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Biomedical subjects

L Deecke

Publications and source records attributed to L Deecke.

At least 109 records · Page 6Linked to original sources
PubMed1994

Tactile mental imagery in sighted persons and in patients suffering from peripheral blindness early in life.

Patterns of cortical activity as measured by scalp-recorded event-related slow negative DC potential shifts were recorded in 9 early blind and 23 sighted normals while they imagined the feel of textures with the fingertips of one hand. All sighted subjects reported to have concomitant visual imagery as well. Hence, it was not surprising to observe occipital negative shifts, previously described as a sign of occipital visual cortex involvement in visual mental imagery. Though having never had visual perception, the blind, too, had occipital negativities. Their absolute amplitudes were smaller than in the sighted, not only occipitally but also and more pronounced at other areas, particularly frontally where amplitudes were even positive. On the hypothesis that the smaller overall amplitudes in the blind could obscure topographical differences between groups, the relative distribution of negativity across the scalp was assessed, using normalized data. Such normalized parameters significantly differed between groups, indicating that the occipital potentials of the blind were relatively more negative as related to the other scalp areas, than were the occipital potentials of the sighted as related to the other scalp areas. This occipital finding might indicate a participation of the blind's visually deprived occipital cortex in tactile imagery. Second, parietal DC potentials were maximal over the hemisphere contralateral to the imaging hand, possibly indicating involvement of the contralateral parietal association cortex in tactile imagery. Reasons why this was true only for the sighted, are discussed.

Adolescent↗
PubMed1994

Anterior frontal cortex and the effect of proactive interference in word pair learning--results of Brain-SPECT.

Technetium-99m-HMPAO-Brain-SPECT was performed twice in each of 12 right-handed students. The control condition was a standard word pair learning task. In the experimental condition, subjects had to overcome the detrimental effect that older memories exerted on the acquisition of new information (controlling proactive inhibition): they were presented with taxonomically similar words, which could easily be mixed up, and which reappeared in each list, but in different pairings. Results revealed an increase in right anterior frontal flow indices with the experimental condition. These results parallel the observed increase in negative event-related DC potential shifts. UHL et al. [J. cognit. Neurosci. 2, 373, 1990] recorded at frontopolar (Fp3, Fp4) scalp projections, although the extent of modulation was much higher for DC potentials (100%) than it was for SPECT (3%) thus suggesting different sensitivity.

Adult↗
PubMed1994

[Intraoperative irrigation of the subdural space after traumatic spinal cord lesions (based on 4 case examples)].

In experimental investigations on primates it has been shown that after a standardized transverse lesion of the spinal cord subdural perfusion with an artificial liquor solution (Elliot's B solution) of the region of the injury improved the eventual motoric function achieved. We tried to reproduce these experimental results in the management of four patients with acute spinal cord injury after trauma of the vertebral column. Due to the difficulty of an exact evaluation in this initial study an objective positive effect of perfusion with Ringer solution (at 37 degrees C) could not be confirmed in these patients. Nevertheless, the possibility of a positive influence of this adjuvant operative treatment on spinal cord injuries should be studied in a greater collective of patients. A multicentre study would be essential because of the limited number of cases in a single hospital.

Adult↗
PubMed1993

Changes of serum lipid patterns during long-term anticonvulsive treatment.

Serum lipids were determined in 97 patients (56 men, 41 women; ages 42 +/- 15 years) undergoing long-term anticonvulsive treatment (longer than 6 months). The total group showed increased total cholesterol, decreased high-density lipoprotein HDL cholesterol, an increased ratio of total to HDL cholesterol, and decreased apolipoprotein A1 and B values compared to population means. Considering males and females separately, all differences were significant (P < 0.01) in men, whereas in women only the differences in HDL cholesterol, ratio of total to HDL cholesterol, and apolipoproteins A1 and B reached the level of statistical significance. Considering the different anticonvulsant groups, cholesterol was significantly increased only in phenytoin-treated males; HDL cholesterol was significantly lowered and the ratio of total to HDL cholesterol significantly increased in all groups. Apolipoprotein A1 levels were significantly decreased in phenytoin-treated females and valproate-treated patients of both sexes. Apolipoprotein B levels were significantly decreased in all groups except carbamazepine-treated males. Especially in men treated with anticonvulsants these lipid levels may be considered a risk factor for atherosclerosis.

Adolescent↗
PubMed1993

Topographic mapping of EEG during sleep.

Topographic aspects of all night sleep EEG were investigated in 10 healthy volunteers (age 20-35 years). EEG brain maps showed an increase of delta power from stage 1 to 4, a decrease of alpha power most pronounced parieto-occipitally and a slowing of the dominant alpha frequency. Differences of EEG power in different sleep stages (as compared to wakefulness) are displayed topographically. Analysis of the course of stage 2 showed an increase of delta power and a decrease of theta power in the first sections of the night, and an increase of beta power later in the night.

Adult↗
PubMed1993

Central nervous system function after cardiopulmonary bypass.

In a prospective study, an elderly group of patients (n = 63, 47 male, 16 female, age 40-65 years) was examined before and after open-heart surgery under cardiopulmonary bypass: postoperatively, 19 patients (30%) showed no clinical neuropsychiatric symptoms, whereas in 35 patients (56%) mild or transient neurological signs and in nine (14%) severe neurological complications were found. The postoperative EEG changes were characterized by a slight delta-theta increase, an alpha decrease and a significant slowing of the dominant frequency from 9.7 to 9.3 Hz. In brainstem auditory evoked potentials no changes were found, and in somatosensory evoked potentials (median nerve) the latency of the early cortical component, N20, increased. Cardiovascular reflexes showed increased changes, similar to those found in autonomic neuropathies. In the neuropsychological test battery, the Visual retention test (Benton) and the Rorschach test showed slight postoperative improvement, whereas other psychometric variables (flicker fusion frequency, reaction time) did not change. Despite an improved operative technique some minor clinical and neurophysiological disturbances of the central nervous system remain. However, specific pre- or peri-operative risk factors for these postoperative disturbances or complications could not be identified.

Adult↗
PubMed1993

Occurrence of epileptiform activity in the routine EEG of epileptic patients.

In a retrospective study, the occurrence of epileptiform activity (EA) in routine EEG records of epileptic patients was investigated. Data were obtained from 1078 EEGs of 373 patients (199 men and 174 women; aged 17-87 (mean 34.2 +/-14.7)). The percentage of 38% of patients with EA in a single EEG could be increased to 77% by repeated records. After the 5th record however, the gain in new information decreased remarkably. No differences between seizure types could be detected. There was a relationship between EA and nonspecific EEG abnormalities. High EA rates were found for short time intervals since last seizure, young patients, long durations of the seizure disorder and for high seizure frequencies.

Adolescent↗
PubMed1993

Wilson's disease: evidence of subgroups derived from clinical findings and brain lesions.

Using exploratory factor analysis, we prospectively investigated neuropsychiatric symptoms and structural brain lesions of 47 patients with proven Wilson's disease and identified three subgroups. The first subgroup clinically exhibited bradykinesia, rigidity, cognitive impairment, and an organic mood syndrome and by MRI showed a dilatation of the third ventricle. The second subgroup was characterized by ataxia, tremor, reduced functional capacity, and focal thalamic lesions. The third subgroup showed dyskinesia, dysarthria, an organic personality syndrome, and focal lesions in the putamen and in the pallidum.

Adolescent↗
PubMed1993

[Guidelines for drug treatment of multiple sclerosis].

Strategies proposed for the treatment of multiple sclerosis are numerous and sometimes contradictory. This review summarizes the most recent studies on the treatment of multiple sclerosis. Possibilities of influencing progression of the disease and the degree of disability suffered by patients are discussed. The treatment of acute relapses with high-dose intravenous glucocorticoids is now widely accepted because it has been shown that the duration of the relapse is reduced. Interval therapy between relapses and treatment of the chronic progressive variant of multiple sclerosis are still under debate. Immunosuppression, in particular with azathioprine, appears to have a positive effect on the long-term outcome. Whether other regimens, e.g., treatment with recombinant lymphokines, have a therapeutic effect, is difficult to assess at present since these substances have either never been tested in controlled double blind studies or the results of these studies are not yet available.

Antineoplastic Agents↗
PubMed1993

[Visuo-vestibular interaction in determination of orientation behavior in weightlessness].

We measured vertical vection during a short term space flight and 2 long term space flights to evaluate the state of adaptation to microgravity. The first phase of microgravity adaptation showed with major changes of vertical vection perception such as "inverted vection". This method will be used to reveal mechanisms of adaptation to altered vestibular inputs.

Adaptation, Physiological↗
PubMed1993

[Low dose acetylsalicylic acid in secondary prevention of stroke].

Acetylsalicylic acid (ASA) as secondary prophylaxis after ischaemic cerebrovascular events is well established and its efficacy unquestioned since over 15 years. According to the results of two European studies a dose of 100 mg per day is sufficient to reduce the incidence of further stroke, myocardial infarction, and death due to cardiovascular causes. This satisfactory response to low-dose ASA applies to patients with transient ischaemic attacks, reversible ischaemic events, and minor strokes. In cases with severe cardiac disease, however, a high dosage of ASA or anticoagulation therapy may be necessary to prevent further vascular events.

Aspirin↗
PubMed1993

Posturographic measurement of body sway in survivors of severe closed head injury.

Postural imbalance was measured in 39 survivors of severe closed head injury 7 to 66 months after head injury using a posturographic platform. The results were compared with those derived from age-matched healthy control subjects. Severe postural imbalance, particularly in an anteroposterior direction, was found in 16 patients, whereas 9 patients showed moderate imbalance and 14 patients showed normal results in the posturographic investigation. Low initial Glasgow Coma Scale scores and deep parenchymal brain lesions demonstrated by magnetic resonance imaging were shown to be significant indicators of subsequent severe postural imbalance. The duration of posttraumatic amnesia, the localization and size of cortical contusions and subcortical white matter lesions, on the contrary, were not associated with postural imbalance in the long-term outcome.

Adolescent↗
PubMed1992

[Neurological complications in 95 patients with HIV infection. A retrospective analysis of anamnestic and clinical data].

This retrospective investigation of neurological deficits in 95 consecutive patients (77 men, mean age 35 years; 18 women, mean age 28 years) infected by the human immunodeficiency virus showed that 61% of the female and 47% of the male patients exhibited neurological deficits. In 18% of the total population neurological deficits were the initial sign of acquired immunodeficiency. In addition, we found that a history of headaches and the clinical finding of mental impairment as well as internistic symptoms were significantly correlated with neurological deficits. Patients suffering from cerebral toxoplasmosis developed mental impairment significantly more often than patients with central nervous symptoms of other etiogenesis. Furthermore, it was found that HIV-infected women manifested peripheral neuropathies more often than HIV-infected men. The overall mortality rate over the investigation period of 30 months was 28%. The results of our retrospective investigation indicate that HIV-infected patients have a high risk of developing lesions of the central and peripheral nervous system during the course of the disease. Various reasons might be responsible for these findings: neurotropy and metamorphosis of the human immunodeficiency virus, opportunistic infections and tumors, vitamin deficiencies, and a variety of diseases prior to HIV-infection.

AIDS Dementia Complex↗
PubMed1992

Changes of cortical activity when executing learned motor sequences.

Fifteen right-handed subjects performed a learned sequence of four movements (flex index finger, extend hand, extend index finger, flex hand) either with their left or their right hand. The sequence of movements had to be continuously repeated for 20 s (period of execution). In the beginning of each period of execution large negative DC potentials were recorded in positions located above the mesial fronto-central cortex (Cz) and the sensorimotor hand areas of either hemisphere (C3 and C4). In contrast, DC potentials were absent in Cz at the end of the period of execution. In recordings from a position above the sensorimotor hand area contralateral to the performing side, negative DC potentials declined to some extent during task execution but were still present at the end of the period. Variations of both the amplitude and topography of negative cortical DC potentials during task-execution indicate changes of both the size and pattern of cortical activity. These findings were consistently found at both the beginning and end of the experiment. Motor performance as quantified by movement times and inter-onset latencies of movements showed no change, either during the periods of execution or when comparing the beginning of the experiment with the end. Conclusions are: (1) the execution of a learned motor sequence task cannot be associated with a particular size and pattern of cortical activity. (2) A pronounced decline of neural activity in the mesial, fronto-central area constitutes the predominant feature of the changes of cortical activity during the period of execution.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Frontal DC potentials in auditory selective attention.

Selective dichotic listening during periods of 35 sec was associated with negative shifts of the cortical DC potential. Amplitudes of negative DC potentials had maxima in frontal, in particular, in anterior frontal records. The temporal pattern of negative DC potentials was different between the fronto-lateral records of the two hemispheres: in records from the right side, DC potentials declined during the 35 sec observation period, whereas they remained sustained in those of the left side. Different instructions ("attend left ear," "attend right," "attend both") and different levels of pitch separation between deviants and standards had no effects on frontal negative DC potential shifts, which are discussed in terms of higher order control of selective dichotic listening.

Adult↗
PubMed1992

Frontocentral DC-potential shifts predicting behavior with or without a motor task.

This study was designed to investigate the predictive value of the event-related potentials (ERPs) preceding the initiation of a difficult perceptual-memory task and to investigate whether these ERPs require a motor movement on the part of the subject for their occurrence. Across 4 conditions the DC-potential shifts were recorded from 23 right-handed subjects using DC amplifiers. Although the start of each trial began with a ready signal, the conditions differed in that the subjects initiated the task by a button press in 2 conditions and the computer initiated it in 2 others without a press. The results showed that, especially in the frontocentral electrode sites, the DC-potential shifts which began those trials ending in correct performance were more negative relative to those trials ending in an incorrect response. Those conditions which required the subjects to self-initiate the trial and those which were initiated by the computer showed similar results indicating that the negative DC-potential shifts preceding correct performance are neither produced by nor depend on a task initiating motor movement. The onset of the DC-potential shifts preceded task initiation by up to 4.1 sec indicating that they were more than the Bereitschaftspotential.

Adult↗