Occipital lobe seizures and epilepsies

Developmental outcome of electroencephalographic findings in SYNGAP1 encephalopathy

SYNGAP1 haploinsufficiency results in a developmental and epileptic encephalopathy (DEE) causing generalized epilepsies accompanied by a spectrum of neurodevelopmental symptoms. Concerning interictal epileptiform discharges (IEDs) in electroencephalograms (EEG), potential biomarkers have been postulated, including changes in background activity, fixation-off sensitivity (FOS) or eye closure sensitivity (ECS). In this study we clinically evaluate a new cohort of 36 SYNGAP1-DEE individuals. Standardized questionnaires were employed to collect clinical, electroencephalographic and genetic data. We investigated electroencephalographic findings, focusing on the cortical distribution of interictal abnormalities and their changes with age. Among the 36 SYNGAP1-DEE cases 18 presented variants in the SYNGAP1 gene that had never been previously reported. The mean age of diagnosis was 8 years and 8 months, ranging from 2 to 17 years, with 55.9% being male. All subjects had global neurodevelopmental/language delay and behavioral abnormalities; 83.3% had moderate to profound intellectual disability (ID), 91.7% displayed autistic traits, 73% experienced sleep disorders and 86.1% suffered from epileptic seizures, mainly eyelid myoclonia with absences (55.3%). A total of 63 VEEGs were revised, observing a worsening of certain EEG findings with increasing age. A disorganized background was observed in all age ranges, yet this was more common among older cases. The main IEDs were bilateral synchronous and asynchronous posterior discharges, accounting for ≥50% in all age ranges. Generalized alterations with maximum amplitude in the anterior region showed as the second most frequent IED (≥15% in all age ranges) and were also more common with increasing age. Finally, diffuse fast activity was much more prevalent in cases with 6 years or older. To the best of our knowledge, this is the first study to analyze EEG features across different age groups, revealing an increase in interictal abnormalities over infancy and adolescence. Our findings suggest that SYNGAP1 haploinsufficiency has complex effects in human brain development, some of which might unravel at different developmental stages. Furthermore, they highlight the potential of baseline EEG to identify candidate biomarkers and the importance of natural history studies to develop specialized therapies and clinical trials.

Charles Bonnet Syndrome as Sequelae of Occipital Lobe Infarct With Hemorrhagic Conversion: A Case Report

Charles Bonnet syndrome occurs in the setting of visual impairment with subsequent complex and repetitive visual hallucinations confined in the area of visual loss, with intact cognition and insight. It has been described as a sequelae of ischemic stroke affecting the visual pathway. We report a case of a male presenting with right homonymous hemianopsia secondary to acute left occipital lobe infarct of cardioembolic etiology. He then developed visual hallucinations on the side of the visual loss. MRI showed hemorrhagic conversion of the occipital lobe infarct. Electroencephalogram showed focal and intermittent slowing of the anterior temporal and frontal region. Charles Bonnet syndrome may signify the worsening or progression of a structural lesion affecting the visual pathway, such as hemorrhagic conversion, and warrants prompt and thorough evaluation. Understanding these conditions is crucial for healthcare professionals and caregivers to provide effective support and interventions for those affected.

Structural brain network analysis in occipital lobe epilepsy

BACKGROUND

This study aimed to analyze the structural brain network in patients with occipital lobe epilepsy (OLE) and investigate the differences in structural brain networks between patients with OLE and healthy controls.

METHODS

Patients with OLE and healthy controls with normal brain MRI findings were enrolled. They underwent diffusion tensor imaging using a 3.0T MRI scanner, and we computed the network measures of global and local structural networks in patients with OLE and healthy controls using the DSI studio program. We compared network measures between the groups.

RESULTS

We enrolled 23 patients with OLE and 42 healthy controls. There were significant differences in the global structural network between patients with OLE and healthy controls. The assortativity coefficient (-0.0864 vs. -0.0814, p = 0.0214), mean clustering coefficient (0.0061 vs. 0.0064, p = 0.0203), global efficiency (0.0315 vs. 0.0353, p = 0.0086), and small-worldness index (0.0001 vs. 0.0001, p = 0.0175) were lower, whereas the characteristic path length (59.2724 vs. 53.4684, p = 0.0120) was higher in patients with OLE than those in the healthy controls. There were several nodes beyond the occipital lobe that showed significant differences in the local structural network between the groups. In addition, the assortativity coefficient was negatively correlated with the duration of epilepsy (r=-0.676, p = 0.001).

Maternal diabetes decreases the expression of GABAAα1, GABAB1, and mGlu2 receptors in the visual cortex of male rat neonates

AIMS

This study examines the impact of maternal diabetes on the expression of GABAB1, GABAAα1, and mGlu2 receptors in the primary visual cortex layers of male rat newborns.

MAIN METHODS

In diabetic group (Dia), diabetes was induced in adult female rats using an intraperitoneal dose of Streptozotocin (STZ) 65 (mg/kg). Diabetes was managed by daily subcutaneous injection of NPH insulin in insulin-treated diabetic group (Ins). Control group (Con) received normal saline intraperitoneally rather than STZ. Male offspring born to each group of female rats were euthanized via CO2 inhalation at P0, P7, and P14 days after delivery and the expression of GABAB1, GABAAα1, and mGlu2 receptors in their primary visual cortex was determined using immunohistochemistry (IHC).

KEY FINDINGS

The expression of GABAB1, GABAAα1, and mGlu2 receptors increased gradually with age in the male offspring born to Con group while the highest expression was detected in layer IV of the primary visual cortex. In Dia group newborns, the expression of these receptors was significantly reduced in all layers of the primary visual cortex at every three days. Insulin treatment in diabetic mothers restored the expression of these receptors to normal levels in their newborns.

SIGNIFICANCE

The study indicates that diabetes reduces the expression of GABAB1, GABAAα1, and mGlu2 receptors in the primary visual cortex of male offspring born to diabetic rats at P0, P7, and P14. However, insulin treatment can counteract these effects.

A Narrative Review of Visual Hallucinations in Migraine and Epilepsy: Similarities and Differences in Children and Adolescents

Since the earliest descriptions of the simple visual hallucinations in migraine patients and in subjects suffering from occipital lobe epilepsy, several important issues have arisen in recognizing epileptic seizures of the occipital lobe, which often present with symptoms mimicking migraine. A detailed quantitative and qualitative clinical scrutiny of timing and characteristics of visual impairment can contribute to avoiding mistakes. Differential diagnosis, in children, might be challenging because of the partial clinical, therapeutic, and pathophysiological overlaps between the two diseases that often coexist. Ictal elementary visual hallucinations are defined by color, shape, size, location, movement, speed of appearance and duration, frequency, and associated symptoms and their progression. The evaluation of the distinctive clinical features of visual aura in migraine and visual hallucinations in occipital epilepsy could contribute to understanding the pathogenetic mechanisms of these two conditions. This paper aims to critically review the available scientific evidence on the main clinical criteria that address diagnosis, as well as similarities and differences in the pathophysiological mechanisms underlying the visual impairment in epilepsy and migraine.

Oral lipid-based formulations alter delivery of cannabidiol to different anatomical regions in the brain

Delivery to the brain is a challenging task due to its protection by the blood-brain barrier (BBB). Lipids and fatty acids are reported to affect the permeability of the BBB, although this has not been reported following oral administration. Cannabidiol (CBD) has high therapeutic potential in the brain, therefore, this work investigated CBD delivery to anatomical brain regions following oral administration in lipid-based and lipid-free vehicles. All formulations resulted in a short brain T_max (1 h) and brain-plasma ratios ≥ 3.5, with retention up to 18 h post administration. The highest CBD delivery was observed in the olfactory bulb and striatum, and the medulla pons and cerebellum the lowest. The lipid-free vehicle led to the highest levels of CBD in the whole brain. However, when each anatomical region was assessed individually, the long chain triglyceride-rich rapeseed oil formulation commonly showed optimal performance. The medium chain triglyceride-rich coconut oil formulation did not result in the highest CBD concentration in any brain region. Overall, differences in CBD delivery to the whole brain and various brain regions were observed following administration in different formulations, indicating that the oral formulation selection may be important for optimal delivery to specific regions of the brain.

Thalamic nuclei volumes and intrinsic thalamic network in patients with occipital lobe epilepsy

INTRODUCTION

This study aimed to investigate the alterations in individual thalamic nuclei volumes in patients with occipital lobe epilepsy (OLE) compared with those of healthy controls, and to analyze the intrinsic thalamic network based on these volumes using graph theory.

METHODS

Thirty adult patients with newly diagnosed OLE and 42 healthy controls were retrospectively enrolled (mean age, 33.8 ± 17.0 and 32.2 ± 6.6 years, respectively). The study participants underwent brain magnetic resonance imaging with three-dimensional T1-weighted imaging. The right and left total thalamic and individual thalamic nuclei volumes were obtained using the FreeSurfer program. Then, the intrinsic thalamic network was calculated based on the individual thalamic nuclei volumes and graph theory using a BRAPH program.

RESULTS

There were no differences in the right and left whole-thalamic volumes between the two groups (0.445% vs. 0.469%, p = .142 and 0.481% vs. 0.490%, p = .575, respectively). However, significant differences were observed in the volumes of several thalamic nuclei between the two groups. The right medial geniculate and right suprageniculate nuclei volumes were increased (0.0077% vs. 0.0064%, p = .0003 and 0.0013% vs. 0.0010%, p = .0004, respectively), whereas the right and left parafascicular nuclei volumes were decreased in patients with OLE compared with those in healthy controls (0.0038% vs. 0.0048%, p < .0001 and 0.0037% vs. 0.0045%, p = .0001, respectively). There were no differences in the network measures regarding intrinsic thalamic network between the two groups.

CONCLUSION

We successfully demonstrated the alterations in individual thalamic nuclei volumes, especially the increased medial geniculate and suprageniculate, and decreased parafascicular nuclei volumes in patients with OLE compared with those of healthy controls despite no changes in the whole-thalamic volumes. These findings suggest an important role of the thalamus in the epileptic network of OLE.

Glymphatic system dysfunction in patients with occipital lobe epilepsy

BACKGROUND AND PURPOSE

We aimed to investigate the glymphatic system function in patients with occipital lobe epilepsy (OLE) and healthy controls using diffusion tensor image analysis along the perivascular space (DTI-ALPS) index.

METHODS

We retrospectively included 23 patients with OLE and 30 healthy controls. The participants underwent brain MRI, which was normal, and diffusion tensor imaging. We used the DSI Studio for data preprocessing, obtained the fiber orientation and diffusivities, and calculated the DTI-ALPS index from the diffusivity values associated with the projection and association fibers in the left hemisphere.

RESULTS

There were no differences in mean age (31.6 years [range: 13-58] vs. 31.3 years [range: 20-57], p = .912) and male sex ratio (10/23 [43.5%] vs. 15/30 [50.0%]) between the groups. Compared to healthy controls, the diffusivities in patients with OLE were higher along the Y-axis in the projection fiber and along the Z-axis in the association fiber and lower along the Y-axis in the association fiber. The DTI-ALPS index in patients with OLE was lower than that in the healthy controls (1.421 ± 0.171 vs. 1.667 ± 0.271, p < .001, 95% confidence interval of difference = 0.117-0.376, Test statistic t = 3.823). We found no association between the DTI-ALPS index and clinical characteristics in OLE.

CONCLUSION

The DTI-ALPS index in patients with OLE was significantly lower than that in healthy controls, suggesting glymphatic system dysfunction in OLE. The DTI-ALPS index could help assess the glymphatic system function in patients with epilepsy.

Evaluation of the Patient With Paroxysmal Spells Mimicking Epileptic Seizures

BACKGROUND

The diagnostic issue of paroxysmal spells, including epileptic seizure (ES) mimics, is one that neurologists frequently encounter. This review provides an up-to-date overview of the most common causes of ES mimics encountered in the outpatient setting.

REVIEW SUMMARY

Paroxysmal spells are characterized by changes in awareness, attention, perception, or abnormal movements. These can be broadly classified as ES and nonepileptic spells (NES). NES mimics ES but are distinguished by their symptomatology and lack of epileptiform activity on electroencephalography. NES may have psychological or physiological underpinnings. Psychogenic non-ES are the most common mimics of ES. Physiological causes of NES include syncope, cerebrovascular, movement, and sleep-related disorders.

CONCLUSIONS

Distinguishing NES from ES at times may be challenging even to the most experienced clinicians. However, detailed history with an emphasis on the clinical clues, including taking a moment-by-moment history of the event from the patient and observers and physical examination, helps create an appropriate differential diagnosis to guide further diagnostic testing. An accurate diagnosis of NES prevents iatrogenic harm, including unnecessary exposure to antiseizure medications and overuse of health care resources. It also allows for the correct specialist referral and appropriate treatment.

Jeavons syndrome featured with visual sensitivity existing as occipital cortex originating focal-to-generalized continuum epilepsy

OBJECTIVE

To study the relationship between eye closure sensitivity (ECLS), photosensitivity, and the mechanism of Jeavons syndrome (JS).

METHODS

The interictal and the ictal epileptiform discharges (EDs) of 80 patients with electroencephalograms were classified (I: focal posterior EDs; II: the posterior spread into the frontal EDs; and III: generalized EDs) and analyzed under different provoked conditions.

RESULTS

During the interictal and the ictal period, the positive rates of ECLS were higher than those of photosensitivity (100% vs 57.5%, P = 0.001; 97.5% vs 27.4%, P = 0.001). After a one-year interval, eyelid-myoclonia with ECLS remitted in 16 out of 21 patients (P = 0.002), and eyelid-myoclonia with photo-convulsion response (PCR) disappeared in all the previous six patients (P = 0.021). For the interictal EDs with ECLS, grade I accounted for 11.2%; grade I, II, and III 51.3%; and grade III 32.5%. Interictal EDs classification of photosensitivity showed a similar trend as that of ECLS. For the ictal EDs, grade I accounted for 10.2% of patients with ECLS and 6.7% of patients with PCR; grade I, II, and III, 33.3% of patients with ECLS and 46.6% of patients with PCR; and grade III, 53.9% of patients with ECLS and 40% of patients with PCR.

CONCLUSION

ECLS was more common than photosensitivity in JS. Photosensitivity was more likely to disappear than ECLS. Both eye closure and intermittent-photic-stimulation could induce three grades of EDs, confirming that visual stimuli could trigger occipital cortex originating epileptic neural network to varying degrees, which further recognizes JS as another continuum epilepsy.

International League Against Epilepsy classification and definition of epilepsy syndromes with onset in childhood: Position paper by the ILAE Task Force on Nosology and Definitions

The 2017 International League Against Epilepsy classification has defined a three-tier system with epilepsy syndrome identification at the third level. Although a syndrome cannot be determined in all children with epilepsy, identification of a specific syndrome provides guidance on management and prognosis. In this paper, we describe the childhood onset epilepsy syndromes, most of which have both mandatory seizure type(s) and interictal electroencephalographic (EEG) features. Based on the 2017 Classification of Seizures and Epilepsies, some syndrome names have been updated using terms directly describing the seizure semiology. Epilepsy syndromes beginning in childhood have been divided into three categories: (1) self-limited focal epilepsies, comprising four syndromes: self-limited epilepsy with centrotemporal spikes, self-limited epilepsy with autonomic seizures, childhood occipital visual epilepsy, and photosensitive occipital lobe epilepsy; (2) generalized epilepsies, comprising three syndromes: childhood absence epilepsy, epilepsy with myoclonic absence, and epilepsy with eyelid myoclonia; and (3) developmental and/or epileptic encephalopathies, comprising five syndromes: epilepsy with myoclonic-atonic seizures, Lennox-Gastaut syndrome, developmental and/or epileptic encephalopathy with spike-and-wave activation in sleep, hemiconvulsion-hemiplegia-epilepsy syndrome, and febrile infection-related epilepsy syndrome. We define each, highlighting the mandatory seizure(s), EEG features, phenotypic variations, and findings from key investigations.

Forecasting stroke-like episodes and outcomes in mitochondrial disease

In this retrospective, multicentre, observational cohort study, we sought to determine the clinical, radiological, EEG, genetics and neuropathological characteristics of mitochondrial stroke-like episodes and to identify associated risk predictors. Between January 1998 and June 2018, we identified 111 patients with genetically determined mitochondrial disease who developed stroke-like episodes. Post-mortem cases of mitochondrial disease (n = 26) were identified from Newcastle Brain Tissue Resource. The primary outcome was to interrogate the clinico-radiopathological correlates and prognostic indicators of stroke-like episode in patients with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes syndrome (MELAS). The secondary objective was to develop a multivariable prediction model to forecast stroke-like episode risk. The most common genetic cause of stroke-like episodes was the m.3243A>G variant in MT-TL1 (n = 66), followed by recessive pathogenic POLG variants (n = 22), and 11 other rarer pathogenic mitochondrial DNA variants (n = 23). The age of first stroke-like episode was available for 105 patients [mean (SD) age: 31.8 (16.1)]; a total of 35 patients (32%) presented with their first stroke-like episode ≥40 years of age. The median interval (interquartile range) between first and second stroke-like episodes was 1.33 (2.86) years; 43% of patients developed recurrent stroke-like episodes within 12 months. Clinico-radiological, electrophysiological and neuropathological findings of stroke-like episodes were consistent with the hallmarks of medically refractory epilepsy. Patients with POLG-related stroke-like episodes demonstrated more fulminant disease trajectories than cases of m.3243A>G and other mitochondrial DNA pathogenic variants, in terms of the frequency of refractory status epilepticus, rapidity of progression and overall mortality. In multivariate analysis, baseline factors of body mass index, age-adjusted blood m.3243A>G heteroplasmy, sensorineural hearing loss and serum lactate were significantly associated with risk of stroke-like episodes in patients with the m.3243A>G variant. These factors informed the development of a prediction model to assess the risk of developing stroke-like episodes that demonstrated good overall discrimination (area under the curve = 0.87, 95% CI 0.82-0.93; c-statistic = 0.89). Significant radiological and pathological features of neurodegeneration were more evident in patients harbouring pathogenic mtDNA variants compared with POLG: brain atrophy on cranial MRI (90% versus 44%, P < 0.001) and reduced mean brain weight (SD) [1044 g (148) versus 1304 g (142), P = 0.005]. Our findings highlight the often idiosyncratic clinical, radiological and EEG characteristics of mitochondrial stroke-like episodes. Early recognition of seizures and aggressive instigation of treatment may help circumvent or slow neuronal loss and abate increasing disease burden. The risk-prediction model for the m.3243A>G variant can help inform more tailored genetic counselling and prognostication in routine clinical practice.

Presentation, Etiology, Outcome, and Differentiation of Visual Semiology of Adult Occipital Epilepsy From Visual Aura of Migraine Headache: A Prospective Study in a Tertiary Care Center in Bangladesh

Background: Occipital epilepsy is an uncommon and likely underdiagnosed type of epilepsy that is often misdiagnosed as a migraine with aura. High clinical suspicion and subsequent electroencephalogram (EEG) and brain imaging lead to early diagnosis. 

Methods: We recruited patients with occipital epilepsy based on visual semiology, structural abnormalities in the occipital region, or EEG changes who visited the Department of Neurology of Dhaka Medical College from June 2019 to January 2020. We documented the presentations, etiology, and outcomes at the 12-month follow-up. Additionally, we compared the clinical features of patients with occipital epilepsy (n = 10) and those with migraine with aura (n = 18).

Results: We identified three and seven cases of idiopathic and symptomatic occipital epilepsy, respectively, all presenting with visual semiology. Symptomatic occipital epilepsy occurred due to space-occupying lesions, post-hypoxic damage, post-stroke encephalomalacia, gyral calcification from Sturge-Weber syndrome, and Wilson’s disease. Age, sex, illness duration, headache severity, and associated features were similar between the migraine with aura and epilepsy groups. In occipital epilepsy, the median (IQR) age was 22 (15-47) years, and the patients were predominantly female (8, 80%). The visual auras lasted 35 (3-375) seconds and included colored dots or light flashes that persisted for seconds (50%) before (60%), during (30%), and after (10%) the headache. Compared to migraines, the headaches were global (90%), compressive (90%), and of shorter duration (210 minutes, IQR: 150-630). Except for nausea or osmophobia, vomiting (80%), photophobia (80%), and phonophobia (70%) occurred. Most cases had associated focal or bilateral tonic-clonic seizures (60%; p-value < 0.001). In contrast, the visual auras in migraine were scotomas, white or golden dots, or light flashes lasting for minutes (83.3%; p-value = 0.02) before the headache. The headaches lasted longer (720 minutes, IQR: 345-1,440, p-value < 0.03), were unilateral (44%) or bilateral (50%), and throbbing (72%; p-value = 0.003). Headache was associated with photophobia (94.4%; p-value = 0.28), phonophobia (88.9%; p-value 0.31), and osmophobia (38.9%; p-value 0.03); no associated convulsions occurred. At the 12-month follow-up, most occipital epilepsy patients (9, 90%) responded well to carbamazepine.

Conclusions: Patients with transient and distinct elementary visual hallucinations headache characteristics different from migraines with associated convulsions warrant evaluation for occipital epilepsy.

EEG Essentials

PURPOSE OF REVIEW

EEG is the best study for evaluating the electrophysiologic function of the brain. The relevance of EEG is based on an accurate interpretation of the recording. Understanding the neuroscientific basis for EEG is essential. The basis for recording and interpreting EEG is both brain site-specific and technique-dependent to detect and represent a complex series of waveforms. Separating normal from abnormal EEG lies at the foundation of essential interpretative skills.

RECENT FINDINGS

Seizures and epilepsy are the primary targets for clinical use of EEG in diagnosis, seizure classification, and management. Interictal epileptiform discharges on EEG support a clinical diagnosis of seizures, but only when an electrographic seizure is recorded is the diagnosis confirmed. New variations of normal waveforms, benign variants, and artifacts can mimic epileptiform patterns and are potential pitfalls for misinterpretation for inexperienced interpreters. A plethora of medical conditions involve nonepileptiform and epileptiform abnormalities on EEG along the continuum of people who appear healthy to those who are critically ill. Emerging trends in long-term EEG monitoring to diagnose, classify, quantify, and characterize patients with seizures have unveiled epilepsy syndromes in patients and expanded medical and surgical options for treatment. Advances in terminology and application of continuous EEG help unify neurologists in the diagnosis of nonconvulsive seizures and status epilepticus in patients with encephalopathy and prognosticate recovery from serious neurologic injury involving the brain.

SUMMARY

After 100 years, EEG has retained a key role in the neurologist's toolkit as a safe, widely available, versatile, portable test of neurophysiology, and it is likely to remain at the forefront for patients with neurologic diseases. Interpreting EEG is based on qualitative review, and therefore, the accuracy of reporting is based on the interpreter's training, experience, and exposure to many new and older waveforms.

Localizing and Lateralizing Value of Seizure Onset Pattern on Surface EEG in FCD Type II

BACKGROUND

Surface ictal electroencephalographic (EEG) monitoring has an important role in the presurgical evaluation of patients with focal cortical dysplasia (FCD). This study aimed to examine the characteristics of seizure onset pattern (SOP) on surface ictal EEG. This information will be useful for invasive monitoring planning.

METHODS

We reviewed 290 seizures from 31 patients with intractable seizures related to FCD type II (6 patients with FCD IIa and 25 patients with FCD IIb). We categorized the SOPs into five patterns and evaluated the relationships between the SOPs and the location and pathology of the FCD II subtype.

RESULTS

The most common SOP was no apparent change (39.0%), followed by rhythmic slow wave and repetitive spikes/sharp waves. The SOP of rhythmic slow wave was associated with FCD II in the temporal lobe (P < 0.001), and the SOP of no apparent change was associated with FCD II in the occipital lobe (P = 0.012). The SOPs of rhythmic slow waves and fast activity were most common in FCD IIa, P < 0.001 and 0.031, respectively. The repetitive spikes/sharp waves SOP was the most common pattern in FCD IIb (P < 0.001). The surface SOPs provided correct localization and lateralization of epileptic foci in FCD in 62.1% and 62.7%, respectively. In 61.3% of the patients, over 50% of the SOPs in each patient indicated accurate localization.

CONCLUSIONS

SOPs in surface EEG monitoring are beneficial for presurgical evaluation and lead to localization of epileptic foci and pathologic subtypes of FCD.

Resection of bilateral occipital lobe lesions during a single operation as a treatment for bilateral occipital lobe epilepsy

BACKGROUND

Neurosurgical treatment of severe bilateral occipital lobe epilepsy usually involves two operations several mos apart.

AIM

To evaluate surgical resection of bilateral occipital lobe lesions during a single operation as a treatment for bilateral occipital lobe epilepsy.

METHODS

This retrospective case series included patients with drug-refractory bilateral occipital lobe epilepsy treated surgically between March 2006 and November 2015.

RESULTS

Preoperative evaluation included scalp video-electroencephalography (EEG), magnetic resonance imaging, and PET-CT. During surgery (bilateral occipital craniotomy), epileptic foci and important functional areas were identified by EEG (intracranial cortical electrodes) and cortical functional mapping, respectively. Patients were followed up for at least 5 years to evaluate treatment outcome (Engel grade) and visual function. The 20 patients (12 males) were aged 4-30 years (median age, 12 years). Time since onset was 3-20 years (median, 8 years), and episode frequency was 4-270/mo (median, 15/mo). Common manifestations were elementary visual hallucinations (65.0%), flashing lights (30.0%), blurred vision (20.0%) and visual field defects (20.0%). Most patients were free of disabling seizures (Engel grade I) postoperatively (18/20, 90.0%) and at 1 year (18/20, 90.0%), 3 years (17/20, 85.0%) and ≥ 5 years (17/20, 85.0%). No patients were classified Engel grade IV (no worthwhile improvement). After surgery, there was no change in visual function in 13/20 (65.0%), development of a new visual field defect in 3/20 (15.0%), and worsening of a preexisting defect in 4/20 (20.0%).

CONCLUSION

Resection of bilateral occipital lobe lesions during a single operation may be applicable in bilateral occipital lobe epilepsy.

Temporal Onset Focal Seizures Induced by Intermittent Photic Stimulation

The study aimed to review the clinical, radiological, and pathological findings and electroencephalogram (EEG) of pediatric epilepsy patients with temporal onset focal seizures induced by intermittent photic stimulation (IPS). Four patients with temporal onset photosensitivity focal seizures were analyzed. Three (75%) of the four patients were female. The average age of seizure-onset was 4.4 years. The interictal EEG showed both generalized and focal spike and waves in one patient and focal or multifocal spike and waves alone in three patients. Photoparoxysmal response (PPR) was evoked in all patients and showed generalized discharges (patients 2–4), both generalized and posterior discharges (patient 1). Both generalized and focal discharges could coexist in interictal discharges and PPR. The sensitive frequencies of PPR and photoconvulsive response (PCR) were 12–30 and 10–16 Hz, respectively, which were close to the occipital rhythm. In all patients, the onset of PCR was recorded, namely, the left anterior and mesial temporal lobe (TL), the left posterior TL, and the whole left TL, which showed two forms: the seizure of two patients was the onset of slow waves in the temporal area without spreading generalized discharges (patients 1 and 4), and the other one was fast rhythmic activities in the temporal area, spreading to the occipital area or gradually evolving into the generalized discharges (patients 2 and 3). During follow-up, except for patient 3 who had occasional seizures, the seizures of the remaining patients were under control. Temporal onset focal seizures could be induced by IPS. Temporal onset photosensitivity seizures were mostly easy to control with antiseizure drugs.

Headache in people with epilepsy

Epidemiological estimates indicate that individuals with epilepsy are more likely to experience headaches, including migraine, than individuals without epilepsy. Headaches can be temporally unrelated to seizures, or can occur before, during or after an episode; seizures and migraine attacks are mostly not temporally linked. The pathophysiological links between headaches (including migraine) and epilepsy are complex and have not yet been fully elucidated. Correct diagnoses and appropriate treatment of headaches in individuals with epilepsy is essential, as headaches can contribute substantially to disease burden. Here, we review the insights that have been made into the associations between headache and epilepsy over the past 5 years, including information on the pathophysiological mechanisms and genetic variants that link the two disorders. We also discuss the current best practice for the management of headaches co-occurring with epilepsy and highlight future challenges for this area of research.

Magnetoencephalography to confirm epileptiform discharges mimicking small sharp spikes in temporal lobe epilepsy

OBJECTIVE

To determine whether magnetoencephalography (MEG) can identify epileptiform discharges mimicking small sharp spikes (SSSs) on scalp electroencephalography (EEG) in patients with temporal lobe epilepsy (TLE).

METHODS

We retrospectively reviewed simultaneous scalp EEG and MEG recordings of 83 consecutive patients with TLE and 49 with extra-TLE (ETLE).

RESULTS

SSSs in scalp EEG were detected in 15 (18.1%) of 83 TLE patients compared to only two (4.1%) of 49 ETLE patients (p = 0.029). Five of the 15 TLE patients had MEG spikes with concurrent SSSs in EEG, but neither of the 2 ETLE patients. Three of these 5 TLE patients had additional interictal epileptiform discharges (IEDs) in EEG and MEG. Equivalent current dipoles (ECDs) of MEG spikes with concurrent SSSs and IEDs showed no difference in temporal lobe localization and horizontal orientation, whereas ECD moments were smaller in MEG spikes with concurrent SSSs than those with IEDs.

CONCLUSIONS

SSSs were more common in TLE than in ETLE. At least some morphologically diagnosed SSSs are true but low-amplitude epileptiform discharges in TLE which can be identified with simultaneous MEG.

SIGNIFICANCE

Simultaneous MEG is useful to identify epileptiform discharges mimicking SSSs in patients with TLE.

Pediatric Occipital Spikes at a Single Center Over 26 Years and the Significance of Tangential Dipole

BACKGROUND

Pediatric occipital epileptiform discharges occur in various clinical settings, including self-limited and treatment-resistant epilepsies. The study objective is to determine electro-clinical predictors for prognosis in children with occipital epileptiform discharges.

METHODS

205 patients with occipital epileptiform discharges were classified into seizure groups: self-limited occipital (SLO) (n = 57), including Panayiotopoulos and Gastaut syndrome; non-self-limited occipital (non-SLO) (n = 98), including various seizure etiologies; genetic-generalized (n = 18); febrile (n = 5); and no-seizure (n = 27) groups. Electro-clinical features of the SLO and non-SLO were compared, as this is of most clinical relevance.

RESULTS

The median age of seizure onset was 3 years (range: 0-19). Occipital epileptiform discharges with frontal/central positivity were present in both groups, but more common in the SLO than non-SLO groups; 21/57 (36.8%) and 19/98 (19.4%), respectively (P < .022). However, when occipital epileptiform discharges with tangential dipoles (P < .048) were accompanied by abnormal ictal eye movements (P < .037), they were predictive of SLO epilepsy.

CONCLUSIONS

In our cohort, occipital epileptiform discharges with tangential dipole detected by visual analysis and abnormal ictal eye movements were predictive of SLO epilepsy.

Adult occipital lobe epilepsy: 12-years on

OBJECTIVE

Occipital lobe epilepsies (OLE) comprise 5-10% of focal epilepsies in surgical and paediatric series; with little data from adult medical cohorts. This longitudinal study examined OLE patients, to characterise prevalence, semiology, co-morbidity and prognosis in a neurology outpatient setting.

METHODS

24 adult OLE patients identified over 12 months from 1548 patients in a neurologist's service were followed over 12 years.

RESULTS

92% of these OLE patients had simple visual hallucinations, misdiagnosed in 40% of cases. 75% had co-morbid interictal migraine and 38% had visual field defects. Only 33% achieved long-term remission, and only 2 /10 (20%) of OLE patients with a structural aetiology were seizure-free. The two patients with migralepsy achieved remission.

CONCLUSION

Adult OLE accounted for 7.7% of focal epilepsies in this cohort, misdiagnosed or misclassified in 40%. Most patients had co-existing migraine. A minority had migralepsy characterised by a longer aura and good prognosis. Remission rates were lower than that of childhood OLE and general adult epilepsy populations, strengthening the argument for considering epilepsy surgery in drug-resistant OLE patients with a structural cause. Precision medicine will potentially refine diagnosis and management in those OLE patients without an identified cause but is predicated on accurate clinical phenotyping.

Epilepsy in LAMA2-related muscular dystrophy: An electro-clinico-radiological characterization

OBJECTIVE

To delineate the epileptic phenotype of LAMA2-related muscular dystrophy (MD) and correlate it with the neuroradiological and muscle biopsy findings, as well as the functional motor phenotype.

METHODS

Clinical, electrophysiological, neuroradiological, and histopathological data of 25 patients with diagnosis of LAMA2-related MD were analyzed.

RESULTS

Epilepsy occurred in 36% of patients with LAMA2-related MD. Mean age at first seizure was 8 years. The most common presenting seizure type was focal-onset seizures with or without impaired awareness. Visual aura and autonomic signs, including vomiting, were frequently reported. Despite a certain degree of variability, bilateral occipital or temporo-occipital epileptiform abnormalities were by far the most commonly observed. Refractory epilepsy was found in 75% of these patients. Epilepsy in LAMA2-related MD was significantly more prevalent in those patients in whom the cortical malformations were more extensive. In contrast, the occurrence of epilepsy was not found to be associated with the patients' motor ability, the size of their white matter abnormalities, or the amount of residual merosin expressed on muscle.

SIGNIFICANCE

The epileptic phenotype of LAMA2-related MD is characterized by focal seizures with prominent visual and autonomic features associated with EEG abnormalities that predominate in the posterior quadrants. A consistent correlation between epileptic phenotype and neuroimaging was identified, suggesting that the extension of the polymicrogyria may serve as a predictor of epilepsy occurrence.

Electroencephalography in Epilepsy Evaluation

PURPOSE OF REVIEW

Epilepsy is a heterogeneous disorder that is often associated with abnormal electroencephalogram (EEG) findings. This article provides an overview of common EEG findings in epileptic disorders. The physiologic basis of EEG and intracranial EEG studies is also discussed.

RECENT FINDINGS

EEG is widely used in clinical practice. Because of the paroxysmal nature of seizure disorders, interictal epileptiform discharges, such as spikes and sharp waves, are often used to support the diagnosis of epilepsy when a habitual seizure is not captured by EEG. Interictal and ictal EEG findings also underlie the classification of seizures and epilepsy. Continuous critical care EEG monitoring has become an invaluable study in the diagnosis and treatment of subclinical seizures and nonconvulsive status epilepticus. Intracranial EEG with subdural or intraparenchymal electrodes is warranted when localization of the seizure focus and mapping of eloquent brain areas are required to plan epilepsy surgery.

SUMMARY

The EEG is a key tool in the diagnosis of epilepsy. Interictal and ictal EEG findings are crucial for the confirmation and classification of seizure disorders. Intracranial EEG monitoring is also indispensable for planning surgery for some patients.

Chiasmal and Postchiasmal Disease

PURPOSE OF REVIEW

This article reviews the anatomy, symptoms, examination findings, and causes of diseases affecting the optic chiasm, optic tracts, optic radiations, and occipital lobes.

RECENT FINDINGS

Modern ophthalmic imaging can be used to monitor the effects of diseases of the optic chiasm and tract on the retinal ganglion cells. It can also be used to visualize transsynaptic degeneration of the anterior visual pathway in the setting of acquired retrogeniculate lesions. Visual prostheses that directly stimulate the occipital lobe are a potential strategy for rehabilitation that is in active clinical trials.

SUMMARY

Detecting and characterizing visual deficits due to optic chiasm and retrochiasmal disease are important for the diagnosis, localization, and monitoring of neurologic disease; identifying patient disability; and guiding rehabilitation.

Cases with parietal and occipital lobe epilepsies

Background

For seizures emerging from the posterior cortex it can be a challenge to differentiate if they belong to temporal, parietal or occipital epilepsies. Sensoric auras like visual phenomena may occur in all of these focal epilepsies. Ictal signs may mimic non- epileptic seizures.

Case presentations

Case 1: Patient suffering from a pharmacoresistent focal epilepsy. Focal seizures with sudden visual disturbance, later during the seizure epigastric aura, vertigo-nausea, involvement to bilateral tonic-clonic seizures. MEG detected interictal spikes, source localization indicated focal epileptic activity parietal right.

Case 2: Patient with focal pharmacoresistent epilepsy, semiology with focal unaware seizures, feeling that something like a coat is imposed from behind on him, then feeling cold over the whole body, goose bumbs from both arms to head, then block of motoric activity, later focal unaware seizures with stare gaze, blinking of eyes, clouding of consciousness, elevation of arms and legs, sometimes tonic-clonic convulsions. EEG/MEG source localization and MRI detected an epileptogenic lesion parietal left.

Case 3: Patient with pharmacoresistent focal epilepsy, focal aware seizures, a dark spot occurring in the left visual field, sometimes anxiety during seizures (leading to the suspicion of non-epileptic psychogenic pseudo seizures). MRI demonstrated an atrophy occipito-temporal right after sinus vein thrombosis. Ictal video-EEG showed a focal seizure onset occipital right.

Conclusion

Contribution of noninvasive and/or invasive confirmation of the localization of the underlying focal epileptic activity in posterior cortex is illustrated. Characteristics of posterior cortex epilepsies are ventilated.

Tarik Syndrome: Reversible Postoperative Blindness Secondary to Occipital Seizures

BACKGROUND

Postoperative blindness is a devastating surgical complication. Although usually associated with prolonged cardiac and prone spinal operations, it may follow other procedures as well. Postoperative blindness is most commonly caused by a vascular etiology, but it can more rarely be caused by status epilepticus. We have previously reported a case of this phenomenon following a staged spinal deformity surgery.

CASE DESCRIPTION

Here we report 2 additional cases following a skull base procedure and a single stage lumbar spine surgery. In all instances, rapid recognition that the patients' blindness was due to occipital seizures resulted in acute antiepileptiform treatment and full restoration of vision.

CONCLUSIONS

Although a rare phenomenon, this syndrome, first recognized and described by Tarik F. Ibrahim, should be considered in any patient with postoperative visual impairment.

An update on EEG in migraine

Introduction: In the past few years, brain functional analysis has provided scientific evidence supporting the neuronal basis of migraine. The role of electroencephalography (EEG) in detecting subtle dysfunctions in sensory temporal processing has been fully re-evaluated, thanks to advances in methods of quantitative analysis. However, the diagnostic value of EEG in migraine is very low, and migraine diagnosis is completely based on clinical criteria, while the utility of EEG in migraine pathophysiology has only been confirmed in more recent applications. Areas covered: The present review focuses on the few situations in which EEG may provide diagnostic utility, and on the numerous and intriguing applications of novel analysis, based on time-related changes in neuronal network oscillations and functional connectivity. Expert opinion: Although routine EEG is not particularly useful for the clinical assessment of migraine, novel methods of analysis, mostly based on functional connectivity, could improve knowledge of the migraine brain. The application is worthy of promotion and improvement in support of neuroimaging data to shed light on migraine mechanisms and support the rationale for therapeutic approaches.

Transcranial Alternating Current Stimulation (tACS) Mechanisms and Protocols

Perception, cognition and consciousness can be modulated as a function of oscillating neural activity, while ongoing neuronal dynamics are influenced by synaptic activity and membrane potential. Consequently, transcranial alternating current stimulation (tACS) may be used for neurological intervention. The advantageous features of tACS include the biphasic and sinusoidal tACS currents, the ability to entrain large neuronal populations, and subtle control over somatic effects. Through neuromodulation of phasic, neural activity, tACS is a powerful tool to investigate the neural correlates of cognition. The rapid development in this area requires clarity about best practices. Here we briefly introduce tACS and review the most compelling findings in the literature to provide a starting point for using tACS. We suggest that tACS protocols be based on functional brain mechanisms and appropriate control experiments, including active sham and condition blinding.

[Syncope, transient ischemic attacks, transient global amnesia and migraine]

Epileptic seizures can manifest with a variety of clinical symptoms. Depending on the dominant symptom, several differential diagnoses have to be considered. Their differentiation can be challenging, especially after the first episode. The review article summarizes the most common differential diagnoses as well as their characteristics compared to epileptic seizures, aiming at providing guidelines for their clinical differentiation. Whenever a clear diagnosis is not possible based on the patient history and clinical signs, diagnostic evaluation with, e. g. an electroencephalogram (EEG) and finally EEG video monitoring can be helpful.

Reversible postoperative blindness caused by bilateral status epilepticus amauroticus following thoracolumbar deformity correction: case report

Postoperative vision loss (POVL) is a devastating complication and has been reported after complex spine procedures. Anterior ischemic optic neuropathy and posterior optic neuropathy are the 2 most common causes of POVL. Bilateral occipital lobe seizures causing complete blindness are rare and have not been reported as a cause of POVL after spine surgery with the patient prone. The authors report the case of a 67-year-old man without a history of seizures who underwent a staged thoracolumbar deformity correction and developed POVL 6 hours after surgery. Imaging, laboratory, and ophthalmological examination results were nonrevealing. Routine electroencephalography study results were negative, but continuous electroencephalography captured bilateral occipital lobe seizures. The patient developed nonconvulsive status epilepticus despite initial treatment with benzodiazepines and loading doses of levetiracetam and lacosamide. He was therefore intubated for status epilepticus amauroticus and received a midazolam infusion. After electrographic seizure cessation for 48 hours, the patient was weaned off midazolam. The patient was maintained on levetiracetam and lacosamide without seizure recurrence and returned to his preoperative visual baseline status.

A comparison of occipital and temporal lobe epilepsies

PURPOSE

Differentiating between occipital lobe epilepsy (OLE) and temporal lobe epilepsy (TLE) is often challenging. This retrospective case-control study compares OLE to TLE and explores markers that suggest the diagnosis of OLE.

METHODS

We queried the Jefferson Epilepsy Center surgery database for patients who underwent a resection that involved the occipital lobe. For each patient with OLE, three sequential case-control patients with TLE were matched. Demographic characteristics, symptoms, electrophysiological findings, imaging findings, and surgical outcome were compared.

RESULTS

Nineteen patients with OLE and 57 patients with TLE were included in the study. Visual symptoms were unique to patients with OLE (8/19) and were not reported by patients with TLE (P < 0.0001). Occipital interictal spikes (IIS) were found only in one-third of the patients with OLE (6/19) and in no patients with TLE (P < 0.0001). IIS in the posterior temporal lobe were found in five of 19 patients with OLE vs one of 57 patients with TLE (P = 0.003). IIS involved more than one lobe of the brain in most patients with OLE (11/19) but only in nine of 57 the TLE group. (P = 0.0003) Multilobar resection was needed in most patients with OLE (15/19), typically including the temporal lobe, but in only one of the patients with TLE (P < 0.0001).

CONCLUSION

Occipital lobe epilepsy is difficult to identify and may masquerade as temporal lobe epilepsy. Visual symptoms and occipital findings in the EEG suggest the diagnosis of OLE, but absence of these features, does not exclude the diagnosis. When posterior temporal EEG findings or multilobar involvement occurs, the diagnosis of OLE should be considered.

Migraine mimics

The symptoms of migraine are non-specific and can be present in many other primary and secondary headache disorders, which are reviewed. Even experienced headache specialists may be challenged at times when diagnosing what appears to be first or worst, new type, migraine status, and chronic migraine.

A case of temporal onset partial seizure induced by photic stimuli

There are only a few case reports of photic stimulation induced partial seizures arising from the temporal lobe. A 12-year-old female with a history of three convulsions was admitted for a diagnostic evaluation. During continuous video-electroencephalogram monitoring, a complex partial seizure with secondary generalization was induced immediately after a photoparoxysmal response with a 15-Hz photic stimulation. This is a rare case of photosensitive temporal lobe seizure.

Hemodynamic changes during posterior epilepsies: an EEG-fNIRS study

Posterior epilepsies are mainly characterized clinically by visual symptoms. Functional near-infrared spectroscopy (fNIRS) is an emerging non-invasive imaging technique that has the potential to monitor hemodynamic changes during epileptic activity. Combined with electroencephalography (EEG), 9 patients with posterior epilepsies were recorded using EEG-fNIRS with large sampling (19 EEG electrodes and over 100 fNIRS channels). Spikes and seizures were carefully marked on EEG traces, and convolved with a standard hemodynamic response function for general linear model (GLM) analysis. GLM results for seizures (in 3 patients) and spikes (7 patients) were broadly sensitive to the epileptic focus in 7/9 patients, and specific in 5/9 patients with fNIRS deoxyhemoglobin responses lateralized to the correct lobe, and to plausible locations within the occipital or parietal lobes. This work provides evidence that EEG-fNIRS is a sensitive technique for monitoring posterior epileptic activity.

Epileptiform transients of the occipital lobe in pediatrics

Differentiating between benign occipital transients and epileptic discharges from the occipital lobes is imperative. Focal occipital spikes and sharp waves are not always associated with benign disorders. The occurrence of occipital spikes and spike and wave complexes depends on the child's age, the maturation of the occipital cortex, and the cortex's connection with other structures (Beaumanoir et al. 1993). Clinical manifestations also evolve as the patient ages. Seizure semiology is due to the maturation of the visual system and its connections. An infant from birth to twelve months of age could experience autonomic symptoms such as pallor and vomiting with possible minor motor movements. Visual symptoms and/or headaches are usually not noticed until between five and seven years of age. These visual phenomena can continue into adulthood.