Surgical and postmortem pathology studies: contribution for the investigation of temporal lobe epilepsy

Pathology studies in epilepsy patients bring useful information for comprehending the physiopathology of various forms of epilepsy, as well as aspects related to response to treatment and long-term prognosis. These studies are usually restricted to surgical specimens obtained from patients with refractory focal epilepsies. Therefore, most of them pertain to temporal lobe epilepsy (TLE) with mesial temporal sclerosis (MTS) and malformations of cortical development (MCD), thus providing information of a selected group of patients and restricted regions of the brain. Postmortem whole brain studies are rarely performed in epilepsy patients, however they may provide extensive information on brain pathology, allowing the analysis of areas beyond the putative epileptogenic zone. In this article, we reviewed pathology studies performed in epilepsy patients with emphasis on neuropathological findings in TLE with MTS and MCD. Furthermore, we reviewed data from postmortem studies and discussed the importance of performing these studies in epilepsy populations.

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Neurophysiological phenotypes of pharmacoresistant temporal lobe epilepsy

Medical alphabet ◽

10.33667/2078-5631-2021-15-9-12 ◽

2021 ◽

pp. 9-12

Author(s):

M. V. Aleksandrov ◽

Y. V. Marchenko

Keyword(s):

Surgical Treatment ◽

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Epileptic Focus ◽

Bioelectrical Activity ◽

Epileptogenic Zone ◽

Invasive Monitoring ◽

Ictal Activity ◽

The Brain

Patients with a drug-resistant form of epilepsy can be treated by neurosurgery through the destruction or separation of the epileptic focus. If the results of clinical, neuro-imaging and neurophysiological methods are discordant, then the localization of the epileptogenic zone is performed based on the results of long-term invasive monitoring of the bioelectrical activity of the cortex and deep structures of the brain. The aim of this work was the retrospective analysis of the results of invasive monitoring of the bioelectrical activity of the brain to clarify the mechanisms of the formation of patterns of interictal and ictal activity in structural epilepsy. The study included 35 patients (18 men, 17 women) with drug-resistant temporal lobe epilepsy, who were treated at the Polenov Neurosurgical Institute. The examination included video-EEG monitoring, long-term invasive monitoring of bioelectrical activity of the cortex, and deep brain structures. The patients were divided into two groups according to the type of surgical treatment: 1) micro-surgical resection of the epileptic focus, including the zone of structural changes (24 patients); 2) stereotactic destruction of the amygdala-hippocampal complex (6 patients). The follow-up of the outcomes of the surgical treatment took place over 2-3 years. Depending on the results of the surgical treatment, the patients were divided into two groups: 1) patients with a favorable outcome (Engel 1–2) — 15 patients and 2) patients with no positive dynamics and a relatively poor outcome (Engel 3–4) — 15 patients. The results obtained showed that the patterns of interictal and ictal activity in their totality determine the neurophysiology, i.e the phenotype of temporal lobe epilepsy, reflecting the interference of pathogenetic and sanogenetic mechanisms. The localization of the epileptogenic zone should be based on the cumulative assessment of interictal and ictal activity. The presence of more than one focus of interictal activity, the secondary spread of epileptiform activity from the primary focus, are prognostically unfavorable factors.

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Surgery for temporal lobe epilepsy associated with mesial temporal sclerosis in the older patient: A long-term follow-up

Epilepsia ◽

10.1111/j.1528-1167.2009.02430.x ◽

2010 ◽

Vol 51 (6) ◽

pp. 1024-1029 ◽

Cited By ~ 36

Author(s):

Michael Murphy ◽

Paul D. Smith ◽

Martin Wood ◽

Stephen Bowden ◽

Terence J. O’Brien ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Mesial Temporal Sclerosis ◽

Older Patient ◽

Long Term Follow Up

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The Long-Term Prognosis of Patients with Temporal Lobe Epilepsy for More than 20:Years

Psychiatry and Clinical Neurosciences ◽

10.1111/j.1440-1819.1992.tb00864.x ◽

1992 ◽

Vol 46 (2) ◽

pp. 307-310 ◽

Cited By ~ 1

Author(s):

Masato Matsuura ◽

Shigeru Ohbayashi ◽

Yoshiro Okubo ◽

Takuya Kojima

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Long Term Prognosis

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Recent developments in cognitive fMRI for temporal lobe epilepsy

Zeitschrift für Epileptologie ◽

10.1007/s10309-019-00303-w ◽

2019 ◽

Vol 33 (1) ◽

pp. 30-36 ◽

Cited By ~ 1

Author(s):

Victor Schmidbauer ◽

Silvia Bonelli

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Visual Memory ◽

Imaging Modality ◽

Memory Function ◽

Brain Regions ◽

Epileptogenic Zone ◽

Brain Areas ◽

Recent Developments ◽

The Brain

AbstractEpilepsy is frequently accompanied by severe cognitive side effects. Temporal lobe epilepsy (TLE), and even successful surgical treatment, may affect cognitive function, in particular language as well as verbal and visual memory function. Epilepsy arising from the temporal lobe can be controlled surgically in up to 70% of patients. The goals of epilepsy surgery are to remove the brain areas generating the seizures without causing or aggravating neuropsychological deficits. This requires accurate localization of the brain areas generating the seizures (“epileptogenic zone”) and the areas responsible for motor and cognitive functions, such as language and memory (“essential brain regions”) during presurgical evaluation. In the past decades, functional magnetic resonance imaging (fMRI) has been increasingly used to noninvasively lateralize and localize not only primary motor and somatosensory areas, but also brain areas that are involved in everyday language and memory processes. The imaging modality also shows potential for predicting the effects of temporal lobe resection on language and memory function. Together with other MRI modalities, cognitive fMRI is a promising tool to improve surgical strategies tailored to individual patients with regard to functional outcome, by virtue of definition of epileptic cerebral areas that need to be resected and eloquent areas that need to be spared.The aim of this review is to provide an overview of recent developments and practical recommendations for the clinical use of cognitive fMRI in TLE.

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Multi-institutional Study on Possibility of Prediction of Long-term Prognosis in Temporal Lobe Epilepsy.

Journal of the Japan Epilepsy Society ◽

10.3805/jjes.11.131 ◽

1993 ◽

Vol 11 (2) ◽

pp. 131-137

Author(s):

Yutaka Fukushima ◽

Kazumaru Wada ◽

Fumio Saito ◽

Hisashi Kumashiro ◽

Rumiko Kan ◽

...

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Long Term Prognosis

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Seizure Freedom After Epilepsy Surgery and Higher Baseline Cognition May Be Associated With a Negatively Correlated Epilepsy Network in Temporal Lobe Epilepsy

Frontiers in Neuroscience ◽

10.3389/fnins.2020.629667 ◽

2021 ◽

Vol 14 ◽

Author(s):

Elliot G. Neal ◽

Mike R. Schoenberg ◽

Stephanie Maciver ◽

Yarema B. Bezchlibnyk ◽

Fernando L. Vale

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Epilepsy Surgery ◽

Memory Function ◽

Brain Regions ◽

Seizure Freedom ◽

Epileptogenic Zone ◽

Temporal Lobes ◽

Scalp Eeg ◽

The Brain

Background: Brain regions positively correlated with the epileptogenic zone in patients with temporal lobe epilepsy vary in spread across the brain and in the degree of correlation to the temporal lobes, thalamus, and limbic structures, and these parameters have been associated with pre-operative cognitive impairment and seizure freedom after epilepsy surgery, but negatively correlated regions have not been as well studied. We hypothesize that connectivity within a negatively correlated epilepsy network may predict which patients with temporal lobe epilepsy will respond best to surgery.Methods: Scalp EEG and resting state functional MRI (rsfMRI) were collected from 19 patients with temporal lobe epilepsy and used to estimate the irritative zone. Using patients’ rsfMRI, the negatively correlated epilepsy network was mapped by determining all the brain voxels that were negatively correlated with the voxels in the epileptogenic zone and the spread and average connectivity within the network was determined.Results: Pre-operatively, connectivity within the negatively correlated network was inversely related to the spread (diffuseness) of that network and positively associated with higher baseline verbal and logical memory. Pre-operative connectivity within the negatively correlated network was also significantly higher in patients who would go on to be seizure free.Conclusion: Patients with higher connectivity within brain regions negatively correlated with the epilepsy network had higher baseline memory function, narrower network spread, and were more likely to be seizure free after surgery.

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Temporal Lobe Epilepsy Surgery Failures: A Review

Epilepsy Research and Treatment ◽

10.1155/2012/201651 ◽

2012 ◽

Vol 2012 ◽

pp. 1-10 ◽

Cited By ~ 23

Author(s):

Adil Harroud ◽

Alain Bouthillier ◽

Alexander G. Weil ◽

Dang Khoa Nguyen

Keyword(s):

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Mesial Temporal Sclerosis ◽

Temporal Region ◽

Incomplete Resection ◽

Epileptogenic Zone ◽

Temporal Epilepsy ◽

Dual Pathology ◽

Seizure Relapse ◽

Temporal Structures

Patients with temporal lobe epilepsy (TLE) are refractory to antiepileptic drugs in about 30% of cases. Surgical treatment has been shown to be beneficial for the selected patients but fails to provide a seizure-free outcome in 20–30% of TLE patients. Several reasons have been identified to explain these surgical failures. This paper will address the five most common causes of TLE surgery failure (a) insufficient resection of epileptogenic mesial temporal structures, (b) relapse on the contralateral mesial temporal lobe, (c) lateral temporal neocortical epilepsy, (d) coexistence of mesial temporal sclerosis and a neocortical lesion (dual pathology); and (e) extratemporal lobe epilepsy mimicking TLE or temporal plus epilepsy. Persistence of epileptogenic mesial structures in the posterior temporal region and failure to distinguish mesial and lateral temporal epilepsy are possible causes of seizure persistence after TLE surgery. In cases of dual pathology, failure to identify a subtle mesial temporal sclerosis or regions of cortical microdysgenesis is a likely explanation for some surgical failures. Extratemporal epilepsy syndromes masquerading as or coexistent with TLE result in incomplete resection of the epileptogenic zone and seizure relapse after surgery. In particular, the insula may be an important cause of surgical failure in patients with TLE.

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