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Biomedical subjects

E Marg

Publications and source records attributed to E Marg.

At least 19 recordsLinked to original sources
PubMed1991

Magnetostimulation of vision: direct noninvasive stimulation of the retina and the visual brain.

The history of magnetophosphenes and their closely related predecessor, electrophosphenes, is described from the mid-18th century to the present time. The current era of magnetic stimulation started in 1985 with the development of a practical capacitor-discharge electromagnetic stimulator by Barker and his colleagues at the University of Sheffield, and their application of it to the brain with Merton and Morton at the National Hospital, London. The safety of magnetostimulation of the brain is discussed as well as the advantages of magnetostimulation over electrostimulation. Principles of magnetostimulation of nerves and magnetic measurement are considered. Effects on motor and sensory systems of the brain are described including magnetic perceptual suppression in the visual cortex and other pioneering work of Amassian, Cracco and Maccabee at SUNY Health, Brooklyn. Magnetophosphenes from retinal and cortical magnetostimulation are distinguished. Now that visual cortical stimulation is possible with the strong magnetic pulses generated by capacitor-discharge instruments, the functional viability of the visual cortex may be tested directly and noninvasively.

Electric Stimulation↗
PubMed1988

Imaging visual function of the human brain.

Imaging of human brain structure and activity with particular reference to visual function is reviewed along with methods of obtaining the data including computed tomographic (CT) scan, magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and positron emission tomography (PET). The literature is reviewed and the potential for a new understanding of brain visual function is discussed. PET is reviewed from basic physical principles to the most recent visual brain findings with oxygen-15. It is shown that there is a potential for submillimeter localization of visual functions with sequentially different visual stimuli designed for the temporal separation of the responses. Single photon emission computed tomography (SPECT), a less expensive substitute for PET, is also discussed. MRS is covered from basic physical principles to the current state of the art of in vivo biochemical analysis. Future possible clinical applications are discussed. Improved understanding of the functional neural organization of vision and brain will open a window to maps and circuits of human brain function.

Brain↗
PubMed1988

[HIV infection: neuropsychiatric symptoms].

Basing on the actual publications, the most important neurological and psychopathological symptoms of HIV-infection are systematically reported. Opportunistic infections are producing important neurological symptoms. A case of Cryptococcus neoformans-Infection of the brain is described.

Acquired Immunodeficiency Syndrome↗
PubMed1979

[The clinical picture of essential myoclonus].

Familial essential myoclonus, a rare hereditary disease, is characterized by spontaneous myocloni without any other neurological and psychic symptoms. The report deals with two sisters who suffered from the disease and in whose family the syndrome occurred in two more generations. The outlook for a favourable therapeutic effect is limited. The prognosis is good.

Adolescent↗
PubMed1978

Computer-assisted eye examination. VI. Identification and correction of errors in the Refractor III system for subjective examination.

A computer-assisted subjective eye examination was administered to 80 patients. They were also examined in the conventional manual way. The results of the computer-assisted examination were compared with those obtained by conventional subjective methods to identify errors of hardware, software, and optometric flow charting and other problems. An 87.5% satisfactory prescription level was found for the distance prescription. The 12.5% unsatisfactory results are accounted for by several kinds of error. The percentage of unsatisfactory refractive results was greater for near than for distance measures because of special flow-chart and software problems, which were subsequently corrected. With implementation of the changes initiated as a result of this investigation, satisfactory refractive results approaching 95% can be expected.

Adolescent↗
PubMed1978

[Lymphadenopathy in phenytoin treatment].

The authors report on a 20-year-old patient who developed hydantoin lymphadenopathy during treatment with diphenylhydantoin. The problems associated with clinical and histological delimination from malignant lymphomata are described by reference to the literature. Hydantoin lymphadenopathy is regarded as a drug-induced allergic and toxic process.

Adult↗
PubMed1978

A reconsideration of visual evoked potentials for fast automated ophthalmic refractions.

Visual evoked potentials (VEP's) recorded from the scalp are sensitive to retinal image sharpness and thus to changes in the refractive state of the eye. Initially the responses to checkerboard flash or reversal stimuli were computer-averaged in order to raise the signal above the noise, primarily the electroencephalogram (EEG). Recently analogue Fourier signal analysis has been proposed for using the VEP for rapid clinical refraction. We have confirmed that this method can measure the spherical refractive state to within +/- 0.50D. However, because of large slow-wave fluctuations, measurements of changes within +/- 1.00D are not always clear. Despite its promise the method does not appear to be clinically useful at present.

Diagnosis, Computer-Assisted↗
PubMed1978

Computer-assisted eye examination. VII. Final evaluation of the refractor. III system for subjective examination after reducing software and hardware errors.

Eighty patient-volunteers were refracted by the computer-assisted Refractor III system and the results were compared with those obtained by the usual manual method. For the distance prescription 95% of the results were satisfactory. For the near add all were satisfactory. Relative validity of the system was also measured objectively by repeatability data. System test differences and test-retest manual-examination data were found comparable, indicating that the validity of the system is similar to that of the manual method. Further developments are expected to improve reliability, simplify maintenance, and extend testing so that the system will be an economical and useful instrument in eye clinics.

Adolescent↗
PubMed1977

Computer-assisted eye examination. V. Preliminary evaluation of the refractor III system for subjective examination.

A computer-assisted subjective eye examination was administered to 78 patients as they volunteered. They were also examined in the conventional, manual way, some before and some after the computer-assisted examination. Results of the computer-assisted examination were compared to those obtained by conventional subjective methods. For the distance prescription, satisfactory agreement was obtained for 83% of the patients. The 17% unsatisfactory prescriptions were subdivided into about 6% avoidable errors (caused by errors in software, hardware, or optometric flow charts), about 6% errors of undetermined cause, and 4% fundamental errors (caused by patient's physical and mental impairment or confusion). A similar analysis is made for the near add. With further development of the system it is expected that between 90 and 96% of patients in an optometric clinic can be successfully examined by this computer-assisted method.

Adolescent↗
PubMed1976

[Stevens-Johnson syndrome as an early allergic reaction to diphenylhydantoin].

The case of a 19-year-old patient is reported who during treatment with phenytoin (5,5-dephenylhydantoin) developed a Stevens-Johnson syndrome. The symptomatology is regarded as an early allergic reaction to phenytoin. The risks involved in using a high inital dose are discussed with reference to this particular case.

Adult↗