Learn how to interpret and use intracranial EEG findings.

Epilepsy surgery is the therapy of choice for many patients with drug-resistant focal epilepsy. Recognizing and describing ictal and interictal patterns with intracranial electroencephalography (EEG) recordings is important in order to most efficiently leverage advantages of this technique to accurately delineate the seizure-onset zone before undergoing surgery. In this seminar in epileptology, we address learning objective "1.4.11 Recognize and describe ictal and interictal patterns with intracranial recordings" of the International League against Epilepsy curriculum for epileptologists. We will review principal considerations of the implantation planning, summarize the literature for the most relevant ictal and interictal EEG patterns within and beyond the Berger frequency spectrum, review invasive stimulation for seizure and functional mapping, discuss caveats in the interpretation of intracranial EEG findings, provide an overview on special considerations in children and in subdural grids/strips, and review available quantitative/signal analysis approaches. To be as practically oriented as possible, we will provide a mini atlas of the most frequent EEG patterns, highlight pearls for its not infrequently challenging interpretation, and conclude with two illustrative case examples. This article shall serve as a useful learning resource for trainees in clinical neurophysiology/epileptology by providing a basic understanding on the concepts of invasive intracranial EEG.

Targeted density electrode placement achieves high concordance with traditional high-density EEG for electrical source imaging in epilepsy.

OBJECTIVE: High-density (HD) electroencephalography (EEG) is increasingly used in presurgical epilepsy evaluation, but it is demanding in time and resources. To overcome these issues, we compared EEG source imaging (ESI) solutions with a targeted density and HD-EEG montage. METHODS: HD-EEGs from patients undergoing presurgical evaluation were analyzed. A low-density recording was created by selecting the 25 electrodes of a standard montage from the 83 electrodes of the HD-EEG and adding 8-11 electrodes around the electrode with the highest amplitude interictal epileptiform discharges. The ESI solution from this "targeted" montage was compared to that from the HD-EEG using the distance between peak vertices, sublobar concordance and a qualitative similarity measure. RESULTS: Fifty-eight foci of forty-three patients were included. The median distance between the peak vertices of the two montages was 13.2 mm, irrespective of focus' location. Tangential generators (n = 5/58) showed a higher distance than radial generators (p = 0.04). We found sublobar concordance in 54/58 of the foci (93%). Map similarity, assessed by an epileptologist, had a median score of 4/5. CONCLUSIONS: ESI solutions obtained from a targeted density montage show high concordance with those calculated from HD-EEG. SIGNIFICANCE: Requiring significantly fewer electrodes, targeted density EEG allows obtaining similar ESI solutions as traditional HD-EEG montage.

Tratamiento quirúrgico en estado epiléptico super refractario relacionado con malformación arterio venosa

Introducción: Las malformaciones arteriovenosas cerebrales (MAV) son un conjunto anormal de arterias y venas dilatadas del cerebro y caracterizadas por la pérdida de la organización vascular con una derivación arteriovenosa anormal. La probabilidad de ruptura de una MAV es baja, pudiendo causar déficit hasta en el 45% de los pacientes. La epilepsia puede asociarse con MAV siendo raro el estado epiléptico. La evolución a estado epiléptico refractario o estado epiléptico super refractario (EESR) es excepcional. Se presenta paciente con epilepsia asociada a MAV, con embolización y posterior complicación que evoluciona a EESR, donde se logró una resolución favorable con cirugía. Caso clínico: Paciente masculino de 70 años, con MAV temporal derecha no rota y epilepsia, libre de crisis desde el diagnóstico de ambas condiciones. Se realizó embolización logrando exclusión, pero con evolución a EESR. Tras estudio se realiza resección de MAV y resección parcial de zona de inicio de actividad epileptógena parieto-temporal. Además, se realizó una desconexión de región fronto-parietal central donde había evidencia de propagación de la actividad epiléptica. Paciente logra salir de estado crítico, con recuperación de conciencia y normalización de electroencefalogramas posquirúrgicos. A los 2 años evoluciona con epilepsia controlada (Engel IIa). Discusión y conclusiones: El abordaje quirúrgico es una opción en EESR y debe plantearse en un tiempo precoz de evolución (1-2 semanas). La cirugía se realizó para controlar EESR y fue una intervención exitosa. Esta estrategia puede lograr un cambio dramático en el pronóstico. La cirugía resectiva está indicada cuando hay evidencia etiológica en imágenes y focalidad eléctrica consistente en los estudios.

Introduction: Brain Arteriovenous Malformations (AVM) are an abnormal set of dilated arteries and veins within the brain and are characterized by loss of vascular organization with an abnormal arteriovenous shunt. The probability of AVM rupture is low, but it can cause deficits in up to 45% ofpatients. Epilepsy could be associated with AVM, and status epilepticus is rare. The evolution to refractory status epilepticus or super refractory status epilepticus (SRSE) is very rare. The objective is to present a patient with epilepsy associated with non-ruptured AVM, treated with embolization and a subsequent complication that evolves into SRSE, in which a favorable resolution was achieved after surgery Clinical case: 70-year-old male, with a diagnosis of non-ruptured right temporal AVM and epilepsy, who has been seizure free since the diagnosis, is reported. Embolization of the AVM was performed, achieving total exclusion, after the procedure presented seizures that evolved into SRSE. After investigation, an AVM resection and partial resection of the ictal onset zone on the right parieto-temporal region was performed, including a disconnection of the central fronto-parietal region, where there was evidence of propagation of ictal activity. Patient recovered from the critical condition after surgery, and also presented electrographic normalization. After 2 years, the epilepsy is well controlled (Engel IIa). Discussion and conclusions: The surgical approach is an option in SRSE, and it should be proposed early on, within a reasonable time of evolution (1-2 weeks). The active approach in this case, where the surgery was done for SRSE control, was a successful intervention. Especially when the features are consistent -there is etiological evidence in imaging and electrical focality in studies- there can be a dramatic change in the prognosis.

Alteración de señal periictal transitoria en resonancia magnética de encéfalo simulando lesión estructural: caso clínico / Reversible peri-ictal MRI signal changes mimicking structural lesion: case report

Resumen La presencia de alteraciones de señal en resonancia magnética (RM) cerebral durante o posterior a un evento epiléptico es cada vez más reconocida en la literatura. Los cambios de señal peri-ictales se considera que sería el resultado de edema cerebral localizado, defecto de la autorregulación cerebral y disrupción de la barrera hemato-encefálica que ocurre durante una crisis epiléptica sostenida. Reportamos el caso de un hombre de 62 años diagnosticado de un síndrome parietal de instalación subaguda cuyo estudio con RM de cerebro mostró una lesión tumefacta con edema cortico-subcortical de ubicación temporo-occipital derecha. El estudio con electroencefalograma mostró actividad ictal en la misma localización. Se inició terapia con fármacos anticonvulsivantes mostrando franca mejoría clínica y electrofisiológica. El control con RM diferido mostró resolución completa de las alteraciones descritas.

The presence seizure-induced signal changes on brain magnetic resonance imaging (MRI) have been increasingly recognized in the literature. The reversible MRI changes in epileptic patients may be the result of a local brain swelling, a defect of cerebral autoregulation and a blood-brain barrier disruption during sustained epileptogenic activity. We report a 62 years old man diagnosed with a subacute right parietal syndrome. MRI shows a tumefactive lesion in right temporo-occipital lobes mimicking a structural lesion. Electroencephalogram (EEG) exhibits continuous ictal activity in the same region. Antiepileptic drugs were started achieving progressive electro-clinical improvement. Subsequent MRI showed remission of signal changes.

Infecciones respiratorias agudas inferiores en pacientes hospitalizados / Acute lower respiratory infections in hospitalized patients

Se estudian 216 pacientes con infecciones respiratorias agudas inferiores para determinar la eficacia del programa de Infecciones Respiratorias Agudas, aplicando las normas estandarizadas de la OMS. Se definen algunos signos de importancia diagnóstica y pronóstica (respiración rápida, tiraje, hipotermia) y se administra tratamiento de acuerdo a la etiología más frecuente de esta patología en nuestra región. Se observan factores que influyen en la presentación y pronóstico de la enfermedad como son los antecedentes (bajo peso al nacer, control prenatal, inmunizaciones, lactancia materna entre otros) y el manejo previo a la hospitalización (atención médica, uso de sintomáticos respiratorios y antibióticos). Se concluye que el programa es de fácil aplicación y funciona, debiéndose estudiar aún el manejo de las complicaciones. También se puntualiza la importancia de los signos observados y las dificultades que conlleva la asistencia previa a la hospitalización.

[The prediction of the severity of acute pancreatitis by C-reactive protein]. / Predicción de la severidad de una pancreatitis aguda por la proteína C reactiva.

Reactive C Protein (RCP) has been determined in fifty-one patients with acute pancreatitis. RCP has been compared with Ranson's criteria which include several clinical and biochemical parameters. The value of 20 mg/dl is the one which discriminates serious acute pancreatitis from the mild forms in a 84.3% of patients. Sensitivity and specificity of RCP and Ranson's criteria are compared, the results obtained are similar (88.9% vs. 81.8% and 94.4% vs. 97%). In summary, the determination of RCP is very useful for its simplicity and accuracy in the prognosis of acute pancreatitis.