Movement-related potentials and magnetic fields: new evidence for SMA activation leading MI activation prior to voluntary movement.
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Electromagnetic Fields↗
Biomedical subjects
L Deecke
Publications and source records attributed to L Deecke.
[Creutzfeldt-Jakob disease in a dura transplant recipient: first observation in Austria].
Dura mater grafts can lead to Creutz-feldt-Jakob disease (CJD) as late complication (dura-CJD). So far 61 dura-CJD cases have been described worldwide. We report here the first dura-CJD case in Austria. A 50-year-old man had a traumatic open frontobasal skull fracture with tearing of dura mater in 1977. Reconstructive surgery used Lyodura (braun Melsungen AG, BRD). Lyodura was derived from pooled cadaveric dura. Ten years after the dural transplantation, the patient developed gait ataxia, paresthesia of both legs, myoclonus and visual disturbance. CT was unremarkable. EEG showed diffuse unspecific changes. The patient died 5 months after onset of disease. Neuropathological examination showed typical histopathology of CJD. Immunocytochemistry detected typical type prion protein (PrP) deposits and scattered PrP plaques in cerebral and cerebellar cortex, basal ganglia and spinal cord. Cerebellar white matter contained numerous PrP miniplaques. This pattern is unusual for sporadic CJD, but is similar to that in CJD after human growth hormone treatment. In our patient and 13/19 earlier described cases with dural graft covering the cerebrum ("central inoculation"), cerebellar disturbance was the initial symptom. Therefore, cerebellar signs are characteristic as initial symptoms in iatrogenic CJD, irrespective of central (cerebral dura mater graft) or peripheral inoculation (e.g., human growth hormone treatment). These data do not support the hypothesis that primary cerebellar symptoms in iatrogenic CJD after peripheral inoculation reflect migration of the infectious agent from the periphery via spinal cord and cerebellum to the cerebrum.
Brain↗
Early cortical activation indicates preparation for retrieval of memory for faces: an event-related potential study.
Event-related brain potentials (ERPs) were used to investigate the time course of memory processes following the presentation of faces. Following a phase in which subjects were asked to memorize faces presented on a computer screen (study phase) they had to distinguish the previously presented faces from others new to the experiment (test phase). We found that in a time period from 250 to 350 ms after onset of stimulus presentation ERPs show higher negativity for both repeated and novel faces in the test phase compared to the study phase. This situation dependent effect is most pronounced in occipito-temporal regions. We conclude that memory retrieval for faces is a sequential process. The early part of this process constitutes preparation for the retrieval of stored information, and a later part of the process comprises the discrimination between repeated and novel faces.
Adult↗
Morphological dissociation between visual pathways and cortex: MRI of visually-deprived patients with congenital peripheral blindness.
MRI was used to study possible morphological changes in the visual system in 12 patients suffering from congenital blindness of peripheral (ocular) origin. While their optical pathways showed degeneration, hypoplasia or atrophy in 7 out of 12 cases, the occipital cortex appeared normal in all cases. This dissociation between afferent pathways and the cortex is contrary to the assumption that visually deprived cortex may undergo degeneration. The finding is congruent with evidence that the occipital cortex is used for other, nonvisual functions.
Adult↗
Event-related potentials in patients with temporal lobe epilepsy reveal topography specific lateralization in relation to the side of the epileptic focus.
Event-related potentials (ERPs) were recorded during a continuous recognition memory paradigm in patients with left-sided (LTLE; n = 8) or right-sided temporal lobe epilepsy (RTLE; n = 6), and in healthy control subjects (n = 24). Control subjects and both patient groups exhibited consistent OLD/NEW ERP-differences from 200-600 ms after stimulus onset. ERPs did not differ significantly between LTLE and RTLE patients, with respect to OLD/NEW distinction or the type of presented material (verbal vs. non-verbal). However, ERP topography showed significant differences between LTLE and RTLE patients: in lateral fronto-temporal recordings, patients showed larger negativities contralateral to the seizure focus, whereas we found larger negativities ipsilateral to the seizure focus in parietal recordings. Differences between the groups were significant from 300 to 600 ms post-stimulus. As a consequence, the amplitude gradient from fronto-temporal to parietal recordings was higher on the right side in LTLE patients and on the left side in RTLE patients. Again, differences between LTLE and RTLE patients were highly significant. We assume that ERPs reflect disturbances of a cortico-cortical network dependent on the side of the seizure focus in temporal lobe epilepsy. Furthermore, scalp-recorded ERPs might be a useful tool in the prediction of the side of the seizure focus in patients with temporal lobe epilepsy.
Adult↗
Monitoring of median nerve somatosensory evoked potentials in carotid surgery.
The purpose of this study was to compare median somatosensory evoked potentials (SEP) in patients undergoing carotid endarterectomy (CEA) with routine shunting and nonshunting (excluding the option of selective shunting) and to evaluate the significance of a decrease in the amplitude of the cortically generated waveforms of the SEP and/or an increase in the central conduction time (CCT) on the one hand, and that of a loss of the cortical SEP, on the other. Somatosensory evoked potentials were recorded in 32 patients before, during, and after CEA with routine shunting or nonshunting. The N13 and N20 latency, the CCT, and the N20/P25 amplitude were evaluated. In addition, a meta-analysis of 15 previous studies was performed comprising a total of 3,136 patients. The intraoperative cortical SEP showed no differences between shunted and nonshunted patients, apart from the preclamping value of the N20/P25 amplitude which was lower in the nonshunted subjects. The number of patients with decreased and/or delayed cortical SEP (findings frequently used as criterion for selective shunting) was similar in the two study groups. A loss of the cortical SEP occurred in one patient operated on without an indwelling shunt. None of these patients had a new neurologic deficit after surgery. In the meta-analysis, the positive predictive value of decreased and/or delayed cortical SEP was extremely poor, that of absent cortical SEP was poor to moderate and the prevalence of new neurologic deficits was similar in patients undergoing CEA with routine shunting-nonshunting and those with selective shunting-nonshunting. Our study suggests that decreased and/or delayed cortical SEP are unreliable predictors of the neurological outcome of CEA patients and consequently an unsuitable criterion for selective shunting. The meta-analysis confirms this finding and shows that the neurologic outcome is not improved by using an indwelling shunt selectively based on SEP monitoring.
Aged↗
Ictal scalp EEG in unilateral mesial temporal lobe epilepsy.
PURPOSE: We wished to determine the predictive significance of unilateral hippocampal atrophy and interictal spikes on localization of ictal scalp EEG changes and assess whether ictal EEG provides information that might change treatment or influence prognosis in patients with such characteristics of epilepsy. METHODS: We analyzed EEG seizure patterns in 118 seizures in 24 patients with unilateral mesial temporal lobe epilepsy (MTLE) defined by typical clinical seizure semiology, unilateral hippocampal atrophy on magnetic resonance imaging (MRI) and unitemporal spikes on interictal EEG. Two blinded electroencephalographers independently determined morphology, location, and time course of ictal EEG changes. RESULTS: Lateralization was possible in 88.4-92.0% of seizures and always corresponded to the side of the interictal spike focus and of hippocampal atrophy on MRI. Although only 30.4-33.9% of seizures were lateralized at onset, a later significant pattern emerged (12.6-13.3 s after EEG seizure onset) that allowed lateralization in 82.4-91.0% of seizures with nonlateralized onset. Interobserver reliability for lateralization was excellent, with a K-value of 0.85. In most patients, either all (79.2-83.3%) or >50% (8.3-16.7%) of seizures were lateralized. In only a small proportion of patients (4.2-8.3%) were <50% of seizures lateralized. In 1 patient, no seizure could be lateralized by 1 electroencephalographer. The results of ictal EEG recordings did not alter the surgical approach and did not correlate with surgical outcome. CONCLUSIONS: We conclude that unilateral hippocampal atrophy on MRI and unitemporal interictal spikes can predict localization of ictal scalp EEG changes with a high degree of reliability and that ictal EEG provides no additional localizing information in this particular patient group.
Adult↗
Hypoplasia, stenosis and other alterations of the vertebral artery: does impaired blood rheology manifest a hidden disease?
OBJECTIVES: The clinical relevance of abnormal vessel findings in the posterior circulation is still a matter of controversy. PATIENTS AND METHODS: We compared 48 patients displaying sonographic abnormalities of one vertebral artery, i.e., vertebral artery hypoplasia in 24 cases, stenosis in 13 cases, plaques in 11 cases, with 25 healthy subjects in terms of whole blood viscoelasticity and plasma viscosity. RESULTS: All patients with stenosis and plaques suffered from clinical signs and symptoms of ischemic cerebrovascular disease, predominantly in the posterior circulation. Free of acute clinical symptoms were 5 of the 24 patients with hypoplasia. Highly statistically significant differences in blood viscoelasticity were found between the patients and the healthy subjects. As regards differences between the groups, whole blood viscoelasticity was most impaired in stenosis, shear resistance was significantly higher in stenosis compared to hypoplasia. Symptom-free patients with one-sided vertebral artery hypoplasia had a significantly better, nearly normal blood rheology at a low shear rate (10/s), compared to clinically symptomatic patients with hypoplasia. CONCLUSION: The results of the present study offer some evidence that altered hemorheology may be associated with symptomatic vertebrobasilar occlusive disease.
Arterial Occlusive Diseases↗
Acute porphyric neuropathy during pregnancy--effect of haematin therapy.
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Acute Disease↗
Clinical seizure lateralization in mesial temporal lobe epilepsy: differences between patients with unitemporal and bitemporal interictal spikes.
OBJECTIVE: To compare the reliability of clinical seizure lateralization in temporal lobe epilepsy patients with unitemporal and bitemporal independent interictal spikes and unilateral hippocampal atrophy or sclerosis (HA/HS) on MRI scan. PATIENTS AND METHODS: We studied 11 patients with unitemporal and 10 patients with bitemporal interictal spikes. We calculated a spike ratio by dividing the number of spikes ipsilateral to the side of HA/HS by those occurring contralaterally. RESULTS: Clinical seizure lateralization was correct, i.e., ipsilateral to the side of HA/HS, significantly more often in the unitemporal group. Spike ratios were significantly higher in seizures that were lateralized correctly as compared with both incorrectly and nonlateralized seizures. Within the individual patients, a significant positive correlation between spike ratios and the proportion of correctly lateralized seizures was found. We identified three categories of symptoms according to lateralization accuracy. Category 1 symptoms (version, postictal paresis, and early ictal vomiting/retching) lateralized to the side of HA/HS in 100% of patients in the uni- and bitemporal groups. Category 2 symptoms (dystonic posturing, mouth deviation, postictal dysnomia/dysphasia, and ictal speech) provided a 100% correct lateralization in the unitemporal but not in the bitemporal patients. Category 3 symptoms (nonversive early head turning and unilateral upper extremity automatisms) yielded erroneous lateralization in both patient groups. CONCLUSIONS: We conclude that reliable clinical seizure lateralization in mesial temporal lobe epilepsy can only be achieved in patients with unitemporal interictal spikes, whereas clinical lateralization in patients with bitemporal spikes must be viewed cautiously.
Adult↗
[Prolonged video EEG monitoring in differential diagnosis of seizures and in presurgical epilepsy diagnosis].
Prolonged video-EEG-monitoring facilitates a correlation of clinical seizure semiology and corresponding EEG changes. Indications for prolonged video-EEG-monitoring comprise differential diagnosis of epileptic and psychogenic seizures, correct classification of epileptic syndromes and presurgical evaluation of patients with medically refractory focal epilepsies. 6000 patients in Austria would benefit from epilepsy surgery with an additional 150 bis 200 new patients appearing each year. Presurgical evaluation consists of a non-invasive Phase I and an invasive Phase II. During Phase I each patient is evaluated with a prolonged video-EEG-monitoring with scalp-EEG, a MRI-scan, a SPECT- and/or PET-scan, a neuropsychological evaluation and a Wada-test. If the epileptogenic zone cannot be localized adequately with these methods, invasive electrophysiological techniques with intracranial (epidural peg-electrodes, foramen-ovale electrodes, subdural strip or grid electrodes) or intracerebral electrodes (stereotaxically implanted depth electrodes) have to be applied. Epilepsy surgery renders 70 to 80% of patients seizure free and thus can regarded an effective and safe treatment option for patients with medically refractory focal epilepsies.
Diagnosis, Differential↗
[Stroke and intracranial hemorrhage after cocaine abuse].
Cocaine abuse as a risk factor for acute cerebrovascular events has received too little attention, in particular in young patients. Cocaine hydrochloride causes mainly intracerebral and subarachnoidal bleeding, while crack (freebase) causes intracranial hemorrhage and ischemic infarctions with equal frequency. Although no specific antidote is known, an attempt should be made to detect the substance or its metabolites in the urine so as to provide optimal management, and encourage the patient to seek expert counselling.
Adolescent↗
Cortical DC potential shifts accompanying the central processing of visually presented analogue and digital time displays.
According to studies in brain-lesioned patients, the cortical substrate subserving the reading of digitally presented time displays seems to differ from that of reading analogue displays. While the right hemisphere has been assumed to be important for reading analogue displays, reading digital displays is attributed to the left hemisphere. This study attempts to localize the cortical substrate of reading analogue versus digital time displays in the intact human brain using scalp-recorded event-related slow negative DC potential shifts. In the arithmetic tasks, subjects had to judge whether or not the time conveyed by the last out of three tachistoscopically presented (analogue or digital) slides was the exact difference between the time conveyed by the first and the second slide. In the control condition, subjects only had to attend to (analogue or digital) time displays. With analogue slides, frontolateral recording sites revealed a right hemispheric preponderance of DC shifts measured in the interval between the second and third slide. Anterior temporal recording sites revealed a right hemispheric preponderance only when calculations were performed. By contrast, there was no hemispheric lateralization with digital slides. The arithmetic versus control manipulation modulated waveforms, but did not influence hemispheric laterality.
Adult↗
Magnetoencephalography may help to improve functional MRI brain mapping.
The validity of functional magnetic resonance imaging (FMRI) brain maps with respect to the sites of neuronal activation is still unknown. One source of localization error may be pixels with large signal amplitudes, since such pixels may be expected to overlie large vessels, running remote from the centre of neuronal activation. In this study, magnetoencephalography was used to determine the centre of neuronal activation in a simple finger tapping task. The localization accuracy of conventional FMRI depending on FMRI signal enhancement was investigated relative to the magnetoencephalography reference. The results show a deterioration of FMRI localization with increasing signal amplitude related to increased contributions from large vessels. We conclude that FMRI data analysis should exclude large signal amplitudes and that magnetoencephalography may help to improve FMRI brain mapping results in a multimethod approach.
Adult↗
Olfactory prodromal symptoms and unilateral olfactory dysfunction are associated in patients with right mesial temporal lobe epilepsy.
PURPOSE: We report a patient with mesial temporal lobe epilepsy (MTLE) with olfactory prodromal symptoms manifested as an unpleasant smell of onions, who was found to have an ipsilateral deficit of olfactory naming (olfactory agnosia). METHODS AND RESULTS: Preoperative olfactory testing revealed a selective right-sided olfactory deficit for naming of odors. Olfactory threshold was within the normal range. The patient has been seizure free after selective amygdalohippocampectomy for 4 months. No olfactory prodromal events have occurred since surgery. Olfactory testing 3 months after resection showed that right-sided odor naming was still impaired. CONCLUSIONS: We conclude that olfactory prodromal symptoms may be associated with unilateral olfactory dysfunction, and lateralization of seizure origin may be possible by unilateral olfactory testing.
Agnosia↗
Imaging of dopamine transporters with iodine-123-beta-CIT and SPECT in Parkinson's disease.
UNLABELLED: The aim of the present study was to demonstrate the degeneration of the dopaminergic nigrostriatal pathway in Parkinson's disease by using the cocaine derivative [123I]beta-CIT (2-beta-carbomethoxy-3-beta(4-iodophenyl)-tropane or RTI-55) and SPECT and to relate the findings to the severity of the disease (Hoehn and Yahr scale, H/Y) and to clinical data such as motor score and activities of daily living. METHODS: Thirteen volunteers and 47 patients with idiopathic Parkinson's disease (PD) of H/Y Stage I-V (I:n = 16, II:n = 6, III:n = 14, IV:n = 9, V:n = 2) were investigated. Acquisitions were performed 2, 4, 16, 20 and 24 hr postinjection. ROIs were drawn over the striatum and the cerebellum. Specific beta-CIT binding was defined as striatal minus cerebellar binding. The ratio of specific over nondisplaceable binding (striatum/cerebellum-1) was determined as well as the percent deviation of this ratio from age-expected control values. RESULTS: The time-activity curve of striatal [123I]beta-CIT binding demonstrated a maximum around 20 hr postinjection in controls and a peak 4 hr postinjection in PD patients. Ratios differed significantly between the two groups. A significant correlation existed between this ratio and clinical measures. Hemiparkinsonian patients revealed significantly diminished [123I]beta-CIT binding not only contralateral to the clinically affected but also contralateral to the clinically unaffected side. [123I]beta-CIT binding showed a significant decrease in comparison to age-expected values ranging from 36% in H/Y stage 1 to 71% in H/Y stage V. CONCLUSION: The present study demonstrates that it is possible to visualize and quantify the degeneration of dopaminergic nigrostriatal neurons in PD using [123I]beta-CIT and SPECT with good correlation to clinical parameters.
Adult↗
Iodine-123-epidepride-SPECT: studies in Parkinson's disease, multiple system atrophy and Huntington's disease.
UNLABELLED: Epidepride is a benzamide derivative with very high affinity for D2 receptors, which, in its [123I]-labeled form, can be used for SPECT. The aim of this study was to evaluate the usefulness and accuracy of [123I]epidepride-SPECT for the differential diagnosis of movement disorders. METHODS: SPECT imaging with a triple-headed scintillation camera was performed in 9 patients with Parkinson's disease, 9 patients with probable multiple system atrophy (MSA), 1 patient with progressive supranuclear palsy, 16 patients with Huntington's disease (HD) and 14 controls, 3 hr after the intravenous injection of 3.7 +/- 1.3 mCi of [123I]epidepride. The striatum-to-cerebellum ratio - 1, reflecting the specific-to-nondisplaceable binding ratio, was used as a semiquantitative measure of D2 receptor binding. RESULTS: Kinetic studies showed peak striatal uptake about 3 hr postinjection and a slow decline thereafter. The striatum-to-cerebellum ratio - 1 was significantly reduced in MSA (11.8 +/- 3.9, compared to controls, 19.0 +/- 6.3; p < 0.01) and in patients with HD (8.8 +/- 3.2; p < 0.00005) but normal in Parkinson's disease (15.8 +/- 3.6; not significant). A high interindividual variation of specific striatal epidepride binding (striatum - cerebellum; cpm/mCi x kg) was found in controls and in all patient groups. The interindividual variation of striatum-to-cerebellum ratios was lower but still considerable. In half of the MSA patients, the specific-to-nondisplaceable binding ratio fell within the range of controls. The use of various cortical reference regions did not improve discrimination between MSA and controls or Parkinson's disease patients, respectively. The discrimination of HD patients from controls was better, with overlap in only two cases. In one HD patient, calculation of the striatum-to-cerebellum ratio was almost impossible due to extremely low nonspecific binding. Possible explanations for the large variation of the ratios, resulting in an overlap between controls and different patient groups, are very low counting rates in the reference region and the fact that a transient binding equilibrium may not be achieved after bolus injection of epidepride. CONCLUSION: Epidepride appears to be a useful SPECT ligand for studying dopamine D2 receptors. However, its markedly higher specific-to-nondisplaceable binding ratio in comparison to those of iodobenzamide or other D2 ligands did not result in a better discrimination between different basal ganglia disorders. The calculation of plasma input curves and volumes of distribution might improve the accuracy of [123I]epidepride-SPECT.
Adult↗
Dopamine D2 receptor binding is reduced in Wilson's disease: correlation of neurological deficits with striatal 123I-iodobenzamide binding.
To visualise and quantify dopamine D2 receptor binding in the corpus striatum of patients with neurological Wilson's disease (WD) 123I-Iodobenzamide (IBZM) binding was measured using single photon emission computer tomography (SPECT). Ratios of striatal to frontal countrates were calculated in 8 patients and in 21 healthy control subjects. We found reduced IBZM binding ratios in all patients with WD in comparison to those in controls (1.48 +/- 0.13 vs. 1.73 +/- 0.09). The reduction in IBZM binding was correlated with the overall severity of neurological deficits and the severity of dysarthria (correlation coefficients -0.86 [p < 0.01] and -0.79 [p < 0.01], respectively). When patients of three different subgroups of neurological WD were compared no differences in IBZM binding were found. We conclude that assessing basal ganglia function in vivo using IBZM-SPECT is a valuable diagnostic tool in WD.
Adult↗