Atypical patterns of language activation in functional MRI (fMRI) are not unusual, particularly i... more Atypical patterns of language activation in functional MRI (fMRI) are not unusual, particularly in patients with severe epilepsy. Still, the functional significance of these activations is under debate. We describe a case of a right-handed patient affected by drug-refractory right temporal lobe epilepsy in whom pre-surgical fMRI showed bilateral language activations, greater in the right hemisphere (RH). After surgery, a right subdural hematoma caused epileptic status and severe aphasia. This post-surgical complication of a crossed aphasia confirmed the prior fMRI findings of RH language thus stressing the value of pre-surgical fMRI evaluations, even when surgery is planned in the RH of a right-handed patient.
We performed electroencephalography (EEG) and multimodal evoked potential (EP) studies in 16 pati... more We performed electroencephalography (EEG) and multimodal evoked potential (EP) studies in 16 patients with various forms of mitochondrial encephalomyopathy (ME). The electrophysiological investigations revealed signs of involvement of the peripheral and central nervous system (CNS) in 14 patients, with a high incidence of visual-EP (VEP) alterations, indicative of visual pathway vulnerability in mitochondrial diseases. No specific pattern of abnormalities emerged and, in particular, clinical and laboratory findings did not correlate with each other. EP (particularly VEP and electroretinogram) investigations should be part of the diagnostic work-up of patients with mitochondrial disorders in order to better characterize the clinical picture, disclose involvement of specific sensory systems of the CNS, and assess patients with atypical clinical presentations. Uno studio neurofisiologico (elettroencefalogramma, potenziali evocati multimodali) è stato effettuato in un gruppo di 16 pazienti affetti da encefalopatia mitocondriale. I risultati neurofisiologici hanno permesso di evidenziare anomalie funzionali a carico del sistema nervoso periferico e centrale in 14 dei pazienti esaminati, con una più alta incidenza di alterazioni allo studio dei potenizali evocati visivi, quesai ultimi esprimendo una particolare vulnerabilita della via ottica centrale in questa categoria di malattie neuromuscolari. Non è stato tuttavia identificato uno specifico pattern di alterazione neurofisiologica e non è stata riscontrata nessuna correlazione tra i dati laboratoristici, genetici e le alterazioni funzionali. Sulla base dei dati da not ottenuti emerge come to studio neurofisiologico, e dei potenziali evocati visivi in particolare, debba essere inserito in un protocollo di studio di pazienti sospetti per malattia mitocondriale, in particolare per le forme con più atipica presentazione clinica.
The internal representation of saccade commands has been shown to combine with visual information... more The internal representation of saccade commands has been shown to combine with visual information for saccade programming. In normative studies saccade parameters have been found consistent across tests. Their variability is highly correlated in both eyes suggesting a common saccade generator. Experimental and clinical studies specify the role of frontal eye fields in the volitional, inhibitory control of visually triggered saccades. The parietal lobe instead seems mainly concerned with privileged target selection. A parallel processing of saccade related signals occurs in corticostriatal circuits. Pursuit movements elicited by intermittently illuminated moving targets result from a predictive estimate of eye velocity based on previous eye velocity and visual feedback. Evidence for peristriate and parietal cortical areas to encode the information relevant to smooth pursuit generation is provided by clinical studies.
Two patients with uncontrollable aggressive behaviour underwent the placement of stimulating lead... more Two patients with uncontrollable aggressive behaviour underwent the placement of stimulating leads in the posterior hypothalamus (pHyp). One patient had also multifocal refractory epilepsy. Microrecordings were obtained in both patients during surgery under general anaesthesia. Firing rate, interspike intervals and oscillatory discharge patterns were analysed in 14 neurons. A mean discharge rate of 19 Hz, and oscillatory activity at 7–8 Hz were recorded in the first patient with aggressiveness and epilepsy. In the second patient the mean firing rate was 10 Hz, with evidence of both tonic and random firing patterns. Previous studies in patients with cluster headache showed that a discharge rate around 20 Hz and lack of a specific rhythmic pattern were the most consistent characteristics of neuronal discharge in this area. Our present findings therefore would suggest that the pattern of discharge of neurons in the pHyp should be evaluated with reference to the presence of concurrent pathology.
Simultaneous recording of functional magnetic resonance imaging (fMRI) and electroencephalography... more Simultaneous recording of functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) has been recently used to measure metabolic changes related to interictal spikes in temporal lobe epilepsy (TLE). Since blood oxygen level dependent (BOLD) responses have been often observed in extratemporal regions, we propose to explore interregional brain connectivity using a data-driven method based on partial correlation analysis of fMRI data. This approach allows to extract informations about functional interactivity and to differentiate direct from mediated interactions. We demonstrated that this technique provides a deeper insight into the functional relationships between the areas involved in the generation of spikes in TLE.
We studied the blood oxygen level dependent (BOLD) response to interictal epileptic spikes in a g... more We studied the blood oxygen level dependent (BOLD) response to interictal epileptic spikes in a group of patients with focal epilepsy by simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). The detection of activated areas was performed by using an approach based on the theory of the general linear models (GLM). Since little is know about the haemodynamic response to the interictal epileptiform activity, for each region involved by fMRI response and for each subject we obtained a robust estimation of the haemodynamic response function (HRF) by using a Bayesian approach. We observed important variations in the time course of the haemodynamic response between patients and across the different fMRI areas of a same subject.
Summary: Purpose: Focal negative motor (akinetic) seizures are rare ictal events that are diagnos... more Summary: Purpose: Focal negative motor (akinetic) seizures are rare ictal events that are diagnostically challenging because they are difficult to differentiate from postictal Todd paresis, transient ischemic attacks, migraine events, and psychogenic episodes.Methods: We describe a 45-year-old man in whom, after surgical drainage of a right frontoparietal subdural hematoma, prolonged episodes developed with flaccid paralysis of the left arm.Results: A video-EEG recording demonstrated a close relation between the focal motor impairment and a clear-cut epileptic ictal discharge involving the right perirolandic cortical areas.Conclusions: On the basis of the electroclinical data, we hypothesize the involvement of the primary motor area in the genesis of the epileptic discharge triggering focal negative seizures.
Semantic memory was evaluated in 124 epilepsy patients, including 84 with left (n=44) or right te... more Semantic memory was evaluated in 124 epilepsy patients, including 84 with left (n=44) or right temporal lobe epilepsy (TLE) (n=40) and 40 with left (n=25) or right frontal lobe epilepsy (FLE) (n=15), in order to determine their verbal and visual deficits, and the neuroanatomical relationships between them. The controls were 35 healthy subjects. Semantic memory was assessed by means of Picture Naming, Picture Pointing, the verbal Pyramid and Palm Trees Test (PPTT), the visual PPTT, Object Decision Hard, and Drawing From Memory. Episodic memory was assessed by means of the Short Story, Rey's Complex Figure, the Verbal and Visual Selective Reminding Procedure and Brown-Peterson Procedure. Factor analysis of the epilepsy patients distinguished their semantic memory scores from other neuropsychological domains. The semantic memory factor was significantly related to the side of the epileptic region, with lower scores in the left hemisphere and left TLE patients. In comparison with the controls, the left TLE patients were significantly impaired on Picture Naming, Picture Pointing, and Object Decision Hard. Subsequent analyses showed that, in comparison with the controls and the right TLE patients, the left TLE patients with lateral temporal lobe lesions were impaired in Picture Naming whereas, in comparison with the controls, the left TLE patients with mesial temporal lobe lesions were impaired in Object Decision Hard. On the contrary, the episodic memory factor was not related to the side of the epileptic region, and a few material-specific tests revealed opposite impairments in the left and right hemisphere patients. These results show that left TLE may cause semantic memory deficits involving verbal and visual information. Unlike the material-specific pattern of episodic memory, this pattern of impairment is in line with the view of an amodal semantic store in which all of the information about a thing overlaps. The semantic memory impairment may reflect damage in the lateral and mesial temporal lobe regions that impair neocortical functions in storing and retrieving information or hippocampal functions in processing meaningful stimuli.
Summary: Purpose: A limited number of cases of adult-onset Rasmussen's encephalitis (A-RE) have b... more Summary: Purpose: A limited number of cases of adult-onset Rasmussen's encephalitis (A-RE) have been reported, but the features of the syndrome are still unclear. The aim of this study was to verify the clinical features of A-RE, and outline a noninvasive approach that may allow its early diagnosis and treatment.Methods: Retrospective evaluation of extensive noninvasive work-up of seven patients with A-RE, including repeat clinical, neurophysiological, and neuroimaging investigations.Results: The study identified two distinct patterns of disease presentation, one characterized by focal motor epilepsy (the “epileptic” phenotype), and the other by focal cortical myoclonus (the “myoclonic” phenotype). Unilateral neurological deficits and brain atrophy were progressive in both phenotypes, but they were more prominent and were detected earlier in the “epileptic” phenotype.Conclusions: The anatomo-electroclinical features of these patients allowed a noninvasive diagnosis of A-RE and identification of two distinct disease phenotypes. Early noninvasive diagnosis can allow faster initiation of treatment.
Atypical patterns of language activation in functional MRI (fMRI) are not unusual, particularly i... more Atypical patterns of language activation in functional MRI (fMRI) are not unusual, particularly in patients with severe epilepsy. Still, the functional significance of these activations is under debate. We describe a case of a right-handed patient affected by drug-refractory right temporal lobe epilepsy in whom pre-surgical fMRI showed bilateral language activations, greater in the right hemisphere (RH). After surgery, a right subdural hematoma caused epileptic status and severe aphasia. This post-surgical complication of a crossed aphasia confirmed the prior fMRI findings of RH language thus stressing the value of pre-surgical fMRI evaluations, even when surgery is planned in the RH of a right-handed patient.
We performed electroencephalography (EEG) and multimodal evoked potential (EP) studies in 16 pati... more We performed electroencephalography (EEG) and multimodal evoked potential (EP) studies in 16 patients with various forms of mitochondrial encephalomyopathy (ME). The electrophysiological investigations revealed signs of involvement of the peripheral and central nervous system (CNS) in 14 patients, with a high incidence of visual-EP (VEP) alterations, indicative of visual pathway vulnerability in mitochondrial diseases. No specific pattern of abnormalities emerged and, in particular, clinical and laboratory findings did not correlate with each other. EP (particularly VEP and electroretinogram) investigations should be part of the diagnostic work-up of patients with mitochondrial disorders in order to better characterize the clinical picture, disclose involvement of specific sensory systems of the CNS, and assess patients with atypical clinical presentations. Uno studio neurofisiologico (elettroencefalogramma, potenziali evocati multimodali) è stato effettuato in un gruppo di 16 pazienti affetti da encefalopatia mitocondriale. I risultati neurofisiologici hanno permesso di evidenziare anomalie funzionali a carico del sistema nervoso periferico e centrale in 14 dei pazienti esaminati, con una più alta incidenza di alterazioni allo studio dei potenizali evocati visivi, quesai ultimi esprimendo una particolare vulnerabilita della via ottica centrale in questa categoria di malattie neuromuscolari. Non è stato tuttavia identificato uno specifico pattern di alterazione neurofisiologica e non è stata riscontrata nessuna correlazione tra i dati laboratoristici, genetici e le alterazioni funzionali. Sulla base dei dati da not ottenuti emerge come to studio neurofisiologico, e dei potenziali evocati visivi in particolare, debba essere inserito in un protocollo di studio di pazienti sospetti per malattia mitocondriale, in particolare per le forme con più atipica presentazione clinica.
The internal representation of saccade commands has been shown to combine with visual information... more The internal representation of saccade commands has been shown to combine with visual information for saccade programming. In normative studies saccade parameters have been found consistent across tests. Their variability is highly correlated in both eyes suggesting a common saccade generator. Experimental and clinical studies specify the role of frontal eye fields in the volitional, inhibitory control of visually triggered saccades. The parietal lobe instead seems mainly concerned with privileged target selection. A parallel processing of saccade related signals occurs in corticostriatal circuits. Pursuit movements elicited by intermittently illuminated moving targets result from a predictive estimate of eye velocity based on previous eye velocity and visual feedback. Evidence for peristriate and parietal cortical areas to encode the information relevant to smooth pursuit generation is provided by clinical studies.
Two patients with uncontrollable aggressive behaviour underwent the placement of stimulating lead... more Two patients with uncontrollable aggressive behaviour underwent the placement of stimulating leads in the posterior hypothalamus (pHyp). One patient had also multifocal refractory epilepsy. Microrecordings were obtained in both patients during surgery under general anaesthesia. Firing rate, interspike intervals and oscillatory discharge patterns were analysed in 14 neurons. A mean discharge rate of 19 Hz, and oscillatory activity at 7–8 Hz were recorded in the first patient with aggressiveness and epilepsy. In the second patient the mean firing rate was 10 Hz, with evidence of both tonic and random firing patterns. Previous studies in patients with cluster headache showed that a discharge rate around 20 Hz and lack of a specific rhythmic pattern were the most consistent characteristics of neuronal discharge in this area. Our present findings therefore would suggest that the pattern of discharge of neurons in the pHyp should be evaluated with reference to the presence of concurrent pathology.
Simultaneous recording of functional magnetic resonance imaging (fMRI) and electroencephalography... more Simultaneous recording of functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) has been recently used to measure metabolic changes related to interictal spikes in temporal lobe epilepsy (TLE). Since blood oxygen level dependent (BOLD) responses have been often observed in extratemporal regions, we propose to explore interregional brain connectivity using a data-driven method based on partial correlation analysis of fMRI data. This approach allows to extract informations about functional interactivity and to differentiate direct from mediated interactions. We demonstrated that this technique provides a deeper insight into the functional relationships between the areas involved in the generation of spikes in TLE.
We studied the blood oxygen level dependent (BOLD) response to interictal epileptic spikes in a g... more We studied the blood oxygen level dependent (BOLD) response to interictal epileptic spikes in a group of patients with focal epilepsy by simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). The detection of activated areas was performed by using an approach based on the theory of the general linear models (GLM). Since little is know about the haemodynamic response to the interictal epileptiform activity, for each region involved by fMRI response and for each subject we obtained a robust estimation of the haemodynamic response function (HRF) by using a Bayesian approach. We observed important variations in the time course of the haemodynamic response between patients and across the different fMRI areas of a same subject.
Summary: Purpose: Focal negative motor (akinetic) seizures are rare ictal events that are diagnos... more Summary: Purpose: Focal negative motor (akinetic) seizures are rare ictal events that are diagnostically challenging because they are difficult to differentiate from postictal Todd paresis, transient ischemic attacks, migraine events, and psychogenic episodes.Methods: We describe a 45-year-old man in whom, after surgical drainage of a right frontoparietal subdural hematoma, prolonged episodes developed with flaccid paralysis of the left arm.Results: A video-EEG recording demonstrated a close relation between the focal motor impairment and a clear-cut epileptic ictal discharge involving the right perirolandic cortical areas.Conclusions: On the basis of the electroclinical data, we hypothesize the involvement of the primary motor area in the genesis of the epileptic discharge triggering focal negative seizures.
Semantic memory was evaluated in 124 epilepsy patients, including 84 with left (n=44) or right te... more Semantic memory was evaluated in 124 epilepsy patients, including 84 with left (n=44) or right temporal lobe epilepsy (TLE) (n=40) and 40 with left (n=25) or right frontal lobe epilepsy (FLE) (n=15), in order to determine their verbal and visual deficits, and the neuroanatomical relationships between them. The controls were 35 healthy subjects. Semantic memory was assessed by means of Picture Naming, Picture Pointing, the verbal Pyramid and Palm Trees Test (PPTT), the visual PPTT, Object Decision Hard, and Drawing From Memory. Episodic memory was assessed by means of the Short Story, Rey's Complex Figure, the Verbal and Visual Selective Reminding Procedure and Brown-Peterson Procedure. Factor analysis of the epilepsy patients distinguished their semantic memory scores from other neuropsychological domains. The semantic memory factor was significantly related to the side of the epileptic region, with lower scores in the left hemisphere and left TLE patients. In comparison with the controls, the left TLE patients were significantly impaired on Picture Naming, Picture Pointing, and Object Decision Hard. Subsequent analyses showed that, in comparison with the controls and the right TLE patients, the left TLE patients with lateral temporal lobe lesions were impaired in Picture Naming whereas, in comparison with the controls, the left TLE patients with mesial temporal lobe lesions were impaired in Object Decision Hard. On the contrary, the episodic memory factor was not related to the side of the epileptic region, and a few material-specific tests revealed opposite impairments in the left and right hemisphere patients. These results show that left TLE may cause semantic memory deficits involving verbal and visual information. Unlike the material-specific pattern of episodic memory, this pattern of impairment is in line with the view of an amodal semantic store in which all of the information about a thing overlaps. The semantic memory impairment may reflect damage in the lateral and mesial temporal lobe regions that impair neocortical functions in storing and retrieving information or hippocampal functions in processing meaningful stimuli.
Summary: Purpose: A limited number of cases of adult-onset Rasmussen's encephalitis (A-RE) have b... more Summary: Purpose: A limited number of cases of adult-onset Rasmussen's encephalitis (A-RE) have been reported, but the features of the syndrome are still unclear. The aim of this study was to verify the clinical features of A-RE, and outline a noninvasive approach that may allow its early diagnosis and treatment.Methods: Retrospective evaluation of extensive noninvasive work-up of seven patients with A-RE, including repeat clinical, neurophysiological, and neuroimaging investigations.Results: The study identified two distinct patterns of disease presentation, one characterized by focal motor epilepsy (the “epileptic” phenotype), and the other by focal cortical myoclonus (the “myoclonic” phenotype). Unilateral neurological deficits and brain atrophy were progressive in both phenotypes, but they were more prominent and were detected earlier in the “epileptic” phenotype.Conclusions: The anatomo-electroclinical features of these patients allowed a noninvasive diagnosis of A-RE and identification of two distinct disease phenotypes. Early noninvasive diagnosis can allow faster initiation of treatment.
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Papers by Flavio Villani