The different patterns of seizure-induced aphasia in temporal lobe epilepsies

Focal electroclinical features in generalized tonic-clonic seizures: Decision flowchart for a diagnostic challenge

OBJECTIVE

Bilateral tonic-clonic seizures with focal semiology or focal interictal electroencephalography (EEG) can occur in both focal and generalized epilepsy types, leading to diagnostic errors and inappropriate therapy. We investigated the prevalence and prognostic values of focal features in patients with idiopathic generalized epilepsy (IGE), and we propose a decision flowchart to distinguish between focal and generalized epilepsy in patients with bilateral tonic-clonic seizures and focal EEG or semiology.

METHODS

We retrospectively analyzed video-EEG recordings of 101 bilateral tonic-clonic seizures from 60 patients (18 with IGE, 42 with focal epilepsy). Diagnosis and therapeutic response were extracted after ≥1-year follow-up. The decision flowchart was based on previous observations and assessed concordance between interictal and ictal EEG.

RESULTS

Focal semiology in IGE was observed in 75% of seizures and 77.8% of patients, most often corresponding to forced head version (66.7%). In patients with multiple seizures, direction of head version was consistent across seizures. Focal interictal epileptiform discharges (IEDs) were observed in 61.1% of patients with IGE, whereas focal ictal EEG onset only occurred in 13% of seizures and 16.7% of patients. However, later during the seizures, a reproducible pattern of 7-Hz lateralized ictal rhythm was observed in 56% of seizures, associated with contralateral head version. We did not find correlation between presence of focal features and therapeutic response in IGE patients. Our decision flowchart distinguished between focal and generalized epilepsy in patients with bilateral tonic-clonic seizures and focal features with an accuracy of 96.6%.

SIGNIFICANCE

Focal semiology associated with bilateral tonic-clonic seizures and focal IEDs are common features in patients with IGE, but focal ictal EEG onset is rare. None of these focal findings appears to influence therapeutic response. By assessing the concordance between interictal and ictal EEG findings, one can accurately distinguish between focal and generalized epilepsies.

Basal temporal lobe epilepsy: SEEG electroclinical characteristics

OBJECTIVE

Temporal lobe epilepsy is the most common type of focal drug-resistant epilepsy. Seizures with predominant involvement of basal temporal regions (BTR) are not well characterized. In this stereo electroencephalography (SEEG) study, we aimed at describing the ictal networks involving BTR and the associated clinical features.

METHODS

We studied 24 patients explored with SEEG in our center with BTR sampling. We analyzed their seizures using a quantitative method: the "epileptogenicity index". Then we reported the features of the patients with maximal epileptogenicity within BTR, especially ictal network involved, ictal semiology and post-surgical outcome.

RESULTS

We found that rhinal cortex, parahippocampal cortex and posterior fusiform gyrus were the most epileptogenic structures within the BTR (mean EI: 0.57, 0.55, 0.54 respectively). Three main groups of epileptogenic zone organization were found: anterior (23% of total seizures) posterior (30%) and global (47%, both anterior and posterior). Contralateral spread was found in 35% of left seizures and 20% of right seizures. Naming deficit was more prevalent in left BTR (71% vs 29% in right seizures; p = 0.01) whereas automatic speech production was preferentially represented in right seizures (11% vs 54%; p = 0.001). Surgery was proposed for 11 patients (45.8%), leading to seizure freedom in 72% (Engel Class I). One patient presented post-operative permanent functional deficit.

CONCLUSION

Basal-temporal lobe epilepsy seems to be a specific entity among the temporal epilepsy spectrum with specific clinical characteristics. Resective surgery can be proposed with good outcomes in a significant proportion of patients and is safe provided that adequate language assessment has been preoperatively made.

Value of semiology in predicting epileptogenic zone and surgical outcome following frontal lobe epilepsy surgery

OBJECTIVE

To evaluate the ability of semiology alone in localising the epileptogenic zone (EZ) in people with frontal lobe epilepsy (FLE) who underwent resective surgery.

METHODS

We examined data on all individuals who had FLE surgery at our centre between January 01, 2011 and December 31, 2020. Descriptions of ictal semiology were obtained from video-EEG telemetry reports and presurgical multidisciplinary meeting summaries. The putative EZ was represented by the final site of resection. We assessed how well initial and combined set-of-semiologies correlated anatomically with the EZ, using a semiology visualisation tool to generate probabilistic cortical heatmaps of involvement in seizures.

RESULTS

Sixty-one individuals had FLE surgery over the study period. Twelve months following surgery, 28/61 (46%) were completely seizure-free, with a further eight experiencing only auras. Comparing the semiology database with the putative EZ, combined set-of-semiology correctly lateralised in 77% (95% CI: 69-85%), localised to the frontal lobe in 57% (95% CI: 48-67%), frontal lobe subregions in 52% (95% CI: 43-62%), and frontal gyri in 25% (95% CI: 16-33%). No difference in degree of correlation was seen comparing those with ongoing seizures 12 months after surgery to those seizure free.

SIGNIFICANCE

Semiology alone was able to correctly lateralize the putative EZ in 77%, and localise to a sublobar level in approximately half of individuals who had FLE surgery. Semiology is not adequate alone and must be combined with imaging and EEG data to identify the epileptogenic zone.

Consciousness alteration in focal epilepsy is related to loss of signal complexity and information processing

Alteration of awareness is a main feature of focal epileptic seizures. In this work, we studied how the information contained in EEG signals was modified during temporal lobe seizures with altered awareness by using permutation entropy (PE) as a measure of the complexity of the signal. PE estimation was performed in thirty-six seizures of sixteen patients with temporal lobe epilepsy who underwent SEEG recordings. We tested whether altered awareness (based on the Consciousness Seizure Score) was correlated with a loss of signal complexity. We estimated global changes in PE as well as regional changes to gain insight into the mechanisms associated with awareness impairment. Our results reveal a positive correlation between the decrease of entropy and the consciousness score as well as the existence of a threshold on entropy that could discriminate seizures with no alteration of awareness from seizures with profound alteration of awareness. The loss of signal complexity was diffuse, extending bilaterally and to the associative cortices, in patients with profound alteration of awareness and limited to the temporal mesial structures in patients with no alteration of awareness. Thus PE is a promising tool to discriminate between the different subgroups of awareness alteration in TLE.

Seizure semiology: ILAE glossary of terms and their significance

This educational topical review and Task Force report aims to address learning objectives of the International League Against Epilepsy (ILAE) curriculum. We sought to extract detailed features involving semiology from video recordings and interpret semiological signs and symptoms that reflect the likely localization for focal seizures in patients with epilepsy. This glossary was developed by a working group of the ILAE Commission on Diagnostic Methods incorporating the EEG Task Force. This paper identifies commonly used terms to describe seizure semiology, provides definitions, signs and symptoms, and summarizes their clinical value in localizing and lateralizing focal seizures based on consensus in the published literature. Video-EEG examples are included to illustrate important features of semiology in patients with epilepsy.

Proposal for an updated seizure classification framework in clinical trials

The International League Against Epilepsy (ILAE) seizure classification scheme has been periodically updated to improve its reliability and applicability to clinicians and researchers alike. Here, members of the Epilepsy Study Consortium propose a pragmatic seizure classification, based on the ILAE scheme, designed for use in clinical trials with a focus on outcome measures that have high reliability, broad interpretability across stakeholders, and clinical relevance in the context of the development of novel antiseizure medications. Controversies around the current ILAE classification scheme are discussed in the context of clinical trials, and pragmatic simplifications to the existing scheme are proposed, for intended use by investigators, industry sponsors, and regulatory agencies.

Semiology, EEG, and neuroimaging findings in temporal lobe epilepsies

Temporal lobe epilepsy (TLE) is the most common type of focal epilepsy. First descriptions of TLE date back in time and detailed portraits of epileptic seizures of temporal origin can be found in early medical reports as well as in the works of various artists and dramatists. Depending on the seizure onset zone, several subtypes of TLE have been identified, each one associated with peculiar ictal semiology. TLE can result from multiple etiological causes, ranging from genetic to lesional ones. While the diagnosis of TLE relies on detailed analysis of clinical as well as electroencephalographic (EEG) features, the lesions responsible for seizure generation can be highlighted by multiple brain imaging modalities or, in selected cases, by genetic investigations. TLE is the most common cause of refractory epilepsy and despite the great advances in diagnostic tools, no lesion is found in around one-third of patients. Surgical treatment is a safe and effective option, requiring presurgical investigations to accurately identify the seizure onset zone (SOZ). In selected cases, presurgical investigations need intracerebral investigations (such as stereoelectroencephalography) or dedicated metabolic imaging techniques (interictal PET and ictal SPECT) to correctly identify the brain structures to be removed.

Temporal lobe epilepsy: A never-ending story

INTRODUCTION

Semiology and anatomo-electroclinical correlations remain invaluable for maintaining the level of excellence in temporal lobe epilepsy (TLE) surgery, in parallel to the constantly evolving technical progress. The aim of this study was to address semiological frequent and not so frequent signs, rarities and red flags in a long follow-up surgical series of patients suffering from TLE.

METHODS

Patients operated within the boundaries of the TL at our center, with presurgical video-EEG recorded seizures and seizure free after a postoperative follow-up of at least 24 months were included. Ictal semiology was systematically described and new red flags were explored by comparing with a second group of patients with the same inclusion criteria but whose outcome had been unfavorable (Engel II-IV).

RESULTS

Sixty-two patients were included, 46 seizure free and 16 with outcome Engel II-IV. Most seizure-free patients had a classical semiological presentation including aura (69.6%, abdominal the most frequent), followed by loss of responsiveness (90.2%) oral automatisms (90.7%), ipsilateral gestural automatisms (53.5%), contralateral upper limb dystonia (37.5%) or immobility (39.1%), and early ipsilateral non-versive head orientation (33.3%). More infrequent presentations were also present in the group of seizure-free patients: ictal language disturbance (13%), maintenance of responsiveness during seizures (9.8%), and contralateral rhythmic non manipulative automatism (6.9%). The presence of an isolated viscerosensory and/or psychic aura was significantly more frequent in the seizure-free group (p = 0.017), as well as oroalimentary automatisms (p = 0.005). Two signs were only present in the group with outcome Engel II-IV, constituting possible red flags (0.06 < p < 0.07): inferior limbs stepping-like automatisms and postictal dysarthria.

CONCLUSION

An adequate clinical exam during seizures and a careful analysis of video recordings allow to recognize infrequent but well-characterized ictal signs that are part of the range of semiology in TLE, together with the most frequent and classical ictal presentations. Special attention to the localization hypothesis must be paid in the absence of oroalimentary automatisms or when the signs classified as possible red flags emerge.

Epileptic aphasia - A critical appraisal

INTRODUCTION

Aphasic and other language disturbances occur in patients with epilepsy during and after epileptic seizures. Moreover, the interictal language profile in these patients is heterogeneous, varying from normal language profile to impairment in different language functions. The aim of this paper was to critically review the terms and concepts of ictal language alterations.

MATERIAL AND METHOD

For this review we performed an extensive literature search on the term "epileptic aphasia" and analyzed the semiology and terminology indicating language-associated seizure symptoms. In addition, we give an overview on EEG, etiology, and brain imaging findings and ictal language disorders.

RESULTS

In the literature, a plethora of terms indicates language-associated seizure symptoms. Simultaneous Video-EEG monitoring represents the gold standard to correctly classify ictal versus postictal language disturbances and to differentiate aphasic symptoms from speech automatisms. Different rhythmic and periodic EEG patterns associated with ictal language disturbances are recognized. Cerebral magnetic resonance imaging (cMRI) is essential in the diagnosis of seizures and epilepsy. Brain tumors and acute or remote cerebrovascular lesions are the most frequently reported structural etiologies underlying ictal language alterations. However, it has to be recognized that brain imaging may show alterations being the consequence of seizures itself rather than its cause. Functional brain imaging might be informative in patients with inconclusive EEG and MRI findings. Overall, seizure-associated aphasia is reported to have good lateralizing significance.

CONCLUSION

Various language disturbances are caused by different types of seizures, epilepsies and underlying etiologies. In the clinical context, simultaneous Video-EEG monitoring facilitates precise classification of ictal versus postictal language alterations and differentiation of aphasic symptoms from speech automatisms.

Glioblastoma Multiforme Masquerading as Stroke

Sudden-onset anomic aphasia is a unique symptom that is suggestive of an acute etiology. This case presents a sudden-onset focal neurological deficit with an underlying brain tumor. A 68-year-old female awoke with sudden-onset anomic aphasia, with mild hypertension as her only medical history. After an initial stroke workup was unremarkable, magnetic resonance imaging found a focal lesion on the left temporal lobe. An electroencephalogram showed lateralized periodic discharge and a focal area of increased epileptic potential in the left temporal lobe. Brain biopsy revealed World Health Organization grade IV glioblastoma, followed by resection. This case is an important reminder that chronic etiologies may present with acute symptoms.

Uncinate fasciculus and its cortical terminals in aphasia after subcortical stroke: A multi-modal MRI study

Aphasia, one of the most common cognitive impairments after stroke, is commonly considered to be a cortical deficit. However, many studies have reported cases of post subcortical stroke aphasia (PSSA). The pathology and recovery mechanism of PSSA remain unclear. This study aimed to investigate PSSA mechanism through a multimodal magnetic resonance imaging (MRI) approach and a two-session study design (baseline and one month after treatment). Thirty-six PSSA patients and twenty-four matched healthy controls (HC) were included. All patients had subcortical infarctions involving left subcortical white matter for 1 to 6 months. The patients underwent MRI scan and Western Aphasia Battery (WAB) examination before and after one month's comprehensive treatment. Region-wise lesion-symptom mapping (RLSM), tractography, fractional anisotropy (FA), and amplitude of low-frequency fluctuations (ALFF) analysis were conducted. After MRI preprocessing and exclusion, FA analysis included 35 patients pre-treatment and 16 patients post-treatment. ALFF analysis included 30 patients pre-treatment and 14 patients post-treatment. We found: 1) the amount of damage in the left uncinate fasciculus (UF) was associated with WAB aphasia quotient (AQ); 2) the left UF FA and left temporal pole (TP) ALFF were decreased and positively correlated with WAB-AQ, spontaneous speech, and naming in PSSA patients; and 3) PSSA patients showed increased left TP ALFF when their language ability recovered after treatment. The left TP ALFF change was positively correlated with AQ change. Our results demonstrate the importance of left UF and left TP (one of the cortical terminals of the left UF) in PSSA pathology and recovery. These results may further provide support for the disconnection theory in the mechanism of PSSA.

Contributions of left and right anterior temporal lobes to semantic cognition: Evidence from patients with small temporopolar lesions

Decades of research have increased the understanding of the contribution of the anterior temporal lobes (ATLs) to semantic cognition. Nonetheless, whether semantic processing of different types of information show a selective relationship with left and right ATLs, or whether semantic processing in the ATLs is independent of the modality of the input is currently unknown. There exists evidence supporting each of these alternatives. A fundamental objection to these findings is that they were obtained from studies with patients with brain damage affecting extensive regions, sometimes bilaterally. In the current study, we assessed a group of 38 temporal lobe epilepsy (TLE) patients with either left or right small epileptogenic lesions with a battery of commonly used semantic tasks that tested verbal and non-verbal semantic processing. We found that left TLE patients exhibited worse performance than controls on the verbal semantic tasks, as expected, but also on the non-verbal semantic task. On the other hand, performance of the right TLE group did not differ from controls on the non-verbal task, but was worse on a semantic fluency task. When performance between patient groups was compared, we found that left TLE not only did worse than right TLE on the naming task, but also on the non-verbal associative memory task. When considered together, current data do not support a strong view of input modality differences between left and right ATLs. Additionally, they provide evidence indicating that the left and right ATLs do not make similar contributions to a singular functional system for semantic representation.

If seizures left speechless: CA-P-S C-A-R-E, a proposal of a new ictal language evaluation protocol

INTRODUCTION

We aimed to create standardized protocol for language examination in patients who underwent video-EEG recording and assessed its efficacy in the characterization of ictal language impairment, its ability to differentiate this from impaired awareness, and interobserver reliability in clinical practice.

METHODS

From our database of video-EEG recordings, we selected a representative sample of 63 focal seizures with presumed language impairment. A multidisciplinary team of epileptologists, EEG technicians, and speech therapists analyzed the selected videos to highlight the critical issues of ordinary ictal language evaluation. We subsequently followed a multi-step process to develop the protocol and assess its interobserver reliability.

RESULTS

A protocol based on seven tests in hierarchical succession was created, summed up in the acronym CA-P-S C-A-R-E (Closed Answers, Pro-speak question, Simple orders, Common object denomination, Audio repetition, Reading, Evoke). Following its preliminary administration for 5 months, we assessed the inter-observer reliability of 16 healthcare professionals in distinguishing between language impairment and impaired awareness among a sample of 10 seizures, finding a substantial agreement (kappa 0.61).

CONCLUSION

The proposed protocol, made of simple and easy to memorize tests, is an effective tool that evaluates multiple domains beyond language. Its use could help to recognize ictal aphasia effectively and differentiate it from impaired awareness, minimizing inter-examiner variability.

Contributions of electrophysiology for identifying cortical language systems in patients with epilepsy

A crucial element of the surgical treatment of medically refractory epilepsy is to delineate cortical areas that must be spared in order to avoid clinically relevant neurological and neuropsychological deficits postoperatively. For each patient, this typically necessitates determining the language lateralization between hemispheres and language localization within hemisphere. Understanding cortical language systems is complicated by two primary challenges: the extent of the neural tissue involved and the substantial variability across individuals, especially in pathological populations. We review the contributions made through the study of electrophysiological activity to address these challenges. These contributions are based on the techniques of magnetoencephalography (MEG), intracerebral recordings, electrical-cortical stimulation (ECS), and the electrovideo analyses of seizures and their semiology. We highlight why no single modality alone is adequate to identify cortical language systems and suggest avenues for improving current practice.

A description of verbal and gestural communication during postictal aphasia

Patients suffering from drug-resistant temporal lobe epilepsy show substantial language deficits (i.e., anomia) during their seizures and in the postictal period (postictal aphasia). Verbal impairments observed during the postictal period may be studied to help localizing the epileptogenic zone. These explorations have been essentially based on simple tasks focused on speech, thus disregarding the multimodal nature of verbal communication, particularly the fact that, when speakers want to communicate, they often produce gestures of various kinds. Here, we propose an innovative procedure for testing postictal language and communication abilities, including the assessment of co-speech gestures. We provide a preliminary description of the changes induced on communication during postictal aphasia. We studied 21 seizures that induced postictal aphasia from 12 patients with drug-refractory epilepsy, including left temporal and left frontal seizures. The experimental task required patients to memorize a highly detailed picture and, briefly after, to describe what they had seen, thus eliciting a communicative meaningful monologue. This allowed comparing verbal communication in postictal and interictal conditions within the same individuals. Co-speech gestures were coded according to two categories: "Rhythmic" gestures, thought to be produced in support of speech building, and "illustrative" gestures, thought to be produced to complement the speech content. When postictal and interictal conditions were compared, there was decreased speech flow along with an increase of rhythmic gesture production at the expense of illustrative gesture production. The communication patterns did not differ significantly after temporal and frontal seizures, yet they were illustrated separately, owing to the clinical importance of the distinction, along with considerations of interindividual variability. A contrast between rhythmic and illustrative gestures production is congruent with previous literature in which rhythmic gestures have been linked to lexical retrieval processes. If confirmed in further studies, such evidence for a facilitative role of co-speech gestures in language difficulties could be put to use in the context of multimodal language therapies.

Structured testing during seizures: A practical guide for assessing and interpreting ictal and postictal signs during video EEG long term monitoring

BACKGROUND

Ictal and postictal testing carried out in long-term epilepsy monitoring units is often sub-optimal. Recently, a European consensus protocol for testing patients during and after seizures was developed by a joint taskforce of the International League Against Epilepsy - Commission on European Affairs and the European Epilepsy Monitoring Unit Association.

AIM

Using this recently developed standardised assessment battery as a framework, the goal of this narrative review is to outline the proposed testing procedure in detail and explain the rationale for each individual component, focusing on the underlying neurobiology. This is intended to serve as an educational resource for staff working in epilepsy monitoring units.

METHODS

A literature review of PubMed was performed; using the search terms "seizure", "ictal", "postictal", "testing", "examination", and "interview". Relevant literature was reviewed and relevant references were chosen. The work is presented as a narrative review.

RESULTS

The proposed standardised assessment battery provides a comprehensive and user-friendly format for ictal-postictal testing, and examines consciousness, language, motor, sensory, and visual function.

CONCLUSION

The standardised approach proposed has the potential to make full use of data recorded during video EEG increasing the diagnostic yield with regards to lateralisation and localisation, aiding both presurgical and diagnostic studies.

Morphometric correlates of anomia in patients with small left temporopolar lesions

Visual object naming is a complex cognitive process that engages an interconnected network of cortical regions moving from occipitotemporal to anterior-inferior temporal cortices, and extending into the inferior frontal cortex. Naming can fail for diverse reasons, and different stages of the naming multi-step process appear to be reliant upon the integrity of different neuroanatomical locations. While the neural correlates of semantic errors have been extensively studied, the neural basis of omission errors remains relatively unspecified. Although a strong line of evidence supports an association between anterior temporal lobe damage and semantic errors, there are some studies suggesting that the anterior temporal lobe could be also associated with omissions. However, support for this hypothesis comes from studies with patients in whom damage affected extensive brain regions, sometimes bilaterally. Here, we availed of a group of 12 patients with epilepsy associated with a small lesion at the tip of the left temporal pole. Using an unbiased surface-based morphometry methodology, we correlated two morphological features with errors observed during visual naming. Analyses revealed a correlation between omission errors and reduced local gyrification index in three cortical clusters: one in the left anteromedial temporal lobe region (AMTL) and two in the left anterior cingulate cortex (ACC). Our findings support the view that regions in ACC and AMTL are critical structures within a network engaged in word selection from semantics.

Postseizure aphasia in Wernicke's encephalopathy: a case report and review of literature

This case discusses the course of a woman with a history of epilepsy, alcohol use disorder, herpes simplex virus (HSV) encephalitis, and Wernicke encephalopathy (WE) who presented with altered mental status following approximately 48 hours of vomiting. After experiencing a tonic-clonic seizure in the emergency department, she developed a fluent aphasia. Aphasias are ordinarily attributed to structural changes in the brain parenchyma, often from stroke, neoplasm, or infection. When the magnetic resonance imaging of brain failed to show changes that could explain her fluent aphasia, the neurology team consulted psychiatry to workup psychogenic aphasia. During an admission 9 months earlier, she had been diagnosed with HSV encephalitis and possible WE. There was a high degree of suspicion for recurrent HSV infection, intermittent focal seizure activity, postictal psychosis, pseudobulbar affect, or a vascular cause of her fluent aphasia. After 3 days of treatment with levetiracetam, high-dose intravenous thiamine, and aripiprazole, the patient's fluent aphasia reversed. The authors conclude that the patient's reversible fluent aphasia was not psychiatric in etiology but likely caused by her seizures, the result of subtherapeutic phenytoin levels; her electroencephalogram showed focal seizure activity in the temporal lobes, possibly affecting her language centers. Language-related neurological conditions, or aphasias, can mimic psychiatric conditions such as conversion disorder or psychosis. In patients with substance use disorders, the line between psychiatric and neurological conditions becomes even more difficult to distinguish. The paper also discusses how unique aspects of her medications - levetiracetam conferring neuron membrane fluidity; aripiprazole, a drug shown to halt brain atrophy in mouse models; and parenteral thiamine to address her deficiency and WE - have aided in the reversal of the fluent aphasia. Levetiracetam should be considered in WE and the rare occurrence of aphasia after seizures.