Simultaneous EEG-fMRI in Patients with Unverricht-Lundborg Disease: Event-Related Desynchronization/Synchronization and Hemodynamic Response Analysis

We performed simultaneous acquisition of EEG-fMRI in seven patients with Unverricht-Lundborg disease (ULD) and in six healthy controls using self-paced finger extension as a motor task. The event-related desynchronization/synchronization (ERD/ERS) analysis showed a greater and more diffuse alpha desynchronization in central regions and a strongly reduced post-movement beta-ERS in patients compared with controls, suggesting a significant dysfunction of the mechanisms regulating active movement and movement end. The event-related hemodynamic response obtained from fMRI showed delayed BOLD peak latency in the contralateral primary motor area suggesting a less efficient activity of the neuronal populations driving fine movements, which are specifically impaired in ULD. 1. Introduction The analysis of the EEG recorded during motor performance (self-paced movement) provides information about the movement-related changes in oscillatory cortical activity. In normal subjects, an amplitude attenuation of specific frequency components (event-related desynchronization, ERD) in the - and -bands precedes a voluntary movement and reflects cortical activation concurring with movement planning. At the end of the movement, event-related synchronization (ERS) in the -band replaces ERD [1]. Simultaneous EEG-fMRI acquisition during performance of a motor task enables the identification of changes of brain activity in motor areas and provides information on the source of the event generator. In Unverricht-Lundborg disease (ULD) patients, voluntary movements are selectively impaired by the presence of action myoclonus [2]. In these patients, ERD/ERS changes highlight increased and diffuse activation of the motor cortex during movement planning and severely reduced postexcitatory inhibition of the motor cortex [3]. We simultaneously acquired EEG and fMRI in order to study the spatiotemporal pattern of ERD/ERS resulting from self-paced extension of the index finger in ULD patients and to explore the correlation with hemodynamic changes. 2. Material and Methods We enrolled 7 right-handed patients (mean age: 29.1 10 years; four women) with ULD, whose main clinical features are reported in Table 1 and 6 right-handed healthy controls (mean age: 29.1 6.7 years; five women). In all patients, the diagnosis of ULD was established on the basis of the typical electroclinical presentation and of the genetic finding of dodecamer expansion at cstb gene [4]. Table 1: Patient data. 2.1. Motor Task Inside the bore of the scanner, subjects laid supine with their arms relaxed; their head was