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Biomedical subjects

L Crevits

Publications and source records attributed to L Crevits.

At least 19 recordsLinked to original sources
PubMed1997

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↗
PubMed1997

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↗
PubMed1997

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↗
PubMed1996

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↗
PubMed1995

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↗
PubMed1992

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↗
PubMed1991

Optokinetic nystagmus and spatial-selective attention. An experimental study.

The influence of spatial-selective attention on the direction of the optokinetic nystagmus (OKN) was investigated in normal humans. During horizontal optokinetic stimulation of the peripheral retina, the central visual field was neutralized by ambivalent stimulation. The results showed that the direction of the OKN was modulated by the direction of the attention. A central mechanism that processes the optic information according to spatial-selective attention is proposed.

Attention↗
PubMed1986

Optokinetic nystagmus in patients with defects of the central visual field.

Optokinetic nystagmus (OKN) was studied in patients with central visual field defects. Apart from a classic OKN, an inverted nystagmus was observed in some cases. A prerequisite for eliciting this paradoxic OKN was that the attention of the subject was directed to the field defect. Although other factors seem to be co-determining, a central mechanism is thought to process the visual information according to spatial-selective attention.

Adult↗
PubMed1983

Component analysis of pattern evoked occipital potentials in hemianopic patients.

In a group of 33 patients with hemianopia, interhemispherical differences of the visually evoked potentials after pattern stimulation were studied. Both full field stimulation and vertical half field stimulation were applied. The results were not consistent, i.e. interhemispherical differences were not always according to the hemianopia. In general, with hemifield stimulation a better score was obtained. Differences between vascular accidents and tumours as the underlying cause of the hemianopia could not be established. With full-field stimulation and a midline electrode hemianopias could not reliably be detected.

Brain Neoplasms↗
PubMed1982

Granulomatous angiitis of the nervous system: a clinicopathological study of one case.

The clinical history is presented of a 69-year-old man with a disease starting with a herpes zoster infection and an acute ascending myelopathy, and ending with an intracerebral hemorrhage. The postmortem examination revealed multiple angiitis lesions, restricted to the central nervous system. In review of the 31 previously described cases there were four other patients in whom the granulomatous angiitis of the nervous system (GANS) was associated with a herpes zoster infection. The relation between both disorders is discussed.

Aged↗
PubMed1982

Migraine-like headache in intraventricular tumours.

In a series of 39 intraventricular tumours, 7 patients had paroxysmal headache as the most important early complaint. The striking similarities with migraine and the misleading role of antimigraine drug therapy are illustrated. Special emphasis is placed on the importance of additional investigations such as funduscopy, EEG, skin X-rays and Ct-scan.

Cerebral Ventricle Neoplasms↗
PubMed1982

Ocular lateropulsion in Wallenberg's syndrome: a prospective clinical study.

In order to evaluate the occurrence and clinical value of ocular lateropulsion in Wallenberg's syndrome, a prospective study was carried out. Lateropulsion of the horizontal and vertical refixation saccades was a rather regular finding, especially in complete Wallenberg's syndrome. Lateral ocular deviation after elimination of fixation was present in nearly all cases. The tonic lateral vector was always directed to the involved side. It is concluded that ocular lateropulsion is an easily elicited sign with a lateralizing value in lateral bulbar infarction. Further systematic search of ocular lateropulsion in other posterior fossa disorders is needed to determine its topographical significance.

Aged↗
PubMed1982

On and off contribution to the combined occipital on-off response to a pattern stimulus.

The hypothesis, derived from previous studies, that the off response forms the main part of the second positive wave (P2) in the occipital response to the presentation of patterns was tested by using stimuli of various durations. It was found that the off response merges with P2 of the on response in the combined on-off response. The question, however, whether the on response or the off response contributes most to the combined on-off response could not be answered. By applying hemifield stimulation, the experiments furthermore confirm the concept of the presence of a double dipole in the hemisphere contralateral to the stimulated side.

Evoked Potentials, Visual↗
PubMed1980

Pathogenesis of Binswanger chronic progressive subcortical encephalopathy.

We studied the clinicopathologic findings in four hypertensive patients with multiple leukomalacia, demyelinated lesions, and lacunar state. Only one patient had clinical evidence of dementia. The periventricular watershed infarcts were attributed to transient episodes of cardiac failure in brains with a compromised circulation in the territory of the deep perforating branches. These observations suggest that Binswanger encephalopathy does not differ from multi-infarct dementia.

Aged↗