ISSN:0002-9238    

DOI:10.1080/00029238.1995.11080522

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1995.11080523

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

ABSTRACT.From the very inception of EEG, the distinction between artifactual and cerebral electrical activity has been crucial. Dealing with artifacts effectively is an essential function of the EEG technologist and continues to be challenging. This review includes examples of common artifacts in unfamiliar guises, uncommon artifacts with identifiable characteristics, and some newer artifacts engendered by changing technology.

ISSN:0002-9238    

DOI:10.1080/00029238.1995.11080524

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

ABSTRACT.This article reviews the history of an interesting patient who presented with a prolonged complex partial seizure and headaches. An EEG was performed and showed high voltage delta activity focal to the left posterior quadrant; subsequent to this a CT scan and MRI demonstrated a calcified, ring-like lesion surrounded by edema in the same region. The lesion was surgically resected and pathology confirmed that the lesion was neurocysticercosis (NCC). NCC results when the parasitic disease cysticercosis affects the central nervous system, a complication in 60–90% of cases. This disease is common in developing countries and occurs when an individual becomes the intermediate host to the larval form of the Taenia solium, the pork tapeworm. NCC presents with a complex neurological picture making it difficult to diagnose. The clinical presentation, diagnostic results, and treatment of the disease all vary depending on the location and number of cysts, whether or not the parasite is active and alive or inactive and dead, as well as each individual's immune reaction to the disease. Seizures are the most common symptom; the most frequent seizure types seen are generalized tonic-clonic seizures (30–60%) and simple partial seizures (8–50%). Rarely are complex partial seizures the presenting complaint (2–20%). Hydrocephalus, increased intracranial pressure, meningitis, and intellectual deterioration are also symptoms frequently seen in NCC. It is necessary that NCC become more recognized in industrialized nations, especially if a patient presents with seizures or one of the other more common symptoms, and a history of recent travel to or from a developing country where NCC is unfortunately endemic.

ISSN:0002-9238    

DOI:10.1080/00029238.1995.11080525

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

ABSTRACT.There is an extensive range of EEG patterns associated with drowsiness. The occurrence of burst patterns with a sharp configuration or containing sharp transients was evaluated in 700 consecutive clinical EEGs of adults and children. All recordings included 16 channels of EEG and two channels of eye movements. Recordings included mostly bipolar but also referential montages. Patterns were classified by consensus and regarded as normal variants or of uncertain significance. The main reasons for referral were epilepsy or psychiatric disorders. One or more of 16 different patterns were found in 39% of all subjects. Vertex sharp waves were the most common (n = 178) and were initially asymmetrical in 17 cases. Hypnagogic paroxysmal spike-wave bursts were seen in 21/165 children. Sharp transients were also prominent in generalized sharp bursts (n = 21), frontocentral sharp bursts (n = 3), temporal or vertex sharp waves with alpha (n = 6), and beta bursts (n = 11). Some drowsiness patterns containing spikes included benign sporadic sleep spikes (n = 13), 6/sec spike and wave (n = 2), and 14 and 6/sec positive spikes (n = 10). Arch-shaped series of waves included the midline theta rhythm (n = 19), rhythmical temporal discharge (n = 3), and wicket spikes (n = 1). Subclinical rhythmical epileptiform discharges of adults (SREDA) were found in two subjects. Burst patterns during drowsiness occur sufficiently often in routine clinical EEG recordings to warrant their careful analysis.

ISSN:0002-9238    

DOI:10.1080/00029238.1995.11080526

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

ABSTRACT.Mismatched input electrode impedances can lead to noisy EEG and evoked potential recordings even if the electrode impedances are low. This paper presents a quantitative analysis of the phenomenon and illustrative examples.At each amplifier input, the recording electrode impedance and the amplifier's input impedance form a voltage divider. When input electrode impedances are unequal, a common mode signal that is present equally at the two locations on the patient's body appears at different magnitudes at the two (inverting and noninverting) inputs of the amplifier; thus, part of the common mode signal is amplified as if it were a differential signal. The effective common mode rejection ratio (CMRR) of the amplifier is reduced to a value that can be expressed mathematically as a function of the amplifier's ideal CMRR, its input impedance, and the impedance difference between the two input electrodes.Balanced input electrode impedances are particularly important during intraoperative monitoring, when ambient electrical noise levelsare typically high. Recordings between different types of recording electrodes (e.g., between needle and metal cup surface electrodes) are likely to produce impedance mismatches, and thus noisy recordings.

ISSN:0002-9238    

DOI:10.1080/00029238.1995.11080527

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1995.11080528

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1995.11080529

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1995.11080530

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

ISSN:0002-9238    

DOI:10.1080/00029238.1995.11080531

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor