F. Milanese

EEG and fMRI Coregistration to Investigate the Cortical Oscillatory Activities During Finger Movement

Electroencephalography combined with functional magnetic resonance imaging (EEG-fMRI) may be used to identify blood oxygenation level dependent (BOLD) signal changes associated with physiological and pathological EEG event. In this study we used EEG-fMRI to determine the possible correlation between topographical movement-related EEG changes in brain oscillatory activity recorded from EEG electrodes over the scalp and fMRI-BOLD cortical responses in motor areas during finger movement. Thirty-two channels of EEG were recorded in 9 subjects during eyes-open condition inside a 1.5 T magnetic resonance (MR) scanner using a MR-compatible EEG recording system. Off-line MRI artifact subtraction software was applied to obtain continuous EEG data during␣fMRI acquisition. For EEG data analysis we used the event-related-synchronization/desynchronization (ERS/ERD) approach to investigate where movement-related decreases in alpha and beta power are located. For image statistical analysis we used a general linear model (GLM) approach. There was a significant correlation between the positive-negative ratio of BOLD signal peaks and ERD values in the electrodes over the region of activation. We conclude that combined EEG-fMRI may be used to investigate movement-related oscillations of the human brain inside an MRI scanner and the movement-related changes in the EMG or EEG signals are useful to identify the brain activation sources responsible for BOLD-signal changes.

Changes in cerebral activity after decreased upper-limb hypertonus: an EMG-fMRI study

OBJECTIVE Whereas several studies have used functional magnetic resonance imaging (fMRI) to investigate motor recovery, whether therapy to decrease post-stroke hypertonus alters central motor patterns remains unclear. In this study, we used continuous electromyography (EMG)-fMRI to investigate possible changes in movement-related brain activation in patients receiving Botulinum toxin (BoNT-A) for hand-muscle hypertonus after chronic stroke. METHODS We studied eight stroke patients all of whom had hemiparesis and associated upper-limb hypertonus. All patients underwent an fMRI-EMG recording and clinical-neurological assessment before BoNT-A and 5 weeks thereafter. The handgrip motor task during imaging was fixed across both patients and controls. The movements were metronome paced, movement amplitude and force were controlled with a plastic orthosis, dynamometer and EMG recording. An age-matched control group was recruited from among healthy volunteers underwent the same fMRI-EMG recording. RESULTS Before BoNT-A, while patients moved the paretic hand, fMRI detected wide bilateral activation in the sensorymotor areas (SM1), in the supplementary motor area (SMA) and cerebellum. After BoNT-A blood oxygenation level-dependent (BOLD) activation decreased in ipsilateral and contralateral motor areas and became more lateralized. BOLD activation decreased also in ipsilateral cerebellar regions and in the SMA. CONCLUSION Changes in peripheral upper-limb hypertonus after BoNT-A were associated to an improvement in active movements and more lateralized and focalized activation of motor areas. The clinical and EMG-fMRI coregistration technique we used to study hand-muscle hypertonus in patients receiving BoNT-A after chronic stroke should be useful in future studies seeking improved strategies for post-stroke neurorehabilitation.

Evaluation of botulinum toxin therapy of spastic equinus in paediatric patients with cerebral palsy

OBJECTIVE To develop a clinical and instrumental protocol to assess the postural and dynamic effects following treatment with botulinum neurotoxin A in children with cerebral palsy affected by spastic equinus. DESIGN Open study, in which every patient served as his or her own control. PATIENTS Ten sequential children with cerebral palsy and spastic dynamic equinus foot. METHODS Botulinum neurotoxin A was injected in the gastrocnemius, soleus and tibialis posterior muscles. The main measures were: pedobarometry, dynamic surface electromyography, video gait analysis scale, and the modified Ashworth Scale. RESULTS After treatment with botulinum neurotoxin A, pedobarometric evaluation revealed a significant change in all parameters, including a decrease in the modified Ashworth Scale and an increase in the range of motion. All children showed significant improvement in initial foot contact, as documented by the video gait analysis scale. The calf muscle electromyography pattern showed a decrease in co-contraction during gait in all children. These modifications were statistically significant for all parameters considered (p < 0.05). CONCLUSION This pilot study suggests that dynamic electromyography and pedobarometry are simple to use and provide useful data; this protocol could be preferable in young and uncooperative children in order to monitor rehabilitation treatments.

Continuous EEG-fMRI in Pre-Surgical Evaluation of a Patient with Symptomatic Seizures: Bold Activation Linked to Interictal Epileptic Discharges Caused by Cavernoma

We used continuous electroencephalography-functional magnetic resonance imaging (EEG-fMRI) to identify the linkage between the “epileptogenic” and the “irritative” area in a patient with symptomatic epilepsy (cavernoma, previously diagnosed and surgically treated), i.e. a patient with a well known “epileptogenic area”, and to increase the possibility of a non invasive pre-surgical evaluation of drug-resistant epilepsies. A compatible MRI system was used (EEG with 29 scalp electrodes and two electrodes for ECG and EMG) and signals were recorded with a 1.5 Tesla MRI scanner. After the recording session and MRI artifact removal, EEG data were analyzed offline and used as paradigms in fMRI study. Activation (EEG sequences with interictal slow-spiked-wave activity) and rest (sequences of normal EEG) conditions were compared to identify the potential resulting focal increase in BOLD signal and to consider if this is spatially linked to the interictal focus used as a paradigm and to the lesion. We noted an increase in the BOLD signal in the left neocortical temporal region, laterally and posteriorly to the poro-encephalic cavity (residual of cavernoma previously removed), that is around the “epileptogenic area”. In our study “epileptogenic” and “irritative” areas were connected with each other. Combined EEG-fMRI may become routine in clinical practice for a better identification of an irritative and lesional focus in patients with symptomatic drug-resistant epilepsy.

MO16 Combining EEG and fMRI to investigate the cortical oscillatory activities during finger movement

MO16 Combining EEG and fMRI to investigate the cortical oscillatory activities during finger movement Emanuela Formaggio 1, Mirko Avesani 1, Silvia Francesca Storti 1 , Michele Acler 1, Franco Milanese 1 , Anna Gasparini 2, Roberto Cerini 2, Roberto Pozzi Mucelli 2 , Antonio Fiaschi 1, Paolo Manganotti 1 1Section of Neurological Rehabilitation, Department of Neurological and Visual Sciences, “Gianbattista Rossi” Hospital, University of Verona, Verona, Italy; 2Department of Morphologic and Biomedical Sciences, “Gianbattista Rossi” Hospital, University of Verona, Verona, Italy; 3Section of Neurological Rehabilitation, Department of Neurological and Visual Sciences, “Gianbattista Rossi” Hospital, University of Verona, Verona, Italy.-IRCCS “San Camillo” Hospital-Venice-Italy

P172 Effect of stimulus rate during median nerve stimulation on bold activity: a 3T fMRI Study

Introduction: Functional mapping during craniotomy in awake patients, together with intraoperative ultrasonography and CT/MRI scan, enables the identification and delineation of the motor and sensory cortex and of language cortical sites Patients And Methods: Our series consisted of thirty patients harbouring brain lesions in functional areas with the following locations: 19 precentral: (12 right and 7 left hemisphere), 3 on the right frontal opercular area, 4 postcentral (2 right and 7 left hemisphere) and 4 on the temporal lobe. The presenting symptoms were seizures in 24 patients, paresis in 6, aphasia in 6 and headache in 6 cases. MRI and neuropsychological examination were carried out in all patients. All patients were operated on under local anesthesia. A hand-held bipolar electrode delivering a biphasic current was applied on the brain of the awake patients before resection in order to identify eloquent areas. Motor responses were observed as facial or limb movements as well as registered by EMG recording using subdermal electrodes. Sensory symptoms were also accounted for as paresthesiae. In order to map the language cortical areas the patient was asked to talk freely or to perform counting or naming tasks. Stimulation of the language areas induced speech arrest, anomia or dysarthria. Language tasks and motor clinical examination as well as continuous EMG monitoring were continued whilst the surgical resection was being carried out. Results: Surgical removal was total in 24 patients, subtotal in 4. In 2 cases resection could not be performed. Two patients recovered completely from their preoperative deficit. Two patients presented a severe postoperative deficit. Conclusion: Functional mapping using electrical stimulation is a safe and reliable method to identify eloquent areas, providing invaluable information for defining resection borders and minimizing the risk of damage while increasing the quality of resection.