Biomedical subjects

Maria Grazia Marciani

Publications and source records attributed to Maria Grazia Marciani.

6 recordsLinked to original sources

PubMed2003

Quantitative EEG and dynamic susceptibility contrast MRI in Alzheimer's disease: a correlative study.

OBJECTIVE: To investigate the relationship between the electroencephalographic (EEG) power spectra features obtained by quantitative EEG (qEEG) and the hemodynamic parameters detected by dynamic susceptibility contrast-enhanced MR imaging (DSC MRI) in patients with Alzheimer's disease (AD). METHODS: Fourteen patients with probable AD and 15 elderly healthy controls were included in the study. All subjects underwent both EEG recording in a rest condition and perfusion MRI. Three EEG scalp areas were defined (anterior, central and posterior) and power spectra values were obtained from each scalp area. Relative values of temporoparietal and sensorimotor regional cerebral blood volume (rCBV) were measured bilaterally and successively averaged to obtain a total perfusion index. The brain atrophy index was calculated and used as a covariate to rCBV. Correlation analysis was performed between EEG variables and hemodynamic-morphological parameters. RESULTS: qEEG power spectra of AD patients were characterized by an increase in mean relative power of theta (4-7.75 Hz) associated with a decrease in alpha (8-12.75 Hz) frequency bands with a topographic distribution over the central and posterior EEG scalp regions, when compared with controls; beta (13-31 Hz) frequency band also displayed a significant decrease over the anterior and posterior EEG scalp regions of AD patients with respect to controls. The DSC MRI revealed a bilateral reduction in the temporoparietal and sensorimotor rCBV with respect to controls. Correlation analysis showed that the total level of hypoperfusion selectively correlates with the EEG power spectra in theta and alpha frequency bands distributed over anterior/central and central region, respectively. Within AD patients, the lower the level of hypoperfusion, the higher the content of EEG power spectra in theta frequency band, and the lower the level of hypoperfusion, the lower the content of EEG power spectra in alpha band. CONCLUSIONS: The combined qEEG and DSC MRI technology unveiled a selective correlation between neurophysiological and hemodynamical patterns in AD patients. Further investigations will ascertain the relevance of this multi-modal approach in the heterogeneous clinical context of AD.

Aged↗

PubMed2003

Quantitative EEG patterns following unilateral stroke: a study in chronic stage.

The aim of this study was to investigate the EEG power spectra obtained during rest and mental processing in chronic stroke patients. Seventeen patients with stabilized unilateral cerebral ischemia, grouped according to the side of lesion, underwent quantitative EEG recordings during rest and attentive/cognitive tasks. EEG spectral values were compared with those of 11 healthy subjects. Patients displayed different EEG patterns from controls, under rest condition: patients with left hemispheric lesion were characterized by a preserved alpha and beta band "reactivity," with a lack of significant changes in slow band components. In patients with right hemisphere lesion, no significant changes of the slow and fast band activities were evident during each task. These findings indicate that different EEG patterns of activation characterize stroke patients with left and right hemispheric damage.

Aged↗

PubMed2003

Developing wearable bio-feedback systems: a general-purpose platform.

Microprocessors, even those in PocketPCs, have adequate power for many real-time biofeedback applications for disabled people. This power allows design of portable or wearable devices that are smaller and lighter, and that have longer battery life compared to notebook-based systems. In this paper, we discuss a general-purpose hardware/software solution based on industrial or consumer devices and a C++ framework. Its flexibility and modularity make it adaptable to a wide range of situations. Moreover, its design minimizes system requirements and programming effort, thus allowing efficient systems to be built quickly and easily. Our design has been used to build two brain computer interface systems that were easily ported from the Win32 platform.

Biofeedback, Psychology↗

PubMed2003

The use of EEG modifications due to motor imagery for brain-computer interfaces.

The opening of a communication channel between brain and computer [brain-computer interface (BCI)] is possible by using changes in electroencephalogram (EEG) power spectra related to the imagination of movements. In this paper, we present results obtained by recording EEG during an upper limb motor imagery task in a total of 18 subjects by using low-resolution surface Laplacian, different linear and quadratic classifiers, as well as a variable number of scalp electrodes, from 2 to 26. The results (variable correct classification rate of mental imagery between 75% and 95%) suggest that it is possible to recognize quite reliably ongoing mental movement imagery for BCI applications.

Algorithms↗

PubMed2002

Inter-hemispheric asymmetry of cerebral flow velocities during generalized spike-wave discharges.

The aim of this study was to verify the symmetry of cerebral blood flow changes during the generalized spike-wave discharges of typical absence seizures. A recording of mean flow velocity in the left and right middle cerebral arteries and of electroencephalographic activity was performed simultaneously in two subjects with multiple daily absence seizures. A total of 12 generalized spike-wave discharges were recorded. Mean flow velocities showed a significant increase during the discharges with respect to baseline. The increase of flow velocity started simultaneously or a few seconds before the discharges. In 91.6 % of all recordings, the percentage increase of mean flow velocity was significantly higher in the left than in the right side (7.03 % +/- 3.3 vs 5.14 % +/- 3.3; p < 0.1). The extent of the following decrease of flow velocity was also significantly greater in the left than in the right side (-16.91 % +/- 8.1 vs -14.07 % +/- 8.3; p < 0.01). These findings show an inter-hemispheric asymmetry in cerebral blood flow during generalized spike-wave discharges in two patients with absence seizures. Transcranial Doppler ultrasonography promises to be an interesting approach to detect rapid changes in cerebral hemispheric activity not otherwise recognizable.

Adolescent↗

PubMed2002

Dynamic susceptibility contrast (DSC) MRI and interictal epileptiform activity in cryptogenic partial epilepsy.

PURPOSE: To study the possible correlation between interictal EEG patterns and neuroradiologic data obtained by dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) in patients with partial epilepsy. METHODS: Seventeen subjects with cryptogenic partial epilepsy underwent long-term video-EEG monitoring and DSC-MRI in the same session. Ten patients had temporal lobe epilepsy (TLE) and seven, epilepsy of extratemporal origin (ExTE). MRI data were compared with EEG findings, and the accuracy of DSC-MRI was analyzed considering spiking rate (number of interictal epileptiform abnormalities, IEA/min) and type of epilepsy. RESULTS: DSC-MRI showed a relevant asymmetry in the frontal, temporal, and occipital regions in eight (47%) of 17 patients, consisting of a relative regional cerebral blood volume (rCBV) increase in these areas. Because this region corresponded to the interictal EEG focus (IEF) or to the hemisphere involved in the genesis of epileptic discharges in most patients showing a higher spiking rate, patients were classified in two groups: patients with high spiking rate (HSR, n = 9) and with low spiking rate (LSR, n = 8); the cutoff corresponded to the median value of IEA/min. The rCBV increase corresponded to the IEF or to the hemisphere involved in the genesis of epileptic discharges in seven (77.7%) of nine HSR patients. No patients with LSR showed significant asymmetries in rCBV pattern. In five of six patients with TLE-HSR (83.3%), DSC-MRI showed a relative rCBV increase concordant with IEF or hemisphere involved in the genesis of epileptic discharges; in patients with ExTE-HSR, the concordance was 66%. CONCLUSIONS: DSC-MRI is a noninvasive procedure that may provide useful additional information to lateralize and/or localize the IEF when interictal epileptiform activity is sufficiently elevated.

Adolescent↗