Biomedical subjects
Publications and source records attributed to D Perani.
A giant macroprolactinoma causing hydrocephalus was demonstrated by computed tomography in a 13-year-old boy complaining of headache and visual disturbances. Three weeks after beginning of medical treatment with dopaminergic drugs, an impressive reduction of tumor size and disappearance of hydrocephalus was noted. The patient is doing well at 5 months follow-up.
Three patients with angiographic and CT findings of cerebral sinovenous occlusion are described. Filling defects within the venous pathways are well demonstrated by angiography. Some of the most characteristic CR signs are here described. Full evaluation, including the clinical history, angiography and computed tomography is essential.
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Right brain-damaged patients with unilateral neglect were asked to detect differences within pairs of patterns moving left- or rightward behind a narrow vertical slit. It was seen that differences occurring on the left side of the mentally reconstructed images were less easily detected; therefore it is suggested that a representational disorder plays a primary role in unilateral neglect. In the light of these findings, it is possible to take into consideration some implications of unilateral neglect for theories of conscious brain activity.
The development of neuroimaging methods such as PET, has provided a new impulse to the study of the neural basis of cognitive functions, and has extended the field of inquiry from the analysis of the consequences of brain lesions to the functional investigations of brain activity, either in patients with selective neuropsychological deficits or in normal subjects engaged in cognitive tasks. Specific patterns of hypometabolism in neurological patients are associated with different profiles of memory deficits. [18F]FDG PET studies have confirmed the association of episodic memory with the structures of Papez's circuit and have shown correlations between short-term and semantic memory and the language areas. The identification of anatomo-functional networks involved in specific components of memory function in normal subjects is the aim of several PET activation studies. The results are in agreement with 'neural network' models of the neural basis of memory, as complex functions subserved by multiple interconnected cortical and subcortical structures.
A new head holder for the fixation and repositioning of the patient head in PET, CT, and MR scanners has been designed and tested. With this device, a bidimensional correlation between functional and anatomical brain images can also be obtained. Head fixation and repositioning are achieved using the patient's dental morphology as an anatomical reference. With a dentistic material, a mold of the patient's teeth is obtained in a few minutes. The molding substance rests on a plastic support, fixed to the head holder. Each time the patient undergoes a new study, his/her personal mold is used, ensuring accurate head repositioning. External markers fixed on the head holder (made visible in lateral PET and CT projection images, midsaggital MR images, and also on the axial images) make it possible to record and recognize the angular orientation and the position of the brain in the three-dimensional space, to correlate images of the same patient obtained with different neuroimaging modalities, and to accurately reposition patients for follow-up studies. The head holder was tested on several subjects. Fixation and repositioning accuracy of within 2.5 mm were achieved in the three-dimensional space. Orientation accuracy was 1 degree.
Progression rates of Alzheimer's disease (AD) vary considerably, and they are particularly difficult to predict in patients with mild cognitive impairment. We performed a prospective multicenter cohort study in 186 patients with possible or probable AD, mostly with presenile onset. In a cross-sectional analysis at entry, impairment of glucose metabolism in temporoparietal or frontal association areas measured with positron emission tomography was significantly associated with dementia severity, clinical classification as possible versus probable AD, presence of multiple cognitive deficits and history of progression. A prospective longitudinal analysis showed a significant association between initial metabolic impairment and subsequent clinical deterioration. In patients with mild cognitive deficits at entry, the risk of deterioration was up to 4.7 times higher if the metabolism was severely impaired than with mild or absent metabolic impairment. Copyrightz1999S.KargerAG, Basel
Patient EDS presented with an amnesic disorder of insidious onset (4 years) that remained stable and restricted to memory functions over a 10-year course. Repeated neuropsychological evaluations over 6 years showed a moderate-to-severe, stable impairment of long-term memory and of memory for public events, and a milder, stable impairment of autobiographic memory and of short-term memory. Language, perception, praxis and 'frontal' functions were fully preserved. MRI showed atrophy of the right hippocampus, of the right mammillary body and of the sylvian fissure (bilaterally, but more marked on the left). On PET scan, metabolic activity in the mesial temporal structures was significantly reduced on the right and was at lower normal levels on the left. The disorder observed in EDS is similar to that recently reported in other patients. Possible etiologies of the selective amnesia observed in EDS are considered and their implications discussed.
In a previous transcranial Doppler (TCD) study, we demonstrated a decrease in blood flow velocity in the proximal tract of the middle cerebral artery (MCA) in patients with Alzheimer's disease (AD). In these patients there was also an asymmetry in blood flow velocity which positively correlated with the cognitive asymmetry often seen in the early phase of AD. In this study we found a correlation between the absolute values and asymmetry indexes of MCA blood flow velocity with adjusted metabolic values and asymmetry indexes of the relative cortical frontotemporoparietal (FTP) areas, evaluated by FDG-PET, and with neuropsychological asymmetry indexes. Patients with prevalent visuospatial deficits (right hemisphere dysfunction) showed significant decreases in right MCA blood flow velocity and right FTP cortical glucose hypometabolism, whereas in patients with prevalent language deficits (left hemisphere dysfunction), these signs were observed on the other side. In AD patients, the decrease of blood flow velocity in MCA might be due to reduced metabolic demands in the temporoparietal cortical areas primarily affected by AD.
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Hydatid disease of the primary type may involve CNS and bone. Compression of the spinal cord and spinal nerve roots, caused by hydatid material from an affected vertebra is a rare condition which makes surgical decompression mandatory. We report the neuroradiological findings in a case of vertebral hydatidosis, confirmed by surgical appearance and hystological examination.