure or during injection was less favorable than AEEG due to slowed processing speed of digital processor and central processing unit. Reviewing EEG data was convenient, but paging speed was slow. Storage and mangement of data was handy and economical. Conclusion : Relatively simple digital EEG system utilizing AEEG can be set-up at a laboratory level. It may be possible to make an application for clinical purposes.

Recent advances in computer science made EEG more informative device. Quantification and mapping of the EEG and its incorporation with MRI or other neuroimaging enabled us source localization more clearly. With spectral analysis of EEG waves, neurometrics is a basic concept of cortical EEG mapping. Multivariate analysis and discriminant analysis of neurometric afford improved detectability of abnormal EEG and differential diagnosis as well. Quantitative EEG analysis is very useful in clinical field of bipolar and monopolar affective disorders, schizophrenia, and dementia. Dementia of Alzheimer type and vascular dementia may be reliably defferentiaed by quantitative EEG analysis. Wide variation of normal EEG, difficulty in detection of very brief abnormal discharges, and artifacts commonly occurs in EEG recording are major confrontation in quantitative EEG analysis. Despite of these disadvantages, application of chaos and neural network theory, advances of high-resolution EEG, and the development of other functional neuroimaging techniques may enhance the role of quantitative EEG.

Purpose
: This study was performed to evaluate the antistress effects of two aromatic blends being composed of synergic essential oils and also to differentiate its effectiveness between two. Methods : The subject were 20(10 for men, 10 for women) for vital factors and another 20(10 for men, 10 for women) for serum catecholamine. Vital factors(blood pressure, pulse), electroencephalography, psychological tests(SACL, STAI) and serum catecholaminewere applied to the subjects. Results : 1. All two aromatic synergic blends revealed no significant difference of vital factors after inhalation but stable conditions generally by lowering pulse and blood pressure after inhalation. 2. Both blends were significantly valuable in antianxiety and antistress effects statistically. There were no statistically difference between two blends. 3. There were no significant difference in all brain waves after inhalation of two blends but generally stable brain waves were seen in all areas. 4. There were antistress effects of both blends in accordance of decreased serum catecholamines after inhalation of both blends. There were no significantly difference between two blends statistically. Conclustion : Both two aromatic synergic blends reached effective antistress and antianxiety states after inhalation of each blends. There were no significant difference between two blends. Further studies be considered. Also clinical applications of these two aromatic synergic blending oils to develop the aromatic products would be affordable in the future.

Background
: We studied EEG changes during pilocarpine-induced status epilepticus(SE), a widely used model whose EEG characteristics have not been fully described previously. Method : Male Sprague-Dawley rats weighing 250-350 grams were used as subjects. SE was induced 5-7 days after placement of chronic epidural electrodes, using 360-380mg/Kg pilocarpine IP. Rats were observed with continuous EEG recording following pilocarpine injection until end of the SE episode. Results : SE occurred in 10/12 rats studied. SE began with a series of discrete seizures 11.1?.93 minutes after pilocarpine injection. 5.2?.71 seizures occurred over 10.9?.62 minutes, until the EEG converted to a waxing and waning pattern, during which the amplitude and frequency of epileptiform activity increased. After 1.4?.82 minutes, a pattern of continuous high amplitude rapid spiking was established. Continuous spiking continued for 3.4?.48 hours with a very gradual decline in amplitude and frequency, until periodic epileptiform discharges(PEDs) began to occur. The EEG consisted primarily of PEDs for another 7.4?.09 hours, until electrographic generalized seizures beganto occur. These continued for 5.8?.82 hours until death. Duration of SE was 17.0?.88 hours. Flat periods were a prominent feature during all EEG patterns in this model. Conclusion : EEG features distinctive in pilocarpine SE(but not unique to it) include flat periods during all patterns and resumption of continuous spiking episodes after the onset of PEDs. The sequence of discrete seizures to waxing and waning to continuous spiking to PEDs was identical to that which has been described in humans and other animal models.

Purpose
: Eyeball movement is one of the main artifacts in EEG. A new approach to the removal of these artifacts is presented using independent component analysis(ICA). This technique is a signal-processing algorithm to separate independent sources from unknown mixed signals. This study was performed to show that ICA is a useful method for the separation of EEG components with little data deformity. Methods : 12 sets of 10 sec digital EEG data including eye opening and closure were obtained using international 10~20 system scalp electrodes. ICA with 18 tracings of double banana bipolar montage was performed. Among obtained 18 independent components, two components, which were thought to be eyeball movements were removed. Other 16 components were reconstructed into original bipolar montage. Power spectral analysis of EEGs before and after ICA was done and compared statistically. Total 12 pairs of data were compared by visual inspection and relative power comparison. Results : Waveforms of each pair looked alike by visual inspection. Means of relative before and after ICA were 29.16% vs. 28.27%, 12.12% vs. 12.41%, 10.55% vs. 19.52%, and 19.33% vs. 18.33% for alpha, beta, theta, and delta, respectively. These values were statistically same before and after ICA. Conclusions : We found little data deformity after ICA and it was possible to isolate eyeball movements in EEG recordings. Many other components of EEG could be selectively separated using ICA.

Electroencephalography(EEG) involves the recording and analysis of electrical signals generated by brain. Resolution of true electrical brain activity requires three elements: good equipment, meticulous recording technique, and informed interpretation of data. Every electroencephalographer should be familiar with the science and engineering underlying clinical EEG. This article reviews principle of EEG instrument & methods of recording; History of EEG, EEG instrument, EEG amplifier & its control, Calibration, Electrode, Electrode placement, Montage, and Electrical safety.

Electroencephalogram (EEG) is an indispensable tool for diagnosis of epilepsy and is the only assisting barometer of complete remission of epilepsy, which means prolonged, persistent suppression of cortical excitement in epileptic focus in addition to the clinical control of epileptic seizure. The specific morphologies or distribution of epileptic form discharges give us good information for the classification of seizure or epilepsy and epileptic syndromes, which consists of

The EEG plays an important diagnostic role in epilepsy and provides supporting evidence of a seizure disorder as well as assisting with classification of seizures and epilepsy syndromes. There are a variety of electroclinical syndromes that are really defined by the EEG such as Lennox-Gastaut syndrome, benign rolandic epilepsy, childhood absence epilepsy, juvenile myoclonic epilepsy and also for localization purposes, it is vitally important especially for temporal lobe epilepsy. The sensitivity of first routine EEG in diagnosis of epilepsy has been known about 20-50%, but this proportion rises to 80-90% if sleep EEG and repetitive recording should be added. Convincing evidences suggest that the EEG may also provide useful prognostic information regarding seizure recurrence after a single unprovoked attack and following antiepileptic drug (AED) withdrawal.Moreover, patterns in the EEG make it possible to disclose an ictal feature of nonconvulsive status epilepticus, separate epileptic from other non-epileptic episodes and clarify the clues predictive of the cause of the encephalopathy (i.e., triphasic waves in metabolic encephalopathy).Therefore, regardless of its low sensitivity and other pitfalls, EEG should be considered not only in the situation of new onset episode such as a newly developed, unprovoked seizure or a condition manifesting decreased mentality from obscure origin, but also as a barometer of the long-term outcome following AED withdrawal.

Electroencephalogram (EEG) is a representative diagnostic tool in epilepsy. However, there are several points of debate on the role of EEG in diagnosis and management of epilepsy. We suggest that EEG has some limitations for differential diagnosis from nonepileptic episodic diseases, classification of epilepsy, prediction of recurrence, and evaluation of treatment response. Interictal EEG cannot diagnose or exclude epilepsy because interictal epileptic discharge (IED) is frequently absent in epilepsy and can appear in nonepileptic conditions. Although EEG is helpful in classification of epilepsy, focal spikes in generalized epilepsy and secondary bilateral synchrony in localization related epilepsy cause interrater disagreement. It is controversial whether EEG predicts recurrence after the first seizure in adults. The predictive value of EEG in antiepileptic drug (AED) withdrawal is not absolute. The prognosis after AED withdrawal depends on epilepsy syndrome. Many studies could not confirm the value of EEG in assessing the treatment response. After all, epilepsy is clinically diagnosed and assessed. Interictal EEG alone does not provide decisive information and routine follow-up of EEG is not recommended.

Even though the origin and nature of nocturnal paroxysmal dystonia (NPD) remains unclear, it has been considered as a manifestation of the nocturnal frontal lobe epilepsy. We report a 17-year-old man with abnormal stereotyped movement during sleep. Video-EEG monitoring, ictal SPECT and night polysomnography did not show any evidence of epilepsy. However, the partial response to large dose of carbamazepine and the scoring according to the frontal lobe epilepsy and parasomnias (FLEP) scale suggest his events could be classified as epilepsy. Therefore we think the FLEP scale might be a useful tool for differential diagnosis in a patient presenting NPD.

B a c k g r o u n d : Spatial analysis of EEG is a phenomenal assessment and not so informative for phase space anddynamic aspect of EEG data. In contrast, nonlinear EEG analysis attempts to characterize the dynamics of neural networksin the brain. We have analyzed the features of EEG nonlinearly in subjects with white matter change on brainMRI and compared the results with cognitive function in each.Methods : Digital EEG data were taken for 30 seconds in 9 subjects with white matter degeneration and in 5 healthynormal controls without white matter change on MRI. Then we analyzed them nonlinearly to calculate the correlationdimension(D2) using the MATLAB software. The cognitive function was assessed by 3MS(modified mini-mental stateexamination). The severity of white matter change was assessed by Scheltens scale.Results : The mean D2 value of normal control was greater than that of white matter degeneration group. The D2s ofsome channels were correlative with 3MS and degree of white matter degeneration significantly.Conclusions : nonlinear analysis of EEG can be used as one of adjuvant functional studies for prediction of cognitiveimpairment in subjects with white matter degeneration and subcortical white matter change can be influential on cognitivefunction and correlation dimension of EEG.

Background
s and objective : EEG reflect dynamic changes of continuous neuronal activities by internal and externalstimuli. The aim of this study is to quantify nonlinearly the local dynamic differences among EEG data correspondingto different states of brain.Methods : EEG was recorded from twelve healthy normal subjects(mean age, 29.7 years; 8 men and 4 women) usingdigital EEG machine. 18-channel EEG data were selected during eyes closed(EC), eyes open(EO), and mental arithmetic(MA) in each subject. Correlation dimension(D2) and largest Lyapunov exponent(LLE) were calculated fromthree states and average value was mapped 2 dimensionally and compared with each other.Results : The distribution of D2 was relatively symmetric and its value was higher in frontal than in parieto-occipitalregion during EC. These findings were reversed during EO. Bilateral centro-temporo-parietal region showed high D2value in MA compared with those in EC, which was more prominent in left side. LLE was larger than zero in all stateand showed significant differences among EC, EO and MA(p=0.000).Conclusion : These results suggest that nonlinear analysis of EEG can quantify dynamic state of brain.

Background
A dry-type electrode is an alternative to the conventional wet-type electrode, because it can be applied withoutany skin preparation, such as a conductive electrolyte. However, because a dry-type electrode without electrolyte has highelectrode-to-skin impedance, an impedance-converting amplifier is typically used to minimize the distortion of the bioelectricsignal. In this study, we developed an active dry electroencephalography (EEG) electrode using an impedance converter, andcompared its performance with a conventional Ag/AgCl EEG electrode. Methods: We developed an active dry electrode withan impedance converter using a chopper-stabilized operational amplifier. Two electrodes, a conventional Ag/AgCl electrodeand our active electrode, were used to acquire EEG signals simultaneously, and the performance was tested in terms of (1)the electrode impedance, (2) raw data quality, and (3) the robustness of any artifacts. Results: The contact impedance ofthe developed electrode was lower than that of the Ag/AgCl electrode (0.3