EEG evaluation of fixation-off sensitivity in eyelid myoclonia with absences

A comprehensive narrative review of epilepsy with eyelid myoclonia

Epilepsy with eyelid myoclonia (EEM) is a generalized epilepsy syndrome with childhood-onset and 2:1 female predominance that consists of: 1. eyelid myoclonia with or without absence seizures, 2. eye closure induced seizures or EEG paroxysms, 3. clinical or EEG photosensitivity. While eyelid myoclonia is the disease hallmark, other seizure types, including absence seizures and generalized tonic-clonic seizures, may be present. It is thought to have a genetic etiology, and around one-third of patients may have a positive family history of epilepsy. Recently, specific genetic mutations have been recognized in a minority patients, including in SYNGAP1, NEXMIF, RORB, and CHD2 genes. There are no randomized controlled trials in EEM, and the management literature is largely restricted to small retrospective studies. Broad-spectrum antiseizure medications such as valproate, levetiracetam, lamotrigine, and benzodiazepines are typically used. Seizures typically persist into adulthood, and drug-resistant epilepsy is reported in over 50%.

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.

The clinical significance and electrophysiologic findings of fixation-off and closure of the eyes sensitivity: Data from a prospective unselected population

PURPOSE

Electroencephalography (EEG) findings related to the eye-closing motion can be defined in two ways: 'sensitivity to eyes closed' (SEC) and 'eye closure sensitivity (ECS).' Fixation-off sensitivity (FOS) is a different phenomenon induced by the elimination of central vision/fixation. The purpose of our study was to determine the frequencies of SEC, ESC, and FOS, and to analyze the relationship between eyes closure and the fixation-off phenomenon and clinical importance in an unselected population.

METHODS

We prospectively evaluated 200 routine interictal EEGs by adding a standardized FOS examination protocol between June and September 2015. Goggles covered with semitransparent tape were used to evaluate FOS. We determined SEC when the epileptiform discharges appeared during eye closure and continued during the eye closed state, whereas ECS was defined as transient epileptic abnormalities following the closure of the eyes lasting for 1-4 sec. The patients were evaluated in terms of demographic characteristics, clinical features, and the relationship between SEC, ECS, and FOS.

RESULTS

We detected SEC in 9 (4.4 %) and ECS in 11 (5.4 %) patients. FOS was detected in four (44.4 %) of the patients who showed SEC, all of whom had occipital epileptiform discharges. A statistically significant correlation was found between FOS and treatment resistance in the SEC group (p < 0.001). In logistic regression analysis, occipital lobe epilepsy (p < 0.001) and age under 20 years (p = 0.004) were found as risk factors for SEC. Another interesting finding was the suppression of epileptic discharges with fixation-off in three of 11 patients with ECS.

CONCLUSIONS

According to the results of our study, FOS is related to treatment resistance. Therefore, FOS should be evaluated in patients with SEC.

Preliminary neurocognitive outcomes in Jeavons syndrome

Jeavons syndrome (JS, eyelid myoclonia with absences [EMA]) consists of a triad of symptoms including eyelid myoclonia that may be accompanied by absence seizures, eye closure-induced EEG paroxysms or seizures, and photosensitivity. The age of onset ranges between 2 and 14 years with symptoms peaking between 6 and 8 years of age. Though investigation of the clinical, EEG, and neurological features of JS has occurred, neurocognitive functioning has not been well-delineated despite suggestion that a subtype of the syndrome is characterized in part by cognitive impairment. The purpose of this study was to define neurocognitive functioning in a more detailed manner by examining global IQ and relevant neurocognitive domains (i.e., verbal and nonverbal reasoning, attention, executive functioning, memory) in pediatric patients. The sample (N=6, 4 females) ranged in age from 8 to 15 years (M=11, SD=2.82). All participants completed neuropsychological evaluations. Statistical analyses revealed performance that was below average on measures of global IQ, processing speed and rote, verbal learning coupled with average nonverbal reasoning, and sustained attention. There was also evidence of impaired higher-level verbal reasoning. While global IQ ranged from low average to borderline impaired, no participant could be accurately described as impaired or having intellectual disability (ID) given the consistently average performance noted on some higher-order tasks including nonverbal reasoning.

Coexistence of fixation-off sensitivity and inverted fixation-off sensitivity in a female child with Panayiotopoulos syndrome: Video-electroencephalography documentation

Fixation-off sensitivity (FOS) is a rare phenomenon elicited by elimination of central vision and fixation, which even in the presence of light induces occipital paroxysms or generalized paroxysmal discharges. It is most commonly encountered in patients with idiopathic childhood occipital epilepsies but may also be observed in cases of symptomatic focal and generalized epilepsies. We describe a female Emirati child with Panayiotopoulos syndrome who exhibited FOS in addition to the reverse phenomenon called "inverted fixation-off sensitivity," in which the electroencephalographic discharges were suppressed by the absence of central vision or fixation and activated by central vision or fixation.

Eyelid myoclonia seizures in adults: An alternate look at the syndrome paradox

OBJECTIVES

Eyelid myoclonia (EM), without or with absences (EMA), is induced by eye closure (ECL)-associated generalized paroxysms of polyspikes and waves. Although considered as an epileptic syndrome, it has been listed as a type of seizure in the recent epilepsy classifications, perhaps because of its clinical heterogeneity. In this study, we aimed to specifically study the clinical and electroencephalogram (EEG) features and the prognosis of long-term followed-up adult patients with EMs and to determine common points between EMAs, idiopathic generalized epilepsies (IGEs), and symptomatic epilepsies.

METHODS

Between 1996 and November 2011, 61 adult patients with EMs with or without absences and bilateral EEG paroxysms were retrospectively enrolled in the study and followed up for 1-34 years (mean: 5.8 years).

RESULTS

According to patient history, seizure semiology, and EEG findings, we classified the patients having EM seizures into three main groups. In group 1 (n=31), all patients had prominent EMs with or without absences associated with upward rolling of eyeballs. The second group included 20 patients with EM seizures associated with generalized tonic-clonic seizures (GTCSs) and/or massive myoclonias. The third group of 7 patients had varying diagnosis of symptomatic epilepsies. In the first group with pure EMA, the diagnosis was more delayed than in the other groups (p=0.01). In the group with pure EMA, EMs continued in adulthood (p=0.00), and only 24% of patients were seizure-free, which was considered poor prognosis. On EEG, occipital (n=3) and frontal (n=4) focal discharges were found in the group with pure EMA. Interestingly, 2 patients with symptomatic epilepsy with frontal lesions also had EM seizures.

CONCLUSION

The patients with pure EMA have many similarities to patients with IGEs. We also demonstrated that EMs could be seen as a seizure type in symptomatic epilepsies. Eyelid myoclonia with absences meets the criteria for an epileptic syndrome with the early onset and long duration of seizures, special seizure type, specific EEG findings, possibility of cognitive impairment, precipitating modalities, photosensitivity, and presence of family history, suggesting a strong genetic background.

Quantification of Interictal Neuromagnetic Activity in Absence Epilepsy with Accumulated Source Imaging

Aberrant brain activity in childhood absence epilepsy (CAE) during seizures has been well recognized as synchronous 3 Hz spike-and-wave discharges on electroencephalography. However, brain activity from low- to very high-frequency ranges in subjects with CAE between seizures (interictal) has rarely been studied. Using a high-sampling rate magnetoencephalography (MEG) system, we studied ten subjects with clinically diagnosed but untreated CAE in comparison with age- and gender-matched controls. MEG data were recorded from all subjects during the resting state. MEG sources were assessed with accumulated source imaging, a new method optimized for localizing and quantifying spontaneous brain activity. MEG data were analyzed in nine frequency bands: delta (1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12-30 Hz), low-gamma (30-55 Hz), high-gamma (65-90 Hz), ripple (90-200 Hz), high-frequency oscillation (HFO, 200-1,000 Hz), and very high-frequency oscillation (VHFO, 1,000-2,000 Hz). MEG source imaging revealed that subjects with CAE had higher odds of interictal brain activity in 200-1,000 and 1,000-2,000 Hz in the parieto-occipito-temporal junction and the medial frontal cortices as compared with controls. The strength of the interictal brain activity in these regions was significantly elevated in the frequency bands of 90-200, 200-1,000 and 1,000-2,000 Hz for subjects with CAE as compared with controls. The results indicate that CAE has significantly aberrant brain activity between seizures that can be noninvasively detected. The measurements of high-frequency neuromagnetic oscillations may open a new window for investigating the cerebral mechanisms of interictal abnormalities in CAE.

The electroencephalogram of idiopathic generalized epilepsy

Idiopathic generalized epilepsy (IGE) is classified into several subsyndromes based on clinical and electroencephalography (EEG) features. The EEG signature of IGE is bisynchronous, symmetric, and generalized spike-wave complex; although focal, irregular, and so called "fragments" of discharges are not uncommon. Other characteristic EEG features include polyspikes, polyspike-wave discharges, occipital intermittent rhythmic delta activity, and photoparoxysmal response. Both human and animal data suggest involvement of the thalamus and the cortex in the generation of spike-wave discharges in IGE. Circadian variations of generalized epileptiform discharges are well described, and these can be useful in diagnostic confirmation. Those discharges tend to occur more often after awakening and during cyclic alternating pattern phase-A of non-rapid eye movement sleep. Activation procedures such as hyperventilation, intermittent photic stimulation, eye closure, and fixation-off are useful techniques to increase the yield of both interictal and ictal EEG abnormalities. Although not in routine use, specific triggers such as pattern stimulation and cognitive tasks may also be of value in eliciting rare reflex seizure-related EEG abnormalities. Variations of EEG abnormalities are evident between different electroclinical syndromes. EEG is also affected by certain external as well as internal factors, which should be borne in mind when interpreting EEG studies in IGE.

Jeavons syndrome existing as occipital cortex initiating generalized epilepsy

PURPOSE

Jeavons syndrome (JS) is one of the underreported epileptic syndromes characterized by eyelid myoclonia (EM), eye closure-induced seizures/electroencephalography (EEG) paroxysms, and photosensitivity. JS has been proposed as idiopathic generalized epilepsy (IGE) because of normal posterior dominant background activity and paroxysmal generalized ictal epileptiform discharges (EDs). However, we noticed subtle occipital EDs preceding EM and interictal posterior EDs using digital video-EEG. We studied clinical and EEG findings in JS to determine the specific occipital lobe relation to this "eye closure-induced" reflex IGE.

METHODS

We identified 12 children who met the diagnostic criteria of JS from January 2004 to April 2009 at the Hospital for Sick Children, Toronto, Canada. All patients had EM captured by video-EEG. We reviewed and described ictal EEG patterns, interictal abnormalities, and demographics, clinical, and neuroimaging findings.

KEY FINDINGS

All patients but one were female (92%). Age at seizure onset ranged from 1.5 to 9 years, with a mean age of 4.9 years. Six patients (50%) were previously diagnosed as having absence epilepsy and 10 patients were on antiepileptic medications. All 12 patients had normal posterior dominant alpha rhythm, reactive to eye opening and closure. Spiky posterior alpha activity was noted with sustained eye closure in six patients (50%). Interictally, there were generalized EDs found in 10 patients (83%); four of them also had focal interictal EDs over the posterior head region. Eleven patients (92%) had evidence of focal posterior ictal EDs. EM and/or paroxysmal EDs were induced by photic stimulation in 9 (75%) and hyperventilation in 7 (58%).

SIGNIFICANCE

We observed two neurophysiologic findings in JS: (1) focal interictal EDs from posterior head region; and (2) predominant focal posterior ictal EDs preceding generalized EDs. Further clinical observations of seizures induced by eye closure, photic stimulation, and hyperventilation along with EEG paroxysms would raise the possibility of the occipital cortex initiating generalized epilepsy network involving the brainstem, and thalamocortical and transcortical pathways in JS.

Metabolic correlatives of brain activity in a FOS epilepsy patient

The correlation and the interactions between neuronal activity and underlying metabolic dynamics are still a matter of debate, especially in pathological conditions. This study reports findings obtained on a subject suffering from fixation-off sensitivity (FOS) epilepsy, exploited as a model system of triggerable anomalous electrical activity. Functional Magnetic Resonance Spectroscopy was used to investigate the metabolic response to visual spike-inducing stimuli in a single voxel placed in the temporo-occipital lobe of a FOS epilepsy patient. MRS measurements were additionally performed on a control group of five healthy volunteers. The FOS patient also underwent an EEG session with the same stimulus paradigm. Uniquely in the FOS patient, glutamate and glutamine concentration increased during the first 10 min of stimulation and then returned to baseline. On the other hand, FOS-induced epileptic activity (spiking) endured throughout all the stimulation epoch. The observed metabolic dynamics may be likely linked to a complex interplay between alterations of the metabolic pathways of glutamate and modulation of the neuronal activity.

Absence seizures: a review of recent reports with new concepts

Absence seizures with bilateral spike-wave (SW) complexes at 3Hz are divided into the childhood form, with onset at around 6 years of age, and the juvenile form, with onset usually at 12 years of age. These seizures typically last 9-12s and, at times, are activated by hyperventilation and occasionally by photic stimulation. Generalized tonic-clonic (GTC) seizures may also occur, especially in the juvenile form. There may be cognitive changes, in addition to linguistic and behavioral problems. Possible mechanisms for epileptogenesis may involve GABAergic systems, but especially T-calcium channels. The thalamus, especially the reticular nucleus, plays a major role, as does the frontal cortex, mainly the dorsolateral and orbital frontal areas, to the extent that some investigators have concluded that absence seizures are not truly generalized, but rather have selective cortical networks, mainly ventromesial frontal areas and the somatosensory cortex. The latter network is a departure from the more popular concept of a generalized epilepsy. Between the "centrencephalic" and "corticoreticular" theories, a "unified" theory is presented. Proposed genes include T-calcium channel gene CACNA1H, likely a susceptible gene in the Chinese Han population and a contributory gene in Caucasians. Electroencephalography has revealed an interictal increase in prefrontal activity, essential for the buildup of the ictal SW complexes maximal in that region. Infraslow activity can also be seen during ictal SW complexes. For treatment, counter to common belief, ethosuximide may not increase GTC seizures, as it reduces low-threshold T-calcium currents in thalamic neurons. Valproic acid and lamotrigine are also first-line medications. In addition, zonisamide and levetiracetam can be very helpful in absence epilepsy.

Inverted fixation-off sensitivity in atypical benign partial epilepsy

Fixation-off sensitivity is an electroencephalographic phenomenon characterized by spike-and-wave discharges that only occur when central vision and fixation are eliminated. It is especially seen in children with Panayiotopoulos-type, early-onset, benign childhood occipital epilepsy or Gastaut type, late-onset, childhood occipital epilepsy. It can also be seen in eyelid myoclonia with absences, in other idiopathic generalized epilepsies, and in asymptomatic children without epilepsy. We describe a boy with atypical, benign partial epilepsy of childhood who exhibited the reverse: epileptiform activity that was suppressed by the absence of central vision or fixation, and activated by central vision or fixation.

Unusual focal ictal pattern in children with eyelid myoclonia and absences

Eyelid myoclonia is a type of epileptic seizure characterized by marked jerking of the eyelids, often associated with jerky upward deviation of the eyeballs. It can be triggered by eye closure. The ictal electroencephalographic pattern of eyelid myoclonia consists of generalized polyspike waves at 3 to 6 Hz. Eyelid myoclonia can be a component of the clinical seizures seen with idiopathic, symptomatic, or cryptogenic generalized epilepsy. The objective of this study was to describe the unusual focal ictal electroencephalogram features of two patients with developmental delay and eyelid myoclonia. To the best of our knowledge, this unique electroencephalogram finding was not previously described.

Overlap cases of eyelid myoclonia with absences and juvenile myoclonic epilepsy

Eyelid myoclonia with absences (EMA) and juvenile myoclonic epilepsy (JME) are two separate epileptic syndromes included in the new classification of epilepsies and epileptic syndromes by ILAE in 2001. Both are idiopathic generalized epilepsies with their clinical onset in the first two decades. EMA is characterized by eyelid myoclonia associated with absences and photosensitivity. Self-induced seizures are frequently seen in EMA. It can be associated with mildly mental retardation and resistance to treatment. JME includes three types of generalized seizures: typical absences, myoclonic jerks and generalized tonic-clonic seizures. The myoclonic jerks occur almost exclusively on awakening, involve preferently the upper extremities, may rarely affect the lower extremities or the entire body. More severe attacks may be accompanied by a fall. The myoclonic jerks occur rarely in EMA. They are usually mild and are freqently restricted to the upper extremities. Generalized tonic-clonic seizures, photosensitivity and generalized polyspike-wave discharges provoked by eye closure are features of both epileptic syndromes. In this study, we describe four female patients with eyelid myoclonia associated with absences, myoclonic jerks causing falling down and rare generalized tonic-clonic seizures. All patients had good school performance and total seizure control under sodium valproate treatment. Their EEGs show generalized polyspike-wave discharges with a frequency of 3.5-6Hz always appearing a few seconds after eye closure and photoparoxysmal response. These patients show the characterictics of both epileptic syndromes. It is clinically important to make a syndromic diagnosis for an optimum advise on treatment, lifestyle restrictions and prognosis. In this study, we have gathered evidence that EMA and JME are dynamic syndromes that tend to evolve into one another.