Off-line removal of TMS-induced artifacts on human electroencephalography by Kalman filter

In this paper we present an off-line Kalman filter approach to remove transcranial magnetic stimulation (TMS)-induced artifacts from electroencephalographic (EEG) recordings. Two dynamic models describing EEG and TMS signals generation are identified from data and the Kalman filter is applied to the linear system arising from their combination. The keystone of the approach is the use of time-varying covariance matrices suitably tuned on the physical parameters of the problem that allow to model the nonstationary components of the EEG-TMS signal. This guarantees an efficient deletion of TMS-induced artifacts while preserving the integrity of EEG signals around TMS impulses. Experimental results show that the Kalman filter is more effective than stationary filters (Wiener filter) for the problem under investigation.     

Epilepsia partialis continua following a Western variant tick-borne encephalitis

Epilepsia partialis continua (EPC) is a rare entity, first described in 1894 by Ko?evnikov, as a variant of simple focal motor status epilepticus. EPC is most frequently characterized by motor symptoms, but as recently described, non-motor manifestations may occur, such as somatosensory symptoms or aura continua. EPC in adults has been attributed to various etiologies: infectious, vascular, neoplastic, and metabolic. According to the recent definition, we reported a case of EPC with behavioral symptoms, following a tick-borne encephalitis (TBE) contracted in an endemic area (North Eastern Italy). Patient’s symptom was a poorly localized “whole body sensation”, which is reported as a condition occurring only in frontal lobe epilepsy. Patient’s EEG showed a left frontal predominance of epileptiform discharges. Literature highlighted the importance of the Far-eastern TBE variant as a cause of EPC, since no Western variant TBE cases are reported. In contrast to what was claimed so far, our case demonstrates that not only the Far-eastern TBE variant, but also Western variant TBE is a cause of EPC. Prognosis of EPC depends largely on the underlying etiology, and it is frequently drug-resistant. Our patient was treated with intravenous levetiracetam, with a subsequent clinical recovery and a disappearance of epileptiform discharges. The rapid clinic and electroencephalographic response to levetiracetam confirm that it can be a promising therapeutic option for treatment of EPC.     

EEG-fMRI as an useful tool to detect epileptic foci associated with secondary bilateral synchrony

IntroductionTailoring the epileptic cortex is the key issue in the pre-surgical work-up of patients with pharmacoresistant focal epilepsy. Not always, however, the conventional MRI and the scalp EEG are able to provide the information needed to address this issue since the imaging may be normal (criptogenetic epilepsy) and the EEG, even ictal, poorly localizing.Patient and methodsWe present a case of focal criptogenetic epilepsy with speech arrest seizures and bilateral synchronous spike and wave scalp EEG pattern (secondary bilateral synchrony). The patient underwent an EEG-fMRI continuous co-registration.ResultsThe EEG-fMRI showed a clear cut activation of a BOLD signal during the epileptic discharge over the left Supplementary Motor Area (SMA) and, on lesser degree, over the homolateral motor strip.DiscussionKnowledge and expertise about this technique has greatly increased over the last few years making it an useful tool for localizing purposes specially in patients with ambiguous scalp EEG and normal MRI just like the one we presented.     

COVID-19 lockdown attack on headache emergency admissions: a multidisciplinary retrospective study

Neurological Sciences - During the first COVID-19 lockdown in Italy, it was observed a reduction in emergency department (ED) attendances due to non-SARS-COV-2-related acute/chronic conditions. To...     

Changes of motor cortical excitability in human subjects from wakefulness to early stages of sleep: a combined transcranial magnetic stimulation and electroencephalographic study

The effect of sleep on human motor cortical excitability was investigated by evaluating the latency and amplitude of motor evoked potentials in ten subjects using transcranial magnetic stimulation. Motor evoked potentials and electroencephalographic data were recorded simultaneously and analyzed. Recordings were performed before, during and after a sleep period. A significant decrease in motor evoked potentials amplitude and a slight change in motor evoked potentials latency were noted in the recordings during the different sleep stages with a return to baseline values on awakening. A decrease in motor cortical excitability is suggested as explaining the effect of sleep.     

Cutaneomotor integration in human hand motor areas: somatotopic effect and interaction of afferents

The aim of this study was to elucidate sensorimotor integration in human hand motor areas, its time course, somatotopy and the interaction of sensory fields arising from two different fingers. We studied the influence of different intensities of electrical digital stimulation of two different fingers on motor-evoked potentials elicited in hand muscles by transcranial magnetic stimulation (TMS). Single conditioning electrical stimuli were applied to the right second (D2) and fifth fingers (D5) individually and also to both fingers (D2+D5) simultaneously in six normal volunteers. Magnetic tests, adjusted to produce a response in the abductor digiti minimi muscle of the right hand, were delivered using a circular and a focal coil. The digital stimuli were delivered to the finger at the sensory threshold (ST), at 3 and 5 times the ST, and over the pain threshold at interstimulus intervals (ISIs) ranging from 10 to 100 ms. In order to define the anatomical level of the sensorimotor interactions, the effect of the digital stimulation on TMS was compared to the effect on transcranial electrical stimulation. When the peripheral stimulation was delivered at the ST a small inhibitory effect was found only when stimulating both fingers. At 3 times the ST we detected a topographic distribution of motor-evoked potential inhibition, which partially disappeared at higher intensity (5 times the ST); two types of convergence effects took place at different ISIs. When conditioning stimuli were painful, somatotopy and convergence were lost. Sensorimotor integration shows somatotopy and interaction of afferents at different sites. The intensity of the conditioning stimulus plays an important role in topography and sensory convergence. The importance of these mechanisms in physiology and physiopathology is discussed.     

ASL MRI and 18F-FDG-PET in autoimmune limbic encephalitis: clues from two paradigmatic cases

Neurological Sciences - Autoimmune limbic encephalitis (LE) is a neurological condition characterized by seizures and cognitive dysfunction. Fluorine-18 fluorodeoxyglucose (18F-FDG-PET) has...     

Unveiling the relationship between autonomic involvement,fatigue, and cognitive dysfunction in early relapsing–remitting multiple sclerosis

Neurological Sciences - Fatigue is a common, yet disabling, symptom in patients with multiple sclerosis (PwMS). Fatigue has shown to be associated with self-reported autonomic nervous system (ANS)...