Biomedical subjects
Publications and source records attributed to G Sack.
The results of the studies carried out in four carriers of characteristics are presented under localistic aspects proceeding from the different local distribution of rhythmized activity around 4/s with unipopular and bipolar lead technique. A hypothesis of the origin of the activity is presented which would be in agreement with its distribution characteristics and reactivity.
Six persons showing what is called slow posterior activity (4/s rhythm) in the electroencephalogram were reexamined after a period of five years. Sensorimotor reaction times were recorded in addition to the electroencephalogram which was analyzed for the frequency of LPA and for the degree of stability of time dependence. The frequency and distinctness of LPA were found to be stable after five years (r = 0.09 and 0.82, respectively; p less than 0.001), whereas the alpha rhythmus of the subjects had undergone considerable changes (r = 0.34; p greater than 0.05). The extension of reaction times to be observed under the influence of LPA was also seen to remain constant (r = 0.79; p less than 0.05). Accordingly, LPA proved an extremely stable characteristic which did not show any substantial variations in the course of five years.
A case of pattern-sensitive epilepsy is reported which is characterized in that the pattern is formed from images of human faces with clearly recognizable eyes. Similarities to previously reported cases of pattern-sensitive epilepsy as well as dissimilarities from those cases are discussed.
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Electroencephalographic examinations of eighteen patients with spinocerebellar ataxias and of thirteen normal sibs of four of the subjects are reported. The authors frequently observed low levels of potential and a tendency toward slackening in basic activity, which is in agreement with data presented in the literature; theta-delta inclusions in the temporal regions were found especially in cases of cerebellar ataxia. Examinations of the sib frequently showed low-potential curves. However, the use of electroencephalography for the purpose of identifying, in the case of hereditary ataxia, latently diseased sibs for heterozygous individuals does not seem possible.