Clinical outcome of selective amygdalectomy in a series of patients with resistant temporal lobe epilepsy
- Department of Neurosurgery, Skull Base Research Center, Shahid Beheshti University of Medical Science, Tehran, Iran,
- Department for General Psychology and Cognitive Neuroscience, Friedrich Schiller University of Jena, Jena, Thuringia,
- Department of Neurosurgery, Klinikum Saarbrücken, University of Saarland, Saarbrücken, Saarland, Germany.
Arsalan Medical Amin, Skull Base Research Center, Shahid Beheshti University of Medical Science, Tehran, Iran.
DOI:10.25259/SNI_199_2021Copyright: © 2021 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Guive Sharifi1, Mohammad Hallajnejad1, Samaneh Sadat Dastgheib2, Mahmoud Lotfinia3, Omidvar Rezaei Mirghaed1, Arsalan Medical Amin1. Clinical outcome of selective amygdalectomy in a series of patients with resistant temporal lobe epilepsy. 23-Nov-2021;12:575
How to cite this URL: Guive Sharifi1, Mohammad Hallajnejad1, Samaneh Sadat Dastgheib2, Mahmoud Lotfinia3, Omidvar Rezaei Mirghaed1, Arsalan Medical Amin1. Clinical outcome of selective amygdalectomy in a series of patients with resistant temporal lobe epilepsy. 23-Nov-2021;12:575. Available from: https://surgicalneurologyint.com/surgicalint-articles/11240/
Background: Selective amygdalohippocampectomy is one of the main approaches for treating medial temporal lobe epilepsy (TLE). We herewith describe seven cases of amygdala lesions treated with selective amygdalectomy with the hippocampus saving procedure. Furthermore, we explain the trans-middle temporal gyrus transventricular approach for selective amygdalectomy.
Methods: We studied patients with TLE who underwent selective amygdalectomy with hippocampal saving procedure between March 2012 and July 2018. We preferred the trans-middle temporal gyrus transventricular approach. We adopted pterional craniotomy with extensive exposure of the base and posterior of the temporal lobe. The posterior margin of resection in the intraventricular part of the amygdala was considered the inferior choroidal point. Medially anterior part of the uncus was resected until reaching the ambient cistern. We applied the transcortical transventricular approach for selective amygdalectomy in all patients.
Results: We present 11 cases having an amygdala lesion in our series, seven of whom underwent selective amygdalectomy with hippocampal sparing. Nine patients had neoplastic lesions, and in two of them, gliosis was evident. Total resection of the lesion was achieved in all cases based on postoperative magnetic resonance imaging. No unusual complication or surgically-related new neurological deficit occurred.
Conclusion: We consider the resection of the amygdala until the inferior choroidal point sufficient for the disconnection of its circuits, which results in more effective control of seizures and reduction of surgery time and complications.
Keywords: Amygdala, Amygdalectomy, Case series, Clinical outcome, Medial temporal lobe epilepsy
About 50 million people worldwide have epilepsy, which portrays epilepsy as one of the most prevalent diseases of the brain and is responsible for 0.7% of the global burden of disease. With a rate of 5% in Iran, the prevalence is even higher in developing countries.[
Amygdala is a complex structure in the medial temporal lobe.[
We describe 11 MTLE cases associated with amygdala lesions, seven of whom were treated by selective amygdalectomy with a hippocampus saving procedure. We also explained the trans-middle temporal gyrus transventricular approach for selective amygdalectomy, the standard approach in our hospital.
We enrolled patients with TLE referred to our service for amygdalectomy between March 2012 and July 2018. All patients signed informed consent to take part in this study. The institutional research board and committee approved the protocol of this study of ethics.
A thorough history and physical examination, brain magnetic resonance imaging (MRI) for localization of the probable lesions, and identifying the anatomy, plus the electrodiagnostic and neuropsychiatric tests were performed before the operation. Only patients whose MRI did not indicate hippocampal involvement or hippocampal sclerosis were selected for this specific procedure since hippocampal sclerosis alone could develop an epileptic zone.
The surgeon performed selective amygdalectomy using the trans-middle temporal gyrus transventricular approach [
After opening the ependymal layer of the lateral wall of the temporal horn of the lateral ventricle, the collateral eminence, hippocampus, lateral ventricular sulcus, choroidal fissure, inferior choroidal point, choroid plexus, fimbria of the fornix, and amygdala were exposed. Hippocampus is located between the collateral sulcus laterally and choroidal fissure medially. The lateral ventricular sulcus separates the hippocampus from the collateral eminence, extending anteriorly toward the amygdala-hippocampal junction. The medial border of the hippocampus is the choroidal fissure, and the inferior choroidal point is at the most anterior and inferior point of the choroidal fissure. The anterior choroidal artery passes through the inferior choroidal point to enter into the temporal horn of the lateral ventricle. The amygdala forms the anterior wall of the temporal horn of the lateral ventricle. Superiorly, the amygdala blends into the globus pallidus; inferiorly, the temporal amygdala bulges inferiorly into the most anterior portion of the roof of the temporal horn above the hippocampal head and the uncal recess; medially, it is related to the anterior and posterior segments of the uncus. The uncal recess separates it from the head of the hippocampus. The anterior segment of the uncus, which contains the amygdala, has a close anatomical relationship with the internal cerebral artery (from the origin to bifurcation/trifurcation of the middle cerebral artery) M1 segment of the middle cerebral artery and globus pallidus; therefore, extreme care was taken during the removal of the amygdala. After the borders of the planned resection have been delineated via visual inspection and frameless navigation, the amygdala was resected in a sub-pial fashion to the inferior choroidal point. After hemostasis, the dura is closed in a watertight fashion; the bone flap is replaced, the temporal muscle, fascia, galea, and skin are closed properly.
The patients were then transferred to the neurosurgical intensive care unit and managed according to routine protocols. After transfer to the general ward, a postoperative MRI was performed to investigate the extent of resection. With every event during their admission recorded, the patients were followed up for related events after their discharge.
From 2012 to 2018, amygdalohippocampal lesions based on neuroimaging were diagnosed in 11 MTLE cases; of those, seven underwent selective amygdalectomy. The age range was between 17 and 57 years (mean 31 years). The mean follow-up duration was 3.5 years. The clinical characteristics of the patients are summarized in [
The transcortical transventricular approach was applied to perform selective amygdalectomy in all patients. In five patients, neuronavigation was used for localization. In seven patients, selective amygdalectomy was performed [
In a patient with ependymoma as the etiology of the mesial temporal lesion, extensive recurrence with CSF dissemination occurred 1 year after surgery, and finally, he died due to this complication. The patient who presented with depression and anxiety showed improvements in memory function and mood. Other patients did not have any specific event during follow-up.
The amygdala is an evolutionarily ancient structure present even in reptiles. The name, derived from the Greek, denotes an almond-like shape structure in the medial temporal lobe. It is a complex structure where many circuits that correlate affective and social behaviors intertwine.[
Knowledge about amygdala connections is critical to understand the semiology of its lesions. The amygdala received many input fibers from different subcortical structures in the brain, such as the hypothalamus, basal ganglia, septal region, and autonomic centers of the brainstem. The input fibers are mainly sensory, and the amygdala receives input from modalities such as olfactory, somatosensory, gustatory, visceral, auditory, and visual.[
In our series, among 11 cases having amygdala lesions, seven patients underwent selective amygdalectomy. Electrodiagnostic indicated the medial temporal lobe as the epileptogenic zone, and semiology of seizure such as oroalimentary, visual, and olfactory aura seems to relate to the amygdala involvement.[
There are significant controversies regarding the best surgical approach for TLE. Selective amygdalohippocampectomy and anterior temporal lobe resection are the primary surgical approach warranted seizure control and low complication.[
From the pathophysiological view, mesial temporal lobe sclerosis is the leading cause of MTLE, with most of the debate regarding the MTLE’s etiology favors the loss of net inhibition in the hippocampal structure due to the extensive loss of pyramidal neurons in mainly in the CA3 (cornu ammonis) and CA1 subfields of the hippocampus[
Interictal spikes, including spike-wave and polyspike complexes, have been seen in the amygdala during epileptic surgery. However, more studies recruiting intraoperative recordings are crucial before jumping to conclusions.[
Previously, Graebenitz et al. reported spontaneous discharges in the lateral amygdala recorded from brain slices derived from patients with intractable MTLE, especially in those whose sclerosis was minimal.[
In the histopathologic evaluation, three patients were diagnosed with low-grade astrocytoma, one with high-grade astrocytoma, two cases with gliosis, one with ganglioglioma, one ependymoma, and three with focal cortical dysplasia (FCD). We want to highlight FCD as one of the most common pathologies in the amygdala. In most cases, it is frequent in MTLE with normal MRI; its differentiation from neoplasm is almost impossible. FCD often causes amygdalar enlargement, and a volumetric study of the amygdala may help the diagnosis. The surgical outcome of seizure control in a patient with FCD as the cause of MTLE is quite good.[
Before decision-making to remove the amygdala, extreme attention is essential to some rare lesions that could imitate amygdala lesions in neuroimaging. Neoplastic lesions that arose from the optic tract have a closed anatomical relationship with the amygdala. Anatomically, the optic tract is located posteromedial to the amygdala, and sometimes, we can see it after removing the posteromedial border of the amygdala during surgery. It is difficult to differentiate these lesions, but some clues may help the diagnosis. Amygdala tumors usually extend in an anteromedial direction, but optic tract gliomas extension is predominantly posterolateral. Besides, contralateral hemianopia and the absence of seizure are in favor of optic tract lesions. We will discuss the characteristics of these specific types of tumors in another series.
Different approaches are defined as selective amygdalohippocampectomy.[
Our studies have several limitations, including the few numbers of participants. Other limitations are the study’s retrospective nature and the lack of EEG video monitoring after the operation. As a suggestion, some solutions will be designing multicentric studies with a control group and an extended follow-up period.
More extensive studies are required to determine both the role of the amygdala in the pathophysiology of MTLE and the long-term outcome of selective amygdalectomy in patients with resistant MTLE. We consider the resection of the amygdala until the inferior choroidal point sufficient for the disconnection of amygdala circuits, seizure control, and, accordingly, reduce the time of surgery and complications.
The authors certify that they have obtained all appropriate patient consent.
Publication of this article was made possible by the James I. and Carolyn R. Ausman Educational Foundation.
There are no conflicts of interest.
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