Optokinetic nystagmus in patients with central field defects.
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Attention↗
Biomedical subjects
L Crevits
Publications and source records attributed to L Crevits.
Parkinsonism in patients with vascular dementia: clinical, computed- and positron emission-tomographic findings.
PURPOSE: The present study investigates the vascular nature of parkinsonian features in patients with 'probable' vascular dementia. PATIENTS AND METHODS: Forty patients with vascular dementia were studied with positron emission tomography (PET) using the steady state technique with (15)O in order to assess regional cerebral blood flow (rCBF), regional oxygen extraction rate (rOER) and regional metabolic rate for oxygen (rCMRO(2)) in different brain regions. The findings in 10 patients with (VaDP) were compared to 30 without parkinsonism (VaD). RESULTS: The clinical and computed tomographic findings in the parkinsonian patients were similar to those described in the literature as probable vascular parkinsonism. The PET results showed decreased rCBF and rCMRO(2) in the frontal and parietal cortices and in the striatum of the VaDP compared to the VaD group. The decrease of rCBF and rCMRO(2) in frontal and parietal cortices is due to the more severe mental changes in the VaDP group. In the VaDP patients rCBF and rCMRO(2) were more decreased and rOER increased in the striatum contralateral to the most affected parkinsonian side. CONCLUSION: Our PET findings show that local ischemic changes in the striatum contribute to parkinsonism in vascular dementia patients.
Aged↗
MRI of the brain in cerebrotendinous xanthomatosis (van Bogaert-Scherer-Epstein disease).
The clinical, biochemical and magnetic resonance imaging findings of two patients with cerebrotendinous xanthomatosis are reported. This is a rare hereditary disease. Early recognition of this entity is important in view of the existing treatment possibilities. Magnetic resonance imaging findings typically include a bilateral and almost symmetrical increase of the signal intensity on the T2-weighted images in the cerebellar and periventricular cerebral white matter, the basal ganglia, the dentate nuclei and the brainstem as well as cerebellar and cerebral atrophy.
Adult↗
Antisaccades and remembered saccades in mild traumatic brain injury.
The most common site of focal lesions after mild traumatic brain injury (MTBI) is the frontal lobe. This lobe, however, is difficult to examine clinically. Neuroimaging is not performed routinely and usually shows normal results in uncomplicated trauma. Antisaccades (AS) and remembered saccades (RS) are neuro-ophthalmological tests of frontal function. This study examined whether there are disturbances of latency time or error rate of AS and RS in patients within 24 h after MTBI. Eye movements were studied with infrared-oculography. Data were obtained prospectively from 25 patients. An additional group of 6 patients with MTBI and alcohol intoxication were also examined. No statistical differences in AS or RS, either for errors or for latency time, were found between a group of age-matched controls and the patients, except in the group of alcohol-intoxicated MTBI patients. Our findings indicate that visual reflex inhibition and initiation of voluntary saccades were not disturbed in the nonintoxicated patients. It is hypothesized that the responsible frontal area was not affected. It is concluded that error rate and latency time of AS and RS are inappropriate measures for evaluating acute MTBI.
Adolescent↗
The effect of cognitive load on saccadic eye movements.
The present study tested the hypothesis that, unlike prosaccades, antisaccades require controlled processing, due to the prepotent response that needs to be inhibited. The effect of the Random time Interval Generation (RIG) task (Vandierendonck, A., De Vooght, G., & Van der Goten, K. (1998). European Journal of Cognitive Psychology, 10, 413-444) on these saccade latencies and errors was studied. This task has the advantage that it loads executive processes, with only minimal interference with verbal or visuo-spatial components. A first experiment compared saccade performance within the prosaccade and the antisaccade task, executed alone and in combination with the RIG task and fixed tapping (added to exclude possible motor component interference explanations). A second experiment investigated the influence of task characteristics on the effects found. Although it was shown that antisaccades are more prone to interference of an executive interference task, it seems that prosaccades are also vulnerable. Interference on prosaccades could originate from a controlled execution of these saccades. A third experiment confirmed that endogenously generated prosaccades are susceptible to dual-task interference and showed that controlled saccade execution, without the need to inhibit a prepotent response, is sufficient to produce interference.
Adult↗
Antisaccadic effects of a dopamine agonist as add-on therapy in advanced Parkinson's patients.
We wanted to compare clinical neurological and antisaccadic behavior before and after addition of a dopamine agonist to the usual antiparkinsonian drugs in advanced Parkinson's disease. Parkinson's patients in stage 3 and 4 of Hoehn and Yahr not yet taking a dopamine agonist were selected. In 20 patients, the treating neurologist decided to add pergolide. The dose of pergolide was adjusted by the treating neurologist according to clinical response. Antisaccades were studied by infrared oculography before and after addition of pergolide. Antisaccades are voluntary saccades in the opposite direction of an unanticipated visual target. The patients made more errors, i.e. they glanced to the target or they made no eye movement at all. In contradistinction to the global neurological improvement and the better motor scores, antisaccadic disturbances did not improve significantly with pergolide, except in younger patients. These findings suggest that antisaccadic alterations in patients with advanced Parkinson's disease could be multifaceted. Not only depletion of dopamine, but also non-dopaminergic dysfunctions could contribute. Cortical frontal lesions must also be taken into account.
Aged↗
Are better eye movements an advantage in ball games? A study of prosaccadic and antisaccadic eye movements.
The aim of this study was to compare prosaccadic and antisaccadic eye movements of experts in ball sports and controls. In the prosaccadic and antisaccadic task, subjects made saccades respectively towards and away from a suddenly appearing stimulus. By means of infrared-oculography, we compared horizontal eye movements of experts (n=18) and controls (n=20). Experts had shorter overall saccadic latencies, but significantly shorter latencies occurred only on the antisaccade task, not on the prosaccade task. Our findings seem to support the concept that prosaccades and antisaccades have different underlying mechanisms and that expertise in ball games mainly improves antisaccadic performance in terms of latency and variability.
Adult↗
Impaired early visual processing in disorganised schizophrenia.
Topographic differences in flash/pattern shift VEP data are evaluated in paranoid (n: 38), disorganized (n: 23) and residual (n: 23) schizophrenic subtypes and compared to normal controls. Increased early P1 and a restricted diffusion of the late P2 responses suggest dopaminergic over- and cholinergic underactivity in paranoid and residual schizophrenia. A distinctive pattern N145 reflects well-preserved attentional resources in the paranoid subtype. Latency increase and amplitude decrease of the pattern N145 concur with abnormal antisaccades documented in disorganized behaviour. VEP-data might help differentiate between schizophrenic subtypes.
Adult↗
Optic nerve metastasis simulating optic neuritis.
A 68-year-old man developed subacutely bilateral loss of visual acuity without any other neurological sign. Magnetic resonance images showed some small scattered periventricular white matter T2 hypersignals. On spinal fluid analysis a mononuclear pleocytosis and an oligoclonal gamma-pattern was found. Treatment with intravenous corticosteroids had no effect. The clinical situation deteriorated and the patient died of bronchopneumonia. Postmortem examination revealed manifest metastatic invasion of both the optic nerves by a non-detectable primary tumor.
Aged↗
Disturbed striatoprefrontal mediated visual behaviour in moderate to severe parkinsonian patients.
OBJECTIVES: To study visuospatial and visual memory functions in moderate to severe parkinsonian patients. METHODS: Visual antisaccades (AS) and remembered saccades (RS) were examined in 30 patients with moderate to severe Parkinson's disease and in 44 age matched controls. AS are saccades in the direction opposite to the target. RS are saccades towards the remembered position of a target that is no longer visible. RESULTS: Patients with Parkinson's disease had serious difficulties in suppressing a reflex saccade ("visual grasping") or they made no saccade at all ("visual akinesia"). The remembered saccade was often wrongly directed. CONCLUSIONS: These types of errors point to a dysfunction in the striatoprefrontal loop. The discrepancy of the results with those in the literature, which are mostly normal, could be explained by the more advanced stage of our patients. This might correspond to the development of unresponsiveness to levodopa or of non-dopaminergic lesions.
Adult↗
Cerebral oxygen metabolism in patients with progressive supranuclear palsy: a positron emission tomography study.
To investigate cerebral oxygen metabolism in progressive supranuclear palsy (PSP), 5 patients with a clinical diagnosis of PSP and a variable degree of cognitive deficit were selected for positron emission tomography (PET) of the brain. In 4 of them, a significant decrease in oxygen metabolism was found in all cortical regions, without frontal accentuation. In the group as a whole, this decrease was even slightly more marked in parietal and temporal regions. These findings are not consistent with earlier PET studies that demonstrated frontal targeting of hypometabolism in PSP patients. Part of this discrepancy can be explained by differences in methodology, although the use of different clinical criteria and overlap of PSP with other neurodegenerative diseases must be taken into account. It is concluded that the absence of frontal hypometabolism on PET examination does not exclude the diagnosis of PSP.
Aged↗
Raynaud's phenomenon in a case of multiple system atrophy.
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Autonomic Nervous System↗
Traumatic dissection of the internal carotid artery as unusual cause of hypoglossal nerve dysfunction.
A dissection of the internal carotid artery (ICA) in a 50-year-old man with hypoglossal nerve dysfunction is reported. This case illustrates how non-invasive imaging techniques, such as computed tomography and magnetic resonance angiography, can demonstrate this unusual etiology.
Aortic Dissection↗
Benign paroxysmal positional vertigo of the horizontal canal.
OBJECTIVES: To review the clinical features, electronystagmography findings, the possible mechanism, and a possible therapeutic approach to benign paroxysmal positional vertigo (BPPV). METHODS: Sixty-three cases of BPPV of the horizontal canal type have been reviewed. It is characterised by horizontal nystagmus and an intense vertigo, provoked by rotation of the head in a supine patient. The horizontal nystagmus beats towards the ground on both sides, becomes more pronounced when lying on the pathological side, and then the nystagmus often changes direction. RESULTS: Forty-eight patients underwent electronystagmography. On the pathological side, the first phase nystagmus had a mean latency of three seconds and a mean duration of 31.6 seconds. Nystagmus inversion occurred in 36 patients after a nystagmus free interval. The mean second phase nystagmus duration lasted 33.4 seconds. On the healthy side, the nystagmus had a mean latency of 3.4 seconds and a mean duration of 39.5 seconds. Fatigue was seen in six patients. Simultaneous involvement of the posterior canal was present in 16 patients. A liberatory manoeuvre was successful in six patients. CONCLUSIONS: The liberatory manoeuvre should be tried in patients with horizontal canal vertigo. It should not be performed in patients with severe cervical arthrosis, vertebrobasilar insufficiency, or when the patient has neck pain during the manoeuvre.
Adult↗
Positron emission tomographic study of late-onset cryptogenic symptomatic seizures.
Ten patients with epilepsy of unknown origin, starting after the age of 50 years, and without clear evidence of cognitive decline were studied with positron emission tomography, using the steady state technique with 15O. Cerebral blood flow and oxygen metabolism were significantly decreased in all cortical areas. No focal areas of hypometabolism were detected. Treatment with phenytoin did not influence the results. It is suggested that late-onset seizures could be the premonitory signs of a progressive encephalopathy of unknown origin.
Aged↗
Isolated oculomotor nerve palsy.
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Humans↗
Unusual CT and MRI findings in palatal myoclonus.
A 23-year-old man suffered from palatal myoclonus for 2 years. It had appeared one week after a minor head trauma. MRI and basal cisternography revealed a localized atrophy of the left paramedian part of the medulla, encroached upon the left vertebral artery. Clonazepam treatment was beneficial. This particular case is discussed in relation to etiopathogenesis and other causes of palatal myoclonus.
Adult↗