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Biomedical subjects

F Viader

Publications and source records attributed to F Viader.

At least 55 records · Page 3Linked to original sources
PubMed1994

Contralateral cerebellar hypometabolism: a predictor for stroke outcome?

Contralateral cerebellar hypometabolism (CCH) is a well established remote functional effect of cerebral damage. Because CCH has been reported to be reversible in acute stroke in at least some patients, the value of cerebellar metabolic asymmetry (CbMA; a reflection of the degree of CCH) as a predictor of stroke outcome has been assessed. Measurements of cerebellar oxygen consumption were performed by positron emission tomography (PET) in 16 patients within 5-30 hours of onset of their first ever middle cerebral artery territory stroke, and again 13-56 days later in 12 survivors. The neurological state was quantified at the time of each PET study and at day 60, with both the Mathew and Orgogozo scales. In the early PET study, the CbMAs ranged from around 0% to nearly 50% (individually significant at p < 0.05 in 9/16 patients) but were neither strongly nor consistently correlated with neurological outcome or recovery at day 60. Similarly, the changes in CbMAs from the early to the late PET study were not correlated with the concomitant neurological evolution. At the late PET study, however, there were excellent positive correlations between CbMAs and both neurological status and size of infarction (assessed by CT in the chronic stage). The correlation with neurological status was explained by the correlation with size of infarction. The poor predictive value of CbMAs in the early PET study may be partly because the cerebral metabolic disturbance might still be evolving at this early stage in some cases. Despite this lack of a strong quantitative link between CbMAs at the early PET study and outcome, the outcome was good in all the patients who did not exhibit significant CCH, suggesting that lack of CCH may predict good outcome in acute middle cerebral artery stroke.

Aged↗
PubMed1994

[Multimodal or multisensorial agnosia?].

A 75 year-old right handed woman had persistent right homonymous hemianopia and alexia without agraphia caused by a haemorrhagic stroke of the left occipito-temporal region. Six months later she suffered sudden onset visual and auditory agnosia, following a second haematoma, contralateral to the first one, in the right occipito-temporal region including the lingual and fusiform gyri. None of the disorders concerned semantic representation, so that an asemantic agnosia was excluded. Her performance in naming and recognition tests, in both visual and auditory modalities, demonstrated a wide range of responses and errors. The pattern of visual symptoms suggested "associative visual agnosia narrow sense" (Farah, 1990); auditory agnosia concerned only the non verbal stimuli. These findings were discussed in terms of anatomical mechanisms subserving perceptual, semantical, visuo and auditory-verbal representation. In this case, visual and auditory, agnosia appears to be independent.

Aged↗
PubMed1993

PET imaging of cerebral perfusion and oxygen consumption in acute ischaemic stroke: relation to outcome.

We used positron emission tomography (PET) to assess the relation between combined imaging of cerebral blood flow and oxygen consumption 5-18 h after first middle cerebral artery (MCA) stroke and neurological outcome at 2 months. All 18 patients could be classified into three visually defined PET patterns of perfusion and oxygen consumption changes. Pattern I (7 patients) suggested extensive irreversible damage and was consistently associated with poor outcome. Pattern II (5) suggested continuing ischaemia and was associated with variable outcome. Pattern III (6), with hyperperfusion and little or no metabolic alteration, was associated with excellent recovery, which suggests that early reperfusion is beneficial. This relation between PET and outcome was highly significant (p < 0.0005). The results suggest that within 5-18 h of stroke onset, PET is a good predictor of outcome in patterns I and III, for which therapy seems limited. The absence of predictive value for pattern II suggests that it is due to a reversible ischaemic state that is possibly amenable to therapy. These findings may have important implications for acute MCA stroke management and for patients' selection for therapeutic trials.

Aged↗
PubMed1993

Characteristics and evolution of writing impairment in Alzheimer's disease.

Rapcsak et al. (Archs Neurol. 46, 65-67, 1989) proposed a hypothesis describing the evolution of agraphic impairments in dementia of the Alzheimer type (DAT): lexico-semantic disturbances at the beginning of the disease, impairments becoming more and more phonological as the dementia becomes more severe. Our study was conducted in an attempt to prove this hypothesis on the basis of an analysis of the changes observed in the agraphia impairment of patients with DAT. A writing test from dictation was proposed to 22 patients twice, with an interval of 9-12 months between the tests. The results show that within 1 year there was little change in the errors made by the patients in the writing test. The changes observed however were all found to develop within the same logical progression (as demonstrated by Correspondence Analysis). These findings made it possible to develop a general hypothesis indicating that the agraphic impairment evolves through three phases in patients with DAT. The first one is a phase of mild impairment (with a few possible phonologically plausible errors). In the second phase non-phonological spelling errors predominate, phonologically plausible errors are fewer and the errors mostly involve irregular words and non-words. The last phase involves more extreme disorders that affect all types of words. We observe many alterations due to impaired graphic motor capacity. This work would tend to confirm the hypothesis proposed by Rapcsak et al. concerning the development of agraphia, and would emphasize the importance of peripheral impairments, especially grapho-motor impairments which come in addition to the lexical and phonological impairments.

Agraphia↗
PubMed1993

Recurrent oligodendroglioma diagnosed with 11C-L-methionine and PET: a case report.

A benign oligodendroglioma was removed in a young patient who had temporal epileptic seizures. He then became free of any fit until 15 months after the operation, when he developed seizures progressively less controlled by therapy. All investigations were normal (including CT scan and MRI) except a PET study which showed a high uptake of 11C-L-methionine in the area of the previous tumor. The second operation revealed that this area was indeed a tumor recurrence. We briefly discuss the potential usefulness of PET for the follow-up of low grade gliomas.

Adolescent↗
PubMed1992

Right motor neglect associated with dynamic aphasia, loss of drive and amnesia: case report and cerebral blood flow study.

A 30-year-old right-handed man had right motor neglect, amnesia, aphasia and loss of drive following bilateral thalamic and subthalamic infarctions. Serial resting cerebral blood flow (CBF) measurements with either Xenon 133 inhalation or positron emission tomography at 1, 8 and 10 months post-onset showed a widespread and long-lasting low CBF in the cortex. An additional CBF measurement, during motor tasks, showed a marked interhemispheric asymmetry in the pattern of activation: whereas left hand movement resulted in a CBF increase in contralateral superior rolandic and prerolandic areas, no significant regional CBF changes were seen during right hand movement, despite recovery from motor neglect. This loss of CBF increase in cortical motor and premotor areas during voluntary movement of the previously neglected side points to a disruption of cortico-subcortical pathways subserving motor activation. The pathophysiology of aphasia, loss of drive and amnesia as well as their relationships to motor neglect, may also be discussed on the basis of thalamo-cortical disconnections.

Adult↗
PubMed1992

[Familial parkinsonian syndrome with athymhormia and hypoventilation].

Five cases of parkinsonism with athymhormia observed in a single family are reported. Death caused by central respiratory disorders occurred after 6 to 8 years of progressive course. In 2 cases with autopsy, there was a severe neuronal loss predominant in the substantia nigra. Other brain stem nuclei (locus coeruleus, dorsal motor nucleus of the vagus nerve, nucleus of the tractus solitarius) were involved, as well as the striatum, pallidum and frontal cortex. No Lewy body was seen. In the surviving patient, positron emission tomography demonstrated, 4 years after the onset, a bilateral frontal hypometabolism. This disease is a rare variety of familial parkinsonism of dominant inheritance, already reported in 2 Canadian families by Perry et al. (1975) and Purdy et al. (1978) and in a family of West Virginia by Roy et al. (1988). The respiratory disorders can be explained by the involvement of the dorsal medullary nuclei. The peculiar neuropsychological disorder and motor slowing are best accounted for by the functional impairment of both motor and limbic striato-pallido-thalamo-frontal loops.

Cerebral Cortex↗
PubMed1992

[Diffuse cerebral gliomatosis. An anatomoclinical case].

A 52-year old man had a generalized seizure followed by progressive memory disturbances, affective changes, right hemiplegia and aphasia. He died 4 years later after a period of coma. Neuropathological findings included slight cortical atrophy, pallor of the centrum ovale, and infiltration of the cortex and subcortical white matter by neoplastic glial cells, with neither major neuronal loss nor spongiosis. Microglial rod cells were observed. The gliomatosis extended within the thalamus and subthalamic area on both sides, whereas the brain stem was much less involved. The spinal cord and peripheral nerves were not examined. Abnormal glial cells were stained by the glial fibrillary acid protein, which confirms the astrocytic differentiation of the tumoral cells.

Brain↗
PubMed1991

[Aphasic disorders of written language].

After a short overview of classical neuropsychological knowledge about the disorders of written language, the authors review the data of cognitive psychology in this field. They first consider the general principles of cognitive analysis and then describe the specific syndromes of phonological and lexical routes impairment both in reading and writing. The possible correlations between these syndromes and other higher brain function impairments or anatomical localization are briefly considered. Finally an analysis of the impairments to peripheral writing processes, i.e. graphemic buffer and allographic conversion system syndromes, is given. In conclusion the contribution of cognitive psychology to daily neuropsychological practice is discussed.

Aphasia↗
PubMed1991

[Accidental poisoning with podophyllin: a case with study of peripheral nerve].

A 53 year-old veterinary surgeon accidentally ingested 0.8 g of podophyllin. Twelve hours later, he was deeply comatose, with clinical and EMG signs of extensive axonal sensorimotor and autonomic peripheral neuropathy. In addition, transient bone marrow and hepatic toxicity occurred. The coma lasted 2 weeks. Systemic and neurological disturbances started to improve at 3 months post-onset, but the patient died four months later from gastro-intestinal bleeding. Sural nerve biopsy showed loss of myelinated fibers and signs of axonal degeneration with type E teased fibers. The cytoplasm of Schwann and endothelial cells was vacuolated and swelled. Diffuse interstitial aedema was noted. Podophyllin acts as a spindle poison, binds microtubular proteins and inhibits axoplasmic flow.

Accidents↗
PubMed1991

[Isolated exertion headache and Chiari's malformation].

A 47 year-old woman had been suffering from exertional headache for 2 1/2 years. Neurological examination was normal. X-rays of the skull and cranio-cervical junction and CT were normal. MRI sagittal sections disclosed a Chiari type I malformation. The headache disappeared after occipital craniectomy and atlas laminectomy.

Arnold-Chiari Malformation↗
PubMed1990

Identification and discrimination disorders in auditory perception: a report on two cases.

Auditory perception was investigated in two brain-damaged subjects. The first patient had a left temporoparietal ischaemic lesion. He presented a right-ear extinction in dichotic tasks, as well as difficulties in understanding and repeating verbal material and impaired identification of melodies. All discrimination tests were well performed. The second patient had a right capsulolenticular and frontal ischaemic lesion. He presented a left ear dichotic extinction and severe difficulties in discrimination of environmental sounds and melodies but no major difficulty in naming and identification. From these results, it is hypothesized that identification and discrimination involve distinct mechanisms within the processing of auditory stimuli, and that they may be selectively disrupted in brain-damaged subjects.

Adult↗
PubMed1989

Regional cerebral blood flow during comprehension and speech (in cerebrally healthy subjects).

Regional cerebral blood flow (rCBF) was measured by the xenon-133 inhalation method in 10 cerebrally healthy subjects at rest and during linguistic activation tests. These consisted of a comprehension test (binaural listening to a narrative text) and a speech test (making sentences from a list of words presented orally at 30-s intervals). The comprehension task induced a moderate increase in the mean right CBF and in both inferior parietal areas, whereas the speech test resulted in a diffuse increase in the mean CBF of both hemispheres, predominating regionally in both inferior parietal, left operculary, and right upper motor and premotor areas. It is proposed that the activation pattern induced by linguistic stimulation depends on not only specific factors, such as syntactic and semantic aspects of language, but also the contents of the material proposed and the attention required by the test situation.

Adult↗
PubMed1989

Auditory agnosia with relative sparing of speech perception.

We report a case of auditory agnosia in which the initial clinical picture began with generalized auditory agnosia for verbal and non verbal sounds, but rapidly changed to a selective auditory agnosia confined to the perception of non verbal sounds. CT scanning and MRI did not demonstrate cortical or subcortical damage, except for bilateral ventricular enlargement. The patient was submitted to audiological investigations including physical and psychoacoustic studies. Deficits were revealed during the decay and loudness discrimination test, but no temporal auditory acuity deficit was observed. The results of these studies are discussed in relation to the clinical picture. Also the dissociation between verbal perception and non verbal perception is discussed.

Adult↗