Riesgo neuropsicológico en epilepsia del lóbulo temporal / Neuropsychological risk in temporal lobe epilepsy

Introducción: Los síntomas neuropsicológicos son una preocupación importante para los pacientes con epilepsia y pueden llegar a ser muy influyentes en la percepción de calidad de vida. En el caso de la epilepsia del lóbulo temporal, existen muchas variables que influyen en el desempeño cognitivo de los pacientes, entre las más importantes se encuentran la etiología, la edad de inicio, la duración de la enfermedad y la frecuencia de crisis; sin embargo, una de las variables más importantes es la lateralidad de la epilepsia. Está claramente demostrado que los síntomas cognitivos de la epilepsia del lóbulo temporal varían en función del hemisferio cerebral afectado. Contenido: La epilepsia del lóbulo temporal es una de las principales epilepsias focales que es susceptible de manejo quirúrgico, y, en este sentido, el tipo de procedimiento también tiene una gran importancia en el desenlace cognitivo de estos pacientes. En este artículo, realizamos una revisión narrativa de la literatura, con el objetivo de describir el riesgo neuropsicológico relacionado no solamente con la epilepsia del lóbulo temporal per se, sino también con las intervenciones quirúrgicas que se realizan en pacientes refractarios a la medicación. Conclusiones: Es importante conocer los conceptos sobre las implicaciones del impacto cognitivo en los pacientes con epilepsia del lóbulo temporal antes de tomar decisiones quirúrgicas en pacientes refractarios, así como entender que el tipo de cirugía también influye en su desempeño cognitivo. Se debe buscar un equilibrio entre la libertad de crisis y las posibles secuelas neuropsicológicas posquirúrgicas.

Introduction: Neuropsychological symptoms are a major concern for patients with epilepsy and can highly influence the perception of quality of life. In the case of temporal lobe epilepsy, there are many variables that impact the cognitive performance of these people, among the most important are the etiology, the age of onset, the duration of the disease and the frequency of seizures, however, one of the most important variables is the lateralization of the seizure. It has been demonstrated that the cognitive symptoms of temporal lobe epilepsy vary depending on the affected cerebral hemisphere. Contents of the review: Temporal lobe epilepsy is one of the main focal epilepsies that is susceptible to surgical management, and the type of surgery also has great importance in the cognitive outcomes of these patients. In this article, we carry out a narrative review of the literature in order to describe the neuropsychological risk related not only to temporal lobe epilepsy per se, but also to surgical interventions performed in drug-resistant patients. Conclusions: It is important to know the concepts about the implications of cognitive impact in patients with temporal lobe epilepsy before making surgical decisions in refractory patients and to understand that the type of surgery also influences the cognitive performance of these patients. A balance must be sought between the freedom of seizures and the possible postoperative neuropsychological sequelae.

Are HFOs in the Intra-operative ECoG Related to Hippocampal Sclerosis, Volume and IQ?

Temporal lobe epilepsy (TLE) is the most common form of refractory focal epilepsy and is often associated with hippocampal sclerosis (HS) and cognitive disturbances. Over the last decade, high frequency oscillations (HFOs) in the intraoperative electrocorticography (ioECoG) have been proposed to be biomarkers for the delineation of epileptic tissue but hippocampal ripples have also been associated with memory consolidation. Healthy hippocampi can show prolonged ripple activity in stereo- EEG. We aimed to identify how the HFO rates [ripples (80-250 Hz, fast ripples (250-500 Hz); prolonged ripples (80-250 Hz, 200-500 ms)] in the pre-resection ioECoG over subtemporal area (hippocampus) and lateral temporal neocortex relate to presence of hippocampal sclerosis, the hippocampal volume quantified on MRI and the severity of cognitive impairment in TLE patients. Volumetric measurement of hippocampal subregions was performed in 47 patients with TLE, who underwent ioECoG. Ripples, prolonged ripples, and fast ripples were visually marked and rates of HFOs were calculated. The intellectual quotient (IQ) before resection was determined. There was a trend toward higher rates of ripples and fast ripples in subtemporal electrodes vs. the lateral neocortex (ripples: 2.1 vs. 1.3/min; fast ripples: 0.9 vs. 0.2/min). Patients with HS showed higher rates of subtemporal fast ripples than other patients (Z = -2.51, p = 0.012). Prolonged ripples were only found in the lateral temporal neocortex. The normalized ratio (smallest/largest) of hippocampal volume was correlated to pre-resection IQ (r = 0.45, p = 0.015). There was no correlation between HFO rates and hippocampal volumes or HFO rates and IQ. To conclude, intra-operative fast ripples were a marker for HS, but ripples and fast ripples were not linearly correlated with either the amount of hippocampal atrophy, nor for pre-surgical IQ.