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Biomedical subjects

L Deecke

Publications and source records attributed to L Deecke.

At least 145 records · Page 8Linked to original sources
PubMed1991

Early diagnosis of Alzheimer dementia?

The main problems in early diagnosis of Alzheimer dementia (AD) are: 1. The differentiation between normal aging and AD i.e. difficulties in the assessment of cognitive disturbances in the healthy elderly and in early demented subjects. 2. Interference with other dementia syndromes. 3. Lack of information in the population and among physicians about the different causes and courses of dementia syndromes. The first two aspects are discussed in this paper.

Aging↗
PubMed1991

Neuromagnetic investigation of somatotopy of human hand somatosensory cortex.

In order to investigate functional topography of human hand somatosensory cortex we recorded somatosensory evoked fields (SEFs) on MEG during the first 40 ms after stimulation of median nerve, ulnar nerve, and the 5 digits. We applied dipole modeling to determine the three-dimensional cortical representations of different peripheral receptive fields. Median nerve and ulnar nerve SEFs exhibited the previously described N20 and P30 components with a magnetic field pattern emerging from the head superior and re-entering the head inferior for the N20 component; the magnetic field pattern of the P30 component was of reversed orientation. Reversals of field direction were oriented along the anterior-posterior axis. SEFs during digit stimulation showed analogous N22 and P32 components and similar magnetic field patterns. Reversals of field direction showed a shift from lateral inferior to medial superior for thumb to little finger. Dipole modeling yielded good fits at these peak latencies accounting for an average of 83% of the data variance. The cortical digit representations were arranged in an orderly somatotopic way from lateral inferior to medial superior in the sequence thumb, index finger, middle finger, ring finger, and little finger. Median nerve cortical representation was lateral inferior to that of ulnar nerve. Isofield maps and dipole locations for these components are consistent with neuronal activity in the posterior bank of central fissure corresponding to area 3b. We conclude that SEFs recorded on MEG in conjunction with source localization techniques are useful to investigate functional topography of human hand somatosensory cortex non-invasively.

Brain Mapping↗
PubMed1991

Three-dimensional localization of SMA activity preceding voluntary movement. A study of electric and magnetic fields in a patient with infarction of the right supplementary motor area.

Previous studies by magnetoencephalography (MEG) failed to consistently localize the activity of the supplementary motor area (SMA) prior to voluntary movements in healthy human subjects. Based on the assumption that the SMA of either hemisphere is active prior to voluntary movements, the negative findings of previous studies could be explained by the hypothesis that magnetic fields of current dipole sources in the two SMAs may cancel each other. The present MEG study was performed in a patient with a complete vascular lesion of the right SMA. In this case it was possible to consistently localize a current dipole source in the intact left SMA starting about 1200 msec prior to the initiation of voluntary movements of the right thumb. Starting at about 600 msec prior to movement onset the assumption of a current dipole source in the left primary motor cortex was needed to account for the observed fields. Measurements of brain potentials were consistent with MEG findings of activity of the left SMA starting about 1200 msec prior to movement onset.

Brain Mapping↗
PubMed1991

Sensitivity of external cuneate neurons to neck rotation in three-dimensional space.

A functionally meaningful vestibular-neck interaction, such as it has been demonstrated for postural reflexes and self-motion perception, requires the spatial and temporal response characteristics of vestibular and neck signals to be similar. We investigated the spatial coding in neurons of the external cuneate nucleus (ECN) with natural neck and vestibular stimulations, and compared them to that of neurons in the descending and medial vestibular nuclei (DVN and MVN, respectively) obtained with vestibular stimulation. Neurons were recorded extracellularly in chronically prepared cats held under light barbiturate anesthesia. Neck stimulation was performed by sinusoidally rotating the animals' trunk relative to the earth-fixed head in six different vertical planes and in the horizontal plane. Vestibular stimulation was elicited by whole-body rotations in the corresponding planes. During neck stimulation in the vertical planes, most ECN neurons showed an approximately sinusoidal discharge modulation about resting rate, which became maximal during rotation in a specific plane. Off this plane, the response declined along a cosine function and reached zero in the orthogonal plane. The majority of these ECN neurons also responded to horizontal neck rotation; the resulting "optimal" direction of rotation in three-dimensional space varied considerably among the neurons. Yet, there was a certain preference; the majority of these ECN neurons fired maximally if trunk rotation in the yaw plane stretched the neck on the ipsilateral side, if roll brought the contralateral shoulder closer to the head, and if pitch brought the back closer to the occiput. A minority of ECN neurons showed more complex response patterns which could not be described by a single, optimal direction. About one third of the neck-sensitive ECN neurons tested showed weak responses during whole body rotation, which might stem from a weak vestibular input to this nucleus. In the DVN and MVN, the optimal direction in three-dimensional space with vestibular stimulation typically had a cosine-like spatial tuning. The spatial distribution of these directions clearly differed from that of neck-sensitive neurons in the ECN. We therefore assume that a further processing of the two input signals takes place at later stages in the CNS (e.g., in the vestibulo-cerebellum) in order to yield a functionally useful vestibular-neck interaction.

Animals↗
PubMed1991

Neurological and neuropsychiatric spectrum of Wilson's disease: a prospective study of 45 cases.

Forty-five patients with Wilson's disease (WD) were prospectively studied: 27 had neurological deficits, 12 hepatic signs, and 6 were asymptomatic. Kayser-Fleischer rings occurred in 23 of the neurological patients and in only 4 of the hepatic patients. Neurological features were extremely variable with respect to frequency and severity. Most frequent were dysdiadochokinesis (25 patients), dysarthria (23), bradykinesia (17), and posture tremor (14). Fifteen, mainly long-term treated patients, presented with rather discrete neurological abnormalities which predominantly consisted of dysarthria and various forms of tremor. Eight patients had a parkinsonian type of neurological WD associated with signs of an organic mood syndrome. Three patients were predominantly hyperkinetic, presenting with dystonic and choreatic movements. In 1 patient, ataxia was the predominant neurological feature. There was a clear-cut correlation between the severity of neurological impairment and the restriction in functional capacity. Nine patients were not able to engage in salaried employment or were retired. Psychiatric symptoms and behavioural disorders were common, varying from mild personality and psychological disturbances to severe psychiatric illness resembling psychotic disorders and major depressive syndromes. Significant mental deterioration was not found in the patients. Disturbances of mood were observed in 12 patients, all of whom had neurological abnormalities. There was a history of an attempted suicide in 7 patients, and a history of an organic delusional syndrome in 3.

Adolescent↗
PubMed1991

HM-PAO-SPECT in persistent vegetative state after head injury: prognostic indicator of the likelihood of recovery?

Management of patients presenting with traumatic persistent vegetative state (PVS) calls for extensive resources. The ability to predict whether or not a patient is likely to recover is a critical issue. In 12 patients with PVS admitted consecutively for early rehabilitation after head injury, pattern of brain activity was measured by 99mTc-hexamethyl-propylenamineoxime (99mTc-HM-PAO) brain SPECT (single photon emission computer tomography). All patients were re-investigated after a mean observation period of 3 years. A global reduction of cortical blood flow was a reliable predictor of poor long-term outcome, but the demonstration of only focal deficits did not reliably indicate a favourable outcome. Brain SPECT may help to improve outcome prediction in patients with traumatic PVS.

Adolescent↗
PubMed1991

Contributions of occipital and temporal brain regions to visual and acoustic imagery--a spect study.

Regional cerebral blood flow (rCBF) was assessed by means of HMPAO-SPECT in two experimental groups. In a control condition both groups listened to abstract words, in the experimental condition they heard five names of objects. One group was advised to form visual images of the objects, the other group was advised to form acoustic images of the sounds made by these objects. Post-experimental questionnaires revealed that most of the subjects in the acoustic imagery condition had had visual images in addition to the acoustic ones. Both imagery conditions lead to approximately equal increases of rCBF in the left inferior occipital region and in the left thalamus. Flow increases in both hippocampal regions and the right inferior and superior temporal regions were larger in the acoustic than in the visual imagery condition. It is concluded that only the activation of left inferior occipital and left thalamic regions can be interpreted as being related to modality-specific visual aspects of imagery.

Auditory Perception↗
PubMed1991

Neuromagnetic fields accompanying unilateral and bilateral voluntary movements: topography and analysis of cortical sources.

Movement-related magnetic fields (MRMFs) accompanying left and right unilateral and bilateral finger flexions were studied in 6 right-handed subjects. Six different MRMF components occurring prior to, and during both unilateral and bilateral movements are described: a slow pre-movement readiness field (RF, 1-0.5 sec prior to movement onset); a motor field (MF) starting shortly before EMG onset; 3 separate "movement-evoked" fields following EMG onset (MEFI at 100 msec; MEFII at 225 msec; and MEFIII at 320 msec); and a "post-movement" field (PMF) following the movement itself. The bilateral topography of the RF and MF for both unilateral and bilateral movements suggested bilateral generators for both conditions. Least-squares fitting of equivalent current dipole sources also indicated bilateral sources for MF prior to both unilateral and bilateral movements with significantly greater strength of contralateral sources in the case of unilateral movements. Differences in pre-movement field patterns for left versus right unilateral movements indicated possible cerebral dominance effects as well. A single current dipole in the contralateral sensorimotor cortex could account for the MEFI for unilateral movements and bilateral sensorimotor sources for bilateral movements. Other MRMF components following EMG onset indicated similar sources in sensorimotor cortex related to sensory feedback or internal monitoring of the movement. The results are discussed with respect to the possible generators active in sensorimotor cortex during unilateral and bilateral movement preparation and execution and their significance for the study of cortical organization of voluntary movement.

Brain Mapping↗
PubMed1991

Dopamine D2 receptor imaging with SPECT: studies in different neuropsychiatric disorders.

The purpose of the present study is to visualize and quantify dopamine D2 receptors in the living human brain using an 123I-labeled ligand and the single photon emission computerized tomography (SPECT) technique. S-(-)-Iodobenzamide [S-(-)-IBZM] has been shown to be a highly selective ligand with high affinity for D2 receptors in experimental studies. Five millicuries (185 MBq) of 123I-labeled S-(-)-IBZM was administered intravenously to 12 control subjects, 22 parkinsonian patients under L-Dopa therapy, 12 parkinsonian patients without L-Dopa, 10 unmedicated patients with Huntington's disease, and 12 patients under different neuroleptics. Data collection with a rotating double-head scintillation camera started 1 h after injection and lasted for 50 min. In a semiquantitative approach, a ratio was calculated between mean counts per pixel in the striatum and a region in the lateral frontal cortex, which was 1.74 +/- 0.10 in the control group. A marked reduction of this ratio was found in patients with Huntington's disease (1.38 +/- 0.12; p = 0.0001), no significant changes in untreated parkinsonian patients (1.67 +/- 0.14), but a reduction in L-Dopa-treated cases (1.59 +/- 0.13; p = 0.0014). A curvilinear relationship was found between total daily dose of neuroleptics and the reduction of this ratio. Estimated receptor blockade under full neuroleptic treatment was 75-80%. S-(-)-IBZM binding was reduced with increasing age (p less than 0.01). Specific binding was reduced markedly when the racemic mixture of IBZM was used, and no specific binding was seen with the R-(+)-isomer, demonstrating the stereoselectivity of IBZM binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Prognostic factors in rehabilitation after severe craniocerebral injuries].

Even with modern standards of intensive care management and rehabilitation services, severe head injury often results in permanent disability. A review of the literature concerning predictors of outcome after severe head injury is presented. The early identification of those factors which are of greatest significance in determining outcome is of essential value in the appropriate management of rehabilitation therapy. In many cases of severe head injury a reliable assessment of prognosis can be made on the basis of level of coma and brainstem dysfunction, reflecting type and extent of the traumatic brain lesion. Additionally, a broad spectrum of neuroradiological and electrophysiological investigations, as well as measurements of regional cerebral blood flow have been demonstrated to be helpful in establishing rehabilitation prognosis. In studies using a multivariate statistical design, initial level of coma (i.e. initial Glasgow Coma Score), brainstem reflexes, intracranial pressure assessment, the presence/absence of an additional thoracic injury, and age emerged as independent early predictors of outcome after severe head injury. The presence of previous brain damage also seems extremely important. In contrast, the prognostic value of pretraumatic personality factors and of the psychosocial status of the head injured patient requires additional research. Comparison among studies is hindered by differences in patient samples, timing of assessments, and various outcome measures with respect to rehabilitation management.

Brain Damage, Chronic↗
PubMed1991

Thalamic ischemia in transient global amnesia: a SPECT study.

We performed 99mTc-HMPAO SPECT in a patient during transient global amnesia and twice thereafter. SPECT during the attack showed a significant diminution of regional blood flow in the left thalamus and a less marked diminution in the right thalamus. Quantitative evaluation of global 99mTc-HMPAO uptake indicated a diffuse depression of cerebral blood flow. At follow-up to 40 days after the attack, global uptake and thalamic flow indices normalized, but there was a persistent reduction of left frontal flow values.

Amnesia↗
PubMed1991

The sensitivity of transcranial cortical magnetic stimulation in detecting pyramidal tract lesions in clinically definite multiple sclerosis.

We determined central motor conduction time (CMCT) (motor cortex to root C-8 and motor cortex to root S-1) as well as the amplitude of the compound muscle action potentials in the hypothenar and the abductor hallucis muscles on both sides in 44 patients with definite MS. We compared the values with standards obtained from 86 healthy controls and correlated them with the degree of clinical deficit of the limbs examined. Thirty-nine patients (88.6%) showed a prolonged CMCT. By comparison, only 74.4% of patients had abnormal visual evoked potentials.

Action Potentials↗
PubMed1991

Subarachnoid hemorrhage of unknown etiology: early prognostic factors for long-term functional capacity.

Forty-one patients suffering subarachnoid hemorrhage (SAH) of unknown etiology were re-investigated at an average of 91 months after the bleed to determine functional capacity. Nineteen patients were performing at their previous level of work, five were employed part-time, and four could not work due to the SAH. Five patients showed a moderate disability in activities of daily living but were not dependent on help, one patient was severely disabled, and two had died. There was one rebleed. Early prognosis of an unfavorable outcome was possible on the basis of three clinical variables on admission: a history of hypertension, a Hunt and Hess grade of greater than II, and the presence of focal neurological deficits. In addition, the presence of an organic mental syndrome at discharge was identified as a predictive factor for reduced functional capacity later on. Other clinical variables in the acute stage, including sex, age, history of headache, interval between SAH and admission, impaired consciousness, and cognitive deficits, were not related to a limited functional level. Residual neurological deficits and the Glasgow Outcome Scale score on discharge were also not predictive of restrictions in global functions evaluated by means of the Karnofsky Performance Scale status at follow-up review.

Activities of Daily Living↗
PubMed1991

Clinical comparison of dementia in Parkinson's and Alzheimer's disease.

Neuropsychological, neuropathological and neurochemical findings show different types of dementias. Few of them have been able to confirm a division into "subcortical" and "cortical" dementia, so this concept has to be questioned. The present clinical study compared type and severity of dementia in 12 Parkinson-patients (PD) and 12 Alzheimer-patients (AD). The age-adjusted normal value differed a significantly from both patient groups. No significant difference in pattern of neuropsychological deficits between PD- and AD-patients was apparent. However, after similar duration of illness, dementia was more severe in AD- than in PD-patients.

Aged↗
PubMed1991

[Depression, nonverbal intellectual impairment and quality of life following left-brain ischemic insult--results of a catamnestic study].

The purpose of the present study was to establish the relationship between persisting aphasia and the extent of overall disability in the long-term outcome following left hemisphere ischaemic stroke. 55 right-handed patients who had sustained an initial left-sided cerebral infarction, verified by CT scan, were investigated after a mean observation period of six years. 39 patients were categorized as being non-aphasic, and 16 as being aphasic (3 Global, 6 Broca's, 1 conduction, 1 transcortical motor and 5 anomic aphasics) at the end of the follow-up period. Regarding motor and sensory functions, a correlation between the presence of aphasia and the severity of deficits could be established at the end of the follow-up period. With respect to activities of daily living, a significantly larger number of aphasic stroke victims had to rely on help by others. Furthermore, the persistence of aphasia also negatively influenced the subsequent occupational capacity. With regard to social participation and leisure activities, a significant reduction was found in aphasic long-term stroke survivors as compared to non-aphasics. Concerning quality of life, both groups reported a marked decline at the end of the observation period; the presence of aphasia had an additional negative effect. However, as regards the long-term non-verbal cognitive impairment, statistical analysis revealed no significant differences between both groups. In addition, aphasic stroke survivors did not demonstrate a higher incidence of depressive states than those without language deficit. On the basis of our results it is concluded that the presence of aphasia in left-hemispheric ischaemic stroke survivors indicates a more severe stroke, resulting in greater physical disability and social handicap in the long-term outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1991

[The prognostic value of evoked potentials in early neurologic rehabilitation of patients with the apallic syndrome].

In 22 patients with apallic syndrome brainstem auditory and somatosensory evoked potentials were recorded, in 8 patients the course during rehabilitation was observed. Clinically the patients were scored with Glasgow-coma scale, Karnofsky-index and Goldenberg-scale. The outcome of rehabilitation was estimated by the "Glasgow-outcome scale". No correlation was found between results of evoked potentials and clinical state. First evoked potentials measurements of apallic patients allowed no prognosis. Evoked potentials are an important prognostic factor after severe head trauma, but have no value for the prognosis of apallic patients.

Adolescent↗
PubMed1991

Technetium-99m-d,1-hexamethylpropyleneamine oxime (HMPAO) uptake and glutathione content in brain tumors.

Technetium-d, HMPAO SPECT was performed in 70 patients suffering from intracerebral tumors of various histologic types (glioma n = 30, meningioma n = 19, metastases n = 10, angioma n = 3, neuroma n = 2, lymphoma n = 2, neurocytoma n = 1, epidermoid n = 1, gliosis n = 1, cholesteatoma n = 1). Tumor classification was histologically verified in all subjects except in two cases with inoperable angiomas. SPECT was performed under resting state conditions with a dual-head rotating camera (SIEMENS ZLC 37) following intravenous injection of 18-25 mCi 99mTc-d, 1-HMPAO. Regional tracer deposit was expressed in terms of a cerebellar index (CBI). Significantly higher regional HMPAO uptake was found in meningiomas when compared with gliomas of different malignancy (ANOVA p less than 0.05). Within gliomas, regional uptake increased with malignancy (n.s.). In 23 patients, a total of 32 tumor specimens were obtained for histochemical analysis of glutathione (GSH) content using high-pressure liquid chromatography. A significant correlation (least square method, p less than 0.001) between CBIs and GSH values was found, supporting the hypothesis that GSH is the predominant factor for the conversion of the lipophilic complex to hydrophilic derivates.

Adult↗