Rodrigo Rocamora

Pilomotor seizures: An autonomic semiology of limbic encephalitis?

PURPOSE Ictal piloerection is an infrequent seizure semiology that is commonly overlooked as an ictal epileptic manifestation. Piloerection is considered to be principally caused by temporal lobe activity although frontal and hypothalamic seizure origins have been reported. The described etiology has shown a wide variety of structural causes such as mesial temporal sclerosis, tumors, posttraumatic, cavernomas and cryptogenic epilepsies. METHODS We retrospectively reviewed the incidence of ictal piloerection in the clinical records of patients who underwent video-EEG monitoring (VEEGM) between 2007 and 2013 in a multicenter cooperative study. All patients presented refractory epilepsies and were evaluated with a protocol that included brain MRI, neuropsychology and VEEGM. RESULTS A total of 766 patients were evaluated in four tertiary centers in Spain. Five patients showed piloerection as principal seizure semiology (prevalence 0.65%). The mean age at seizure onset was 39.6 years and the average epilepsy duration was 5.2 years (range 2-14) before diagnosis. Four patients were additionally examined with FDG-PET and/or SPECT-SISCOM. All presented temporal lobe epilepsy (TLE), three right-sided and two left-sided. A typical unilateral hippocampal sclerosis was described in 3 cases. The etiology detected in all cases was limbic encephalitis. Three had LGI1, one anti-Hu, and another Ma2 antibodies. CONCLUSION Our series describes a so far not well-recognized autoimmune association of pilomotor seizures to limbic encephalitis. This etiology should be ruled out through a comprehensive diagnostic work-up even in cases of long-lasting TLE with typical hippocampal atrophy on MRI.

The dynamics of human cognition: Increasing global integration coupled with decreasing segregation found using iEEG

&NA; Cognitive processing requires the ability to flexibly integrate and process information across large brain networks. How do brain networks dynamically reorganize to allow broad communication between many different brain regions in order to integrate information? We record neural activity from 12 epileptic patients using intracranial EEG while performing three cognitive tasks. We assess how the functional connectivity between different brain areas changes to facilitate communication across them. At the topological level, this facilitation is characterized by measures of integration and segregation. Across all patients, we found significant increases in integration and decreases in segregation during cognitive processing, especially in the gamma band (50–90 Hz). We also found higher levels of global synchronization and functional connectivity during task execution, again particularly in the gamma band. More importantly, functional connectivity modulations were not caused by changes in the level of the underlying oscillations. Instead, these modulations were caused by a rearrangement of the mutual synchronization between the different nodes as proposed by the “Communication Through Coherence” Theory. HighlightsCognitive processing drives increases of integration and decreases of segregation.The modulations in FC are not caused by changes in the underlying oscillations.Cognition causes a rearrangement of the mutual synchronisation within the network.Our study confirms the prediction of the CTC theory but on a whole‐brain level.

A Temporal Estimate of Integrated Information for Intracranial Functional Connectivity

A major challenge in computational and systems neuroscience concerns the quantification of information processing at various scales of the brain’s anatomy. In particular, using human intracranial recordings, the question we ask in this paper is: How can we estimate the informational complexity of the brain given the complex temporal nature of its dynamics? To address this we work with a recent formulation of network integrated information that is based on the Kullback-Leibler divergence between the multivariate distribution on the set of network states versus the corresponding factorized distribution over its parts. In this work, we extend this formulation for temporal networks and then apply it to human brain data obtained from intracranial recordings in epilepsy patients. Our findings show that compared to random re-wirings of the data, functional connectivity networks, constructed from human brain data, score consistently higher in the above measure of integrated information. This work suggests that temporal integrated information may indeed be a good starting point as a future measure of cognitive complexity.

Human hippocampal theta oscillations reflect sequential dependencies during spatial planning.

Movement-related theta oscillations in rodent hippocampus coordinate ‘forward sweeps’ of location-specific neural activity that could be used to evaluate spatial trajectories online. This raises the possibility that increases in human hippocampal theta power accompany the evaluation of upcoming spatial choices. To test this hypothesis, we measured neural oscillations during a spatial planning task that closely resembles a perceptual decision-making paradigm. In this task, participants searched visually for the shortest path between a start and goal location in novel mazes that contained multiple choice points, and were subsequently asked to make a spatial decision at one of those choice points. We observed ~4-8 Hz hippocampal/medial temporal lobe theta power increases specific to sequential planning that were negatively correlated with subsequent decision speed, where decision speed was inversely correlated with choice accuracy. These results implicate the hippocampal theta rhythm in decision tree search during planning in novel environments.

Ictal spitting in non-dominant temporal lobe epilepsy: an anatomo-electrophysiological correlation.

We report a patient presenting drug-resistant, non-dominant temporal lobe epilepsy with ictal spitting and prosopometamorphopsia, both extremely rare semiologies. Second-phase pre-surgical monitoring was performed using SEEG due to lesion-negative imaging and the rare semiology. The seizure onset zone was delimited to the right anterior hippocampus and the temporobasal cortex, with the propagation zone within the entorhinal cortex. Interestingly, direct electrical stimulation to the entorhinal cortex, which was reproduced in a number of trials, evoked spitting without leading to seizures or post-discharges. After the resection of the epileptogenic zone, the patient remained seizure-free without AEDs for a follow-up period of five years (Engel Class 1a). The neuropathology revealed a focal cortical dysplasia type FCD-Ia. Spectral analysis of intracranial ictal EEG (iEEG) data suggested a possible role of the basal temporal and entorhinal cortex as a necessary node in ictal spitting. [Published with video sequences on www.epilepticdisorders.com].

Post-ictal atrial fibrillation detected during video-EEG monitoring: Case report, proposed physiopathologic mechanism and therapeutic considerations

a Epilepsy Monitoring Unit, Department of Neurology, Hospital del Mar, Passeig Marítim 25-29, 08003 Barcelona, Spain b Epilepsy Monitoring Unit, Pediatric Department, Hospital del Mar, Passeig Marítim 25-29, 08003 Barcelona, Spain c Electrophysiology Unit, Department of Cardiology, Hospital del Mar, Passeig Marítim 25-29, 08003 Barcelona, Spain d IMIM (Hospital del Mar Medical Research Institute), Carrer del Dr. Aiguader 88, 08003 Barcelona, Spain

Detection of recurrent activation patterns across focal seizures: Application to seizure onset zone identification

OBJECTIVE We introduce a method that quantifies the consistent involvement of intracranially monitored regions in recurrent focal seizures. METHODS We evaluated the consistency of two ictal spectral activation patterns (mean power change and power change onset time) in intracranial recordings across focal seizures from seven patients with clinically marked seizure onset zone (SOZ). We examined SOZ discrimination using both patterns in different frequency bands and periods of interest. RESULTS Activation patterns were proved to be consistent across more than 80% of recurrent ictal epochs. In all patients, whole-seizure mean activations were significantly higher for SOZ than non-SOZ regions (P<0.05) while activation onset times were significantly lower for SOZ than for non-SOZ regions (P<0.001) in six patients. Alpha-beta bands (8-20Hz) achieved the highest patient-average effect size on the whole-seizure period while gamma band (20-70Hz) achieved the highest discrimination values between SOZ and non-SOZ sites near seizure onset (0-5s). CONCLUSIONS Consistent spectral activation patterns in focal epilepsies discriminate the SOZ with high effect sizes upon appropriate selection of frequency bands and activation periods. SIGNIFICANCE The present method may be used to improve epileptogenic identification as well as pinpoint additional regions that are functionally altered during ictal events.

The dynamics of human cognition: increasing global integration coupled with decreasing segregation found using intracortical EEG

Cognitive processing requires the ability to flexibly adjust and integrate information across large brain networks. More information is needed on how brain networks dynamically reorganize to allow such broad communication across many different brain regions in order to integrate the necessary information. Here, we use intracranial EEG to record neural activity from 12 epileptic patients while they perform a cognitive task in order to study how the broadness of communication changes across the underlying network spanning many different brain regions. The broadness of communication is characterized by functional measures of integration and segregation. Across all patients, we found significant increases in integration and decreases in segregation during cognitive processing, especially in the gamma band (50-90 Hz). Accordingly, we also found significantly higher level of global synchronization and functional connectivity during the execution of the cognitive task, again particularly in the gamma band. Furthermore, we demonstrate that these modulations in the level of communication across the network were not caused by changes in the level of the underlying oscillations as reflected by the corresponding power spectra.