Biomedical subjects

A Venneri

Publications and source records attributed to A Venneri.

32 records · Page 2Linked to original sources

PubMed1999

Delusions in Alzheimer's disease: spet evidence of right hemispheric dysfunction.

Delusional thinking and related behaviours are common symptoms in Alzheimer's disease (AD). The aim of the study was to determine if any consistent cerebral image pattern can be identified using Tc99m-hexamethylpropyleneamine (HMPAO) SPET in AD patients with and without delusions. 18 AD patients with delusion and 15 AD patients without delusion underwent neuropsychological testing and regional cerebral blood flow imaging using Tc99m-HMPAO SPET. The reconstructed data was compared using regions of interest drawn over each cerebral lobe and a statistical parametric mapping (SPM) approach. The neuropsychological testing showed that there was no difference in the profiles of the deluded and non deluded AD patients. The imaging results showed a significant degree of image asymmetry. This took the form of a right hemisphere hypoperfusion mainly in the right frontal and limbic regions. The results do not indicate a specific focal site of hypoperfusion in the patients with delusion. They do, however, indicate that delusions in AD may be associated with areas of hypoperfusion in the right anterior hemisphere.

Aged↗

PubMed1998

Unilateral spatial neglect in the late stage of Alzheimer's disease.

We report two patients with presumptive diagnosis of dementia of the Alzheimer's type (AD) who manifested a clear unilateral neglect syndrome in the late stage of the disease. At onset, their cognitive profiles were broadly similar to the usual cases of degenerative dementia, but, as the disease progressed, neglect appeared, becoming gradually more severe. MRI showed more pronounced cerebral atrophy in the right hemisphere in both patients and larger ventricles on the right in one of them. These two longitudinal single case studies show that neglect can occur in AD despite the insidious and progressive nature of this disease, and in spite of the fact that the underlying pathology affects the brain bilaterally. The appearance of neglect in the late stages of the patients' illness is interpreted as resulting from both the asymmetry in the atrophy and the disruption of compensatory mechanisms caused by the progressively worsening of the atrophy in the left hemisphere.

Alzheimer Disease↗

PubMed1998

Transient global amnesia triggered by mild head injury.

An episode of transient global memory loss was observed in a 27-year-old woman following a mild head injury in a car accident. Her clinical and neuropsychological profiles were indistinguishable from those of transient global amnesia (TGA). This paper argues that a cause-effect relationship may be postulated between head trauma and transient memory loss, perhaps as the result of a very stressful situation such as a car crash.

Acute Disease↗

PubMed1998

Transient autobiographic amnesia: EEG and single-photon emission CT evidence of an organic etiology.

We describe a 44-year-old patient who had a transient attack of autobiographic amnesia. When assessed during the attack, her learning abilities were normal, with no sign of anterograde amnesia. In the remote memory domain, she showed a striking dissociation between a detailed knowledge of public events and famous people and a complete loss of autobiographic information. During the attack, EEG recorded bilateral frontotemporal slow waves and single-photon emission CT (SPECT) showed hypoperfusion in the right temporal and parietal lobes; no abnormalities were detected when both EEG and SPECT were repeated 1 week later. This case provides evidence for an organic etiology for the episode and supports the hypothesis that autobiographic memory is independent of other forms of retrograde memory.

Adult↗

PubMed1997

Persistent global amnesia following right thalamic stroke: an 11-year longitudinal study.

The 11-year longitudinal study of a right-handed male patient, L. C., who suffered from a severe amnesic syndrome following a softening in the right thalamus, is reported. Memory impairment involving retrograde and long-term anterograde memory, both verbal and spatial, persisted without modification. Investigation revealed some residual implicit learning ability. Positron emission tomography studies in the resting state displayed a bilateral hypometabolism of the mesial frontal lobes. Evidence suggests that a lesion confined to the thalamus may not on its own account for severe amnesia; that involvement of other structures is necessary for severe amnesia to appear; and that a functional investigation should always be included in cases of small thalamic lesions before drawing conclusions about the structures responsible for a given deficit.

Aged↗

PubMed1997

Impairment in dating and retrieving remote events in patients with early Parkinson's disease.

Remote memory has been studied in a group of 25 non-demented patients with Parkinson's disease and their performance has been compared with that of 22 healthy control subjects. Only patients who scored > or = 27 on the mini mental state examination and with no anticholinergic treatment were included in the sample. A remote memory questionnaire was given, to evaluate memory for public events that occurred from 1966 to 1990. Each event was probed with five questions concerning its content and one for the date. Compared with healthy subjects, patients with Parkinson's disease were significantly impaired both in recalling the content and in dating remote events. These results support the claim that remote memory in patients with Parkinson's disease is disrupted independently of dementia. This impairment might result from a dysfunction at the level of the circuit connecting the basal ganglia to the frontal lobes.

Adult↗

PubMed1996

Accidental choke-cherry poisoning: early symptoms and neurological sequelae of an unusual case of cyanide intoxication.

We report the case of a 56-year-old woman who was accidentally poisoned when she ingested choke cherries whose pulp contained cyanide, and describe the acute clinical picture, the neurological sequelae and the neuroradiological findings. After recovery from coma, the patient showed signs of a parkinsonian syndrome, retrobulbar neuritis and sensory-motor neuropathy. MRI showed abnormal signal intensities involving the basal ganglia. Since no memory deficits were observed, we argue that the parkinsonian syndrome was caused by cyanide intoxication rather than by subcortical damage due to hypoxia.

Amygdalin↗

PubMed1994

Perseverative dysgraphia: a selective disorder in writing double letters.

Models of writing processes postulate that abstract graphemic representations contain information about letter doubling independent of letter identity. We describe a patient, R.T., who made perseverative errors only in handwriting geminate letters, [e.g.: "CORTECCIA" (cortex)-->"CORTECCCIA"]. Perseveration was specific to orthography. To explain R.T.'s errors, we argue that after the selection of the correct graphic motor programs, the geminate feature induced a perseverative graphic behaviour. This form of dysgraphia supports the notion that graphemic representations contain specific information about letter doubling.

Agraphia↗

PubMed1993

Horizontal and vertical neglect dyslexia.

This case study concerns a 25-year-old right-handed male patient (G.G.) with post-traumatic lesions involving the right temporal and occipital lobe as well as the basal forebrain of the same side. G.G., who had a visual field defect almost limited to the upper left quadrant, showed both left horizontal and lower vertical neglect dyslexia, disproportionately severe when compared with left and lower visuo-spatial neglect. This is the first case report of a patient whose neglect dyslexia for vertical stimuli depended upon stimulus orientation, i.e., errors affected the final letters of top-down words and the initial letters of the bottom-up ones. This implies that neglect dyslexia can affect the internal letter shape map not only along the horizontal, but also along the vertical axis.

Adult↗

PubMed1993

Precision and accuracy of subjective time estimation in different memory disorders.

The aim of this study was to evaluate how different memory disorders affect subjective time durations. For this purpose we studied prospective time estimations in 4 amnesic (A) and in 15 Alzheimer's disease (AD) patients, and compared their performance with that of 5 matched young normal controls (YC) and 15 elderly subjects (EC). For the short-time durations we asked the subject to repeatedly reproduce a standard interval of 1 s. To test how subjects evaluated longer time durations, we choose a verbal estimation procedure. The subjects' task was to read either 5, 10, 20, or 40 digits appearing one at a time, while concurrently keeping the rhythm of 1 key press per second. At the end of each sequence, subjects had to judge the elapsed time from the beginning of the trial. Results showed that amnesics can correctly reproduce 1-s intervals. However, their accuracy of verbal estimates of longer durations was severely impaired. AD patients showed increased variability on repeated reproduction of 1-s intervals and were both inaccurate and imprecise in their verbal estimate of longer durations. Using the framework of the Scalar Timing Model, we conclude that amnesic patients exhibit a deficit in encoding and storing the current time for intervals that exceed their short-term memory range, while AD patients show a pattern of deficit that is explained by a more widespread involvement of both the clock, the memory, and the decisional mechanisms.

Adult↗

PubMedDate not supplied

Effect of a directional cue on line bisection.

Normal participants display a leftward bias when bisecting horizontal lines. It has been proposed that bisection errors can be affected by representational biases. We investigated the possibility that this effect could also be explained as the result of perceptual cueing. Participants bisected horizontal lines with identical arrows arranged around the lines, all pointing to the same end. The arrows significantly affected bisection placement, although participants bisected significantly away from the direction the arrows pointed to. The findings favor the hypothesis that cueing, rather than representation, can affect bisection errors.

Adult↗

PubMedDate not supplied

Dementia of the frontal lobe type: report of the neuroimaging and neuropsychological results of a case study.

We report the behavioural abnormalities, neuroimaging, and neuropsychological results of a 62-year-old patient, i.p., who shows a clinical profile that fulfils all characteristics of dementia of frontal lobe type. The patient has been followed up over 5 years with psychometric testing. Comparing her cognitive profiles across examinations, her performance was substantially unchanged apart from behavioural disturbances and performance on frontal tasks which showed a progressive worsening. MRI finding evidenced marked ventricular enlargement, prevalent frontal atrophy and hypertrophy of the genus of corpus callosum. SPECT investigation showed a considerable reduction of cerebral blood flow in the mesial parts of the frontal lobes, in the lateral surface of the right fronto-parietal lobe, and hypo-perfusion in the right thalamic area. The results are discussed with reference to the features (clinical and neuropsychological) which distinguish different profiles of dementia.

Behavior↗

PubMedDate not supplied

Passive and active processes in visuo-spatial memory: double dissociation in developmental learning disabilities.

The distinction between passive and active visuo-spatial memory has been useful to interpret various pattern of deficits reported in individual differences studies. However, this interpretation raises the issue of task difficulty, since active tasks could be failed simply because more complex and the corresponding deficit could reflect a reduced capacity of the system. We describe two children with Nonverbal Learning Disability whose performance provides evidence of a dissociation between passive and active memory processes. One of the children showed a selective impairment in passive tasks and performed flawlessly in active tasks, whereas the second child displayed the opposite pattern. These data suggest that a qualitative difference between passive and active processes does exist and that differences in performance do not reflect a lower/higher level of task difficulty. Further, these data underlie the importance of formulating theoretical models of visuo-spatial memory including both material-related (i.e., visual vs spatial) and process-related (i.e., passive vs active) distinctions.

Adolescent↗

PubMedDate not supplied

[Amalgam gingival tatoo].

The Authors present (5) cases of gingival tattooing resulted by rapport between argentum amalgam and prosthetic reconstruction with aurum or combination. Theu concluded is opportune to substitute the stumps reconstructions in amalgam with other materials not cause of electrogalvanism. So we avaid principally the antiaesthetic aspect of pigmentation.

Dental Amalgam↗