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Biomedical subjects

L Deecke

Publications and source records attributed to L Deecke.

At least 19 recordsLinked to original sources
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↗
PubMed1992

Cortical DC potential shifts accompanying auditory and visual short-term memory.

Negative DC potential shifts appeared over the scalp during the performance of verbal and non-verbal short-term memory tasks. Three items were successively presented (presentation of memory items) and then had to be retained in memory for 3 sec (memory retention) before being compared to a probe which was either a member (in set) or not a member (out of set) of the memory set. Verbal items (the digits "1" through "9") were tested in the auditory and visual modality and non-verbal items (musical notes) were tested in the auditory modality. Stimulus modality had a significant effect on DC potential shifts during both presentation of memory items and memory retention. There was a sustained negative shift during these periods which was larger over frontal regions with auditory than with visual material whereas the negative shift was larger over posterior temporal regions with visual than with auditory material. Out of 21 subjects who participated in the study, 9 reported the use of visual images in the auditory task, 5 used subvocal auditory rehearsal in the visual task and 7 used imagery concordant with the stimulus modality being memorized. These different strategies had a significant effect on the amplitudes and distribution of the DC potential shifts. The speed of response affected the amplitude of the DC potential shifts in the frontal regions, being larger with fast RTs than with slow RTs but only when verbal items were being processed. These results indicate that stimulus modality, modality of mental imagery, and speed of scanning of the memory store affect DC potential shifts during a 3 sec period of memory retention.

Acoustic Stimulation↗
PubMed1992

Regional cerebral blood flow patterns related to verification of low- and high-imagery sentences.

Although several SPECT studies have shown left inferior occipital activation with visual imagery, the reliability of this finding remains doubtful. The present study replicated two conditions of a previous SPECT-study exploring rCBF in subjects verifying the correctness of low- and high-imagery sentences. As in the previous study, verification of high-imagery sentences was associated with higher flow rates in the left inferior occipital region and lower flow rates in the right anterior frontal region. By contrast, a bilateral increase of thalamic flow rates with imagery was not replicated, and there was a higher flow rate in the left inferior temporal region with low-imagery sentences which had not been found in the original study.

Adult↗
PubMed1992

Different risk factor profiles in young and elderly stroke patients with special reference to cardiac disorders.

The risk factors of ischemic cerebrovascular disorders in 77 young patients (< or = 40 years) were compared to those in 138 older patients (> 40 years). The risk factor profile of patients with juvenile stroke was considerably different from that of older patients. Migrainous headache and mitral valve prolapse occurred more frequently in the younger age group, whereas hypertension, diabetes mellitus, high levels of cholesterol and triglycerides were found more often in older patients with stroke. 65% of the women under the age of 40 took oral contraceptives which compares to the baseline community value of 28% of women in childbearing age in this country. Cardiac disorders such as atrial fibrillation, left ventricular hypertrophy, coronary heart disease including a history of myocardial infarction, as well as mitral valve disease were demonstrated more often in the group of elderly patients. 7 out of 77 younger patients (9.1%), and 59 out of 138 older patients (42.8%) were considered to belong to a group with "high cardiac risk for stroke". The results of this study indicate that electrocardiographic screening is of prime importance for detecting cardiac risk factors. However, echocardiographic examination often yields additional diagnostic information, particularly in younger patients. The conflicting opinions concerning the relevance of certain risk factors for ischemic stroke could partly be explained by the fact that these risk factors are distributed unevenly depending on age.

Adolescent↗
PubMed1992

Behavioural and psychosocial sequelae of severe closed head injury and regional cerebral blood flow: a SPECT study.

Thirty six patients (31 male, 5 female) who had suffered severe closed head injury were re-examined at an average of 39.3 (SD 12.8, range 7-66) months after the injury. Behavioural symptoms were measured using the Giessen test. The relatives' reports were used for data analysis to ensure that results were valid. The neurophysical impairment subscale of the Glasgow assessment schedule was completed by two neurologists, and the number connection test was completed by each patient. The adjective mood scale was completed by each relative. All patients were investigated by single photon emission computerised tomography (SPECT). Exploratory factor analysis using the principal components method was carried out separately for SPECT results and psychological measures and correlations were sought between the resulting factors. Factor analysis of the data from the Giessen test identified social isolation, disinhibition, and aggressive behaviour as major components of post-traumatic personality changes; it indicates that these behavioural features are independent of the level of neurological and neuropsychological impairment, which loaded on a single independent factor. Relatives' psychic health seemed to be relatively resistant to physical and cognitive disability and was mainly affected by disinhibitive behaviour. The highest correlation was between frontal flow indices and disinhibitive behaviour (p less than 0.01): the severity of disinhibition increased with lower frontal flow rates. There was a significant but somewhat weaker correlation (p less than 0.05) between flow indices of the left cerebral hemisphere and social isolation. Low flow values of the right brain regions were related to aggressive behaviour (p less than 0.05). Neurological and cognitive impairment correlated negatively with the thalamus; worse neurological and cognitive performance indicate by raised scores on the neurophysical scale and on the number connection test was associated with low thalamic flow values. The results support the importance of lesion location in the production of post traumatic behavioural disorders.

Adolescent↗
PubMed1992

Spontaneous body sway as a function of sex, age, and vision: posturographic study in 30 healthy adults.

Detailed neurological examinations and body sway measurements with a stable force measuring platform were carried out on 30 healthy adults between 21 and 63 years of age. The results were analyzed for sex- and age-associated changes with regard to three different sway components (total sway, anterio-posterior sway, lateral sway) and two different conditions (eyes open, eyes closed). Sex-associated differences were highly significant for all sway components in the oldest age group (51-65 years) in which men exhibited more spontaneous postural sway than women in the condition eyes open. With eyes closed these differences increased. Middle-aged men (36-50 years) also exhibited significantly more postural sway than women of the same age. In the condition eyes open especially total sway and anterioposterior sway were increased, whereas in the condition eyes closed total sway and lateral sway were predominantly higher in men than in women. In the youngest age group (21-35 years) no sex-related differences in postural sway were found. Age-associated differences were significant for anterioposterior sway (eyes open) in men, increasing continuously from the young to the middle-aged, and again from the middle-aged to the older age group. Anterioposterior sway in women, on the contrary, did not change with age. Age-associated differences in women were found for total sway (eyes open) and lateral sway (eyes closed). However, the highest values for total sway and lateral sway within the female group were obtained from young women in both conditions eyes open and eyes closed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Speech arrest as first symptom of a tumour in the supplementary motor area.

There are only few reports in the literature on isolated episodes of speech arrest as first symptom of a tumour in the supplementary motor area. These episodes of speech arrest are due to seizure activity and must be distinguished from speech arrest due to transient ischaemic attacks. The diagnosis may be difficult because the tumour may erroneously be suspected in the lower portion of the sensorimotor strip and may, hence, be missed on CT if apical sections of the regions are not performed. Clinical and experimental aspects of this problem are discussed on the basis of a case report and a review of the literature.

Aged↗
PubMed1992

[Etiology of Alzheimer's disease].

The major factor that causes problems in studies on the aetiology of Alzheimer's disease (AD) is the clinical heterogeneity of the condition. Familial early-onset AD and familial late-onset AD are differentiated from sporadic AD. Aetiologically a genetic defect on chromosome 21 is the most important factor, at least in some cases of AD. In familial AD and autosomal dominant inheritance with complete penetrance in old age is thought to be possible. In sporadic AD the role of genetic and exogenous factors (infectious agents, aluminium) is unknown. The current status of knowledge about the aetiology of Alzheimer's disease is reviewed with reference to the literature.

Aged↗
PubMed1991

Human somatosensory cortical finger representation as studied by combined neuromagnetic and neuroelectric measurements.

We studied somatotopy of human hand somatosensory cortex using evoked responses recorded on magnetoencephalogram (MEG) and scalp-electroencephalogram (EEG) in conjunction with dipole modeling. We found a somatotopic arrangement of cortical digit representations with a sensory sequence from lateral inferior to medial superior in the anatomical order thumb, index finger, middle finger, ring finger, and little finger. MEG alone was able to reproduce this sensory sequence more accurately than scalp-EEG alone. However, the combined information provided by both techniques improved localization accuracy even further. As MEG and scalp-EEG are complementary and confirmatory techniques, this combined approach was useful to get more complete information on the functional organization of human hand somatosensory cortex.

Brain Mapping↗
PubMed1991

Distribution of ischemic cerebrovascular events in cardiac embolism.

Distribution and number of ischemic cerebrovascular events were studied in 57 patients who suffered from heart disorders with proven or highly probable source of cardiac embolism and compared to 39 patients with ulcerations of the craniocervical vessels. Patients with coexisting lesions were excluded from the present study. Out of the 57 patients with cardiac disorders, a single episode of cerebral embolism occurred in 33 patients. Of the 24 patients with recurrent ischemic episodes, different vascular territories were involved in only six cases. There was no evidence of a distinct distribution of vascular territories involved in cerebral embolism. The left middle cerebral artery was affected in 42.9%, the right middle cerebral artery in 23.8%, the vertebrobasilar territory in 19%, and the ophthalmic arteries in 14.2%. Statistical analysis revealed no significant differences in lesion localization between the group with a cardiac source of embolism and the group with ulcerations of the craniocervical vessels. There was a high frequency of patients with recurrent cardiogenic emboli in the ophthalmic (6 of 9 patients) as well as in the vertebrobasilar (6 of 12 patients) circulation who experienced a delayed initiation of cardiac assessment. The possibility of cardiac embolism should be considered in any patient with cerebral ischemia, independently of the vascular territory affected.

Adult↗
PubMed1991

Localization of brain activity during auditory verbal short-term memory derived from magnetic recordings.

We have studied magnetic and electrical fields of the brain in normal subjects during the performance of an auditory verbal short-term memory task. On each trial 3 digits, selected from the numbers 'one' through 'nine', were presented for memorization followed by a probe number which could or could not be a member of the preceding memory set. The subject pressed an appropriate response button and accuracy and reaction time were measured. Magnetic fields recorded from up to 63 sites over both hemispheres revealed a transient field at 110 ms to both the memory item and the probe consistent with a dipole source in Heschl's gyrus; a sustained magnetic field between 300 and 800 ms to just the memory items localized to the temporal lobe slightly deeper and posterior to Heschl's gyri; and a sustained magnetic field between 300 and 800 ms to just the probes localized bilaterally to the medio-basal temporal lobes. These results are related to clinical disorders of short-term memory in man.

Adult↗
PubMed1991

[Prognosis after transient ischemic attacks].

Transient ischemic attacks (TIAs) are reversible neurological deficits due to cerebral ischemia in a vascular territory lasting less than 24 hours, usually less than one hour. The natural course of TIAs is variable. One third of the patients suffer from a subsequent completed stroke with lasting disability, one third of the patients continues to experience TIAs and in one third no further symptoms are encountered. TIAs are a warning symptom of a generalized vascular process, myocardial infarction being the most common cause of mortality and ischemic brain infarction being the most common cause of morbidity. Clinical parameters--besides age--seem to be of minor prognostic relevance. Vascular risk factors should be evaluated in all TIA patients; especially, a cardiac work up including 2D-echocardiography and an exercise stress test should be performed. Duplex sonography of craniocervical vessels shows atherosclerotic lesions in a considerable proportion of patients with TIA; however, localization of these lesions does not always correspond to clinical symptomatology. Some angiographic features are of prognostic relevance. Computed tomography (CT) and magnetic resonance imaging (MRI) show ischemic lesions in a considerable proportion of patients, which connects TIAs directly to ischemic brain infarcts. The extent and localization of these lesions are of some prognostic relevance. Blow flow studies on single photon emission computed tomography (SPECT) and studies of brain metabolism on positron emission tomography (PET) are abnormal in many TIA patients for prolonged periods and also have some prognostic impact. TIA patients probably are a heterogeneous group with a common symptom. A detailed diagnostic work-up may have implications on a more specific and efficient therapy.

Aged↗
PubMed1991

[Neurologic and psychiatric complications after heart surgery].

In 63 patients undergoing heart operations with extracorporeal circulation (47 males, 16 females, mean age 54 years; coronary artery bypass in 38 cases, valvular surgery in the rest) postoperative neurological and psychiatric complications were evaluated. 18 patients (29%) had no complications, whereas 35 patients (56%) showed minor or transient neurological symptoms, and 9 patients (14%) exhibited severe symptoms. Nine of the patients had slight psychiatric disturbances (affective disturbances, disorientation). No correlation was found between risk factors (age, nicotine abuse, hypertension, hypercholesteremia, neurologic and cardiac history), intraoperative parameters (duration of extracorporeal bypass, aortic clamp time, deviation of mean arterial pressure), postoperative parameters (internal complications) and the complication rate. Therefore no predisposing factors could be identified.

Adult↗
PubMed1991

On the functionality of the visually deprived occipital cortex in early blind persons.

In early blind mammals, the deprived visual cortex undergoes anatomical and functional alterations. Its functional role was investigated in the early human blind by using patterns of cortical activation as measured by scalp-recorded event-related slow negative DC potential shifts. The blind showed higher occipital negativity than did sighted persons both during a tactile reading task and a non-reading tactile control task. Results point to a possible role for the blind's visual cortex in tactile processes.

Adult↗