Biomedical subjects

M G Marciani

Publications and source records attributed to M G Marciani.

At least 19 recordsLinked to original sources

PubMed2003

Bilateral frontal polymicrogyria and epilepsy in a patient with Turner mosaicism: a case report.

Turner's syndrome (TS) is rarely associated with serious abnormalities of brain structure or malformations of cortical development. We report a 17-year-old girl with TS and 45,XO/46,XX mosaicism presenting bilateral frontal polymicrogyria (BFP) and epilepsy. To our knowledge, the association between TS and BFP has never been reported to date. Our observation confirms that in humans the X-chromosome plays an important role in the development and specialization of brain structure and function. We hypothesize that the absence or abnormalities of developmental genes localized on the X-chromosome could be involved in the pathogenesis of BFP observed in our patient.

Adolescent↗

PubMed2003

Cortical dysplasia, temporal atrophy, mental retardation, dysmorphic facies, and partial epilepsy: an EEG and dynamic susceptibility contrast (DSC) MRI study in a new possible genetic syndrome.

We report the case of a 24-year-old female with partial epilepsy, mental retardation, and dysmorphic facies. In EEG, a high spiking rate (HSR) was evident with abnormalities in the right frontal region. Morphological MRI showed a left temporo-mesial sclerosis and a cortical dysplasia localized in the right frontal cortex. Dynamic susceptibility contrast (DSC) MRI showed hyperperfusion in right frontal region and hypoperfusion in left fronto-temporal region. Left fronto-temporal hypoperfusion is consistent with temporo-mesial sclerosis. Right frontal hyperperfusion is related to the cortical dysplasia area with HSR. HSR may resemble both electroencephalographic and perfusional ictal pattern. DSC MRI is useful in the evaluation of regions involved in the genesis of ictal and interictal epileptiform activity. Furthermore, we hypothesize that our patient would be affected by a new possible genetic syndrome.

Adult↗

PubMed2003

Introducing BF++: AC++ framework for cognitive bio-feedback systems design.

OBJECTIVE: This paper addressed the issue of building-up a framework for the realization of several cognitive bio-feedback (CBF) systems. It minimizes the programming effort and maximizes the efficiency and the cross-platform portability so that it can be used with many platforms (either software or hardware). METHODS: A generic CBF system was decomposed into six modules: acquisition, kernel, feedback rule, patient feedback, operator user interface and persistent storage. The way in which these modules interact was defined by immutable software interfaces in a way that allows to completely substitute a module without the need to modify the others. RESULTS: Three Brain Computer Interface engines were developed with less than 40 lines of C++ code each. They can also be used under virtually any platform that supports an ANSI C++ compiler. CONCLUSION: A framework for the implementation of a wide range of CBF systems was developed. Compared to the other approaches that are described in the literature, the proposed one is the most efficient, the most protable across different platforms, the most generic and the one that allows the realization of the cheapest final systems.

Cognition↗

PubMed2002

Deep brain stimulation of both subthalamic nucleus and internal globus pallidus restores intracortical inhibition in Parkinson's disease paralleling apomorphine effects: a paired magnetic stimulation study.

OBJECTIVE: We investigated the effect of bilateral subthalamic nucleus (STN) and internal globus pallidus (GPi) deep brain stimulation (DBS) on intracortical inhibition (ICI) in patients with advanced Parkinson's disease (PD). METHODS: The activity of intracortical inhibitory circuits was studied in 4 PD patients implanted with stimulating electrodes both in STN and GPi by means of paired-pulse transcranial magnetic stimulation, delivered in a conditioning-test design at short (1-6 ms) interstimulus intervals (ISI). The effect of apomorphine on the same PD patients was also investigated. RESULTS: We observed that implanted PD patients showed a significant increase in ICI during either bilateral STN or GPi DBS at 3 ms ISI, and during bilateral STN DBS at 2 ms ISI in comparison to their off DBS condition. The same statistical improvement was observed during apomorphine infusion at 3 and 2 ms ISI. In each condition, the electrophysiological changes were associated with a significant clinical improvement as measured by the Unified Parkinson's Disease Rating Scale motor examination. CONCLUSIONS: These results are consistent with the hypothesis that basal ganglia DBS can mimic the effects of pharmacological dopaminergic therapy on PD patients cortical activity. We propose that in PD patients, the basal ganglia DBS-induced improvement of ICI may be related to a recovery in modulation of thalamo-cortical motor pathway.

Antiparkinson Agents↗

PubMed2002

Classification of EEG mental patterns by using two scalp electrodes and Mahalanobis distance-based classifiers.

OBJECTIVES: In this paper, we explored the use of quadratic classifiers based on Mahalanobis distance to detect mental EEG patterns from a reduced set of scalp recording electrodes. METHODS: Electrodes are placed in scalp centro-parietal zones (C3, P3, C4 and P4 positions of the international 10-20 system). A Mahalanobis distance classifier based on the use of full covariance matrix was used. RESULTS: The quadratic classifier was able to detect EEG activity related to imagination of movement with an affordable accuracy (97% correct classification, on average) by using only C3 and C4 electrodes. CONCLUSIONS: Such a result is interesting for the use of Mahalanobis-based classifiers in the brain computer interface area.

Biomedical Engineering↗

PubMed2001

Ketotic hyperglycemia and epilepsia partialis continua.

Epilepsia partialis continua (EPC) may occur during nonketotic hyperglycemia but has not been described with diabetic ketoacidosis. The authors report a patient with EPC associated with ketotic hyperglycemia. Brain MRI showed two areas of abnormal signal intensity in the left precentral gyrus and in the right cerebellar hemisphere. Hyperglycemia may reduce seizure threshold because of the increase in gamma-aminobutyric acid metabolism and may trigger epileptic discharges.

Adult↗

PubMed2001

Effect of apomorphine on cortical inhibition in Parkinson's disease patients: a transcranial magnetic stimulation study.

In this study, transcranial magnetic stimulation (TMS) of the primary motor hand area was used to test cortical excitability in Parkinson's disease (PD) patients. Motor evoked potentials (MEPs) to TMS were studied at rest by utilising distinct paired-pulse TMS protocols. Out of 29 untreated PD patients and 29 healthy subjects, early cortical inhibition (1-6 ms) was studied in a first subgroup of 17 PD patients and 15 healthy subjects, whereas late cortical inhibition (20-200 ms) was studied in a second subgroup of 21 PD patients and 19 healthy subjects. In all PD patients the same TMS protocols were performed before and after 3 h of apomorphine infusion. In comparison to healthy subjects, untreated PD patients showed a significant reduction of both early and late cortical inhibition, which was maximal at 2-3 ms, and at 80-100 ms, respectively. Apomorphine administration consistently reversed all the MEP abnormalities found in PD patients. The lack of TMS effects on the Hoffman's reflex (HR), at those intervals revealing the reduced inhibition in PD patients, is compatible with a supraspinal origin of the observed MEP abnormalities. Our data suggest that the cortical and/or subcortical loss of dopaminergic transmission in PD patients is associated with impaired motor cortical inhibitory mechanisms, as tested by a decreased early and late MEP inhibition.

Adult↗

PubMed2001

Reduced L-dopa absorption and increased clinical fluctuations in Helicobacter pylori-infected Parkinson's disease patients.

We report that the area under the curve of L-dopa plasma concentration, following the administration of a single 250 mg L-dopa dose, is augmented after Helicobacter pylori (HP) eradication in six Parkinson's disease (PD) patients showing high IgG antibody titer against HP. A prolongation of L-dopa clinical benefit was also observed. We suggest that HP infection-activated gastric alterations may be responsible, at least in part, for the reported erratic efficacy of oral L-dopa therapy in some advanced PD patients. Given the high percentage of HP-positivity in the age cohorts including the largest prevalence of PD patients, we propose that HP eradication be recommended in all PD patients under L-dopa therapy.

Aged↗

PubMed2001

Recognition of imagined hand movements with low resolution surface Laplacian and linear classifiers.

EEG-based Brain Computer Interfaces (BCIs) require on-line detection of mental states from spontaneous EEG signals. In this framework, it was suggested that EEG patterns can be better detected with EEG data transformed with Surface Laplacian computation (SL) than with the unprocessed raw potentials. However, accurate SL estimates require the use of many EEG electrodes, when local estimation methods are used. Since BCI devices have to use a limited number of electrodes for practical reasons, we investigated the performances of spline methods for SL estimates using a limited number of electrodes (low resolution SL). Recognition of mental activity was attempted on both raw and SL-transformed EEG data from five healthy people performing two mental tasks, namely imagined right and left hand movements. Linear classifiers were used including Signal Space Projection (SSP) and Fisher's linear discriminant. Results showed an acceptable average correlation between the waveforms obtained with the low resolution SL and these obtained with the SL computed from 26 electrodes (full resolution SL). More importantly, satisfactorily recognition scores for mental EEG-patterns were obtained with the low-resolution surface Laplacian transformation of the recorded potentials when compared with those obtained by using full resolution SL (82%). These results demonstrated also the utility of linear classifiers for the detection of mental patterns in the BCI field.

Biomedical Engineering↗

PubMed2000

Transcranial magnetic stimulation reveals an interhemispheric asymmetry of cortical inhibition in focal epilepsy.

Transcranial magnetic stimulation (TCS) was applied to both hemispheres of 16 patients affected by criptogenic focal epilepsy to evaluate the interhemispheric symmetry of the motor cortex excitability. The amplitude of the motor evoked potentials (MEPs) and the duration of the post-MEP silent period (SP) were measured at threshold (THR) and at increasing TCS stimulation intensities. The THR was significantly higher in patients than in 16 age-matched control subjects (p < 0.01). No interhemispheric differences were found in MEP amplitude. In controls, the correlation between SP duration and increasing TCS stimulus intensity was linear with a symmetrical progression of the SP duration over the two hemispheres. In patients this linear SP progression was lacking on the 'epileptic' hemisphere: the SP duration did not increase following TCS > 40% above THR, indicating abnormal interhemispheric asymmetry. This finding suggests a selective dysfunction of inhibition in the epileptic hemisphere as signaled by an abnormal SP duration in response to progressively higher TCS intensities.

Adolescent↗

PubMed2000

Curariform peripheral block of muscular tone selectively increases precentral N30 somatosensory evoked potentials component. A pharmacological study carried out on healthy subjects and parkinsonian syndromes.

In the present study we investigated whether the precentral component (N30) of short somatosensory evoked potentials (SEPs) to median nerve stimulation may be modified by peripheral neuromuscular blocking agent in patients affected by rigidity. We, therefore, recorded SEPs in nine Parkinson's disease (PD) patients and in seven psychotic patients affected by neuroleptic malignant syndrome (NMS), all showing severe rigidity. Each patient group was studied before and after the placebo, and before and after an atracurium besilate bolus of 0.05 mg/kg, in a single recording session. At the time of the test the PD patients had not taken any antiparkinsonian therapy for at least 48 h. The same recordings were also taken on nine neurologically normal subjects undergoing surgical procedures. Atracurium administration produced a remarkable amplitude increase of the major precentral component (N30) of SEPs. An atracurium-induced N30 amplitude increase was observed in both PD patients (from 2.41 to 4.07 microV) and NMS psychotic patients (from 2.03 to 3.97 microV), whereas there was a minor N30 amplitude increase in healthy subjects (from 3.53 to 4. 10 microV). The N30 latency was unaffected. Amplitude and latency of the major parietal SEPs component (N20) was unchanged in the three groups studied. Our results lead to the conclusion that a neuromuscular blocking agent is capable of increasing the N30 amplitude in patients affected by severe rigidity, exclusively reducing their muscular tone without interfering with the central dopaminergic system. Thus, a "peripheral gating" of sensory input to the supplementary motor area due to rigidity may play a relevant role in producing the N30 amplitude decrease described in patients affected by degenerative or pharmacologically induced parkinsonism. The reduction of rigidity could be the mechanism by which dopamine may increase the precentral N30 amplitude in parkinsonian syndromes.

Adult↗

PubMed2000

Gabapentin-induced modulation of interictal epileptiform activity related to different vigilance levels.

OBJECTIVES: Gabapentin (GBP) is a novel antiepileptic drug (AED), currently used as add-on therapy in patients with partial seizures. Similar to other AEDs, little is known about its effects on nocturnal sleep, despite the strict relationship between sleep and epileptic discharges. The aim of our study was to evaluate the effects of chronic therapy with GBP on both nocturnal sleep and on interictal epileptiform abnormalities (IEA) in relation to the different sleep stages. METHODS: Eighteen patients affected by partial seizures resistant to common AEDs were submitted to nocturnal polygraphic recordings under baseline conditions and after 4 months of add-on GBP treatment. RESULTS: We observed a significant increase in unilateral/focal IEA during light NREM sleep and a significant reduction in bilateral/diffuse IEA during wakefulness after sleep onset (WASO) with respect to the baseline condition. A significant increase in REM sleep and slow wave sleep (SWS) associated with a reduction in the number of awakenings and Stage 1 was also observed after GBP chronic therapy. CONCLUSIONS: GBP therapy improves the sleep pattern of epileptic patients and it seems to modulate the expression of IEA with different effects in relation to the various vigilance levels.

Acetates↗

PubMed2000

Effect of antiepileptic drugs on sleep.

The interactions between sleep and epilepsy are well known. A nodal point of the relationship between sleep and epilepsy is represented by pharmacological treatment. Sleep disturbances such as drowsiness are among the most frequent side effects of treatment with antiepileptic drugs, since they can deeply modify both sleep architecture and the sleep-wake cycle. Severe daytime somnolence affects patients' activities and it may facilitate the occurrence of seizures. These considerations underline the importance of antiepileptic drugs having anticonvulsant properties that do not negatively influence sleep and daytime somnolence. In this paper we review some relevant aspects of the effects of antiepileptic drugs on sleep.

Anticonvulsants↗

PubMed2000

Gabapentin as add-on therapy in focal epilepsy: a computerized EEG study.

OBJECTIVES: Gabapentin (GBP) possesses a well documented clinical efficacy in those types of focal epilepsy otherwise resistant to conventional antiepileptic drugs (AEDs); on the basis of this, it appears important to investigate the drug effects on the EEG epileptiform and background activity. METHODS: Twenty-five patients with cryptogenic or symptomatic partial epilepsy resistant to conventional AED treatment were included in the study. All patients underwent long-term video-EEG recordings before and after GBP addition (900-1200 mg/day). RESULTS: Quantitative analysis of the interictal EEG paroxysms revealed that GBP had no effect on the rate of occurrence of interictal and ictal EEG abnormalities. GBP was active in delimiting the spatial extent of the interictal spiking activity in those patients who displayed a significant reduction (> or =50%) in seizure occurrence (32% of the patients). EEG background activity recorded under rest condition from 18 out of 25 epileptic patients, before GBP therapy, was characterised by a higher content of the slow spectral components (delta and theta) with respect to control subjects. After GBP addition, the increase of theta relative power was also evident during task performance. CONCLUSIONS: These findings suggest that GBP does not interfere with the generation of interictal EEG spiking while it appears to reduce the susceptibility to seizures concomitantly with a limiting effect on the spiking activity spatial extent. The utilization of GBP in controlling focal seizures is reinforced by the absence of negative influence on cognitive functioning.

Acetates↗

PubMed2000

Effects of lamotrigine on nocturnal sleep, daytime somnolence and cognitive functions in focal epilepsy.

OBJECTIVES: The aim of our study was to evaluate possible changes in nocturnal sleep, daytime somnolence and cognitive functions induced by add-on therapy with lamotrigine (LTG). MATERIAL AND METHODS: Thirteen patients affected by seizures resistant to common antiepileptic drugs (AEDs) underwent nocturnal polysomnographic monitorings, daytime somnolence evaluations and a neuropsychological battery before and after 3 months of treatment with LTG. RESULTS: With LTG therapy we observed a significant increase in REM sleep and a significant reduction in the number of entries into REM and stage shifts. No significant correlation was observed between the decrease in nocturnal epileptiform activity and the increase in REM sleep. Other sleep parameters were unmodified. No significant changes were observed in daytime somnolence and in cognitive performances. CONCLUSION: LTG may produce positive effects on epileptic seizures and interictal abnormalities without interfering negatively on REM sleep, with improvement of sleep stability and without changes in daytime somnolence and neuropsychological performances. For these reasons it could be an important drug for improving epileptic patients' quality of life.

Adolescent↗

PubMed2000

Linear classification of low-resolution EEG patterns produced by imagined hand movements.

Electroencephalograph (EEG)-based brain-computer interfaces (BCI's) require on-line detection of mental states from spontaneous EEG signals. In this framework, surface Laplacian (SL) transformation of EEG signals has proved to improve the recognition scores of imagined motor activity. The results we obtained in the first year of an European project named adaptive brain interfaces (ABI) suggest that: 1) the detection of mental imagined activity can be obtained by using the signal space projection (SSP) method as a classifier and 2) a particular type of electrodes can be used in such a BCI device, reconciling the benefits of SL waveforms and the need for the use of few electrodes. Recognition of mental activity was attempted on both raw and SL-transformed EEG data from five healthy people performing two mental tasks, namely imagined right and left hand movements.

Adult↗

PubMed2000

Effect of anticonvulsants on nocturnal sleep in epilepsy.

Our objective was to determine, in three separate studies, the effects of controlled-release carbamazepine (CBZ-CR), lamotrigine (LTG), and gabapentin (GBP) on nocturnal sleep in epilepsy. Antiepileptic drugs (AEDs) control seizures and also modify hypnic structure. Despite widespread clinical use, their effects on sleep are not well known. PSG was performed in all three studies as follows: CBZ-CR: at baseline, after initial administration of CBZ-CR 400 mg, and after 1 month of CBZ-CR treatment (400 mg BID) in a sample of seven temporal lobe epileptic (TLE) patients. Results were compared with those of nine healthy volunteers; LTG: at baseline, after 3 months of stable treatment with LTG (300 mg/day); GBP: at baseline, after 3 months of stable treatment with GBP (1800 mg/day). Significant findings are as follows for each study. The acute administration of CBZ-CR increased number of stage shifts, reduced REM sleep, and increased REM sleep fragmentation. In the TLE group, these effects were almost completely reversed after chronic treatment. LTG increased REM sleep, reduced number of entries into REM sleep, decreased number of phase shifts, and decreased percentage of slow-wave sleep. GBP increased REM sleep percentage, increased mean duration of REM periods, reduced number of awakenings, and reduced stage 1 sleep percentage. We conclude that CBZ-CR disrupts REM sleep, but only during acute administration. LTG and GBP improve sleep stability while reducing seizures.

Acetates↗

PubMed1998

Changes in cerebral blood flow velocities during childhood absence seizures.

A simultaneous recording of mean flow velocity in the right middle cerebral artery by transcranial Doppler ultrasonography and electroencephalographic activity was performed in 5 children with multiple daily typical absence seizures. Twenty-eight absence episodes were recorded. Mean flow velocity increased gradually a few seconds before the clinical and electroencephalographic manifestations of each seizure and reached the maximum values (range of increase: 25.5-42.8% with respect to baseline) within 2-3 seconds from their onset. This increase was then followed by a fast reduction in flow velocity, with the lowest levels (range of decrease: 30.8-44.0% with respect to baseline) recorded within 4-6 seconds from the end of each absence seizure. These findings suggest that changes in cerebral blood flow and activity are quite complex during absence seizures and that they do not fully correlate with clinical and electroencephalographic manifestations.

Analysis of Variance↗