Consciousness transitions during epilepsy seizures through the lens of integrated information theory.

Consciousness is one of the most complex aspects of human experience. Studying the mechanisms involved in the transitions among different levels of consciousness remains as one of the greatest challenges in neuroscience. In this study we use a measure of integrated information (ΦAR) to evaluate dynamic changes during consciousness transitions. We applied the measure to intracranial electroencephalography (SEEG) recordings collected from 6 patients that suffer from refractory epilepsy, taking into account inter-ictal, pre-ictal and ictal periods. We analyzed the dynamical evolution of ΦAR in groups of electrode contacts outside the epileptogenic region and compared it with the Consciousness Seizure Scale (CCS). We show that changes on ΦAR are significantly correlated with changes in the reported states of consciousness.

Crossed aphasia after right anterior temporal lobectomy. A case report.

The occurrence of crossed aphasia as a complication after temporal lobe epilepsy surgery is extremely rare. We report the case of a 47-year-old right-handed patient with drug-resistant mesial temporal lobe epilepsy (MTLE) who developed a transitory aphasic syndrome after a right temporal anterior lobectomy. This syndrome was characterized by anomia, poor verbal fluency, verbal perseveration, and verbal comprehension difficulties. He also showed writing difficulties, reading substitutions, and calculation task errors. The patient was regularly assessed with language tasks, and showed a spontaneous and progressive recovery of his symptoms, with remaining naming difficulties. We discuss the role that epileptogenic zone could play in cortical reorganization of the language systems.

Clinical characteristics of vulnerable populations hospitalized and diagnosed with COVID-19 in Buenos Aires, Argentina.

There is not in Argentina publications regarding the presentation of patients with COVID-19 requiring hospitalized and emergency care in vulnerable populations (lower incomes and less education tend at greater risk for poor health status and healthcare access), and it has few reports in developing countries. The objective is to determine whether in the care of vulnerable patients, to succeed against COVID-19, multiple public health tools and interventions will be needed to minimize morbidity and mortality. The study is a prospective cohort investigation of patients with lab-confirmed COVID-19, who required to any of the Health Centers response from April 8, 2020, to August 18, 2020. In Buenos Aires Metropolitan Area (AMBA), April 8, 2020 the virus was identified in patients hospitalized in the "Southeast Network" (SN), AMBA. SN covering an area of 661 square kilometers, with 1.8 million inhabitants residing in urban, and rural areas. A total of 14 health centers with different levels of care complexity provide care to patients in the region. The information of each patient with COVID-19 evaluated by SN, was incorporated in an Epidemiological Dashboard. The investigation was designed and reported with consideration of observational studies in epidemiology. We describe the hospitals presentation and care of persons who required SN response and were ultimately diagnosed with COVID-19. From April 8, 2020, to August 18, 2020, were included 1495 patients with lab-confirmed COVID-19 in SN. A total of 58% patients were men, and the mean age (SD) was 48.9 (15.59) years. Eighty one percent patients with pre-existing diseases, most frequent hypertension and diabetes, but hypertension, chronic lung disease, and cardiovascular disease presented higher risk. A total of 13% were hospitalized in Intensive Therapy Unit. The mortality of the cohort was 9.77%. Mortality was higher for patients aged 65 or more (OR 5.09), and for those had some pre-existing disease (OR 2.61). Our observations are consistent with reports demonstrating older persons, and those with comorbidities have the highest risk of mortality related to COVID-19. However, unlike other reports from developed or some developing countries, the mortality in our study is lower. This finding may be related to age of our cohort is younger than other published. Also, the health system was able to respond to the demand.

Latin American Brain Mapping Network (LABMAN).

On March 8, 2008 in Havana, the Latin American Network for Brain Mapping (LABMAN) was created with participants from Argentina, Brazil, Colombia, Cuba and Mexico. The focus of LABMAN is to promote neuroimaging and systems neuroscience in the region through the implementation of training and exchange programs, and to increase public awareness of the Latin American potential to contribute both to basic and applied research in human brain mapping.

Clinical spectrum and difficulties in management of hypothalamic hamartoma in a developing country.

AIM: We describe the clinical features, treatment and prognosis in a series of patients with epilepsy secondary to hypothalamic hamarthomas (HH) in a developing country. MATERIALS AND METHODS: Eight patients with epilepsy and HH were included between 1997 and 2006. We analyzed gender, age, age at seizure onset (ASO), seizure types (ST), mental retardation (MR), precocious puberty (PP), electroencephalogram (EEG)-magnetic resonance imaging (MRI) features and response to treatment. RESULTS: Mean age 25.1 years, 2/6 female/male, none had PP, ASO 4.5 years. Complex partial seizure were the most frequent (100%), mean similar to those seen in temporal (62.5%) or frontal lobe epilepsy (37.5%). Exactly 87.5% developed gelastic seizures (GS). Half of the patients showed MR. Mild-to-severe MR was associated with the presence of multiple ST including atonic and complex partial seizures with frontal semiology. Interictal EEG was abnormal in 87.5% patients. Video EEG was performed in three cases with unspecific findings. HH were small and sessile in seven patients whereas large and pedunculated in one. All patients were refractory to medical treatment. In five, an additional procedure was performed without any significant improvement. CONCLUSION: These series show the heterogeneous spectrum of this entity and the difficulties in its treatment in a developing country.

Dentate gyrus expression of nestin-immunoreactivity in patients with drug-resistant temporal lobe epilepsy and hippocampal sclerosis.

PURPOSE: Granule cells pathology in dentate gyrus, have received considerable attention in terms of understanding the pathophysiology of temporal lobe epilepsy with hippocampal sclerosis. The aim of this study was to determine the nestin (an intermediate filament protein expressed by newly formed cells), immunoreactivity (IR) in granular cells layers of hippocampal tissue extirpated during epilepsy surgical procedure, in patients with drug-resistant epilepsy. METHODS: Hippocampal sections of 16 patients with hippocampal sclerosis and drug-resistant temporal lobe epilepsy were processed using immunoperoxidase with antibody to nestin. Archival material from 8 normal post-mortem hippocampus, were simultaneously processed. Reactive area for nestin-IR, the total number of positive nestin cells per field (20×), and the MGV (mean gray value) was determined by computerized image analysis (ImageJ), and compared between groups. Student's t test was used for statistical analysis. RESULTS: Nestin-IR cells were found in granule cells layers of both controls and patients. Larger reactive somas (p < 0.01) were found in epileptic's sections but a significant reduction in the total number of nestin-IR cells per field and in the MGV was found in granular cells layers of patients with hippocampal sclerosis (p < 0.01). CONCLUSION: Reduced expression of nestin-IR in granular cells layers of epileptic's dentate gyrus may reflect changes in dentate gyrus neuroplasticity associated to chronic temporal epilepsy with hippocampal sclerosis. Further studies are required to determine the clinical implications on memory an emotional alterations such as depression.

Prediction of epileptic seizures using accumulated energy in a multiresolution framework.

Records of brain electrical activity from intracranial EEG of four patients with different types of epilepsy are analyzed to predict the epileptic seizure onset. A method based on the evolution of the accumulated energy using wavelet analysis is introduced. This is an efficient method to predict epileptic seizures: from 13 preseizure signals, the seizure onset in 12 of those are predicted.

Clinical-electroencephalogram patterns at seizure onset in patients with hippocampal sclerosis.

OBJECTIVE: The purpose of this study is to identify specific clinical-electroencephalogram (EEG) patterns at seizure onset in patients with hippocampal sclerosis (HS). METHODS: Sixty-six ictal video-EEG recordings corresponding to 26 patients with HS have been reviewed, focusing on the EEG features found during the first 30 ictal s. The EEG activity has been classified into the following groups: (A) according to spatial distribution: type 1: temporal electrodes on one side; type 2: temporal and adjacent frontal electrodes on one side; and type 3: non-lateralizing electrographic activity; and (B) according to morphology; subtype (a): regular 5-9 Hz rhythmic activity (RA); subtype (b): low-voltage rapid activity, followed by a 5-9 Hz RA; and subtype (c): irregular EEG sharp waves. We analyzed the clinical symptoms sequence and established the relationship with the ictal EEG patterns. RESULTS: Considering spatial distribution and morphology, the most frequent ictal EEG patterns were type 1 (57%), type 2 (37%), and subtype (a): 62%; subtype (b): 27%; and subtype (c): 11%. The sequence of clinical symptoms observed was: aura-->behavioral arrest-->oro-alimentary automatisms-->unilateral hand automatisms. All seizures with aura and including two or more symptoms of the clinical sequence (65%) were associated with a 1a, 1b, 2a or 2b EEG pattern. CONCLUSIONS: The identification of a specific clinical-EEG pattern provides a useful tool for the epileptogenic zone localization in non-invasive pre-surgical assessment of patients with hippocampal sclerosis. SIGNIFICANCE: The identification of a specific clinical-EEG pattern associated to neuroimaging findings and neuropsychological testing allows indicating surgery for the treatment of epilepsy in patients with hippocampal sclerosis, without performing any further complementary studies.

Seizures of temporal lobe epilepsy: identification of subtypes by coherence analysis using stereo-electro-encephalography.

OBJECTIVES: Two subtypes of temporal lobe epilepsy (TLE) according to the structures initially involved during seizures are currently recognized: medial TLE (MTLE) and lateral (or neocortical) TLE (LTLE). A few reports have suggested that the classification of TLE subtypes might be larger according to variations in the interactions between medial structures and the neocortex. In this study, we analyzed these interactions using coherence analysis of stereo-encephalographic (SEEG) signals during spontaneous seizures. METHODS: Twenty-seven patients with drug-resistant TLE, diagnosed from ictal SEEG recordings obtained during pre-surgical evaluation, were studied. Orthogonally implanted depth electrodes with multiple leads according to Talairach's method were used to sample medial and neocortical structures. Coherence analysis of ictal discharges was performed between two SEEG bipolar signals from adjacent leads located either in medial structures (amygdala and hippocampus) or in neocortical regions of the temporal lobe. A new algorithm, which was designed to reduce the bias inherent in coherence estimation, was used to compute the coherence. RESULTS: We were able to classify TLE seizures (TLES) into 4 distinct categories: (1) 'medial' TLES, characterized by medial onset with later involvement of the neocortex in the form of a 'phasic' discharge. High ictal coherence values were observed between medial structures; (2) 'medial-lateral' TLES which started in medial structures with a fast low-voltage discharge (FLVD) which rapidly affects the neocortex (< or = 3 s). High coherence values were observed between medial and lateral structures; (3) 'lateral-medial' TLES, which are different from medial-lateral TLES in that the FLVD starts in the lateral neocortex and involves the amygdala and/or hippocampus almost immediately after; (4) 'lateral' TLES: characterized by a neocortical onset, a delayed involvement of medial structures (when present), and high coherence values between neocortical structures. CONCLUSIONS: These results demonstrate the existence of numerous interactions between medial limbic structures and the neocortex during TLE seizures. Such findings could have implications for surgical strategies and the prognosis of epilepsy surgery, particularly when limited resection is indicated.

A double-blind controlled clinical trial of oxcarbazepine versus phenytoin in adults with previously untreated epilepsy.

In the last 5 years oxcarbazepine (OXC) has been registered in many countries for use as first-line and add-on treatment for partial seizures with or without secondarily generalized seizures (PS) and generalized tonic-clonic seizures without partial onset (GTCS). Its use as monotherapy in adults with newly diagnosed epilepsy was investigated in this double-blind, randomized, parallel-group comparison with phenytoin (PHT). A total of 287 adult patients, with either PS or GTCS, were randomized. After retrospective baseline assessment, patients were randomized to OXC or PHT in a 1:1 ratio. The double-blind treatment phase was divided into two periods: a flexible titration period of 8 weeks, followed by 48 weeks of maintenance treatment. In the efficacy analyses, no statistically significant differences were found between the treatment groups. Seventy patients (59.3%) in the OXC group and 69 (58.0%) in the PHT group were seizure-free during the maintenance period. A total of 56 of the patients in the OXC group discontinued treatment prematurely (five because of tolerability reasons) compared to 61 in the PHT group (16 for tolerability reasons). The number of premature discontinuations due to adverse experiences showed a statistically significant difference in favour of OXC. There was no statistically significant difference between the groups with respect to the total number of premature discontinuations. This trial provides further support for the efficacy and safety of OXC as first-line treatment in adults with PS and GTCS. In addition, the results show that OXC has significant advantages over PHT in terms of tolerability.

[Status of cerebral cortical excitability in juvenile myoclonus epilepsy]. / Estado de excitabilidad cortical cerebral en la epilepsia mioclónica juvenil.

The myoclonic epilepsies constitute an heterogeneous group of entities characterized by primary generalized seizures, whose common critical manifestation is myoclonus. Within this group there is a subset of patients, identified by Janz in 1955 as "Impulsive petit mal" and later named "Janz juvenile myoclonic epilepsy" (JJME) by Delgado-Escueta. Its most important clinical features are myoclonus, expressed as mild to moderate jerks of neck, shoulders and arms. These jerks are more frequent when awakening; they can be caused by sleep deprivation and emotional stress, without consciousness impairment. Usually neurologic examinations and mental status are normal. Response to specific treatment is good, with disappearance of seizures in most patients. We attempted to assess the pathophysiologic mechanisms involved in this kind of epilepsy. The existence of differences or similarities with the findings described in the other forms of myoclonic epilepsy was specially considered. In 14 patients with JJME, we performed C reflex studies with negative results. The mean amplitude of somato sensitive evoked potential (SSEP) was around 5 microV (normal values: 2.5 microV) in its different components. Shibasaki et al. suggested that the amplitude increase could be related to a cortical excitability increase at the somatosensory and motor level, which is the probable site of the epileptogenic area. Within the patient group with myoclonic progressive epilepsy (EMP) and continuous partial epilepsy (CPE), SSPEs amplitude ranged from 8 microV to 40 microV. In our patient group, the increase in SSPEs amplitude was smaller than the one observed in the other two entities. However, it was significantly higher than the mean value for the normal population.(ABSTRACT TRUNCATED AT 250 WORDS)

[The role of the temporal cortex in long-latency auditory evoked potentials]. / El rol de la corteza temporal en los potenciales evocados auditivos de larga latencia.

There is no definite agreement on the localization of the PEAL generators. However, some authors have claimed that the temporal auditive cortex plays a role. Based on these assumptions we searched for the eventual changes developing in PEALs in patients who applied for temporal epilepsy, where the temporal cortex activity is somehow impaired. Altogether 19 patients were explored. The results were compared with 17 matched healthy controls and 4 patients with focal epilepsy who, at the time of the study, received the same treatment as the temporal epileptic subjects. In every case PEATs and PEALs were studied. One thousand Hz less than time monoaural stimulation, 50 db and 50 ms duration was employed for evoking PEALs. Recording was done with surface electrodes located at Cz, F3 and F4 coupled with an electrode placed at the contralateral mastoid; 500 ms sweep were averaged. Band-pass was set up between 1 and 125 Hz and latencies and amplitudes were studied for both types of evoked responses, PEATs and PEALs. No statistical difference was found between patients and both control groups when PEATs mean parameters were analyzed. For further PEALs results, patients were divided into 3 groups; a) Those with right temporal epilepsy (n = 6) (R); b) Those with left temporal epilepsy (n = 7) (L); c) Those in whom the affected side could not be determined (n = 7) (N). In R it was observed, when stimulating the left ear, a delay in the arrival of P1 (F4 mea 87 +/- 10.4 ms) and N1 (F4 mean 122.33 +/- 6.1 ms; Cz mean 170.75 +/- 18.8 ms) waves.(ABSTRACT TRUNCATED AT 250 WORDS)

[Mesial temporal sclerosis syndrome in adult patients]. / Síndrome de la esclerosis mesial temporal en pacientes adultos.

Magnetic resonance imaging (MRI) has become an essential tool in the work-up of epilepsy. Since its appearance it has been possible to identify pathologies, such as hippocampal sclerosis (HS), that had previously only been detected by histopathological assays. The aim of this study was to analyze the clinical manifestations, EEG and the outcome of patients with HS as shown by MRI. We revised the clinical histories of 384 outpatients from the Epilepsy Center, Ramos Mejía Hospital, who had been studied by MRI. Thirty five of them (15.5%) had a diagnosis of HS, based on the structural changes observed on the images. Six patients were excluded because of incomplete clinical data. Therefore, we studied 29 patients including 15 men. The mean age was 32.7 +/- 10.2 years (range: 19-58). All of them had partial seizures. Ten subjects had had febrile convulsions (34.5%) in childhood. Neurological examination was normal in all subjects. Interictal EEG showed focal abnormalities that were coincident in their location with the MRI abnormalities in 16 patients (55.1%). Fourteen patients (48.3%) showed right side hippocampal lesions on MRI, thirteen on the left side (44.9%) and 2 bilateral HS (6.8%). Twenty-seven patients (93.1%) had intractable epilepsy. Anterior temporal lobectomy was performed in 3 subjects with good outcome. The identification of these patients who present certain clinical and MRI characteristics, provides an opportunity to define the mesial temporal sclerosis syndrome. This could benefit patients in their prognosis and for specific treatments.

[Magnetic resonance and clinical and electroencephalographical localization in focal epilepsy]. / Resonancia magnética y localización clínica y electroencefalográfica en la epilepsia focal.

Magnetic Resonance Imaging (MRI) is the method of choice to search for epileptogenic lesions. We correlated MRI findings with the epileptogenic zone (EZ) depicted by clinical and electroencephalographic (EEG) data. We studied 400 clinical records of patients who had been submitted to MRI studies and we analyzed, retrospectively, their ictal semiology, EEG characteristics and response to treatment. They were classified into 3 groups: A) temporal lobe epilepsy, B) frontal lobe epilepsy and C) parieto-occipital epilepsy. We included 155 patients: Group A) 68 cases (43.9%), 28 men (41.1%), mean age 32 +/- 11 years old, abnormal IMR in 44 (64.7%), refractory to treatment 48 (70.5%). Group B) 68 cases (43.9%), 38 men (55.8%), mean age 30 +/- 15 years old, abnormal IMR in 26 (38.2%), refractory to treatment 30 (44.1%). Group C) 19 cases (12.2%), 13 men (68.4%), mean age 27 +/- 11 years old, abnormal IMR in 11 (57.8%), refractory to treatment 12 (63.1%). Results showed that there were higher possibilities of detecting lesions which correlate with EZ in temporal than in frontal or parieto-occipital lobes epilepsy. The chances to find abnormalities on the MRI were 5 times higher in refractory patients than in those who were non-refractory.

[Partial non convulsive epileptic status as initial presentation of limbic encephalitis]. / Estado epiléptico no convulsivo como forma de presentación de encefalitis límbica.

INTRODUCTION: Limbic encephalitis is an unusual presentation of paraneoplastic syndrome, which includes among its symptoms seizures. CLINICAL CASE: We report a case with a rare presentation of limbic encephalitis as initial symptom of small cell lung carcinoma. A 69 year-old woman presented with partial non convulsive status epilepticus and neuropsychiatric disturbances. Chest radiography and computed tomography showed mediastinal lymphadenopathy and lung nodules. Subsequently, small cell lung carcinoma was diagnosed by lymph node biopsy. The cerebrospinal fluid study was normal. The electroencephalography and magnetic resonance imaging (MRI) findings had distinctive features compatible with temporo-limbic dysfunction. The anti-Hu antibodies were negative. The neuropsychiatric symptoms improved significantly after systemic chemotherapy and adjuvant radiotherapy. A serial follow-up MRI of the head showed no evidence of intracranial metastasis three months after the diagnosis of cancer. Limbic encephalitis may be an initial manifestation of lung cancer. Paraneoplastic limbic encephalitis is considered a remote effect of cancer commonly associated with anti-neuronal antibodies (anti-Hu) and small cell lung carcinoma. CONCLUSIONS: Status epilepticus could be an early sign of limbic encephalitis. The absence of anti-Hu antibodies does not rule out the presence of an underlying small cell lung carcinoma in patients with a clinical diagnosis of limbic encephalitis. Greater awareness for diagnosis and early treatment of the primary tumor offers the best chance for improvement in patients with lung cancer presenting with limbic encephalitis.

[Contribution of diffusion tensor magnetic resonance imaging to the diagnosis of focal cortical dysplasias]. / Contribucion de las imagenes de resonancia magnetica por tensor de difusion al diagnostico de displasias corticales focales.

INTRODUCTION: Focal cortical dysplasias (FCD) are cortical malformations and, although they display typical characteristics in conventional magnetic resonance imaging (MRI), the precise determination of the epileptogenic zone remains a controversial issue. The less favourable progress during the post-operative period with respect to other symptomatic epilepsies could be explained by the existence of epileptogenic areas that do not show up in conventional MRI. Diffusion tensor imaging (DTI) is sensitive to subtle microstructural abnormalities, and fractional anisotropy, which is an indirect indicator, shows areas with reductions in the underlying white matter that go beyond the alterations detected with conventional MRI in isolated cases in previous works. AIM: In this study we analyse the characteristics of fractional anisotropy in a series of patients with FCD in order to evaluate the contribution made to diagnosis by MRI by DTI. SUBJECTS AND METHODS: Twenty-one controls and eleven patients with FCD that was visible in MRI were scanned, and clinical and imaging variables were both recorded. A visual analysis of the fractional anisotropy maps was conducted to search for asymmetries between hemispheres and biases in the clinical or structural MRI data. RESULTS: Two females and nine males, aged 30 ± 9.7 years took part in the study; time to progression of epilepsy: 22 ± 9.3 years; average frequency of the seizures: 3/month (range: 0.16-8/month). All of them showed inter-hemispheric asymmetries, which went beyond the structural limits of FCD in the case of 10 of the patients (90%). None of the controls displayed asymmetries in the fractional anisotropy. No significant relation was found with the variables that were compared. CONCLUSIONS: Further studies need to be conducted with larger numbers of patients in order to evaluate the usefulness of DTI in defining the location and extension of the epileptogenic zone in this population.

Malformations of cortical development and epilepsy in adult patients.

OBJECTIVE: To describe clinical features of epilepsy secondary to Malformation of Cortical Development (MCD) in a series of adult patients. MATERIALS AND METHODS: We searched our database for all cases with confirmed epilepsy and MCD and included in the study only those with complete data. Mean age, sex, age at seizure onset (ASO), seizure types, abnormal neurological exam (ANE), mental retardation, family history, gestational or perinatal insults (G-PI), interictal EEG and response to treatment were analyzed. Cases were classified into the 3 main groups (G) according to the Barkovich classification (BC) and then compared: (G1) "malformations due to abnormal cell proliferation", (G2) "malformations due to abnormal migration" and (G3) "malformations due to abnormal cortical organization". RESULTS: We identified 152 (5.06%) patients with MCD from a total of 3000 with epilepsy. In total, 138 patients with complete medical data were included in this study. The mean age of patients was 36.2 years, 52.2% were female, the mean ASO was 12.3 years, 5.1% of cases had a positive family history and 21% had G-PI. An ANE was observed in 21% and mental retardation in 31.9%. Most of the patients (84.8%) had refractory epilepsy. The distribution of cases according to the BC was: 51.4% in G1, 28.9% in G2 and 19.6% in G3. Comparing the 3 groups, we found that an ANE was statistically more frequent in G3 and was present in 70.4% of cases. CONCLUSION: Our series of adult patients with epilepsy and MCD suggests that MCD are identified as commonly in a developing country as in previous "first world" series. Neurological deficits were more common in the subgroup of patients with polymicrogyria and schizencephaly (BC Group 3).

A study of word finding difficulties in Spanish speakers with temporal lobe epilepsy.

It is well established that naming deficits can be found in temporal lobe epilepsy (TLE). The aim of this study was to determine in Spanish speakers with pharmacoresistant TLE the characteristics of subjective naming difficulties and to examine performance in a definition task and a picture task in left TLE and right TLE. We observed that almost one-third of patients report frequent and severe word finding problems during spontaneous speech. In naming tests, our patients exhibited delayed times for finding words. Even if the target word was identified and semantically activated, there was difficulty with lexical access, which improved when a phonetic cue was given. Left TLE patients derived a lower benefit from phonetic cues in accessing words, even when the word is known and recognized semantically. These findings were not related to any demographic or clinical characteristics analyzed. The fact that the only weakly lateralized variable has been a lexical access facilitation measurement could support a lexical access hypothesis for naming deficits in TLE.