| Juhan Kim | 6 Articles |
The performance of electroencephalogram (EEG) recordings is affected by electrode type, electronic parameters such as filtering, amplification, signal conversion, data storage; and environmental conditions. However, no single method has been identified for optimal EEG recording quality in all situations. Therefore, we aimed to provide general principles for EEG electrode selection as well as electronic noise reduction, and to present comprehensive information regarding the acquisition of satisfactory EEG signals. The standards provided in this document may be regarded as Korean guidelines for the clinical recording of EEG data. The equipment, types and nomenclature of electrodes, and the details for EEG recording are discussed.
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Electroencephalography (EEG) is frequently used to assist the diagnosis of brain death. However, to date there have been no guidelines in terms of EEG criteria for determining brain death in Korea, despite EEG being mandatory. The purpose of this review is to provide an update on the evidence and controversies with regarding to the utilization of EEG for determining brain death and to serve as a cornerstone for the development of future guidelines. To determine brain death, electrocerebral inactivity (ECI) should be demonstrated on EEG at a sensitivity of 2 μV/mm using double-distance electrodes spaced 10 centimeters or more apart from each other for at least 30 minutes, with intense somatosensory or audiovisual stimuli. ECI should be also verified by checking the integrity of the system. Additional monitoring is needed if extracerebral potentials cannot be eliminated. Interpreting EEG at high sensitivities, which is required for the diagnosis of brain death, can pose a diagnostic challenge. Furthermore, EEG is affected by physiologic variables and drugs. However, no consensus exists as to the minimal requirements for blood pressure, oxygen saturation, and body temperature during the EEG recording itself, the minimal time for observation after the brain injury or rewarming from hypothermia, and how to determine brain death when the findings of ECI is equivocal. Therefore, there is a strong need to establish detailed guidelines for performing EEG to determine brain death.
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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.
Background
s : Carpal tunnel syndrome(CTS) is a common condition that is usually diagnosed by electrophysiologic studies. However, CTS provide limited information to determine the causes of CTS and to choose the treatment method. We evaluated diagnostic sensitivity of MR imaging and treatment decisions by MR imaging in electrodiagnosed CTS. Methods : 14 patients (26 wrists) with electrodiagnosed CTS were studied using MR imaging. In 26 wrists for which axial T1 & T2 weighted images were obtained at 1.5T with a decided wrist coil. Previously described MR imaging of CTS such as increased median nerve signal, flattening of median nerve, reticular bowing, tenosynovitis and space occupying lesions were retrospectively evaluated. Degree of improvement was evaluated by global symptom score(GSS). The GSS rated symptoms from 0 (no symptoms) to 10 (severe0 in each of five categories; pain, numbness, paresthesia, weakness/clumsiness, and nocturnal awaking. Subjects' GSS was recorded at baseline, 2 weeks, 1 month,6 months after treatment. We decided to medical treatment that showed mainly inflammatory sign such as increased median nerve signal, tenosinvitis and to surgical treatment such as space occupying lesion, high canal pressure sign. Results : MR imaging showed that increased median nerve signal were in 29 wrists(77%), flattening of median nerve were in 6 wrists (23%), reticular bowing were in 3 wrists (12%), tenosyovitis were in 8 wrists (32%), decreased canal size in 2 wrists (7.6%), space occupying lesion were in 1 wrists (4%). A good outcome was revealed in 21 wrists by medical treatment that showed mainly increased median nerve signal, tenosynovitis. The mean GSS were 27.7 at baseline 11.2 at 2 weeks, 11.0 at 6 month in medical treatment group. Another 5 wrists had surgical treatment shown by ganglion and high canal pressure sign such as median nerve flattening, reticular bowing, decreased canal size : 3 wrists had good prognosis, but 2 wrists (one patient) had no significant improvement due to small carpal tunnel size. Conclusions : Our results are in agreement with most previously described MR imaging signs of CTS. MR imaging plays an important role in several cases and especially in the assessment of failure of surgical treatment. Knowledge of MR findings may permit more rational choice of treatment.
Background
: Backpack palsy was described in military personnel with shoulder girdle and proximal upper extremity symptoms, predominantly motor in nature related to the use of heavy backpack. Currently, backpack were used for sports, transpoting, school books and child carriers. We evaluated clinical and electrophysiological feature of backpack palsy. Methods : We included 11 patients with brachial plexopathy as a results of wearing a heavy backpack on long distance marches. All patients were done routine blood sampling, chest X-ray, C-spine X-ray and electrophysiological studies. Results : All patients were right handed person and were not as having a thoracic outlet syndrome. Sensory changes were main initial symptoms and major persistent symptoms were motor weakness. 9 patients(81.8%) were damaged the brachial plexus on non-dominant side, 1 patients was dominant and 1 patient was bilateral involvement. 10 patients(90.9%) were damaged to upper trunk of the brachial plexus by EMG findings. The prognosis was good, 10 patients(90.0%) were complete recovery during 8 weeks, 1 patient was developed reflex sympathetic dystrophy confirmed by 3-phase bone scan. Conclusions : Depression of the clavicle and costoclavicular space probably plays a certain role in pathogenic mechanism. The non-doinant side is more frequently affected, probably due to underdevelopment of the musculature in that side.
Miller Fisher syndrome(MFS) has been the focus of conflicting opinions regarding the peripheral versus the central nature of the site of major neural injury. We present out electrophysiological findings in one case of MFS to help clarify the patterns of peripheral nerve injury in this syndrome. A 45-year-old man visited our hospital due to sudden diplopia. Initial examination revealed internuclear opthalmoplegia. The next day, his symptoms rapidly aggravated to complete external opthalmoplegia, ataxia, and areflexia with hand and foot numbness. Serial electrophysiological studies were performed. The results of brainstem evoked potential(BAEP) and blink reflex were normal in the serial studies. Motor and sensory nerve conduction study(NCS) were normal findings in second hospital day, but ulnar sensory nerve shows no sensory nerve action potential(SNAP) and sural sensory conduction velocity was delayed in 7th hospital day. Our patient's clinical presentation began to improve on 15th hospital day, and his electrophysiologic study showed improvement on 29th hospital day. We believe that all the manifestations of MFS can be explained by the involvement of peripheral nerves without brainstem or cerebellar lesion with the serial electrophysiological studies.
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