Photic Stimulation Research Articles

Role of Electroencephalogram (EEG) and Magnetic Resonance Imaging (MRI) Findings in Early Recognition and Diagnosis of Neuronal Ceroid Lipofuscinosis Type 2 Disease.

Neuronal ceroid lipofuscinosis type 2 (CLN2) disease is a very rare neurodegenerative lysosomal storage disorder. Progression is rapid and irreversible, making early diagnosis crucial for timely treatment. A group of pediatric neurologists and neuroradiologists with expertise in CLN2 convened to discuss early electroencephalogram (EEG) and magnetic resonance imaging (MRI) findings in CLN2 diagnosis. Of 18 CLN2 cases, 16 (88.9%) had background slowing and 16 (88.9%) had epileptiform discharges on initial EEG. Seven of 17 (41.2%) patients who received intermittent low-frequency photic stimulation had a photoparoxysmal response. Initial MRIs showed subtle cerebellar (n = 14, 77.8%) or cerebral (n = 9, 50.0%) atrophy, white matter abnormalities (n = 11, 61.1%), and basal ganglia T2 hypointensity (n = 6, 33.3%), which became more apparent on follow-up MRI. The recognition of even subtle cerebellar atrophy and white matter signal changes in children aged 2-5 years who present with language delay, new-onset seizures, and an EEG with epileptiform discharges and background slowing should prompt investigation for CLN2. Because these early signs are not unique to CLN2, genetic testing is essential early in the diagnostic journey.

Pediatric electroencephalography

Background Routine electroencephalography (EEG) is a widely used test in children for the evaluation of many neurological conditions. It is specifically important in the diagnosis of epilepsy and the differentiation of epilepsy from nonepileptic events. Aim This study aimed to evaluate the current situation of EEG recording at Alexandria University Children’s Hospital. Patients and methods All patients who had a routine EEG recording during a period of 6 months were included in the study. Review of the records was done including personal data, place and indication of referral, and initial diagnosis. EEG data included condition during recording, activation procedures, EEG interpretation regarding background activity, presence or absence of epileptiform activity, type and origin of epileptiform discharges, and the final yield of EEG. Results The study included 570 children, comprising 336 males and 234 females, with a mean age of 5.5±4.1 years. The main indication for referral was epilepsy in 69.8%. Most of the cases (83.3%) had an awake recording. Photic stimulation and hyperventilation were done in 93.3 and 31.9%, respectively, and abnormal response to hyperventilation was observed in 9.9% of them. Ictal recording was done in 22 (3.8%) cases. Abnormal epileptiform discharges were detected in 173 (30.4%) of the studied children; of them, 162 cases were initially referred for established epilepsy and 11 cases for other reasons. The abnormality was generalized in 53.8% and focal in 46.2% of the cases. The commonest types of epileptiform discharges were spikes (65.9%) followed by spike-and-wave complexes (56.1%). Hypsarrhythmia, 3-Hz spike-and-wave complexes, and nonconvulsive status epilepticus were detected in 12.7, 10.4, and 2.9%, respectively. Phase reversal, sharp waves, and polyspikes were detected in 15.6, 5.2, and 2.3%, respectively. Conclusion Routine EEG is a valuable test for evaluation of seizures and epilepsy. Specific abnormal epileptiform discharges are diagnostic for certain epileptic syndromes. EEG finding may be normal in children with epilepsy and should be interpreted in the context of the clinical settings.

Cortical spreading depression can be triggered by sensory stimulation in primed wild type mouse brain: a mechanistic insight to migraine aura generation

BackgroundUnlike the spontaneously appearing aura in migraineurs, experimentally, cortical spreading depression (CSD), the neurophysiological correlate of aura is induced by non-physiological stimuli. Consequently, neural mechanisms involved in spontaneous CSD generation, which may provide insight into how migraine starts in an otherwise healthy brain, remain largely unclear. We hypothesized that CSD can be physiologically induced by sensory stimulation in primed mouse brain.MethodsCortex was made susceptible to CSD with partial inhibition of Na+/K+-ATPase by epidural application of a low concentration of Na+/K+-ATPase blocker ouabain, allowing longer than 30-min intervals between CSDs or by knocking-down α2 subunit of Na+/K+-ATPase, which is crucial for K+ and glutamate re-uptake, with shRNA. Stimulation-triggered CSDs and extracellular K+ changes were monitored in vivo electrophysiologically and a K+-sensitive fluoroprobe (IPG-4), respectively.ResultsAfter priming with ouabain, photic stimulation significantly increased the CSD incidence compared with non-stimulated animals (44.0 vs. 4.9%, p < 0.001). Whisker stimulation also significantly increased the CSD incidence, albeit less effectively (14.9 vs. 2.4%, p = 0.02). Knocking-down Na+/K+-ATPase (50% decrease in mRNA) lowered the CSD threshold in all mice tested with KCl but triggered CSDs in 14.3% and 16.7% of mice with photic and whisker stimulation, respectively. Confirming Na+/K+-ATPase hypofunction, extracellular K+ significantly rose during sensory stimulation after ouabain or shRNA treatment unlike controls. In line with the higher CSD susceptibility observed, K+ rise was more prominent after ouabain. To gain insight to preventive mechanisms reducing the probability of stimulus-evoked CSDs, we applied an A1-receptor antagonist (DPCPX) to the occipital cortex, because adenosine formed during stimulation from ATP can reduce CSD susceptibility. DPCPX induced spontaneous CSDs but only small-DC shifts along with suppression of EEG spikes during photic stimulation, suggesting that the inhibition co-activated with sensory stimulation could limit CSD ignition when K+ uptake was not sufficiently suppressed as with ouabain.ConclusionsNormal brain is well protected against CSD generation. For CSD to be ignited under physiological conditions, priming and predisposing factors are required as seen in migraine patients. Intense sensory stimulation has potential to trigger CSD when co-existing conditions bring extracellular K+ and glutamate concentrations over CSD-ignition threshold and stimulation-evoked inhibitory mechanisms are overcome.

Elevated photic response is followed by a rapid decay and depressed state in ictogenic networks.

The switch between nonseizure and seizure states involves profound alterations in network excitability and synchrony. In this study, we aimed to identify and compare features of neural excitability and dynamics across multiple zebrafish seizure and epilepsy models. Inspired by video-electroencephalographic recordings in patients, we developed a framework to study spontaneous and photically evoked neural and locomotor activity in zebrafish larvae, by combining high-throughput behavioral tracking and whole-brain in vivo two-photon calcium imaging. Our setup allowed us to dissect behavioral and physiological features that are divergent or convergent across multiple models. We observed that spontaneous locomotor and neural activity exhibit great diversity across models. Nonetheless, during photic stimulation, hyperexcitability and rapid response dynamics were well conserved across multiple models, highlighting the reliability of photically evoked activity for high-throughput assays. Intriguingly, in several models, we observed that the initial elevated photic response is often followed by rapid decay of neural activity and a prominent depressed state. Elevated photic response and following depressed state in seizure-prone networks are significantly reduced by the antiseizure medication valproic acid. Finally, rapid decay and depression of neural activity following photic stimulation temporally overlap with slow recruitment of astroglial calcium signals that are enhanced in seizure-prone networks. We argue that fast decay of neural activity and depressed states following photic response are likely due to homeostatic mechanisms triggered by excessive neural activity. An improved understanding of the interplay between elevated and depressed excitability states might suggest tailored epilepsy therapies.

Intensity dependence of sub-harmonics in cortical response to photic stimulation

Objective. Periodic photic stimulation of human volunteers at 10 Hz is known to entrain their electroencephalography (EEG) signals. This entrainment manifests as an increment in power at 10, 20, 30 Hz. We observed that this entrainment is accompanied by the emergence of sub-harmonics, but only at specific frequencies and higher intensities of the stimulating signal. Thereafter, we describe our results and explain them using the physiologically inspired Jansen and Rit neural mass model (NMM). Approach. Four human volunteers were separately exposed to both high and low intensity 10 Hz and 6 Hz stimulation. A total of four experiments per subject were therefore performed. Simulations and bifurcation analysis of the NMM were carried out and compared with the experimental findings. Main results. High intensity 10 Hz stimulation led to an increment in power at 5 Hz across all the four subjects. No increment of power was observed with low intensity stimulation. However, when the same protocol was repeated with a 6 Hz photic stimulation, neither high nor low intensity stimulation were found to cause a discernible change in power at 3 Hz. We found that the NMM was able to recapitulate these results. A further numerical analysis indicated that this arises from the underlying bifurcation structure of the NMM. Significance. The excellent match between theory and experiment suggest that the bifurcation properties of the NMM are mirroring similar features possessed by the actual neural masses producing the EEG dynamics. NMMs could thus be valuable for understanding properties and pathologies of EEG dynamics, and may contribute to the engineering of brain–computer interface technologies.

Electroencephalogram Detection for Insomnia Patients: A Preliminary Study

Measurement of insomnia is currently generally carried out by medical practitioners by looking at the patient's condition accompanied by symptoms that refer to insomnia. In contrast, minimal quantitative measurements were found. This study proposes an alternative measurement with the acquisition of brainwave activity through electroencephalogram (EEG) in identifying sleep disorders. Insomnia is a common sleep disorder that can make it difficult to fall asleep difficult to stay asleep, or cause waking up too early and not being able to go back to sleep. Insomnia not only weakens energy levels and moods, but also a person's health, performance, and quality of life. This sleep disorder appears due to several factors, such as anxiety, stress, depression, bipolar disorder, or trauma. Photic stimulation is given as an attempt to find a person's body's response to light. Late adolescents with insomnia symptoms with an age range of 17-25 years were included as respondents, had previously been given a simulation test related to the treatment of sleep disorders, and identified severe, moderate, and mild insomnia. Acquisition using Narosky Mindwave Mobile 2 with the electrode in forehead position, Fp1. This study compares several types of insomnia data acquisition from previous studies and obtains patterns of insomniacs based on photic stimulation.

Aberrant visual-related networks in familial cortical myoclonic tremor with epilepsy

IntroductionIn familial cortical myoclonic tremor with epilepsy, photic stimulation can trigger visual symptoms and induce a photoparoxysmal response, or photosensitivity, on electroencephalography. However, the mechanism is poorly understood. In this study, we aimed to explore the neuroimaging changes related to visual symptoms and photosensitivity in genetically confirmed familial cortical myoclonic tremor with epilepsy type 1. MethodsResting-state functional magnetic resonance imaging and electroencephalography data were collected from 31 patients carrying the heterozygous pathogenic intronic pentanucleotide (TTTCA)n insertion in the sterile alpha motif domain-containing 12 gene and from 52 age- and sex-matched healthy controls. Results(1) Both regional homogeneity and degree centrality values in the bilateral calcarine sulcus were significantly increased in patients compared with healthy controls. (2) When the calcarine sulcus area with increased regional homogeneity was taken as a seed, increased functional connectivity values were observed in the right precentral gyrus, while decreased functional connectivity values were observed in the right superior frontal gyrus and right inferior parietal lobule. (3) Independent component analysis showed increased connectivity in the left calcarine sulcus inside the medial visual network. (4) Correlation analysis revealed a significant positive correlation between regional homogeneity values and frequency of seizure, and photoparoxysmal response grades were positively correlated with the severity of cortical tremor and duration of epilepsy. ConclusionThese findings provide strong evidence for the interpretation of visual symptoms and photosensitivity in familial cortical myoclonic tremor with epilepsy. We speculate that functional changes in the primary visual cortex may be an imaging biomarker for the disease.

Photo-Dependent Reflex Seizures-A Scoping Review with Proposal of Classification.

Children and adolescents are the largest at-risk group for the appearance of reflex seizures or epilepsy syndromes with a photoparoxysmal response. The aim of this study was to present an overview of the literature regarding photo-dependent reflex seizures. Epilepsy with seizures provoked by intermittent light stimulation is a distinct group of epilepsies; therefore, we focused on reflex seizures provoked by different factors whose common feature is the patient’s response to intermittent photic stimulation. A qualitative search of PubMed/MEDLINE, Scopus, EBSCO, and Cochrane Library electronic databases for selected terms was carried out for scientific articles published up to May 2020 outlining the outcomes of control, observational, and case studies. This scoping review was developed and followed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. The review of the qualitative evidence for the synthesis of photosensitive epilepsy allowed us to distinguish the following categories: light-induced seizures and light-deprived seizures. Differentiating between intermittent photic stimulation-related epilepsy syndromes and seizures is essential in order to determine the length of appropriate treatment. Photo-dependent reflex seizures make up the majority of this type of disorder among reflex seizures. Since there are many seizures provoking factors in the world around us, it is important to distinguish amongst them in order to be able to protect the patient exposed to this factor. It is recommended that the photostimulation procedure be performed during a routine electroencephalogram study.

A Preliminary Study on Photic Driving in the Electroencephalogram of Children with Autism across a Wide Cognitive and Behavioral Range

Intermittent photic stimulation (IPS) is a useful technique in electroencephalography (EEG) to investigate the neurophysiological anomalies of brain activity. Although not an active task, IPS has also been explored in ASD; it is thought to capture local potential oscillators at specific frequencies and perhaps tap into rhythmic activity in a way that general resting-state recordings cannot. Previous studies suggest that individuals with ASD showed photic driving reactivity predominantly at lower frequencies of stimulation. In our study we used IPS to measure rhythmic oscillatory activity in a sample of 81 ASD children. We found a significant correlation linking ASD children with photic driving activation only at low frequencies (δθ band) and increased severity of “restricted behavior”. This suggests that ASD children with higher severity of restricted behaviors could have a hypersynchronous θ power and an impaired resonance synchronization at middle-ranged frequencies (α). Furthermore, we found some evidence of hemispherical oscillatory asymmetry linked particularly to behavioral impairments. This result is in line with the EEG pattern model indicating a “U-shaped profile” of electrophysiological power alterations with excess power in low- and high-frequency bands and a reduction of power in the middle-ranged frequencies. IPS technique in electroencephalography is confirmed to reveal EEG biomarkers in autistic children, with a focus on spectral power, coherence, and hemisphere asymmetries.

P.073 Diagnostic utility of specific abnormal EEG patterns in children

Background: CTS and PPR are common EEG findings that are classically associated with CECTS and GGE respectively. PPD and sleep spindles are physiologic phenomenon that occur in respond to intermittent photic stimulation and sleep respectively. Methods: We reviewed EEG studies with CTS, PPR, asymmetric PPD, or asymmetric sleep spindles. For CTS, we determined sensitivity, specificity, PPV and NPV for a diagnosis of CECTS. For PPR, we determined the same diagnostic outcome measures for a diagnosis of GGE or JME. For each of asymmetric PPD and asymmetric sleep spindles, we determined the same diagnostic outcome measures for the presence of a structural abnormality on brain MRI. Results: CTS had 83% specificity and 75% PPV in children with normal neurological examination. PPR had high specificity of 92% and NPV 92% for GGE; for JME, PPR also had high sensitivity (92%). Asymmetric PPD had low sensitivity for structural brain abnormalities (17%), with specificity 80%. In contrast, asymmetric sleep spindles had higher sensitivity and specificity, 44% and 97%, respectively. Conclusions: CTS are seen with CECTS and other conditions. PPR is highly indicative of a GGE, though may be seen other conditions. Relative attenuation of sleep spindles is a more reliable indicator of structural brain malformation than asymmetric PPD.

A Computational Biomarker of Photosensitive Epilepsy from Interictal EEG

People with photosensitive epilepsy (PSE) are prone to seizures elicited by visual stimuli. The possibility of inducing epileptiform activity in a reliable way makes PSE a useful model to understand epilepsy, with potential applications for the development of new diagnostic methods and new treatments for epilepsy. A relationship has been demonstrated between PSE and both occipital and more widespread cortical hyperexcitability using various types of stimulation. Here we aimed to test whether hyperexcitability could be inferred from resting interictal electroencephalographic (EEG) data without stimulation. We considered a cohort of 46 individuals with idiopathic generalized epilepsy who underwent EEG during intermittent photic stimulation: 26 had a photoparoxysmal response (PPR), the PPR group, and 20 did not, the non-PPR group. For each individual, we computed functional networks from the resting EEG data before stimulation. We then placed a computer model of ictogenicity into the networks and simulated the propensity of the network to generate seizures in silico [the brain network ictogenicity (BNI)]. Furthermore, we computed the node ictogenicity (NI), a measure of how much each brain region contributes to the overall ictogenic propensity. We used the BNI and NI as proxies for testing widespread and occipital hyperexcitability, respectively. We found that the BNI was not higher in the PPR group relative to the non-PPR group. However, we observed that the (right) occipital NI was significantly higher in the PPR group relative to the non-PPR group. Other regions did not have significant differences in NI values between groups.

P378. Blue Light Photic Stimulator for Augmentation of Electroconvulsive Therapy

Photic stimulation has been used long before to provoke seizures during diagnostic EEG and it as considered as an alternative for electroconvulsive therapy with combination of sub convulsive metrazol treatment in 1940s (1). As 5 % of the patients may not have adequate seizures in current max ECT stimulus dose and increased stimulus dose is associated with more memory side effects, we aimed to design an experimental prototype of photic stimulator to use just before ECT treatment.

P 62 Does Photosensitivity matter? Clinical relevance

Photosensitivity is a phenomenon which is defined more precisely by intermittent photic stimulation that elicits a photoparoxysmal response (PPR). Data about the prognosis of people with PPR are scarce. Pure PPR mostly appears in later childhood and adolescence, has a female preponderance and disappears in many people during the third decade. However, whether or not it disappears is mainly dependent whether or not it is associated with an underlying disease with a benign spontaneous course like Rolandic epilepsy, a good therapy prognosis like juvenile myoclonic epilepsy (which is the epilepsy syndrome with the highest proportion of PPR) or a bad prognosis like progressive myoclonic epilepsies. If PPR persists in epilepsy patients stimulus avoidance and suppression is an appropriate additional approach beyond antiepileptic drug treatment. A typical case is reported. Keywords photosensitivity photoparoxysmal response prognosis

Brain Dynamics in Response to Intermittent Photic Stimulation in Epilepsy

Purpose: Routine electroencephalogram (EEG) examinations uses intermittent photic stimulation (IPS) for investigation of the visual cortex EEG responses during resting time. This study aimed to discover brain dynamics effects of IPS in 28 generalized epilepsy patients and 28 healthy subjects. Methodology: Signal processing techniques were used in feature extraction by Fast Fourier transform (FFT), feature dimension reduction by t-test (significant, p&lt;0.05) and classification by nearest neighbor (k-NN) and support vector machine (SVM). Results: The epilepsy group had higher level of amplitude in Theta waves compared to the healthy group. The Alpha waves in the resting time and for all IPS frequencies were observed with lower level of amplitude in healthy subjects compared to the epilepsy group. The k-NN (85.7% accuracy) classifier had the best discrimination of epilepsy from healthy group for resting time versus during IPS at 18 Hz IPS. However, using SVM (75.0% accuracy), IPS at 25 Hz yielded the best discrimination between resting time versus IPS in epilepsy where the healthy group responded similarly in all IPS frequencies. Conclusions: This study shows that IPS at 18 Hz and 25 Hz are suitable IPS frequencies for k-NN and SVM, respectively, to discriminate non-photosensitive generalized epilepsy from normal subjects during interictal.

Electrographic Features of Epilepsy With Eyelid Myoclonia With Photoparoxysmal Responses.

Epilepsy with eyelid myoclonia (EMA) is characterized by eyelid myoclonia, eyelid closure sensitivity, and photosensitivity. EEG may manifest with frontal-predominant (FPEDs) or occipital-predominant epileptiform discharges (OPEDs). Data on clinical and electrographic features of these two subtypes are lacking. The purpose of our research was to look at baseline electroclinical features of EMA subtypes and to study electrographic findings of patients with EMA during intermittent photic stimulation (IPS). We retrospectively identified all patients who had photoparoxysmal responses on EEGs performed at Cleveland clinic between January 01, 2012, and December 31, 2019. Patients who met diagnostic criteria for EMA were studied further. Of the 249 patients with photoparoxysmal responses, 70 (28.1%) had EMA (62 [88.6%] female; the mean age of epilepsy onset: 7.0 ± 7.9 years). Patients with EMA had either FPEDs or OPEDs. Eleven patients with EMA (15.7%) had seizures (4 absence, 5 myoclonic and 2 bilateral tonic-clonic) during IPS. Patients with OPEDs were more likely to have drug-resistant epilepsy; occipital focal IEDs and other focal IEDs (other than frontal/occipital) on baseline EEG; and generalized IEDs with occipital predominance, generalized IEDs with no predominance, or focal IEDs during IPS. Predictors of seizure occurrence during photic stimulation included the presence of focal occipital IEDs on baseline EEG, generalized IEDs with frontal predominance during IPS, and photoparoxysmal response outlasting the stimulus. Our study provides evidence that EMA has two distinct subtypes, which differ in clinical characteristics, baseline EEG, and EEG during photic stimulation. We highlight diagnostic and prognostic implications of these findings. Our study also details EEG characteristics of patients with EMA during IPS.

Neurophysiological Findings in Neuronal Ceroid Lipofuscinoses.

Neuronal ceroid lipofuscinoses (NCLs) are a heterogeneous group of neurodegenerative diseases, characterized by progressive cerebral atrophy due to lysosomal storage disorder. Common clinical features include epileptic seizures, progressive cognitive and motor decline, and visual failure, which occur over different time courses according to subtypes. During the latest years, many advances have been done in the field of targeted treatments, and in the next future, gene therapies and enzyme replacement treatments may be available for several NCL variants. Considering that there is rapid disease progression in NCLs, an early diagnosis is crucial, and neurophysiological features might have a key role for this purpose. Across the different subtypes of NCLs, electroencephalogram (EEG) is characterized by a progressive deterioration of cerebral activity with slowing of background activity and disappearance of spindles during sleep. Some types of heterogeneous abnormalities, diffuse or focal, prevalent over temporal and occipital regions, are described in many NCL variants. Photoparoxysmal response to low-frequency intermittent photic stimulation (IPS) is a typical EEG finding, mostly described in CLN2, CLN5, and CLN6 diseases. Visual evoked potentials (VEPs) allow to monitor the visual functions, and the lack of response at electroretinogram (ERG) reflects retinal neurodegeneration. Taken together, EEG, VEPs, and ERG may represent essential tools toward an early diagnosis of NCLs.

Virtual reality and machine learning in the automatic photoparoxysmal response detection

Photosensitivity, in relation to epilepsy, is a genetically determined condition in which patients have epileptic seizures of different severity provoked by visual stimuli. It can be diagnosed by detecting epileptiform discharges in their electroencephalogram (EEG), known as photoparoxysmal responses (PPR). The most accepted PPR detection method—a manual method—considered as the standard one, consists in submitting the subject to intermittent photic stimulation (IPS), i.e. a flashing light stimulation at increasing and decreasing flickering frequencies in a hospital room under controlled ambient conditions, while at the same time recording her/his brain response by means of EEG signals. This research focuses on introducing virtual reality (VR) in this context, adding, to the conventional infrastructure a more flexible one that can be programmed and that will allow developing a much wider and richer set of experiments in order to detect neurological illnesses, and to study subjects’ behaviours automatically. The loop includes the subject, the VR device, the EEG infrastructure and a computer to analyse and monitor the EEG signal and, in some cases, provide feedback to the VR. As will be shown, AI modelling will be needed in the automatic detection of PPR, but it would also be used in extending the functionality of this system with more advanced features. This system is currently in study with subjects at Burgos University Hospital, Spain.

Gratifying Gizmos for Research and Clinical MEG.

Experimental designs are of utmost importance in neuroimaging. Experimental repertoire needs to be designed with the understanding of physiology, clinical feasibility, and constraints posed by a particular neuroimaging method. Innovations in introducing natural, ecologically-relevant stimuli, with successful collaboration across disciplines, correct timing, and a bit of luck may cultivate novel experiments, new discoveries, and open pathways to new clinical practices. Here I introduce some gizmos that I have initiated in magnetoencephalography (MEG) and applied with my collaborators in my home laboratory and in several other laboratories. These gizmos have been applied to address neuronal correlates of audiotactile interactions, tactile sense, active and passive movements, speech processing, and intermittent photic stimulation (IPS) in humans. This review also includes additional notes on the ideas behind the gizmos, their evolution, and results obtained.

Successful use of perampanel in GABRA1-related myoclonic epilepsy with photosensitivity.

Pathogenic variants in gamma-aminobutyric acid type A receptor subunit alpha1 (GABRA1) is a protein coding gene that has been associated with a broad phenotypic spectrum of epilepsies. These have ranged from mild generalized forms to early-onset severe epileptic encephalopathies. Both in mild and in severe forms, tonic-clonic and myoclonic seizures with generalized spike and wave discharges and photoparoxysmal responses are common clinical manifestations. We present the case of a 14-year-old girl referred to our clinic with uncontrolled epilepsy. She was found to carry a heterozygous variant (c.335G>A) in GABRA1, already described in the literature and classified as "pathogenic" according to ACMG guidelines. The patient showed severe drug resistance with seizures often triggered by photic stimulation. The introduction of perampanel therapy led to overall reduction of the focal and generalized myoclonic seizures and complete clinical control of the light-triggered seizures. To our knowledge this is the first report of perampanel efficacy in photosensitive epilepsy, and in particular in the presence of a GABRA1 variant. New evidence is needed to confirm our findings in this case.

Contribution of intermittent photic stimulation to routine EEG

ObjectiveIntermittent photic stimulation (IPS) is an activation procedure performed during electroencephalography (EEG) to detect photosensitive patients. This procedure is recommended in routine EEGs but the benefit of IPS in the general population is not clearly ascertained. MethodsWe retrospectively analyzed 7683 EEGs of patients referred for a routine EEG to the Clinical Physiology Department of Lariboisière hospital, mainly from the emergency ward and the department of neurology, not specifically involved in epilepsy. All EEGs were performed with a standardized protocol. Photic driving response, photomyoclonic response and photoparoxysmal response (PPR) were specifically collected. A correlation analysis was performed between the response induced by IPS, demographical and clinical data, and current treatment or recreational drug use. ResultsMedian age was 56.4 years (41.7-71.2); 3,042 (39.6%) of patients were female; 1,208 patients (15.7%) had a past medical history of epilepsy. Photic driving response occurred in 67 EEGs (0.9%), and PPR in 6 EEGs (0.1%), all with a known history of epilepsy. Thus 0.5% (6/1,208) of epilepsy patients had a PPR. Photomyoclonic responses were not observed. Juvenile myoclonic epilepsy was the only factor associated with the presence of PPR (RR=75.26 [11.82-479.21]). PPR was not associated with clinical symptoms or seizures. There was no correlation with the type of treatment or recreational drug use. ConclusionsOur results confirm that responses to IPS are rare in adult patients and especially PPR. Moreover, all patients with a PPR had a known previous history of epilepsy. These results question the benefit of IPS in adult patients with no history of epilepsy.