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Biomedical subjects

R Sterzi

Publications and source records attributed to R Sterzi.

At least 37 records · Page 2Linked to original sources
PubMed1996

Neurological complications of liver transplantation.

We examined 199 consecutive patients who underwent 220 liver transplantations, to define the type, frequency and aetiology of posttransplant neurological complications and their prognostic value. We found neurological complications in 63 patients (32%), mostly involving the central nervous system. The most frequent complications were mental status changes ranging from delirium to coma and seizures. The aetiology was multifactorial, cyclosporin A neurotoxicity being the main cause. Patients with neurological complications had a higher mortality rate than those without. In our series, neurological complications represented a major medical problem with increased morbidity and mortality.

Adolescent↗
PubMed1996

Perceptual and premotor components of unilateral auditory neglect.

Recent investigations have distinguished between ophthalmokinetic and melokinetic factors of unilateral neglect. The aim of our study was to investigate the possible dissociation between melokinetic (premotor) and perceptual factors, avoiding any overt oculokinetic components. We asked four blindfolded left neglect patients to set a dichotic sound in central position, by moving a handle controlling the difference of intensity between the sounds delivered to the left and to the right ears. Two conflicting conditions were used. In the congruent condition, the sound moved in the same direction as the hand movement; in the noncongruent condition, it moved in the opposite direction. One patient performed as if suffering from melokinetic neglect, and another as if suffering from perceptual neglect. The behavior of the other two subjects did not lend itself to a clearcut interpretation.

Aged↗
PubMed1995

Modulation of conscious experience by peripheral sensory stimuli.

Lack of awareness of touch associated with brain damage may transiently recover after stimulation of the vestibular system. We used positron emission tomographic regional cerebral blood flow measurements to study the neurophysiological effect of vestibular stimulation on touch imperception in a subject with a right brain lesion. We tested the hypothesis that the vestibular system aids conscious tactile perception by introducing a bias in the neural system subserving body representation. We show that in normal subjects touch and vestibular signals share projections to the putamen, insula, somatosensory area II, premotor cortex and supramarginal gyrus. In our patient a subset of these regions (right putamen and insula) was spared by the lesion and was maximally active when touch and vestibular stimulations were combined. These results support the suggestion that our phenomenological consciousness is associated with activation in circumscribed brain areas specific to the particular sensation of which we are aware.

Adult↗
PubMed1995

Intramodal somaesthetic recognition disorders following right and left hemisphere damage.

A dissociation between apperceptive and associative processing after right and left hemisphere damage, respectively, has been suggested for visual, auditory and visuo-tactile matching tasks. This study was aimed at testing for this dissociation in a purely somaesthetic task. Forty consecutive patients with recent right and left hemispheric vascular lesions and 10 normal controls were studied. The groups were compared on two intramodal somaesthetic matching tasks, consisting of either meaningless shapes (apperceptive recognition) or meaningful objects (associative recognition). In normal controls, no significant difference was found either between the two tests, indicating a similar degree of difficulty, or between hands. An analysis of variance indicated a differential impairment of the two hemisphere-damaged groups on the two tests in comparison with normal controls. Right hemisphere lesions impaired the apperceptive, but not the associative, task, while the reverse occurred after left hemisphere lesions. This double dissociation between side of hemispheric lesion (right and left) and level of recognition impairment (apperceptive and associative) extends the results reported for other sensory modalities to intramodal tactile recognition matching.

Aged↗
PubMed1994

Identification of the central vestibular projections in man: a positron emission tomography activation study.

The cerebral representation of space depends on the integration of many different sensory inputs. The vestibular system provides one such input and its dysfunction can cause profound spatial disorientation. Using positron emission tomography (PET), we measured regional cerebral perfusion with various vestibular stimulations to map central vestibular projections and to investigate the cerebral basis of spatial disorientation. We showed that the temporoparietal cortex, the insula, the putamen, and the anterior cingulate cortex are the cerebral projections of the vestibular system in man and that the spatial disorientation caused by unilateral vestibular stimulation is associated with their asymmetric activation.

Adult↗
PubMed1994

The role of the right hemisphere in the interpretation of figurative aspects of language. A positron emission tomography activation study.

We investigated cerebral activity in six normal volunteers using PET to explore the hypothesis that the right hemisphere has a specific role in the interpretation of figurative aspects of language such as metaphors. We also mapped the anatomical structures involved in sentence comprehension. During regional cerebral blood flow measurement subjects were asked to perform three different linguistic tasks: (i) metaphorical comprehension; (ii) literal comprehension of sentences; and (iii) a lexical-decision task. We found that comprehension of sentences compared with the lexical-decision task, induced extensive activation in several regions of the left hemisphere, including the prefrontal and basal frontal cortex, the middle and inferior temporal gyri and temporal pole, the parietal cortex and the precuneus. Comprehension of metaphors was associated with similar activations in the left hemisphere, but in addition, a number of sites were activated in the right hemisphere: the prefrontal cortex, the middle temporal gyrus, the precuneus and the posterior cingulate. We conclude that the interpretation of language involves widespread distributed systems bilaterally with the right hemisphere having a special role in the appreciation of metaphors.

Adult↗
PubMed1993

Exploring somatosensory hemineglect by vestibular stimulation.

The effects of vestibular stimulation upon somatosensory deficits or tactile extinction contralateral to a hemispheric lesion were investigated in 20 right brain-damaged patients and 11 left brain-damaged patients. After stimulation, right brain-damaged patients showed a temporary partial recovery from left hemianaesthesia or extinction. Conversely, right somatosensory deficits associated with left brain damage were virtually unaffected by vestibular stimulation. Temporary recovery from somatosensory deficits was independent of the presence of visuo-spatial hemineglect. The suggestion is made that somatosensory deficits and extinction produced by right brain damage have an important non-sensory or perceptual component, that may be positively affected by vestibular stimulation. The mechanisms whereby this treatment may ameliorate somatosensory deficits may involve the restoration of the normal correspondence between somatotopic and egocentric representations of the body.

Adolescent↗
PubMed1993

Hemianopia, hemianaesthesia, and hemiplegia after right and left hemisphere damage. A hemispheric difference.

The incidence of somatosensory, visual half-field and motor deficits contralateral to a hemispheric lesion in a continuous series of 154 left brain damaged and 144 right brain damaged stroke patients were investigated. These contralateral disorders were more frequent after lesions of the right hemisphere. This difference cannot be attributed to a bias in patients' selection. It is suggested that left spatial neglect is the factor underlying this hemispheric difference.

Aged↗
PubMed1992

Directional hypokinesia in spatial hemineglect: a case study.

A patient with an ischaemic lesion involving the right frontal lobe and basal ganglia showed left spatial hemineglect in visuomotor exploratory tasks, requiring the use of the right unaffected hand. Her performance was, however, entirely preserved, with no evidence of neglect, when she was required to identify targets among distractors in both the left and right halves of space, and in the Wundt-Jastrow illusion test. The latter tasks do not require any arm movement in extrapersonal space. In this patient spatial hemineglect may be explained in terms of defective organisation of movements towards the left half-space (directional hypokinesia). The frontal lesion of the patient may be the neural correlate of this selective disorder. This pattern of impairment may be contrasted with the typical deficit found in patients with right brain damage with perceptual neglect. One case had a defective performance both in visuomotor and in purely perceptual tasks.

Aged↗
PubMed1991

Sneddon syndrome: cerebral perfusion studies by Tc99m HM-PAO and SPECT.

Sneddon syndrome is a non-inflammatory, non-atherosclerotic disease involving small and medium-sized arteries of the brain and of the skin. The arteriographic examination is often negative despite progressive impairment of the neurological status. In 3 patients with Sneddon syndrome cerebral perfusion was assessed with single photon emission computerized tomography (SPECT) and technetium99 m-hexamethylpropylenamineoxime (Tc99 HM PAO). A correlation between clinical and SPECT finding was found, with significant focal reduction of regional cerebral blood flow (rCBF) in the two more severely affected patients.

Adult↗
PubMed1991

Hemianesthesia, sensory neglect, and defective access to conscious experience.

We report a patient with an ischemic stroke in the vascular territory of the right middle cerebral artery who had left spatial neglect and left hemianesthesia. The patient showed a dissociation between defective verbal reporting of somatosensory stimuli delivered to the left hand and physiologic evidence from an autonomic index. This indicates that there was processing of undetected stimuli without the patient's awareness, and suggests that the hemianesthesia was due, at least in part, to somesthetic hemi-inattention.

Cerebral Angiography↗
PubMed1990

Topographic disorientation--a case report.

Topographical disorientation can be dissociated in two levels, agnosic and amnesic. A case of topographical disorientation due to a glioma of the splenium of corpus callosum illustrates the dissociation between the topographical memory impairment and the normal performances on the perceptual topographic tests.

Aged↗
PubMed1990

Temporary remission of left hemianesthesia after vestibular stimulation. A sensory neglect phenomenon.

In three right-brain damaged patients with contralesional neglect vestibular stimulation induced a temporary remission of left hemianesthesia, in addition to the well-known transient recovery of extrapersonal and personal neglect. These findings indicate that in neglect patients attentional factors may play an important role in producing apparently "primary" sensory deficits, which may be interpreted in terms of defective access to conscious processing.

Aged↗
PubMed1988

Left hemisphere contribution to motor programming of aphasic speech: a reaction time experiment in aphasic patients.

Simple reaction time to lateralized visual dot stimuli was studied in 10 fluent and 10 nonfluent right-handed chronic aphasics with left hemisphere lesions. As well as the standard simple reaction time condition, the patients were given a concomitant verbal task, requiring overt articulation while reacting to the visual stimuli. Compared with the control condition, in both aphasic groups the verbal task produced an overall lengthening of latencies, with a significant slowing down of responses to the stimuli located in the right visual half-field. According to these results the verbal concurrent activity appears to involve the left hemisphere as in normal subjects, suggesting that the undamaged regions of the left hemisphere have a role to play in the motor programming of aphasic speech. As a collateral finding, the difference between latencies to stimuli ipsilateral and contralateral to the responding hand--a measure of interhemispheric transmission time--is greatly increased in patients with motor deficits. This is consistent with the view that, in simple visuo-motor reaction time, interhemispheric transfer takes place between anterior regions of the brain.

Adult↗
PubMed1987

Remission of hemineglect and anosognosia during vestibular stimulation.

The effects of vestibular stimulation on extrapersonal and personal neglect and on awareness of disease were investigated in four patients with severe neglect and anosognosia. Neglect phenomena improved in all patients, while an effect on anosognosia was found in two cases. These preliminary findings indicate a possible role of vestibular stimulation on hemispheric activation.

Aged↗
PubMed1986

Neurological complications of cerebral angiography.

We report a prospective study of 218 consecutive patients undergoing cerebral diagnostical angiography, before during and 24 hours after the procedure, to identify the neurological complication rate and the risk factors related to the patients and to the procedure. We observed 15 neurologic accidents (6.9%) with permanent sequelae in one case (0.4%). Two risk factors proved to correlate significantly with accidents, i.e. the time that the catheter remained within a vessel and difficulty in performing the procedure.

Adult↗